WO2017188021A1 - Electrochemical element electrode and lithium ion secondary battery - Google Patents
Electrochemical element electrode and lithium ion secondary battery Download PDFInfo
- Publication number
- WO2017188021A1 WO2017188021A1 PCT/JP2017/015233 JP2017015233W WO2017188021A1 WO 2017188021 A1 WO2017188021 A1 WO 2017188021A1 JP 2017015233 W JP2017015233 W JP 2017015233W WO 2017188021 A1 WO2017188021 A1 WO 2017188021A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- current collector
- negative electrode
- positive electrode
- lithium ion
- Prior art date
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
- H01G11/66—Current collectors
- H01G11/70—Current collectors characterised by their structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
- H01M4/72—Grids
- H01M4/74—Meshes or woven material; Expanded metal
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M6/00—Primary cells; Manufacture thereof
- H01M6/02—Details
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Definitions
- the present invention relates to an electrode for an electrochemical element excellent in reliability and a lithium ion secondary battery having the electrode.
- lithium ion secondary batteries have high voltage and high capacity, there are great expectations for their development.
- such a high capacity negative electrode material has a large irreversible capacity, and a relatively large amount of Li released from the positive electrode by the initial charge of the battery and occluded in the high capacity negative electrode material is negative during the next discharge.
- the battery capacity could not be sufficiently increased due to the use of a high capacity negative electrode material.
- the positive electrode current collector and the negative electrode current collector having through-holes are used for various purposes other than the pre-doping as described above, for example, for the purpose of maintaining good properties of the electrode mixture layer. (Patent Document 2, etc.).
- an electrode mixture layer (a positive electrode mixture layer containing a positive electrode active material or a negative electrode mixture layer containing a negative electrode active material such as a high-capacity negative electrode material) is obtained using a current collector having a plurality of through holes.
- an electrode in the form of a tab is formed by a portion of the current collector that is exposed without being formed, or when a lithium ion secondary battery is formed using such an electrode, the current is collected at a specific portion of the electrode. It has been clarified by the present inventors that defects such as body breakage tend to occur.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide an electrode for an electrochemical element excellent in reliability and a lithium ion secondary battery having the electrode.
- the electrode for an electrochemical element of the present invention that can achieve the above object is used for the positive electrode or the negative electrode of an electrochemical element having a wound electrode body in which a positive electrode and a negative electrode are wound through a separator.
- the main body is a rectangle having a pair of short sides and a pair of long sides in a plan view, and the current collector has a plurality of through holes penetrating from one side to the other side.
- the plurality of through holes are regularly arranged, and a straight line connecting one through hole and the other through hole closest to the one through hole is parallel to the short side of the main body portion. It is characterized by not existing within the range of 0 ° ⁇ 20 ° from any direction.
- the lithium ion secondary battery of the present invention has a wound electrode body in which a positive electrode and a negative electrode are wound via a separator, and a non-aqueous electrolyte, and at least the positive electrode is the present invention.
- This is an electrode for an electrochemical element.
- an electrochemical element electrode having excellent reliability and a lithium ion secondary battery having the electrode.
- Electrode for electrochemical device of the present invention is used as a positive electrode or a negative electrode of an electrochemical element such as a lithium ion secondary battery, a lithium primary battery, or a capacitor.
- the electrode of the present invention includes a main body (electrode) having an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer) containing an electrode active material (positive electrode active material or negative electrode active material) on one side or both sides of a current collector. It has a mixture layer forming part) and is exposed to form a part of the current collector without forming an electrode mixture layer, and is used to electrically connect the part to other members of the electrochemical element. And a tab portion adapted to do so.
- FIG. 1 is a plan view schematically showing an example of the electrode (positive electrode) of the present invention.
- An electrode (positive electrode) 10 shown in FIG. 1 has an electrode mixture layer (positive electrode mixture layer) 11 on the surface of a current collector 12.
- a portion having the electrode mixture layer 11 is a main body portion (electrode mixture layer forming portion).
- the electrode 10 is provided with a tab portion 13 composed of an exposed portion where the electrode mixture layer is not formed on both surfaces of the current collector 12.
- the tab portion 13 is provided with a positive electrode tab 14.
- the main body of the electrode shown in FIG. 1 is rectangular in plan view (the shape of the main body described below means the shape in plan view unless otherwise specified).
- the electrode (positive electrode) of the present invention comprises a main body portion (electrode mixture layer forming portion) having an electrode mixture layer (positive electrode mixture layer) on the surface of a current collector, and a tab portion.
- the tab portion 13 is provided at the right end of the electrode (positive electrode) 10, but may be provided near the center of the electrode (positive electrode) 10.
- the main body portion of the electrode (positive electrode) may be divided into a plurality of locations (usually two locations) (the same applies when the electrode of the present invention is a negative electrode).
- the current collector according to the electrode of the present invention has a plurality of through holes penetrating from one side to the other side.
- These through holes of the current collector have, for example, an effect of increasing the adhesion between the electrode mixture layer and the current collector, and also serve as a passage for the non-aqueous electrolyte solution of the electrochemical element. Since the non-aqueous electrolyte can penetrate more uniformly throughout the mixture layer, it contributes to improving the characteristics of the electrochemical device.
- the through hole of the current collector according to the electrode of the present invention has Since the Li ion released from the Li supply source (non-aqueous electrolyte containing the released Li ion) becomes a path, it becomes possible to advance pre-doping more efficiently.
- FIG. 1 in order to avoid that drawing becomes complicated, the through-hole is not shown in the exposed part of the electrical power collector 12 which comprises the tab part 13.
- FIG. 1 in order to avoid that drawing becomes complicated, the through-hole is not shown in the exposed part of the electrical power collector 12 which comprises the tab part 13.
- the negative electrode expands greatly due to charging.
- the stress caused by the expansion of the negative electrode is applied to the negative electrode or the stress (pushing pressure) due to the expansion of the negative electrode. Pressure) is applied to the positive electrode.
- the present inventors have an influence on the arrangement of a plurality of through holes provided in the current collector. I found out. That is, in a current collector having a plurality of through holes, anisotropy occurs in the ease of tearing depending on the arrangement of these through holes, and the direction in which tearing is easier is parallel to the short side direction of the rectangular main body. When facing a direction that is close to parallel (that is, a direction that is parallel or close to parallel to the short-side direction of the rectangular current collector), cracks and breaks in the tab portion and the main body portion are likely to occur. . The reason is as follows.
- an electrode wound as in the present invention is conveyed while applying a tension in a long side direction in a manufacturing process, and a tab is installed and wound.
- the direction in which the current collector is easily torn is parallel or nearly parallel to the short side direction of the main body (parallel to the short side direction of the current collector). If it is oriented in a direction close to parallel), cracks are likely to occur in that direction of the electrode.
- the current collector does not tear during the manufacturing process, cracks may occur due to the residual strain of the current collector due to the expansion and contraction of the electrode during charge and discharge after the electrode is made an electrochemical element. There is.
- the part where the tab is welded to the current collector is susceptible to mechanical damage.
- a current collector having a plurality of through holes has a lower strength than that of a normal current collector having no through holes, and is more significantly damaged.
- the tab is welded and fixed to the exterior body. Therefore, if the electrode expands or contracts during charge and discharge and deforms, the tab and the current collector cannot follow the deformation. Cracks and breaks are likely to occur at the welded part. In particular, cracks and breaks tend to occur in a direction parallel to the short side direction of the rectangular main body (a direction parallel to the short side direction of the rectangular current collector).
- the arrangement of the plurality of through holes in the current collector used for the electrode is adjusted, and the direction in which the current collector is more easily torn is parallel and nearly parallel to the short side direction of the rectangular main body ( By preventing the rectangular current collector from facing the short side of the rectangular current collector), it is possible to prevent the occurrence of cracks and breaks in the tab part and body part as described above, and to improve reliability. It is possible to provide excellent electrodes.
- a plurality of through holes are regularly arranged, and a straight line connecting one through hole and another through hole closest to the through hole. Is not in the range of 0 ° ⁇ 20 ° from the direction parallel to the short side direction of the rectangular main body (the direction parallel to the short side direction of the rectangular current collector).
- FIG. 2 is a plan view schematically showing an example of the arrangement of the through holes in the current collector used for the electrode of the present invention.
- the current collector 12 shown in FIG. 2 has a plurality of through holes (indicated by circles in the figure) that penetrate from one side to the other side.
- each through hole is arranged in a specific pattern, specifically, in a staggered arrangement, and includes one through hole 120 and six surrounding holes. The distances from the through holes are all equal, and these six through holes correspond to the through hole closest to one through hole 120.
- straight lines connecting the through holes 120 and the six through holes closest to the through holes 120 are indicated by alternate long and short dash lines, but the current collector 12 is easily split along the direction indicated by the alternate long and short dashed lines. . Therefore, in the electrode of the present invention, when a current collector in which a plurality of through holes are arranged in the pattern shown in FIG. 2 is used, the direction indicated by the alternate long and short dash line in the figure is the short of the rectangular main body. The direction of the current collector is adjusted so that it does not exist within the range of 0 ° ⁇ 20 ° from the direction parallel to the side (the direction parallel to the short side of the rectangular current collector 12).
- the electrode when the electrode is manufactured, the electrochemical element is manufactured, and further, when the lithium ion secondary battery is used, the direction in which the tab portion and the main body portion of the electrode are likely to be cracked or broken easily breaks the current collector. Since the direction does not match, the reliability of the electrode can be improved.
- FIG. 3 and 4 are plan views schematically showing another example of the arrangement of the through holes in the current collector used for the electrode of the present invention.
- the current collector 12 shown in FIG. 3 is an example in which the through holes (indicated by circles in the figure) are arranged in a staggered arrangement. Since the interval between the upper and lower rows is narrower, a straight line (one-dot chain line in the figure) connecting one through hole 120 and the other through hole closest to the through hole 120 exists only in the vertical direction in the figure.
- the downward direction in the figure is a direction parallel to the short side of the rectangular main body (rectangular current collector). The direction of the current collector is adjusted so that it does not exist within the range of 0 ° ⁇ 20 ° from the direction parallel to the short side of the electric body 12.
- each through hole (indicated by a circle in the figure) is arranged linearly in the vertical direction and the horizontal direction in the figure, that is, arranged in a parallel arrangement (series arrangement).
- the interval between the upper and lower columns and the interval between the left and right columns in the drawing of the through hole are the same. Therefore, in the current collector shown in FIG. 4, straight lines (one-dot chain lines in the figure) connecting one through hole 120 and the other through hole closest to the through hole 120 exist in the vertical direction and the horizontal direction in the figure. is doing.
- the vertical direction and the horizontal direction in the figure are directions parallel to the short side of the rectangular main body ( The direction of the current collector is adjusted so that it does not exist within the range of 0 ° ⁇ 20 ° from the direction parallel to the short side of the rectangular current collector 12.
- the arrangement of the plurality of through holes in the current collector according to the electrode of the present invention is not limited to that shown in FIGS. 2 to 4, but is regularly arranged, more specifically, a specific pattern is repeated. As long as they are arranged.
- One type of repeated pattern may be used, or two or more types may be used.
- the average diameter of the through-holes in the current collector is such that when the through-holes are used as Li ions (non-aqueous electrolyte containing the same), the current distribution and the electrodes are improved by the through-holes. From the standpoint of ensuring better the effect of improving the adhesion with the mixture layer, it is preferably 1 ⁇ m or more, and more preferably 50 ⁇ m or more. In addition, since the strength of the current collector may decrease if the size of the through hole is too large, the average diameter of the through holes in the current collector is preferably 400 ⁇ m or less, and more preferably 350 ⁇ m or less. preferable.
- the average diameter of the through-holes in the current collector referred to in this specification is determined by observing the current collector with a scanning electron microscope (SEM) and measuring the rectangular shape of the electrode body portion of at least 20 through-holes in the field of view. This is a value obtained by measuring the diameter in a direction parallel to the short side of the main body and a direction perpendicular to the short side using a scale and calculating the average of these as the average diameter.
- SEM scanning electron microscope
- the porosity of the current collector having a plurality of through-holes can be determined from the viewpoint of improving the flow when the through-hole is a passage for Li ions (non-aqueous electrolyte containing the same), Is preferably 3% or more, and more preferably 8% or more from the viewpoint of better ensuring the effect of enhancing the adhesion between the current collector and the electrode mixture layer.
- the porosity of the current collector having a plurality of through holes is preferably 50% or less. More preferably, it is 45% or less.
- the distance between one through hole in the current collector having a plurality of through holes and the other through hole closest to the through hole is 30 to It is preferable that it is 1000 micrometers.
- the distance between the two through holes in this specification is calculated by observing the current collector with an SEM, measuring the distance between at least 40 sets of through holes in the field of view using a scale, and averaging these. It is the value.
- an electrode for a lithium ion secondary battery (a positive electrode for a lithium ion secondary battery or a negative electrode for a lithium ion secondary battery) which is a main embodiment of the electrode of the present invention.
- the electrode mixture layer will be described later in the section of a lithium ion secondary battery).
- the current collector is a punching metal made of aluminum or aluminum alloy, or an aluminum foil or aluminum alloy foil with through holes formed by etching. Can be used.
- the thickness of the current collector is preferably 6 to 30 ⁇ m.
- the current collector used is a punching metal made of copper or copper alloy, or a copper foil or copper alloy foil with through holes formed by etching. can do.
- the thickness of the current collector is preferably 6 to 30 ⁇ m.
- the lithium ion secondary battery of the present invention includes an electrode body (winding electrode body) in which a positive electrode and a negative electrode are wound via a separator, a non-aqueous electrolyte, And at least the positive electrode of the positive electrode and the negative electrode is the electrode of the present invention.
- the negative electrode is also preferably the electrode of the present invention, although depending on the aspect of the Li supply source other than the positive electrode.
- the electrode of the present invention can be used for the negative electrode as necessary.
- the negative electrode has the same configuration as that of the electrode of the present invention except that the current collector has a through-hole, and the current collector is regular.
- a straight line connecting a through hole and another through hole closest to the through hole is zero from a direction parallel to the short side direction of the rectangular main body.
- a negative electrode having the same configuration as that of the electrode of the present invention can be used except that it is within the range of ⁇ 20 °.
- the positive electrode mixture layer (the electrode mixture layer when the electrode of the present invention is used as a positive electrode) according to the positive electrode of the battery of the present invention contains a positive electrode active material (electrode active material).
- a positive electrode active material electrode active material
- a conductive additive and a binder are included.
- a metal oxide composed of a metal M (Co, Mn, Ni, Ti, Fe, etc.) other than Li and Li can be used. More specifically, lithium cobalt oxide such as LiCoO 2 ; lithium manganese oxide such as LiMnO 2 and Li 2 MnO 3 ; lithium nickel oxide such as LiNiO 2 ; lithium having a layered structure such as LiCo 1-x NiO 2 Containing complex oxide; lithium-containing complex oxide having a spinel structure such as LiMn 2 O 4 , Li 4/3 Ti 5/3 O 4 ; lithium-containing complex oxide having an olivine structure such as LiFePO 4 ; Examples include lithium-containing composite oxides such as oxides substituted with various elements as compositions.
- lithium cobalt oxide such as LiCoO 2 ; lithium manganese oxide such as LiMnO 2 and Li 2 MnO 3 ; lithium nickel oxide such as LiNiO 2 ; lithium having a layered structure such as LiCo 1-x NiO 2 Containing complex oxide; lithium-containing complex oxide
- the positive electrode mixture layer usually contains a conductive additive and a binder.
- a conductive additive such as carbon blacks such as graphite, acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black; carbon fiber; Conductive fibers such as fibers; carbon fluoride; metal powders such as aluminum; zinc oxide; conductive whiskers such as potassium titanate; conductive metal oxides such as titanium oxide; organic conductive materials such as polyphenylene derivatives ; Can also be used.
- PVDF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- SBR styrene butadiene rubber
- the thickness of the positive electrode mixture layer is preferably, for example, 10 to 100 ⁇ m per one side of the current collector.
- the amount of the positive electrode active material is preferably 65 to 98% by mass
- the amount of the binder is preferably 0.5 to 15% by mass
- the conductive auxiliary agent Is preferably 0.5 to 20% by mass.
- the positive electrode mixture layer is, for example, a paste-like or slurry-like positive electrode mixture in which a positive electrode active material, a binder, and a conductive auxiliary agent are dispersed in an organic solvent such as N-methyl-2-pyrrolidone (NMP) or a solvent such as water.
- NMP N-methyl-2-pyrrolidone
- Prepare an agent-containing composition (however, the binder may be dissolved in a solvent), apply it to one or both sides of the current collector, dry it, and then apply a press treatment such as calendering if necessary. It can form through the process to give.
- the negative electrode mixture layer (the electrode mixture layer when the electrode of the present invention is used as a negative electrode) according to the negative electrode of the battery of the present invention contains a negative electrode active material (electrode active material).
- a binder is included.
- Examples of the negative electrode active material include graphite [natural graphite such as scale-like graphite; artificial graphite obtained by graphitizing easily graphitized carbon such as pyrolytic carbons, mesophase carbon microbeads (MCMB) and carbon fibers at 2800 ° C. or more; ], Pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, MCMB, carbon fibers, activated carbon and other carbon materials; metals that can be alloyed with lithium (Si, Sn, etc.), and these These materials include metals (alloys, oxides, etc.), and one or more of these can be used.
- negative electrode active materials materials containing Si and O as constituent elements (provided that the atomic ratio x of O to Si is 0.5 ⁇ x ⁇ 1.5. x ”)) is preferred. Since SiO x is a so-called high capacity negative electrode material, the capacity of the electrode (negative electrode) can be increased by using this as a negative electrode active material.
- a negative electrode using a high-capacity negative electrode material such as SiO x greatly expands when the battery is charged, as described above, in a lithium ion secondary battery using such a negative electrode, a positive electrode or a negative electrode current collector is used.
- the current collector is easily broken as described above.
- the negative electrode contains a high-capacity negative electrode material such as SiO x as the negative electrode active material
- the positive electrode current collector is broken because the electrode of the present invention is used for the positive electrode.
- breakage of the negative electrode current collector can be suppressed well.
- the SiO x may contain Si microcrystal or amorphous phase.
- the atomic ratio of Si and O is a ratio including Si microcrystal or amorphous phase Si. That is, SiO x includes a structure in which Si (for example, microcrystalline Si) is dispersed in an amorphous SiO 2 matrix, and this amorphous SiO 2 is dispersed in the SiO 2 matrix. It is sufficient that the atomic ratio x satisfies 0.5 ⁇ x ⁇ 1.5 in combination with Si.
- x 1, so that the structural formula is represented by SiO.
- a material having such a structure for example, in X-ray diffraction analysis, a peak due to the presence of Si (microcrystalline Si) may not be observed, but when observed with a transmission electron microscope, the presence of fine Si Can be confirmed.
- SiO x is compounded with a carbon material.
- the surface of SiO x is preferably covered with a carbon material. Since SiO x has poor conductivity, when it is used as a negative electrode active material, from the viewpoint of securing good battery characteristics, a conductive material (conductive aid) is used, and SiO x and conductive material in the negative electrode are used. Therefore, it is necessary to form a good conductive network by mixing and dispersing with each other. If complexes complexed with carbon material SiO x, for example, simply than with a material obtained by mixing a conductive material such as SiO x and the carbon material, good conductive network in the negative electrode Formed.
- the composite in which the surface of SiO x is coated with a carbon material is further combined with a conductive material (carbon material or the like), a better conductive network can be formed in the negative electrode.
- a battery with higher capacity and more excellent battery characteristics (for example, charge / discharge cycle characteristics).
- the complex of the SiO x and the carbon material coated with a carbon material for example, like granules the mixture was further granulated with SiO x and the carbon material coated with a carbon material.
- SiO x whose surface is coated with a carbon material
- the surface of a composite (for example, a granulated body) of SiO x and a carbon material having a smaller specific resistance value is further coated with a carbon material.
- a carbon material for example, a granulated body
- Those can also be preferably used.
- a better conductive network can be formed. Therefore, in a battery having a negative electrode containing SiO x as a negative electrode active material, heavy load discharge characteristics, etc. The battery characteristics can be further improved.
- Preferred examples of the carbon material that can be used to form a composite with SiO x include carbon materials such as low crystalline carbon, carbon nanotubes, and vapor grown carbon fibers.
- the details of the carbon material include at least one selected from the group consisting of fibrous or coiled carbon materials, carbon black (including acetylene black and ketjen black), artificial graphite, graphitizable carbon, and non-graphitizable carbon.
- a seed material is preferred.
- a fibrous or coiled carbon material is preferable in that it easily forms a conductive network and has a large surface area.
- Carbon black (including acetylene black and ketjen black), graphitizable carbon, and non-graphitizable carbon have high electrical conductivity and high liquid retention, and even if SiO x particles expand and contract. This is preferable in that it has a property of easily maintaining contact with the particles.
- graphite can also be used as a carbon material related to a composite of SiO x and a carbon material.
- Graphite like carbon black, has high electrical conductivity and high liquid retention, and also has the property of easily maintaining contact with the SiO x particles even if they expand and contract. Therefore, it can be preferably used for forming a complex with SiO x .
- a fibrous carbon material is particularly preferable for use when the composite with SiO x is a granulated body. Fibrous carbon material can follow the expansion and contraction of SiO x with the charging and discharging of the battery due to the high shape is thin threadlike flexibility, also because bulk density is large, many and SiO x particles It is because it can have a junction.
- the fibrous carbon include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, and carbon nanotube, and any of these may be used.
- the fibrous carbon material can also be formed on the surface of the SiO x particles by, for example, a vapor phase method.
- the composite of SiO x and the carbon material may further have a material layer (a material layer containing non-graphitizable carbon) that covers the carbon material coating layer on the particle surface.
- SiO x relative to 100 parts by mass, a carbon material
- the amount is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more.
- SiO x relative to 100 parts by weight, the carbon material, and more preferably preferably not more than 50 parts by weight, more than 40 parts by weight.
- the composite of the SiO x and the carbon material can be obtained, for example, by the following method.
- a manufacturing method in the case of combining SiO x will be described.
- a dispersion liquid in which SiO x is dispersed in a dispersion medium is prepared, and sprayed and dried to produce composite particles including a plurality of particles.
- ethanol or the like can be used as the dispersion medium. It is appropriate to spray the dispersion liquid in an atmosphere of 50 to 300 ° C.
- similar composite particles can be produced also by a granulation method by a mechanical method using a vibration type or planetary type ball mill or rod mill.
- the SiO x in the case of manufacturing a granulated body with small carbon material resistivity value than SiO x is adding the carbon material in the dispersion liquid of SiO x are dispersed in a dispersion medium, the dispersion by using a liquid, by a similar method to the case of composite of SiO x may be a composite particle (granule). Further, by granulation process according to the similar mechanical method, it is possible to produce a granular material of the SiO x and the carbon material.
- SiO x particles SiO x composite particles or a granulated body of SiO x and a carbon material
- a carbon material for example, the SiO x particles and the hydrocarbon-based material
- the gas is heated in the gas phase, and carbon generated by pyrolysis of the hydrocarbon-based gas is deposited on the surface of the particles.
- the hydrocarbon-based gas spreads to every corner of the composite particle, and the surface of the particle and the pores in the surface are thin and contain a conductive carbon material. Since a uniform film (carbon material coating layer) can be formed, the SiO x particles can be imparted with good conductivity with a small amount of carbon material.
- the processing temperature (atmosphere temperature) of the vapor deposition (CVD) method varies depending on the type of hydrocarbon gas, but usually 600 to 1200 ° C. is appropriate. Among these, the temperature is preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the treatment temperature, the less the remaining impurities, and the formation of a coating layer containing carbon having high conductivity.
- liquid source of hydrocarbon gas toluene, benzene, xylene, mesitylene and the like can be used, but toluene that is easy to handle is particularly preferable.
- a hydrocarbon-based gas can be obtained by vaporizing them (for example, bubbling with nitrogen gas).
- methane gas, acetylene gas, etc. can also be used.
- SiO x particles SiO x composite particles or a granulated body of SiO x and a carbon material
- a carbon material by a vapor deposition (CVD) method
- a petroleum-based pitch or a coal-based pitch is used.
- At least one organic compound selected from the group consisting of a thermosetting resin and a condensate of naphthalene sulfonate and aldehydes is attached to a coating layer containing a carbon material, and then the organic compound is attached.
- the obtained particles may be fired.
- a dispersion liquid in which a SiO x particle (SiO x composite particle or a granulated body of SiO x and a carbon material) coated with a carbon material and the organic compound are dispersed in a dispersion medium is prepared, The dispersion is sprayed and dried to form particles coated with the organic compound, and the particles coated with the organic compound are fired.
- Isotropic pitch can be used as the pitch, and phenol resin, furan resin, furfural resin, or the like can be used as the thermosetting resin.
- phenol resin, furan resin, furfural resin, or the like can be used as the thermosetting resin.
- condensate of naphthalene sulfonate and aldehydes naphthalene sulfonic acid formaldehyde condensate can be used.
- a dispersion medium for dispersing the SiO x particles coated with the carbon material and the organic compound for example, water or alcohols (ethanol or the like) can be used. It is appropriate to spray the dispersion liquid in an atmosphere of 50 to 300 ° C.
- the firing temperature is usually 600 to 1200 ° C., preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the processing temperature, the less the remaining impurities, and the formation of a coating layer containing a high-quality carbon material with high conductivity. However, the processing temperature needs to be lower than the melting point of SiO x .
- SiO x When SiO x is used for the negative electrode active material, only SiO x may be used, or SiO x and the negative electrode active material may be used in combination. When SiO x and other negative electrode active materials are used in combination, among the various negative electrode active materials exemplified above, materials other than SiO x can be used as the other negative electrode active materials.
- graphite materials such as highly crystalline natural graphite and artificial graphite are preferable. When natural graphite is used, heat treatment may be performed at a higher temperature, artificial graphite fine particles (granular, flat, etc.) may be coated, or an organic substance such as a resin may be coated.
- the proportion of SiO x is 5% by mass or more from the viewpoint of increasing the capacity of the battery. It is preferably 10% by mass or more. Even when SiO x is used in a relatively large proportion as described above, since the positive electrode is the electrode of the present invention, it is possible to suppress breakage of the positive electrode current collector due to charge / discharge of the battery, When the electrode of the present invention is used as a negative electrode, breakage of the negative electrode current collector accompanying charging / discharging of the battery can be suppressed.
- the ratio of SiO x when the total of all the negative electrode active materials is 100% by mass may be 100% by mass.
- the charge / discharge cycle characteristics of the battery can be further enhanced by using a graphite material or the like in this case.
- the ratio of SiO x when the total of all the negative electrode active materials is 100% by mass. Is preferably 95% by mass or less, and more preferably 85% by mass or less.
- PVDF polyvinylpyrrolidone
- SBR carboxymethylcellulose
- PVP polyvinylpyrrolidone
- polyamideimide polyimide
- polyamide polyamide
- R in the formula (2) represents hydrogen or a methyl group
- M 1 represents an alkali metal element such as sodium, potassium, or lithium
- the negative electrode mixture layer can also contain a conductive additive.
- a conductive additive The same thing as what was illustrated previously as what can be used for a positive mix layer can be used for the conductive support agent which concerns on a negative mix layer.
- the thickness of the negative electrode mixture layer is preferably, for example, 10 to 100 ⁇ m per one side of the current collector.
- the amount of the negative electrode active material is preferably 85 to 95% by mass
- the amount of the binder is preferably 1 to 15% by mass
- a conductive assistant is used. In that case, the amount is preferably 1 to 10% by mass.
- the negative electrode mixture layer is, for example, a paste-like or slurry-like negative electrode mixture-containing composition in which a negative electrode active material and a binder, and further a conductive auxiliary agent, if necessary, are dispersed in an organic solvent such as NMP or a solvent such as water. (However, the binder may be dissolved in a solvent), and this is applied to one or both sides of the current collector, dried, and then subjected to pressing treatment such as calendering as necessary. It can be formed through.
- the lithium ion secondary battery of the present invention when a material having a high capacity and a large irreversible capacity such as SiO x is used for the negative electrode active material, it is released from the positive electrode (positive electrode active material) by the initial charge of the battery. Since relatively many of the Li ions cannot return to the positive electrode at the next discharge, there is a possibility that the capacity that the positive electrode originally has cannot be sufficiently extracted. Therefore, in the lithium ion secondary battery of the present invention, when a negative electrode active material having a large irreversible capacity such as SiO x is used, an Li supply source (Li for pre-doping) is used to fill the irreversible capacity during assembly. It is preferable to have a supply source) separately from the positive electrode.
- Li supply source Li for pre-doping
- Li supply source examples include Li metal foil and Li alloy foil (hereinafter collectively referred to as “Li foil”) and the like, and can be in contact with any part of the battery outer body (non-aqueous electrolyte solution).
- This Li supply source may be arranged at a certain point. Specifically, for example, a Li electrode formed by attaching a Li foil as a Li supply source to a metal foil such as a copper foil as a current collector can be used. By being electrically connected, the Li electrode Li foil functions as a Li supply source. Alternatively, a portion where the negative electrode mixture layer is not formed may be provided in a part of the current collector of the negative electrode (for example, a tab portion), and a Li supply source may be provided by attaching a Li foil to this portion.
- the amount of Li supply source to be introduced (the amount of Li contained in the Li supply source) is set to 0.
- the molar ratio Li / M of Li and metal M contained in the positive electrode active material is 0.9 to 1.05. It is preferable to make it.
- the Li supply source (the Li foil) is incorporated into the negative electrode active material in order to fill the irreversible capacity of the negative electrode active material.
- the battery is a battery in which a negative electrode active material is pre-doped by introducing a Li supply source.
- the molar ratio Li / M does not vary greatly after the discharge in the first charge / discharge. Therefore, in a battery that has passed the number of charge / discharge cycles of about 100 cycles or less, when the molar ratio Li / M satisfies the above value, a Li supply source is introduced at the time of battery assembly and the negative electrode active material is pre-doped. Can be considered.
- FIG. 5 is a plan view schematically showing an example of the electrode (negative electrode) of the present invention.
- the electrode (negative electrode) 20 shown in FIG. 5 has an electrode mixture layer (negative electrode mixture layer) 21 on the surface of the current collector 22.
- a portion having the electrode mixture layer 21 (shown with dots in the drawing) is a main body portion.
- the electrode (negative electrode) 20 is provided with a tab portion 23 formed of an exposed portion where the electrode mixture layer is not formed on both surfaces of the current collector 22.
- the tab portion 23 is provided with a negative electrode tab 24 and a Li supply source 25. Note that the electrode main body shown in FIG. 5 is rectangular in plan view.
- the electrode (negative electrode) 20 of the present invention has a main body portion having an electrode mixture layer (negative electrode mixture layer) 21 on the surface of a current collector 22 and a tab portion.
- the tab portion 23 is provided at the right end of the electrode (negative electrode) 20, but may be provided near the center of the electrode (negative electrode) 20.
- a porous film composed of a resin such as polyolefin, polyester, polyimide, polyamide, polyurethane can be used.
- a resin such as polyolefin, polyester, polyimide, polyamide, polyurethane
- polyolefin is used. It is preferred to use a porous membrane made of
- polystyrene resin examples include polyethylene (PE) such as low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene; polypropylene (PP); etc., and only one of these may be used. You may use together.
- PE polyethylene
- PP polypropylene
- a porous film using two or more kinds of polyolefin for example, a porous film having a three-layer structure in which a PP layer is laminated on a PP layer via a PE layer can be mentioned.
- polyolefins those having a melting point, that is, a melting temperature measured by DSC of 80 to 150 ° C., in accordance with JIS K 7121 are preferably used.
- a porous film containing a polyolefin having such a melting point can be a separator having a shutdown characteristic starting temperature of 90 to 150 ° C. in which the polyolefin is softened and the pores of the separator are closed. By using the separator, it is possible to further improve the safety of the battery.
- porous membranes used in separators include ion-permeable porous membranes having a large number of pores formed by a conventionally known solvent extraction method, dry type or wet drawing method (generally used as battery separators). A microporous film) can be used.
- a laminated separator in which a heat-resistant porous layer containing a heat-resistant inorganic filler is formed on the surface of the porous film (microporous film) may be used.
- a stacked separator When such a stacked separator is used, the shrinkage of the separator is suppressed even when the temperature in the battery rises, and a short circuit due to contact between the positive electrode and the negative electrode can be suppressed. A high non-aqueous secondary battery can be obtained.
- boehmite As the inorganic filler to be contained in the heat-resistant porous layer, boehmite, alumina, silica, titanium oxide and the like are preferable, and one or more of these can be used.
- the heat-resistant porous layer preferably contains a binder for binding the inorganic fillers or bonding the heat-resistant porous layer and the microporous film.
- the binder includes an ethylene-vinyl acetate copolymer (EVA, having a structural unit derived from vinyl acetate of 20 to 35 mol%), an ethylene-acrylic acid copolymer such as an ethylene-ethyl acrylate copolymer, and a fluorine-based rubber.
- CMC carboxymethyl cellulose
- HEC hydroxyethyl cellulose
- PVA polyvinyl alcohol
- PVB polyvinyl butyral
- PVP polyvinyl pyrrolidone
- crosslinked acrylic resin polyurethane, epoxy resin, etc.
- the content of the inorganic filler in the heat-resistant porous layer is preferably 50% by volume or more in the entire volume of the components constituting the heat-resistant porous layer (in the entire volume excluding the pores), 70 It is more preferable that the volume is not less than volume%, and it is more preferable that the volume be not more than 99 volume% (the remainder may be the above binder).
- the thickness of the separator (a separator made of a microporous membrane made of polyolefin, or the laminated separator) is to reduce the occupancy of the battery internal volume of components that are not involved in the battery reaction and increase the amount of active material of the positive and negative electrodes From the viewpoint of increasing the design capacity and output density of the battery, it is preferably 30 ⁇ m or less, and more preferably 16 ⁇ m or less. However, from the viewpoint of sufficiently maintaining the strength of the separator, the thickness of the separator is preferably 5 ⁇ m or more, and more preferably 10 ⁇ m or more.
- the heat-resistant porous layer preferably has a thickness of 3 to 8 ⁇ m.
- the porosity of the heat resistant porous layer is preferably 40 to 70%.
- non-aqueous electrolyte solution for the non-aqueous electrolyte solution according to the battery of the present invention, a solution prepared by dissolving a lithium salt in the following non-aqueous solvent can be used.
- the solvent examples include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ⁇ -butyrolactone ( ⁇ - BL), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO), 1,3-dioxolane, formamide, dimethylformamide (DMF), dioxolane, acetonitrile, nitromethane Aprotic such as methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3-propane sultone
- the organic solvent can be
- the lithium salt according to the non-aqueous electrolyte solution for example, LiClO 4, LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2, At least selected from LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (n ⁇ 2), LiN (RfOSO 2 ) 2 [where Rf is a fluoroalkyl group] One type is mentioned.
- the concentration of these lithium salts in the non-aqueous electrolyte is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l.
- Additives such as dinitrile, 1,3-propane sultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene, and t-butylbenzene can be added as appropriate.
- non-aqueous electrolyte a gel (gel electrolyte) obtained by adding a known gelling agent such as a polymer can be used.
- the lithium ion secondary battery of the present invention may be a flat or cylindrical steel can or aluminum can used as an outer can, or may be a soft package battery using a metal-deposited laminated film as an outer package. it can.
- Example 1 Preparation of positive electrode> LiCoO 2 as a positive electrode active material: 96.5 parts by mass, NMP solution containing PVDF as a binder at a concentration of 10% by mass: 20 parts by mass, and acetylene black as a conductive auxiliary agent: 1.5 parts by mass
- NMP was added to adjust the viscosity to prepare a positive electrode mixture-containing paste.
- this paste is intermittently applied to both sides of a rectangular aluminum foil having a plurality of through-holes and having a thickness of 15 ⁇ m while applying tension in the long side direction of the main body portion, and then dried to obtain aluminum.
- a positive electrode mixture layer is formed on one or both sides of the foil, and press treatment is continuously performed while applying tension in the long side direction of the main body so that the coating film density of the mixture layer is 3.80 g / cm 3.
- the thickness of the positive electrode mixture layer was adjusted, and the main body was cut so that the short side direction was 52 mm and the long side direction was 705 mm.
- a positive electrode tab (made of aluminum) was welded to the tab portion where the aluminum foil was exposed to produce a positive electrode having the same structure as that shown in FIG. 1 except for the size of each component.
- the positive electrode current collector is provided with through holes having a hole diameter of 150 ⁇ m in a staggered arrangement shown in FIG. 2 (hereinafter referred to as “pattern A”), and the positive electrode current collector has a porosity of 17%.
- the distance between one through hole 120 and the six through holes closest to the through hole 120 is 400 ⁇ m.
- two diagonal lines in the figure are 30 ° from the direction parallel to the short side of the main body, respectively, It arrange
- the average particle diameter D50% is 22 .mu.m, with d 002 is 0.338 nm, the graphite BET specific surface area is 3.8m 2 / g A (graphite no surface coating with amorphous carbon), the average particle diameter D50% is 10 [mu] m, with d 002 is 0.336 nm, the graphite BET specific surface area is 3.9m2 / g B (graphite covering the surface of the mother particle made of graphite with amorphous carbon), SiO 47.5: 47.5 is a composite in which the surface is coated with carbon (average particle size 8 ⁇ m, the amount of carbon in the composite is 20 mass%, hereinafter referred to as “SiO / carbon composite”).
- a water-based negative electrode mixture-containing paste was prepared by mixing with water.
- the negative electrode mixture-containing paste has a thickness of 10 ⁇ m and has a thickness of 10 ⁇ m, and is continuously applied intermittently while applying tension to the long side direction of the main body on both sides of the rectangular copper foil.
- a 300 ⁇ m thick Li foil (for Li pre-doping to the negative electrode) was pressure-bonded to the exposed tab portion of the copper foil to produce a negative electrode having the same structure as that shown in FIG. 5 except for the size of each component. .
- the negative electrode current collector is provided with through holes having a hole diameter of 150 ⁇ m in the pattern A arrangement (however, in FIG. 5, the through holes are shown in the tab portion 23 which is the exposed portion of the current collector 22).
- the porosity of the negative electrode current collector is 17%, and the distance between one through hole 120 and the six through holes closest to it is 180 ⁇ m.
- two diagonal lines in the figure are 30 ° from the direction parallel to the short side of the main body, respectively, It arrange
- ⁇ Preparation of separator> Add 5 kg of ion-exchanged water and 0.5 kg of a dispersant (aqueous polycarboxylic acid ammonium salt, solid content concentration 40%) to 5 kg of secondary aggregate boehmite, and use a ball mill for 20 hours with an internal volume of 20 L and a rotation speed of 40 times / minute for 10 hours.
- a dispersion was prepared by crushing treatment. The treated dispersion was vacuum-dried at 120 ° C. and observed by SEM. As a result, the shape of boehmite was almost plate-like. Further, when the average particle diameter (D50%) of boehmite was measured with a refractive index of 1.65 using a laser scattering particle size distribution analyzer (“LA-920” manufactured by HORIBA), it was 1.0 ⁇ m.
- a dispersant aqueous polycarboxylic acid ammonium salt, solid content concentration 40%
- PE microporous separator for lithium ion secondary battery [Porous layer (I): thickness 8 ⁇ m, porosity 40%, average pore diameter 0.02 ⁇ m, PE melting point 135 ° C.] on one side corona discharge treatment (discharge amount) 40 W ⁇ min / m 2 ) was applied, and the slurry a for forming the porous layer (II) was applied to the treated surface with a microgravure coater and dried to form a porous layer (II) to obtain a separator. The thickness of the porous layer (II) was adjusted to 4 ⁇ m. The boehmite content in the total volume of the constituent components of the porous layer (II) was 88% by volume.
- FIG. 6 is a plan view schematically showing the arrangement of the positive electrode, the negative electrode, and the separator when the wound electrode body is manufactured.
- FIG. 6 is for demonstrating arrangement
- the positive electrode 10 and the negative electrode 20 were overlapped via the separator 3 (however, the porous layer (II) of the separator 3 was overlapped so as to face the positive electrode 10).
- the Li supply source of the negative electrode is not shown.
- the positive electrode 10, the negative electrode 20, and the separator 3 were wound in a spiral shape with the short electrode end on the left side in FIG. 6 as the winding core side, and further crushed into a flat shape to obtain a wound electrode body.
- a perspective view schematically showing the obtained wound electrode body is shown in FIG.
- the positive electrode tab 14 and the negative electrode tab 24 of the wound electrode body 30 are located on the outermost peripheral side of the wound electrode body.
- the said winding electrode body is inserted in the said hollow of the aluminum laminate film of thickness: 0.15mm, width: 61mm, and height: 68mm which formed the hollow so that the said winding electrode body might be accommodated, and on it
- FIG. 8 is a plan view schematically showing a lithium ion secondary battery
- FIG. 9 is a cross-sectional view taken along the line II of FIG.
- a lithium ion secondary battery 100 includes a wound electrode body in which a positive electrode and a negative electrode are laminated via a separator in an aluminum laminate film outer package 101 composed of two aluminum laminate films and wound in a spiral shape. 30 and a non-aqueous electrolyte (not shown) are accommodated, and the aluminum laminate film exterior body 101 is sealed by heat-sealing the upper and lower aluminum laminate films at the outer peripheral portion thereof.
- FIG. 9 in order to avoid making the drawing complicated, each layer constituting the aluminum laminate film outer package 101 and the positive electrode, the negative electrode and the separator constituting the wound electrode body are shown separately. Absent.
- the positive electrode tab 14 of the positive electrode and the negative electrode tab 24 of the negative electrode of the wound electrode body 30 are drawn out to the outside of the aluminum laminate film exterior body 101 so that they can be connected to an external device or the like.
- Example 2 The positive electrode current collector is provided with through holes having a hole diameter of 150 ⁇ m in the staggered arrangement shown in FIG. 3 (hereinafter referred to as “pattern B”), and the porosity is 17%. The distance between the through hole closest to this is changed to 380 ⁇ m, and the positive electrode current collector is changed from the direction in which the straight line indicated by the alternate long and short dash line in the figure is parallel to the short side of the main body portion.
- a positive electrode for a battery was produced in the same manner as in Example 1 except that the positive electrode for a battery was arranged so as to be at 0 °. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Example 3 The positive electrode current collector is provided with through holes having a hole diameter of 150 ⁇ m in the parallel arrangement shown in FIG. 3 (hereinafter referred to as “pattern C”), and the porosity is 17%. The distance between the through hole closest to this is changed to 370 ⁇ m, and the two straight lines indicated by the alternate long and short dash line in the figure of this positive electrode current collector are parallel to the short side of the main body part, respectively.
- a positive electrode for a battery was produced in the same manner as in Example 1 except that it was disposed at 45 ° from the right direction. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Example 4 The positive electrode current collector is provided with through holes having a hole diameter of 150 ⁇ m arranged in the pattern A, the porosity is 35%, and the distance between one through hole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Example 1 except that the thickness was changed to 180 ⁇ m. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Example 5 The direction of the negative electrode current collector is such that one of the three straight lines shown in FIG. 2 is parallel to the short side of the main body, and the other two are the short sides of the main body.
- a negative electrode for a battery was produced in the same manner as in Example 1 except that it was arranged at 30 ° from a direction parallel to the negative electrode.
- the lithium ion secondary battery was produced like Example 1 except having used the said negative electrode for batteries.
- Example 6 The positive electrode current collector is provided with through holes having a hole diameter of 150 ⁇ m arranged in the pattern A, the porosity is 50%, and the distance between one through hole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Example 1 except that the thickness was changed to 100 ⁇ m. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Example 7 The positive electrode current collector is provided with through holes having a hole diameter of 450 ⁇ m arranged in the pattern A, the porosity is 25%, and the distance between one through hole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Example 1 except that the thickness was changed to 800 ⁇ m. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Comparative Example 1 As for the direction of the positive electrode current collector, one of the three straight lines shown in FIG. 2 is parallel to the short side of the main body, and the other two are the short sides of the main body.
- a positive electrode for a battery was produced in the same manner as in Example 1 except that it was arranged at 30 ° from a direction parallel to the positive electrode.
- the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Comparative Example 2 The positive electrode current collector is provided with through holes having a hole diameter of 350 ⁇ m arranged in the pattern A, the porosity is 17%, and the distance between one through hole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Comparative Example 1 except that the thickness was changed to 900 ⁇ m. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Comparative Example 3 A positive electrode for a battery was produced in the same manner as in Example 2 except that the direction of the positive electrode current collector was arranged so that the straight line indicated by the alternate long and short dash line in FIG. 3 was parallel to the short side of the main body. did. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Comparative Example 4 In the direction of the positive electrode current collector, one of the two straight lines shown in FIG. 4 is a direction parallel to the short side of the main body, and the other one is the short side of the main body.
- a positive electrode for a battery was produced in the same manner as in Example 3, except that it was disposed at 90 ° from a direction parallel to the positive electrode.
- the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
- Table 1 shows the configuration of the positive electrode current collector in each lithium ion secondary battery of Examples and Comparative Examples
- Table 2 shows the configuration of the negative electrode current collector
- Table 3 shows the evaluation results.
- the “angle” in Tables 1 and 2 is the angle from the direction parallel to the short side of the main body of the straight line between one through hole and the other through hole closest to the through hole (current collection). Angle from a direction parallel to the short side of the body).
- the lithium ion secondary batteries of Examples 1 to 7 using the positive electrode with the proper arrangement of the through-holes in the current collector are current collectors in the main body of the positive electrode after the charge / discharge cycle.
- the occurrence of breakage of the body was suppressed, and it had high reliability.
- the positive electrodes used in the lithium ion secondary batteries of Examples 1 to 7 the occurrence of breakage of the tab portion during welding of the positive electrode tab was well suppressed, but the average diameter of the through holes and the positive electrode current collector In the positive electrodes according to Examples 1 to 5 having more preferable porosity, the occurrence of cracks in the tab portion was well suppressed.
- the batteries of Comparative Examples 1 to 4 using the positive electrode in which the arrangement of the through holes in the current collector was inadequate were inferior in reliability because the positive electrode current collector was broken after the charge / discharge cycle.
- the positive electrode used in these batteries was inferior in reliability due to the occurrence of breakage in the current collector during welding during the production of the wound electrode body.
- the lithium ion secondary battery of the present invention can be applied to the same applications as various applications to which conventionally known lithium ion secondary batteries are applied.
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Abstract
Provided are a highly reliable electrochemical element electrode and a lithium ion secondary battery having said electrode. The electrochemical element electrode according to the present invention is used for a positive electrode or a negative electrode of an electrochemical element having a wound electrode body, and includes: a main section where an electrode mixture layer containing an electrode active material is present on one surface or both surfaces of a current collector; and a tab section where the electrode mixture layer is not present on both surfaces of the current collector. The main section in plan view is a rectangle having a pair of short sides and a pair of long sides. The current collector has multiple through holes that extend from one surface to the other surface, and the multiple through holes are regularly arranged. A straight line connecting one through hole with another through hole that is closest to the one through hole is not present within the range of 0° ± 20° from the direction parallel to the short side of the main section. The lithium ion secondary battery according to the present invention has a wound electrode body, and at least the positive electrode is the electrochemical device electrode according to the present invention.
Description
本発明は、信頼性に優れた電気化学素子用電極と、前記電極を有するリチウムイオン二次電池に関するものである。
The present invention relates to an electrode for an electrochemical element excellent in reliability and a lithium ion secondary battery having the electrode.
リチウムイオン二次電池は、高電圧・高容量であることから、その発展に対して大きな期待が寄せられている。
Since lithium ion secondary batteries have high voltage and high capacity, there are great expectations for their development.
ところで、最近では、小型化および多機能化した携帯機器用のリチウムイオン二次電池について更なる高容量化が望まれており、これを受けて、負極活物質を、従来から汎用されている黒鉛から、低結晶性炭素、Ｓｉ（シリコン）、Ｓｎ（錫）などのように、より多くのＬｉを吸蔵可能な材料（以下、「高容量負極材料」ともいう）へ変更することも検討されている。
By the way, recently, a further increase in capacity has been desired for a lithium-ion secondary battery for portable devices that has been downsized and multifunctional, and in response to this, a negative electrode active material has been used as a widely used graphite. In addition, a change to a material capable of occluding more Li, such as low crystalline carbon, Si (silicon), Sn (tin), etc. (hereinafter also referred to as “high-capacity negative electrode material”) has been studied. Yes.
その一方で、こうした高容量負極材料は不可逆容量が大きく、電池の初期の充電によって正極から放出され、高容量負極材料に吸蔵されたＬｉのうちの比較的多くの量が、次回の放電時に負極から放出されず、電池の容量に関与できなくなるため、高容量負極材料の使用によって想定していた電池の高容量化を、十分に図ることができない場合があった。
On the other hand, such a high capacity negative electrode material has a large irreversible capacity, and a relatively large amount of Li released from the positive electrode by the initial charge of the battery and occluded in the high capacity negative electrode material is negative during the next discharge. In other words, the battery capacity could not be sufficiently increased due to the use of a high capacity negative electrode material.
ところで、Ｌｉを含有しない正極活物質を用いたリチウムイオン二次電池において、正極活物質および負極活物質とは別にＬｉ金属箔などを電池内に導入して電池の充放電に活用する、いわゆるプレドープを行う技術が検討されている（特許文献１など）。かかる技術を、高容量負極材料を使用するリチウムイオン二次電池に適用すれば、前記の不可逆容量による問題を回避できる可能性がある。
By the way, in a lithium ion secondary battery using a positive electrode active material that does not contain Li, a so-called pre-dope that uses a Li metal foil or the like in the battery separately from the positive electrode active material and the negative electrode active material and uses it for charging and discharging of the battery. A technique for performing the above has been studied (for example, Patent Document 1). If this technique is applied to a lithium ion secondary battery using a high-capacity negative electrode material, there is a possibility that the problem due to the irreversible capacity can be avoided.
なお、特許文献１に記載の技術では、電池内に導入したＬｉ金属箔から放出されるＬｉイオンを、効率的に電極へ到達させる目的で、正極集電体および負極集電体に、Ｌｉイオンの通り道となる貫通孔を有するものを使用している。
In the technique described in Patent Document 1, Li ions released from the Li metal foil introduced into the battery are efficiently supplied to the positive electrode current collector and the negative electrode current collector for the purpose of efficiently reaching the electrodes. What has a through-hole used as a passage way is used.
また、貫通孔を有する正極集電体や負極集電体は、前記のようなプレドープ時以外にも、種々の目的、例えば、電極の合剤層の性状を良好に保つなどの目的で、利用されることもある（特許文献２など）。
Moreover, the positive electrode current collector and the negative electrode current collector having through-holes are used for various purposes other than the pre-doping as described above, for example, for the purpose of maintaining good properties of the electrode mixture layer. (Patent Document 2, etc.).
ところで、複数の貫通孔を有する集電体を用いて、電極合剤層（正極活物質を含有する正極合剤層や、高容量負極材料などの負極活物質を含有する負極合剤層）を形成せずに露出した集電体の部分によってタブ部とした形態の電極を作製したり、このような電極を用いてリチウムイオン二次電池としたりした場合に、前記電極の特定箇所で集電体の破断などの欠陥が生じやすいことが、本発明者らの検討によって明らかとなった。
By the way, an electrode mixture layer (a positive electrode mixture layer containing a positive electrode active material or a negative electrode mixture layer containing a negative electrode active material such as a high-capacity negative electrode material) is obtained using a current collector having a plurality of through holes. When an electrode in the form of a tab is formed by a portion of the current collector that is exposed without being formed, or when a lithium ion secondary battery is formed using such an electrode, the current is collected at a specific portion of the electrode. It has been clarified by the present inventors that defects such as body breakage tend to occur.
本発明は、前記事情に鑑みてなされたものであり、その目的は、信頼性に優れた電気化学素子用電極と、前記電極を有するリチウムイオン二次電池とを提供することにある。
The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrode for an electrochemical element excellent in reliability and a lithium ion secondary battery having the electrode.
前記目的を達成し得た本発明の電気化学素子用電極は、正極および負極がセパレータを介して巻回されてなる巻回電極体を有する電気化学素子の、前記正極または前記負極に使用されるものであって、電極活物質を含有する電極合剤層を集電体の片面または両面に有する本体部と、前記集電体の両面に電極合剤層を有しないタブ部とを有しており、前記本体部は、平面視で、１対の短辺と１対の長辺とを有する長方形であり、前記集電体は、片面から他面に貫通する複数の貫通孔を有しており、かつ前記複数の貫通孔は規則的に配置されており、１つの貫通孔と、前記１つの貫通孔と最も近接する他の貫通孔とを結ぶ直線が、前記本体部の短辺に平行な方向から０°±２０°の範囲内に存在していないことを特徴とするものである。
The electrode for an electrochemical element of the present invention that can achieve the above object is used for the positive electrode or the negative electrode of an electrochemical element having a wound electrode body in which a positive electrode and a negative electrode are wound through a separator. A main body having an electrode mixture layer containing an electrode active material on one or both sides of the current collector, and a tab portion having no electrode mixture layer on both sides of the current collector. The main body is a rectangle having a pair of short sides and a pair of long sides in a plan view, and the current collector has a plurality of through holes penetrating from one side to the other side. The plurality of through holes are regularly arranged, and a straight line connecting one through hole and the other through hole closest to the one through hole is parallel to the short side of the main body portion. It is characterized by not existing within the range of 0 ° ± 20 ° from any direction.
また、本発明のリチウムイオン二次電池は、正極と負極とがセパレータを介して巻回されてなる巻回電極体と、非水電解液とを有しており、少なくとも前記正極が、本発明の電気化学素子用電極であることを特徴とするものである。
Further, the lithium ion secondary battery of the present invention has a wound electrode body in which a positive electrode and a negative electrode are wound via a separator, and a non-aqueous electrolyte, and at least the positive electrode is the present invention. This is an electrode for an electrochemical element.
本発明によれば、信頼性に優れた電気化学素子用電極と、前記電極を有するリチウムイオン二次電池とを提供することができる。
According to the present invention, it is possible to provide an electrochemical element electrode having excellent reliability and a lithium ion secondary battery having the electrode.
＜本発明の電気化学素子用電極＞
本発明の電気化学素子用電極（以下、単に「電極」という）は、リチウムイオン二次電池やリチウム一次電池、キャパシタなどの電気化学素子の正極または負極として使用されるものである。 <Electrode for electrochemical device of the present invention>
The electrode for an electrochemical element (hereinafter simply referred to as “electrode”) of the present invention is used as a positive electrode or a negative electrode of an electrochemical element such as a lithium ion secondary battery, a lithium primary battery, or a capacitor.
本発明の電気化学素子用電極（以下、単に「電極」という）は、リチウムイオン二次電池やリチウム一次電池、キャパシタなどの電気化学素子の正極または負極として使用されるものである。 <Electrode for electrochemical device of the present invention>
The electrode for an electrochemical element (hereinafter simply referred to as “electrode”) of the present invention is used as a positive electrode or a negative electrode of an electrochemical element such as a lithium ion secondary battery, a lithium primary battery, or a capacitor.
本発明の電極は、電極活物質（正極活物質または負極活物質）を含有する電極合剤層（正極合剤層または負極合剤層）を集電体の片面または両面に有する本体部（電極合剤層形成部）を有すると共に、集電体の一部に電極合剤層を形成せずに露出させて、かかる部分を電気化学素子の他の部材などと電気的に接続するために利用するようにしたタブ部とを有している。
The electrode of the present invention includes a main body (electrode) having an electrode mixture layer (positive electrode mixture layer or negative electrode mixture layer) containing an electrode active material (positive electrode active material or negative electrode active material) on one side or both sides of a current collector. It has a mixture layer forming part) and is exposed to form a part of the current collector without forming an electrode mixture layer, and is used to electrically connect the part to other members of the electrochemical element. And a tab portion adapted to do so.
図１に、本発明の電極（正極）の一例を模式的に表す平面図を示す。図１に示す電極（正極）１０は、集電体１２の表面に電極合剤層（正極合剤層）１１を有している。この電極合剤層１１を有する部分（図中、ドットを付して表示）が本体部（電極合剤層形成部）である。また、電極１０には、集電体１２の両面に電極合剤層が形成されていない露出部からなるタブ部１３が設けられている。そして、タブ部１３には正極タブ１４が設置されている。なお、図１に示す電極の本体部は、平面視で長方形である（以下に記載する本体部の形状は、特に断らない限り、平面視での形状を意味している）。
FIG. 1 is a plan view schematically showing an example of the electrode (positive electrode) of the present invention. An electrode (positive electrode) 10 shown in FIG. 1 has an electrode mixture layer (positive electrode mixture layer) 11 on the surface of a current collector 12. A portion having the electrode mixture layer 11 (shown with dots in the drawing) is a main body portion (electrode mixture layer forming portion). Further, the electrode 10 is provided with a tab portion 13 composed of an exposed portion where the electrode mixture layer is not formed on both surfaces of the current collector 12. The tab portion 13 is provided with a positive electrode tab 14. Note that the main body of the electrode shown in FIG. 1 is rectangular in plan view (the shape of the main body described below means the shape in plan view unless otherwise specified).
図１に示すように、本発明の電極（正極）は、集電体の表面に電極合剤層（正極合剤層）を有する本体部（電極合剤層形成部）と、タブ部とを有している。なお、図１においてはタブ部１３を電極（正極）１０の右端に設けているが、電極（正極）１０の中央付近に設けてもよい。タブ部を電極の中央付近に設けた場合、電極（正極）の本体部は複数箇所（通常２箇所）に分かれていてもよい（本発明の電極が負極の場合も同様である）。
As shown in FIG. 1, the electrode (positive electrode) of the present invention comprises a main body portion (electrode mixture layer forming portion) having an electrode mixture layer (positive electrode mixture layer) on the surface of a current collector, and a tab portion. Have. In FIG. 1, the tab portion 13 is provided at the right end of the electrode (positive electrode) 10, but may be provided near the center of the electrode (positive electrode) 10. When the tab portion is provided near the center of the electrode, the main body portion of the electrode (positive electrode) may be divided into a plurality of locations (usually two locations) (the same applies when the electrode of the present invention is a negative electrode).
また、本発明の電極に係る集電体は、片面から他面まで貫通する複数の貫通孔を有している。集電体が有するこれらの貫通孔は、例えば、電極合剤層と集電体との密着性を高める作用を有しており、また、電気化学素子が有する非水電解液の通り道となり、電極合剤層の全体にわたってより均一に非水電解液が浸透するようにできるため、電気化学素子の特性向上に寄与する。更に、前記のように、正極以外にＬｉ供給源を導入して負極活物質にＬｉのプレドープを行うタイプのリチウムイオン二次電池においては、本発明の電極に係る集電体の貫通孔が、Ｌｉ供給源から放出されるＬｉイオン（放出されたＬｉイオンを含む非水電解液）の通り道となるため、より効率的にプレドープを進めることが可能となる。
Further, the current collector according to the electrode of the present invention has a plurality of through holes penetrating from one side to the other side. These through holes of the current collector have, for example, an effect of increasing the adhesion between the electrode mixture layer and the current collector, and also serve as a passage for the non-aqueous electrolyte solution of the electrochemical element. Since the non-aqueous electrolyte can penetrate more uniformly throughout the mixture layer, it contributes to improving the characteristics of the electrochemical device. Furthermore, as described above, in the lithium ion secondary battery of a type in which a Li supply source is introduced in addition to the positive electrode and the negative electrode active material is pre-doped with Li, the through hole of the current collector according to the electrode of the present invention has Since the Li ion released from the Li supply source (non-aqueous electrolyte containing the released Li ion) becomes a path, it becomes possible to advance pre-doping more efficiently.
なお、図１では、図面が複雑になることを回避するために、タブ部１３を構成している集電体１２の露出部には貫通孔を示していない。
In addition, in FIG. 1, in order to avoid that drawing becomes complicated, the through-hole is not shown in the exposed part of the electrical power collector 12 which comprises the tab part 13. FIG.
高容量負極材料を用いた負極を有するリチウムイオン二次電池では、充電によって負極が大きく膨張するが、この場合、負極の膨張に伴って生じる応力が負極にかかったり、負極の膨張による応力（押圧力）が正極にかかったりする。
In a lithium ion secondary battery having a negative electrode using a high-capacity negative electrode material, the negative electrode expands greatly due to charging. In this case, the stress caused by the expansion of the negative electrode is applied to the negative electrode or the stress (pushing pressure) due to the expansion of the negative electrode. Pressure) is applied to the positive electrode.
複数の貫通孔を有する集電体を用いた電極の場合、負極の膨張に基づく応力が電極（正極または負極）にかかったりすると、電極のタブ部や本体部において、その短辺に平行な方向や、それに近い方向に亀裂が入って破断が生じやすいことが判明した。
In the case of an electrode using a current collector having a plurality of through-holes, if stress due to expansion of the negative electrode is applied to the electrode (positive electrode or negative electrode), the direction parallel to the short side of the electrode tab portion or body portion It was also found that cracks are likely to occur in the direction close to that and breakage easily occurs.
本発明者らは、前記のような電極のタブ部や本体部で生じる亀裂や破断の理由について、鋭意検討を重ねた結果、集電体に設けた複数の貫通孔の配置が影響していることを見出した。すなわち、複数の貫通孔を有する集電体においては、これらの貫通孔の配置の仕方によって裂けやすさに異方性が生じ、より裂けやすい方向が、長方形の本体部の短辺方向に平行や平行に近い方向（すなわち、長方形の集電体の短辺方向に平行や平行に近い方向）を向いている場合には、前記のようなタブ部や本体部での亀裂や破断が生じやすくなる。その理由は以下の通りである。
As a result of intensive investigations on the reason for cracks and breakage occurring in the tab portion and main body portion of the electrode as described above, the present inventors have an influence on the arrangement of a plurality of through holes provided in the current collector. I found out. That is, in a current collector having a plurality of through holes, anisotropy occurs in the ease of tearing depending on the arrangement of these through holes, and the direction in which tearing is easier is parallel to the short side direction of the rectangular main body. When facing a direction that is close to parallel (that is, a direction that is parallel or close to parallel to the short-side direction of the rectangular current collector), cracks and breaks in the tab portion and the main body portion are likely to occur. . The reason is as follows.
一般に、本発明のように巻回される電極は、製造工程で長辺方向にテンションを掛けながら、搬送され、タブを設置し、巻回される。このように、長辺方向へテンションを掛けながら行う工程が続くため、集電体の裂けやすい方向が、本体部の短辺方向に平行または平行に近い方向（集電体の短辺方向に平行または平行に近い方向）を向いていると、電極の当該方向へ亀裂が入りやすくなってしまう。また、製造工程で集電体が裂けなかったとしても、電極を電気化学素子とした後の充放電時の電極の膨張収縮などにより、集電体の残留ひずみが影響を受けて亀裂が入ることがある。
Generally, an electrode wound as in the present invention is conveyed while applying a tension in a long side direction in a manufacturing process, and a tab is installed and wound. Thus, since the process performed while applying tension in the long side direction continues, the direction in which the current collector is easily torn is parallel or nearly parallel to the short side direction of the main body (parallel to the short side direction of the current collector). If it is oriented in a direction close to parallel), cracks are likely to occur in that direction of the electrode. In addition, even if the current collector does not tear during the manufacturing process, cracks may occur due to the residual strain of the current collector due to the expansion and contraction of the electrode during charge and discharge after the electrode is made an electrochemical element. There is.
更に、集電体にタブを溶接した部分は機械的ダメージを受けやすい。特に複数の貫通孔を有する集電体は、貫通孔を有しない通常の集電体と比較して集電体そのものの強度が低く、より顕著にダメージを受ける。また、通常のリチウムイオン二次電池では、タブは外装体に溶接固定されているので、充放電時に電極が膨張または収縮して変形を生じると、その変形に追随できず、タブと集電体との溶接部分で亀裂や破断を生じやすくなる。特に、長方形の本体部の短辺方向に平行な方向（長方形の集電体の短辺方向に平行な方向）に亀裂や破断は生じやすい。
Furthermore, the part where the tab is welded to the current collector is susceptible to mechanical damage. In particular, a current collector having a plurality of through holes has a lower strength than that of a normal current collector having no through holes, and is more significantly damaged. Further, in a normal lithium ion secondary battery, the tab is welded and fixed to the exterior body. Therefore, if the electrode expands or contracts during charge and discharge and deforms, the tab and the current collector cannot follow the deformation. Cracks and breaks are likely to occur at the welded part. In particular, cracks and breaks tend to occur in a direction parallel to the short side direction of the rectangular main body (a direction parallel to the short side direction of the rectangular current collector).
そこで、本発明では、電極に使用する集電体における複数の貫通孔の配置を調整し、集電体のより裂けやすい方向が、長方形の本体部の短辺方向に平行および平行に近い方向（長方形の集電体の短辺方向に平行および平行に近い方向）を向かないようにすることで、前記のようなタブ部や本体部での亀裂や破断の発生を防止して、信頼性に優れた電極の提供を可能としている。
Therefore, in the present invention, the arrangement of the plurality of through holes in the current collector used for the electrode is adjusted, and the direction in which the current collector is more easily torn is parallel and nearly parallel to the short side direction of the rectangular main body ( By preventing the rectangular current collector from facing the short side of the rectangular current collector), it is possible to prevent the occurrence of cracks and breaks in the tab part and body part as described above, and to improve reliability. It is possible to provide excellent electrodes.
具体的には、本発明の電極に係る集電体においては、複数の貫通孔を規則的に配置し、かつ１つの貫通孔と、この貫通孔と最も近接する他の貫通孔とを結ぶ直線が、長方形の本体部の短辺方向に平行な方向（長方形の集電体の短辺方向に平行な方向）から０°±２０°の範囲内に存在しないようにする。
Specifically, in the current collector according to the electrode of the present invention, a plurality of through holes are regularly arranged, and a straight line connecting one through hole and another through hole closest to the through hole. Is not in the range of 0 ° ± 20 ° from the direction parallel to the short side direction of the rectangular main body (the direction parallel to the short side direction of the rectangular current collector).
図２に、本発明の電極に使用する集電体における貫通孔の配置の一例を模式的に表す平面図を示す。図２に示す集電体１２は、片面から他面に貫通する複数の貫通孔（図中、円で表示）を有している。
FIG. 2 is a plan view schematically showing an example of the arrangement of the through holes in the current collector used for the electrode of the present invention. The current collector 12 shown in FIG. 2 has a plurality of through holes (indicated by circles in the figure) that penetrate from one side to the other side.
そして、図２に示す集電体１２においては、各貫通孔が、特定のパターンの繰り返し、具体的には千鳥配列によって配置されており、１つの貫通孔１２０と、その周囲の存在する６つの貫通孔との距離が、いずれも等間隔であり、これらの６つの貫通孔が、１つの貫通孔１２０に最も近接する貫通孔に該当する。
In the current collector 12 shown in FIG. 2, each through hole is arranged in a specific pattern, specifically, in a staggered arrangement, and includes one through hole 120 and six surrounding holes. The distances from the through holes are all equal, and these six through holes correspond to the through hole closest to one through hole 120.
図２には、貫通孔１２０と、これに最も近接する６つの貫通孔とを結ぶ直線を一点鎖線で示しているが、集電体１２は、これらの一点鎖線で示す方向に沿って裂けやすい。よって、本発明の電極において、複数の貫通孔が図２に示すパターンで配置されている集電体を使用する場合には、図中の各一点鎖線で示す方向が、長方形の本体部の短辺に平行な方向（長方形の集電体１２の短辺に平行な方向）から０°±２０°の範囲内に存在しないように、集電体の向きを調整する。これにより、電極の製造時や電気化学素子の製造時、更にはリチウムイオン二次電池の使用時において、電極のタブ部および本体部に亀裂や破断が生じやすい方向が、集電体の裂けやすい方向と一致しないようになるため、電極の信頼性の向上が可能となる。
In FIG. 2, straight lines connecting the through holes 120 and the six through holes closest to the through holes 120 are indicated by alternate long and short dash lines, but the current collector 12 is easily split along the direction indicated by the alternate long and short dashed lines. . Therefore, in the electrode of the present invention, when a current collector in which a plurality of through holes are arranged in the pattern shown in FIG. 2 is used, the direction indicated by the alternate long and short dash line in the figure is the short of the rectangular main body. The direction of the current collector is adjusted so that it does not exist within the range of 0 ° ± 20 ° from the direction parallel to the side (the direction parallel to the short side of the rectangular current collector 12). As a result, when the electrode is manufactured, the electrochemical element is manufactured, and further, when the lithium ion secondary battery is used, the direction in which the tab portion and the main body portion of the electrode are likely to be cracked or broken easily breaks the current collector. Since the direction does not match, the reliability of the electrode can be improved.
図３および図４に、本発明の電極に使用する集電体における貫通孔の配置の他の例を模式的に表す平面図を示す。図３に示す集電体１２も、図２に示す集電体と同様に、各貫通孔（図中、円で表示）が千鳥配列によって配置されている例であるが、貫通孔の図中上下の列の間隔がより狭いため、１つの貫通孔１２０と、これに最も近接する他の貫通孔とを結ぶ直線（図中の一点鎖線）が、図中上下方向にのみ存在している。本発明の電極において、貫通孔が図３に示すパターンで配置されている集電体を使用する場合には、図中下方向が、長方形の本体部の短辺に平行な方向（長方形の集電体１２の短辺に平行な方向）から０°±２０°の範囲内に存在しないように、集電体の向きを調整する。
3 and 4 are plan views schematically showing another example of the arrangement of the through holes in the current collector used for the electrode of the present invention. Similarly to the current collector shown in FIG. 2, the current collector 12 shown in FIG. 3 is an example in which the through holes (indicated by circles in the figure) are arranged in a staggered arrangement. Since the interval between the upper and lower rows is narrower, a straight line (one-dot chain line in the figure) connecting one through hole 120 and the other through hole closest to the through hole 120 exists only in the vertical direction in the figure. In the electrode of the present invention, when a current collector having through holes arranged in the pattern shown in FIG. 3 is used, the downward direction in the figure is a direction parallel to the short side of the rectangular main body (rectangular current collector). The direction of the current collector is adjusted so that it does not exist within the range of 0 ° ± 20 ° from the direction parallel to the short side of the electric body 12.
また、図４に示す集電体１２においては、各貫通孔（図中、円で表示）が、図中上下方向および左右方向に直線状に配置、すなわち並列配列（直列配列）によって配置されており、貫通孔の図中上下の列の間隔および左右の列の間隔が同じである。よって、図４に示す集電体においては、１つの貫通孔１２０と、これに最も近接する他の貫通孔とを結ぶ直線（図中の一点鎖線）が、図中上下方向および左右方向に存在している。本発明の電極において、貫通孔が図４に示すパターンで配置されている集電体を使用する場合には、図中上下方向および左右方向が、長方形の本体部の短辺に平行な方向（長方形の集電体１２の短辺に平行な方向）から０°±２０°の範囲内に存在しないように、集電体の向きを調整する。
Further, in the current collector 12 shown in FIG. 4, each through hole (indicated by a circle in the figure) is arranged linearly in the vertical direction and the horizontal direction in the figure, that is, arranged in a parallel arrangement (series arrangement). The interval between the upper and lower columns and the interval between the left and right columns in the drawing of the through hole are the same. Therefore, in the current collector shown in FIG. 4, straight lines (one-dot chain lines in the figure) connecting one through hole 120 and the other through hole closest to the through hole 120 exist in the vertical direction and the horizontal direction in the figure. is doing. In the electrode of the present invention, when a current collector having through holes arranged in the pattern shown in FIG. 4 is used, the vertical direction and the horizontal direction in the figure are directions parallel to the short side of the rectangular main body ( The direction of the current collector is adjusted so that it does not exist within the range of 0 ° ± 20 ° from the direction parallel to the short side of the rectangular current collector 12.
本発明の電極に係る集電体における複数の貫通孔の配置は、図２から図４に示すものに限定される訳ではなく、規則的に配置、より具体的には、特定のパターンの繰り返しによって配置されていればよい。繰り返されるパターンは、１種類であってもよく、２種類以上であってもよい。
The arrangement of the plurality of through holes in the current collector according to the electrode of the present invention is not limited to that shown in FIGS. 2 to 4, but is regularly arranged, more specifically, a specific pattern is repeated. As long as they are arranged. One type of repeated pattern may be used, or two or more types may be used.
なお、貫通孔を比較的多く設ける場合などでは、集電体の強度低下を可及的に抑制できることから、図２や図３に示す千鳥配列によって、複数の貫通孔を配置することが好ましい。
In addition, in the case where a relatively large number of through holes are provided, it is possible to suppress a decrease in strength of the current collector as much as possible. Therefore, it is preferable to arrange a plurality of through holes by the staggered arrangement shown in FIGS.
集電体における貫通孔の平均径は、貫通孔をＬｉイオン（それを含む非水電解液）の通り道とする場合の、その流通をより良好にする観点や、貫通孔によって集電体と電極合剤層との密着性を高める効果をより良好に確保するなどの観点から、１μｍ以上であることが好ましく、５０μｍ以上であることがより好ましい。また、貫通孔のサイズが大きすぎると集電体の強度が低下する虞があることから、集電体における貫通孔の平均径は、４００μｍ以下であることが好ましく、３５０μｍ以下であることがより好ましい。
The average diameter of the through-holes in the current collector is such that when the through-holes are used as Li ions (non-aqueous electrolyte containing the same), the current distribution and the electrodes are improved by the through-holes. From the standpoint of ensuring better the effect of improving the adhesion with the mixture layer, it is preferably 1 μm or more, and more preferably 50 μm or more. In addition, since the strength of the current collector may decrease if the size of the through hole is too large, the average diameter of the through holes in the current collector is preferably 400 μm or less, and more preferably 350 μm or less. preferable.
本明細書でいう集電体における貫通孔の平均径は、集電体を走査型電子顕微鏡（ＳＥＭ）にて観察し、視野内の少なくとも２０個の貫通孔の、電極本体部の、長方形の本体部の短辺に平行な向きと垂直な向きの直径をスケールを用いて計測し、これらの平均を平均径として算出した値である。
The average diameter of the through-holes in the current collector referred to in this specification is determined by observing the current collector with a scanning electron microscope (SEM) and measuring the rectangular shape of the electrode body portion of at least 20 through-holes in the field of view. This is a value obtained by measuring the diameter in a direction parallel to the short side of the main body and a direction perpendicular to the short side using a scale and calculating the average of these as the average diameter.
更に、複数の貫通孔を有する集電体における空孔率は、貫通孔をＬｉイオン（それを含む非水電解液）の通り道とする場合の、その流通をより良好にする観点や、貫通孔によって集電体と電極合剤層との密着性を高める効果をより良好に確保する観点から、３％以上であることが好ましく、８％以上であることがより好ましい。また、集電体の空孔率が高すぎると集電体の強度が低下する虞があることから、複数の貫通孔を有する集電体における空孔率は、５０％以下であることが好ましく、４５％以下であることがより好ましい。
Furthermore, the porosity of the current collector having a plurality of through-holes can be determined from the viewpoint of improving the flow when the through-hole is a passage for Li ions (non-aqueous electrolyte containing the same), Is preferably 3% or more, and more preferably 8% or more from the viewpoint of better ensuring the effect of enhancing the adhesion between the current collector and the electrode mixture layer. Moreover, since the strength of the current collector may decrease if the porosity of the current collector is too high, the porosity of the current collector having a plurality of through holes is preferably 50% or less. More preferably, it is 45% or less.
更に、複数の貫通孔を有する集電体における１つの貫通孔と、この貫通孔と最も近接する他の貫通孔との間の距離（２つの貫通孔の最短円周間距離）は、３０～１０００μｍであることが好ましい。本明細書でいう２つの貫通孔間の距離は、集電体をＳＥＭにて観察し、視野内の少なくとも４０組の貫通孔間の距離をスケールを用いて計測し、これらを平均して算出した値である。
Further, the distance between one through hole in the current collector having a plurality of through holes and the other through hole closest to the through hole (the shortest circumferential distance between the two through holes) is 30 to It is preferable that it is 1000 micrometers. The distance between the two through holes in this specification is calculated by observing the current collector with an SEM, measuring the distance between at least 40 sets of through holes in the field of view using a scale, and averaging these. It is the value.
以下には、本発明の電極の主要な実施態様であるリチウムイオン二次電池用電極（リチウムイオン二次電池用正極またはリチウムイオン二次電池用負極）を例にとり、集電体の構成について説明する（電極合剤層については、後述するリチウムイオン二次電池の箇所で説明する）。
In the following, the configuration of the current collector will be described by taking, as an example, an electrode for a lithium ion secondary battery (a positive electrode for a lithium ion secondary battery or a negative electrode for a lithium ion secondary battery) which is a main embodiment of the electrode of the present invention. (The electrode mixture layer will be described later in the section of a lithium ion secondary battery).
本発明の電極がリチウムイオン二次電池用正極である場合、集電体には、アルミニウム製やアルミニウム合金製のパンチングメタルや、アルミニウム箔やアルミニウム合金箔にエッチングによって貫通孔を形成したものなどを使用することができる。この場合の集電体の厚みは、６～３０μｍであることが好ましい。
When the electrode of the present invention is a positive electrode for a lithium ion secondary battery, the current collector is a punching metal made of aluminum or aluminum alloy, or an aluminum foil or aluminum alloy foil with through holes formed by etching. Can be used. In this case, the thickness of the current collector is preferably 6 to 30 μm.
本発明の電極がリチウムイオン二次電池用負極である場合、集電体には、銅製や銅合金製のパンチングメタルや、銅箔や銅合金箔にエッチングによって貫通孔を形成したものなどを使用することができる。この場合の集電体の厚みは、６～３０μｍであることが好ましい。
When the electrode of the present invention is a negative electrode for a lithium ion secondary battery, the current collector used is a punching metal made of copper or copper alloy, or a copper foil or copper alloy foil with through holes formed by etching. can do. In this case, the thickness of the current collector is preferably 6 to 30 μm.
＜本発明のリチウムイオン二次電池＞
本発明のリチウムイオン二次電池（以下、単に「電池」という場合がある）は、正極と負極とがセパレータを介して巻回された電極体（巻回電極体）と、非水電解液とを有しており、正極および負極のうちの少なくとも正極が、本発明の電極であるものである。なお、例えば、前記のような負極へのプレドープを行うタイプのリチウムイオン二次電池などでは、正極以外のＬｉ供給源の態様にもよるが、負極も本発明の電極とすることが好ましく、また、他の態様の電池においても、必要に応じて負極にも本発明の電極を使用することができる。 <Lithium ion secondary battery of the present invention>
The lithium ion secondary battery of the present invention (hereinafter sometimes simply referred to as “battery”) includes an electrode body (winding electrode body) in which a positive electrode and a negative electrode are wound via a separator, a non-aqueous electrolyte, And at least the positive electrode of the positive electrode and the negative electrode is the electrode of the present invention. For example, in a lithium ion secondary battery of the type in which the negative electrode is pre-doped as described above, the negative electrode is also preferably the electrode of the present invention, although depending on the aspect of the Li supply source other than the positive electrode. In the batteries of other embodiments, the electrode of the present invention can be used for the negative electrode as necessary.
本発明のリチウムイオン二次電池（以下、単に「電池」という場合がある）は、正極と負極とがセパレータを介して巻回された電極体（巻回電極体）と、非水電解液とを有しており、正極および負極のうちの少なくとも正極が、本発明の電極であるものである。なお、例えば、前記のような負極へのプレドープを行うタイプのリチウムイオン二次電池などでは、正極以外のＬｉ供給源の態様にもよるが、負極も本発明の電極とすることが好ましく、また、他の態様の電池においても、必要に応じて負極にも本発明の電極を使用することができる。 <Lithium ion secondary battery of the present invention>
The lithium ion secondary battery of the present invention (hereinafter sometimes simply referred to as “battery”) includes an electrode body (winding electrode body) in which a positive electrode and a negative electrode are wound via a separator, a non-aqueous electrolyte, And at least the positive electrode of the positive electrode and the negative electrode is the electrode of the present invention. For example, in a lithium ion secondary battery of the type in which the negative electrode is pre-doped as described above, the negative electrode is also preferably the electrode of the present invention, although depending on the aspect of the Li supply source other than the positive electrode. In the batteries of other embodiments, the electrode of the present invention can be used for the negative electrode as necessary.
なお、本発明の電極を正極にのみ使用する場合には、負極には、例えば、集電体が貫通孔を有することを除いて本発明の電極と同じ構成の負極や、集電体が規則的に配置された複数の貫通孔を有し、１つの貫通孔と、この貫通孔と最も近接する他の貫通孔とを結ぶ直線が、長方形の本体部の短辺方向に平行な方向から０°±２０°の範囲内に存在する以外は、本発明の電極と同じ構成の負極を使用することができる。
When the electrode of the present invention is used only for the positive electrode, for example, the negative electrode has the same configuration as that of the electrode of the present invention except that the current collector has a through-hole, and the current collector is regular. A straight line connecting a through hole and another through hole closest to the through hole is zero from a direction parallel to the short side direction of the rectangular main body. A negative electrode having the same configuration as that of the electrode of the present invention can be used except that it is within the range of ± 20 °.
本発明の電池の正極に係る正極合剤層（本発明の電極を正極として使用する場合における電極合剤層）には、正極活物質（電極活物質）を含有させるが、通常は、正極活物質の他に、導電助剤やバインダを含有させる。
The positive electrode mixture layer (the electrode mixture layer when the electrode of the present invention is used as a positive electrode) according to the positive electrode of the battery of the present invention contains a positive electrode active material (electrode active material). In addition to the substance, a conductive additive and a binder are included.
正極活物質には、ＬｉとＬｉ以外の金属Ｍ（Ｃｏ、Ｍｎ、Ｎｉ、Ｔｉ、Ｆｅなど）で構成される金属酸化物を使用することができる。より具体的には、ＬｉＣｏＯ２などのリチウムコバルト酸化物；ＬｉＭｎＯ２、Ｌｉ２ＭｎＯ３などのリチウムマンガン酸化物；ＬｉＮｉＯ２などのリチウムニッケル酸化物；ＬｉＣｏ１－ｘＮｉＯ２などの層状構造のリチウム含有複合酸化物；ＬｉＭｎ２Ｏ４、Ｌｉ４／３Ｔｉ５／３Ｏ４などのスピネル構造のリチウム含有複合酸化物；ＬｉＦｅＰＯ４などのオリビン構造のリチウム含有複合酸化物；前記の酸化物を基本組成とし各種元素で置換した酸化物；などのリチウム含有複合酸化物が挙げられる。
As the positive electrode active material, a metal oxide composed of a metal M (Co, Mn, Ni, Ti, Fe, etc.) other than Li and Li can be used. More specifically, lithium cobalt oxide such as LiCoO 2 ; lithium manganese oxide such as LiMnO 2 and Li 2 MnO 3 ; lithium nickel oxide such as LiNiO 2 ; lithium having a layered structure such as LiCo 1-x NiO 2 Containing complex oxide; lithium-containing complex oxide having a spinel structure such as LiMn 2 O 4 , Li 4/3 Ti 5/3 O 4 ; lithium-containing complex oxide having an olivine structure such as LiFePO 4 ; Examples include lithium-containing composite oxides such as oxides substituted with various elements as compositions.
正極合剤層には、正極活物質の他に、通常、導電助剤およびバインダを含有させる。導電助剤としては、黒鉛、アセチレンブラック、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックなどのカ－ボンブラック類；炭素繊維；などの炭素材料を用いることが好ましく、また、金属繊維などの導電性繊維類；フッ化カーボン；アルミニウムなどの金属粉末類；酸化亜鉛；チタン酸カリウムなどの導電性ウィスカー類；酸化チタンなどの導電性金属酸化物；ポリフェニレン誘導体などの有機導電性材料；などを用いることもできる。
In addition to the positive electrode active material, the positive electrode mixture layer usually contains a conductive additive and a binder. As the conductive aid, carbon materials such as carbon blacks such as graphite, acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black; carbon fiber; Conductive fibers such as fibers; carbon fluoride; metal powders such as aluminum; zinc oxide; conductive whiskers such as potassium titanate; conductive metal oxides such as titanium oxide; organic conductive materials such as polyphenylene derivatives ; Can also be used.
また、正極合剤層に係るバインダには、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、スチレンブタジエンゴム（ＳＢＲ）などを用いることができる。
Also, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), or the like can be used for the binder related to the positive electrode mixture layer.
正極合剤層の厚みは、例えば、集電体の片面あたり１０～１００μｍであることが好ましい。また、正極合剤層の組成としては、例えば、正極活物質の量が６５～９８質量％であることが好ましく、バインダの量が０．５～１５質量％であることが好ましく、導電助剤の量が０．５～２０質量％であることが好ましい。
The thickness of the positive electrode mixture layer is preferably, for example, 10 to 100 μm per one side of the current collector. As the composition of the positive electrode mixture layer, for example, the amount of the positive electrode active material is preferably 65 to 98% by mass, the amount of the binder is preferably 0.5 to 15% by mass, and the conductive auxiliary agent Is preferably 0.5 to 20% by mass.
正極合剤層は、例えば、正極活物質、バインダおよび導電助剤などを、Ｎ－メチル－２－ピロリドン（ＮＭＰ）などの有機溶剤や水といった溶剤に分散させたペースト状やスラリー状の正極合剤含有組成物を調製し（ただし、バインダは溶剤に溶解していてもよい）、これを集電体の片面または両面に塗布し、乾燥した後に、必要に応じてカレンダー処理などのプレス処理を施す工程を経て形成することができる。
The positive electrode mixture layer is, for example, a paste-like or slurry-like positive electrode mixture in which a positive electrode active material, a binder, and a conductive auxiliary agent are dispersed in an organic solvent such as N-methyl-2-pyrrolidone (NMP) or a solvent such as water. Prepare an agent-containing composition (however, the binder may be dissolved in a solvent), apply it to one or both sides of the current collector, dry it, and then apply a press treatment such as calendering if necessary. It can form through the process to give.
本発明の電池の負極に係る負極合剤層（本発明の電極を負極として使用する場合における電極合剤層）には、負極活物質（電極活物質）を含有させるが、通常は、負極活物質の他にバインダを含有させる。
The negative electrode mixture layer (the electrode mixture layer when the electrode of the present invention is used as a negative electrode) according to the negative electrode of the battery of the present invention contains a negative electrode active material (electrode active material). In addition to the substance, a binder is included.
負極活物質には、黒鉛〔鱗片状黒鉛などの天然黒鉛；熱分解炭素類、メソフェーズカーボンマイクロビーズ（ＭＣＭＢ）、炭素繊維などの易黒鉛化炭素を２８００℃以上で黒鉛化処理した人造黒鉛；など〕、熱分解炭素類、コークス類、ガラス状炭素類、有機高分子化合物の焼成体、ＭＣＭＢ、炭素繊維、活性炭などの炭素材料；リチウムと合金化可能な金属（Ｓｉ、Ｓｎなど）や、これらの金属を含む材料（合金、酸化物など）；などが挙げられ、これらのうちの１種または２種以上を用いることができる。
Examples of the negative electrode active material include graphite [natural graphite such as scale-like graphite; artificial graphite obtained by graphitizing easily graphitized carbon such as pyrolytic carbons, mesophase carbon microbeads (MCMB) and carbon fibers at 2800 ° C. or more; ], Pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, MCMB, carbon fibers, activated carbon and other carbon materials; metals that can be alloyed with lithium (Si, Sn, etc.), and these These materials include metals (alloys, oxides, etc.), and one or more of these can be used.
前記例示の負極活物質の中でも、ＳｉとＯとを構成元素に含む材料（ただし、Ｓｉに対するＯの原子比ｘは、０．５≦ｘ≦１．５である。以下、当該材料を「ＳｉＯｘ」と記載する。）を使用することが好ましい。ＳｉＯｘは、いわゆる高容量負極材料であるため、これを負極活物質に用いることで、電極（負極）の高容量化を図ることができる。
Among the above-described negative electrode active materials, materials containing Si and O as constituent elements (provided that the atomic ratio x of O to Si is 0.5 ≦ x ≦ 1.5. x ")) is preferred. Since SiO x is a so-called high capacity negative electrode material, the capacity of the electrode (negative electrode) can be increased by using this as a negative electrode active material.
なお、ＳｉＯｘなどの高容量負極材料を使用した負極は電池の充電時に大きく膨張するため、このような負極を用いたリチウムイオン二次電池では、前記の通り、正極や負極の集電体に貫通孔を有するものを使用していると、前記のような集電体の破断が生じやすい。しかしながら、本発明の電池においては、負極がＳｉＯｘなどの高容量負極材料を負極活物質として含有していても、正極に本発明の電極を用いているために、正極集電体の破断を良好に抑制でき、また、本発明の電極を負極にも用いた場合には、負極集電体の破断も良好に抑制できる。
In addition, since a negative electrode using a high-capacity negative electrode material such as SiO x greatly expands when the battery is charged, as described above, in a lithium ion secondary battery using such a negative electrode, a positive electrode or a negative electrode current collector is used. When the one having a through hole is used, the current collector is easily broken as described above. However, in the battery of the present invention, even if the negative electrode contains a high-capacity negative electrode material such as SiO x as the negative electrode active material, the positive electrode current collector is broken because the electrode of the present invention is used for the positive electrode. When the electrode of the present invention is also used for the negative electrode, breakage of the negative electrode current collector can be suppressed well.
ＳｉＯｘは、Ｓｉの微結晶または非晶質相を含んでいてもよく、この場合、ＳｉとＯの原子比は、Ｓｉの微結晶または非晶質相のＳｉを含めた比率となる。すなわち、ＳｉＯｘには、非晶質のＳｉＯ２マトリックス中に、Ｓｉ（例えば、微結晶Ｓｉ）が分散した構造のものが含まれ、この非晶質のＳｉＯ２と、その中に分散しているＳｉを合わせて、前記の原子比ｘが０．５≦ｘ≦１．５を満足していればよい。例えば、非晶質のＳｉＯ２マトリックス中に、Ｓｉが分散した構造で、ＳｉＯ２とＳｉのモル比が１：１の材料の場合、ｘ＝１であるので、構造式としてはＳｉＯで表記される。このような構造の材料の場合、例えば、Ｘ線回折分析では、Ｓｉ（微結晶Ｓｉ）の存在に起因するピークが観察されない場合もあるが、透過型電子顕微鏡で観察すると、微細なＳｉの存在が確認できる。
The SiO x may contain Si microcrystal or amorphous phase. In this case, the atomic ratio of Si and O is a ratio including Si microcrystal or amorphous phase Si. That is, SiO x includes a structure in which Si (for example, microcrystalline Si) is dispersed in an amorphous SiO 2 matrix, and this amorphous SiO 2 is dispersed in the SiO 2 matrix. It is sufficient that the atomic ratio x satisfies 0.5 ≦ x ≦ 1.5 in combination with Si. For example, in the case of a material in which Si is dispersed in an amorphous SiO 2 matrix and the material has a molar ratio of SiO 2 to Si of 1: 1, x = 1, so that the structural formula is represented by SiO. The In the case of a material having such a structure, for example, in X-ray diffraction analysis, a peak due to the presence of Si (microcrystalline Si) may not be observed, but when observed with a transmission electron microscope, the presence of fine Si Can be confirmed.
そして、ＳｉＯｘは、炭素材料と複合化したものであることが望ましく、例えば、ＳｉＯｘの表面が炭素材料で被覆されていることが好ましい。ＳｉＯｘは導電性が乏しいため、これを負極活物質として用いる際には、良好な電池特性確保の観点から、導電性材料（導電助剤）を使用し、負極内におけるＳｉＯｘと導電性材料との混合・分散を良好にして、優れた導電ネットワークを形成する必要がある。ＳｉＯｘを炭素材料と複合化した複合体であれば、例えば、単にＳｉＯｘと炭素材料などの導電性材料とを混合して得られた材料を用いた場合よりも、負極における導電ネットワークが良好に形成される。
And it is desirable that SiO x is compounded with a carbon material. For example, the surface of SiO x is preferably covered with a carbon material. Since SiO x has poor conductivity, when it is used as a negative electrode active material, from the viewpoint of securing good battery characteristics, a conductive material (conductive aid) is used, and SiO x and conductive material in the negative electrode are used. Therefore, it is necessary to form a good conductive network by mixing and dispersing with each other. If complexes complexed with carbon material SiO x, for example, simply than with a material obtained by mixing a conductive material such as SiO x and the carbon material, good conductive network in the negative electrode Formed.
ＳｉＯｘと炭素材料との複合体としては、前記のように、ＳｉＯｘの表面を炭素材料で被覆したものの他、ＳｉＯｘと炭素材料との造粒体などが挙げられる。
The complex of the SiO x and the carbon material, as described above, other although the surface of the SiO x coated with carbon material, such as granules of SiO x and the carbon material can be cited.
また、前記の、ＳｉＯｘの表面を炭素材料で被覆した複合体を、更に導電性材料（炭素材料など）と複合化して用いることで、負極において更に良好な導電ネットワークの形成が可能となるため、より高容量で、より電池特性（例えば、充放電サイクル特性）に優れた電池の実現が可能となる。炭素材料で被覆されたＳｉＯｘと炭素材料との複合体としては、例えば、炭素材料で被覆されたＳｉＯｘと炭素材料との混合物を更に造粒した造粒体などが挙げられる。
In addition, since the composite in which the surface of SiO x is coated with a carbon material is further combined with a conductive material (carbon material or the like), a better conductive network can be formed in the negative electrode. Thus, it is possible to realize a battery with higher capacity and more excellent battery characteristics (for example, charge / discharge cycle characteristics). The complex of the SiO x and the carbon material coated with a carbon material, for example, like granules the mixture was further granulated with SiO x and the carbon material coated with a carbon material.
また、表面が炭素材料で被覆されたＳｉＯｘとしては、ＳｉＯｘとそれよりも比抵抗値が小さい炭素材料との複合体（例えば造粒体）の表面が、更に炭素材料で被覆されてなるものも、好ましく用いることができる。前記造粒体内部でＳｉＯｘと炭素材料とが分散した状態であると、より良好な導電ネットワークを形成できるため、ＳｉＯｘを負極活物質として含有する負極を有する電池において、重負荷放電特性などの電池特性を更に向上させることができる。
Further, as SiO x whose surface is coated with a carbon material, the surface of a composite (for example, a granulated body) of SiO x and a carbon material having a smaller specific resistance value is further coated with a carbon material. Those can also be preferably used. In the state where SiO x and the carbon material are dispersed in the granulated body, a better conductive network can be formed. Therefore, in a battery having a negative electrode containing SiO x as a negative electrode active material, heavy load discharge characteristics, etc. The battery characteristics can be further improved.
ＳｉＯｘとの複合体の形成に用い得る前記炭素材料としては、例えば、低結晶性炭素、カーボンナノチューブ、気相成長炭素繊維などの炭素材料が好ましいものとして挙げられる。
Preferred examples of the carbon material that can be used to form a composite with SiO x include carbon materials such as low crystalline carbon, carbon nanotubes, and vapor grown carbon fibers.
前記炭素材料の詳細としては、繊維状またはコイル状の炭素材料、カーボンブラック（アセチレンブラック、ケッチェンブラックを含む）、人造黒鉛、易黒鉛化炭素および難黒鉛化炭素よりなる群から選ばれる少なくとも１種の材料が好ましい。繊維状またはコイル状の炭素材料は、導電ネットワークを形成しやすく、かつ表面積の大きい点において好ましい。カーボンブラック（アセチレンブラック，ケッチェンブラックを含む）、易黒鉛化炭素および難黒鉛化炭素は、高い電気伝導性、高い保液性を有しており、更に、ＳｉＯｘ粒子が膨張収縮しても、その粒子との接触を保持しやすい性質を有している点において好ましい。
The details of the carbon material include at least one selected from the group consisting of fibrous or coiled carbon materials, carbon black (including acetylene black and ketjen black), artificial graphite, graphitizable carbon, and non-graphitizable carbon. A seed material is preferred. A fibrous or coiled carbon material is preferable in that it easily forms a conductive network and has a large surface area. Carbon black (including acetylene black and ketjen black), graphitizable carbon, and non-graphitizable carbon have high electrical conductivity and high liquid retention, and even if SiO x particles expand and contract. This is preferable in that it has a property of easily maintaining contact with the particles.
また、黒鉛をＳｉＯｘと炭素材料との複合体に係る炭素材料として使用することもできる。黒鉛も、カーボンブラックなどと同様に、高い電気伝導性、高い保液性を有しており、更に、ＳｉＯｘ粒子が膨張収縮しても、その粒子との接触を保持しやすい性質を有しているため、ＳｉＯｘとの複合体形成に好ましく使用することができる。
Moreover, graphite can also be used as a carbon material related to a composite of SiO x and a carbon material. Graphite, like carbon black, has high electrical conductivity and high liquid retention, and also has the property of easily maintaining contact with the SiO x particles even if they expand and contract. Therefore, it can be preferably used for forming a complex with SiO x .
前記例示の炭素材料の中でも、ＳｉＯｘとの複合体が造粒体である場合に用いるものとしては、繊維状の炭素材料が特に好ましい。繊維状の炭素材料は、その形状が細い糸状であり柔軟性が高いために電池の充放電に伴うＳｉＯｘの膨張収縮に追従でき、また、嵩密度が大きいために、ＳｉＯｘ粒子と多くの接合点を持つことができるからである。繊維状の炭素としては、例えば、ポリアクリロニトリル（ＰＡＮ）系炭素繊維、ピッチ系炭素繊維、気相成長炭素繊維、カーボンナノチューブなどが挙げられ、これらの何れを用いてもよい。
Among the carbon materials exemplified above, a fibrous carbon material is particularly preferable for use when the composite with SiO x is a granulated body. Fibrous carbon material can follow the expansion and contraction of SiO x with the charging and discharging of the battery due to the high shape is thin threadlike flexibility, also because bulk density is large, many and SiO x particles It is because it can have a junction. Examples of the fibrous carbon include polyacrylonitrile (PAN) -based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, and carbon nanotube, and any of these may be used.
なお、繊維状の炭素材料は、例えば、気相法にてＳｉＯｘ粒子の表面に形成することもできる。
The fibrous carbon material can also be formed on the surface of the SiO x particles by, for example, a vapor phase method.
また、ＳｉＯｘと炭素材料との複合体は、粒子表面の炭素材料被覆層を覆う材料層（難黒鉛化炭素を含む材料層）を更に有していてもよい。
The composite of SiO x and the carbon material may further have a material layer (a material layer containing non-graphitizable carbon) that covers the carbon material coating layer on the particle surface.
ＳｉＯｘと炭素材料との複合体において、ＳｉＯｘと炭素材料との比率は、炭素材料との複合化による作用を良好に発揮させる観点から、ＳｉＯｘ：１００質量部に対して、炭素材料が、５質量部以上であることが好ましく、１０質量部以上であることがより好ましい。また、前記複合体において、ＳｉＯｘと複合化する炭素材料の比率が多すぎると、負極合剤層中のＳｉＯｘ量の低下に繋がり、高容量化の効果が小さくなる虞があることから、ＳｉＯｘ：１００質量部に対して、炭素材料は、５０質量部以下であることが好ましく、４０質量部以下であることがより好ましい。
In complex with SiO x and the carbon material, the ratio between the SiO x and the carbon material, from the viewpoint of satisfactorily exhibiting action by complexation with carbon materials, SiO x: relative to 100 parts by mass, a carbon material The amount is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. Further, in the composite, if the ratio of the carbon material to be combined with SiO x is too large, it may lead to a decrease in the amount of SiO x in the negative electrode mixture layer, and the effect of increasing the capacity may be reduced. SiO x: relative to 100 parts by weight, the carbon material, and more preferably preferably not more than 50 parts by weight, more than 40 parts by weight.
前記のＳｉＯｘと炭素材料との複合体は、例えば下記の方法によって得ることができる。まず、ＳｉＯｘを複合化する場合の作製方法について説明する。ＳｉＯｘが分散媒に分散した分散液を用意し、それを噴霧し乾燥して、複数の粒子を含む複合粒子を作製する。分散媒としては、例えば、エタノールなどを用いることができる。分散液の噴霧は、通常、５０～３００℃の雰囲気内で行うことが適当である。前記の方法以外にも、振動型や遊星型のボールミルやロッドミルなどを用いた機械的な方法による造粒方法においても、同様の複合粒子を作製することができる。
The composite of the SiO x and the carbon material can be obtained, for example, by the following method. First, a manufacturing method in the case of combining SiO x will be described. A dispersion liquid in which SiO x is dispersed in a dispersion medium is prepared, and sprayed and dried to produce composite particles including a plurality of particles. For example, ethanol or the like can be used as the dispersion medium. It is appropriate to spray the dispersion liquid in an atmosphere of 50 to 300 ° C. In addition to the above method, similar composite particles can be produced also by a granulation method by a mechanical method using a vibration type or planetary type ball mill or rod mill.
なお、ＳｉＯｘと、ＳｉＯｘよりも比抵抗値の小さい炭素材料との造粒体を作製する場合には、ＳｉＯｘが分散媒に分散した分散液中に前記炭素材料を添加し、この分散液を用いて、ＳｉＯｘを複合化する場合と同様の手法によって複合粒子（造粒体）とすればよい。また、前記と同様の機械的な方法による造粒方法によっても、ＳｉＯｘと炭素材料との造粒体を作製することができる。
Incidentally, the SiO x, in the case of manufacturing a granulated body with small carbon material resistivity value than SiO x is adding the carbon material in the dispersion liquid of SiO x are dispersed in a dispersion medium, the dispersion by using a liquid, by a similar method to the case of composite of SiO x may be a composite particle (granule). Further, by granulation process according to the similar mechanical method, it is possible to produce a granular material of the SiO x and the carbon material.
次に、ＳｉＯｘ粒子（ＳｉＯｘ複合粒子、またはＳｉＯｘと炭素材料との造粒体）の表面を炭素材料で被覆して複合体とする場合には、例えば、ＳｉＯｘ粒子と炭化水素系ガスとを気相中にて加熱して、炭化水素系ガスの熱分解により生じた炭素を、粒子の表面上に堆積させる。このように、気相成長（ＣＶＤ）法によれば、炭化水素系ガスが複合粒子の隅々にまで行き渡り、粒子の表面や表面の空孔内に、導電性を有する炭素材料を含む薄くて均一な皮膜（炭素材料被覆層）を形成できることから、少量の炭素材料によってＳｉＯｘ粒子に均一性よく導電性を付与できる。
Next, when the surface of SiO x particles (SiO x composite particles or a granulated body of SiO x and a carbon material) is coated with a carbon material to form a composite, for example, the SiO x particles and the hydrocarbon-based material The gas is heated in the gas phase, and carbon generated by pyrolysis of the hydrocarbon-based gas is deposited on the surface of the particles. As described above, according to the vapor deposition (CVD) method, the hydrocarbon-based gas spreads to every corner of the composite particle, and the surface of the particle and the pores in the surface are thin and contain a conductive carbon material. Since a uniform film (carbon material coating layer) can be formed, the SiO x particles can be imparted with good conductivity with a small amount of carbon material.
炭素材料で被覆されたＳｉＯｘの製造において、気相成長（ＣＶＤ）法の処理温度（雰囲気温度）については、炭化水素系ガスの種類によっても異なるが、通常、６００～１２００℃が適当であり、中でも、７００℃以上であることが好ましく、８００℃以上であることが更に好ましい。処理温度が高い方が不純物の残存が少なく、かつ導電性の高い炭素を含む被覆層を形成できるからである。
In the production of SiO x coated with a carbon material, the processing temperature (atmosphere temperature) of the vapor deposition (CVD) method varies depending on the type of hydrocarbon gas, but usually 600 to 1200 ° C. is appropriate. Among these, the temperature is preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the treatment temperature, the less the remaining impurities, and the formation of a coating layer containing carbon having high conductivity.
炭化水素系ガスの液体ソースとしては、トルエン、ベンゼン、キシレン、メシチレンなどを用いることができるが、取り扱いやすいトルエンが特に好ましい。これらを気化させる（例えば、窒素ガスでバブリングする）ことにより炭化水素系ガスを得ることができる。また、メタンガスやアセチレンガスなどを用いることもできる。
As the liquid source of hydrocarbon gas, toluene, benzene, xylene, mesitylene and the like can be used, but toluene that is easy to handle is particularly preferable. A hydrocarbon-based gas can be obtained by vaporizing them (for example, bubbling with nitrogen gas). Moreover, methane gas, acetylene gas, etc. can also be used.
また、気相成長（ＣＶＤ）法にてＳｉＯｘ粒子（ＳｉＯｘ複合粒子、またはＳｉＯｘと炭素材料との造粒体）の表面を炭素材料で覆った後に、石油系ピッチ、石炭系のピッチ、熱硬化性樹脂、およびナフタレンスルホン酸塩とアルデヒド類との縮合物よりなる群から選択される少なくとも１種の有機化合物を、炭素材料を含む被覆層に付着させた後、前記有機化合物が付着した粒子を焼成してもよい。
In addition, after the surface of SiO x particles (SiO x composite particles or a granulated body of SiO x and a carbon material) is covered with a carbon material by a vapor deposition (CVD) method, a petroleum-based pitch or a coal-based pitch is used. At least one organic compound selected from the group consisting of a thermosetting resin and a condensate of naphthalene sulfonate and aldehydes is attached to a coating layer containing a carbon material, and then the organic compound is attached. The obtained particles may be fired.
具体的には、炭素材料で被覆されたＳｉＯｘ粒子（ＳｉＯｘ複合粒子、またはＳｉＯｘと炭素材料との造粒体）と、前記有機化合物とが分散媒に分散した分散液を用意し、この分散液を噴霧し乾燥して、有機化合物によって被覆された粒子を形成し、その有機化合物によって被覆された粒子を焼成する。
Specifically, a dispersion liquid in which a SiO x particle (SiO x composite particle or a granulated body of SiO x and a carbon material) coated with a carbon material and the organic compound are dispersed in a dispersion medium is prepared, The dispersion is sprayed and dried to form particles coated with the organic compound, and the particles coated with the organic compound are fired.
前記ピッチとしては等方性ピッチを、熱硬化性樹脂としてはフェノール樹脂、フラン樹脂、フルフラール樹脂などを用いることができる。ナフタレンスルホン酸塩とアルデヒド類との縮合物としては、ナフタレンスルホン酸ホルムアルデヒド縮合物を用いることができる。
Isotropic pitch can be used as the pitch, and phenol resin, furan resin, furfural resin, or the like can be used as the thermosetting resin. As the condensate of naphthalene sulfonate and aldehydes, naphthalene sulfonic acid formaldehyde condensate can be used.
炭素材料で被覆されたＳｉＯｘ粒子と前記有機化合物とを分散させるための分散媒には、例えば、水、アルコール類（エタノールなど）を用いることができる。分散液の噴霧は、通常、５０～３００℃の雰囲気内で行うことが適当である。焼成温度は、通常、６００～１２００℃が適当であるが、中でも７００℃以上が好ましく、８００℃以上であることが更に好ましい。処理温度が高い方が不純物の残存が少なく、かつ導電性の高い良質な炭素材料を含む被覆層を形成できるからである。ただし、処理温度はＳｉＯｘの融点以下であることを要する。
As a dispersion medium for dispersing the SiO x particles coated with the carbon material and the organic compound, for example, water or alcohols (ethanol or the like) can be used. It is appropriate to spray the dispersion liquid in an atmosphere of 50 to 300 ° C. The firing temperature is usually 600 to 1200 ° C., preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. This is because the higher the processing temperature, the less the remaining impurities, and the formation of a coating layer containing a high-quality carbon material with high conductivity. However, the processing temperature needs to be lower than the melting point of SiO x .
負極活物質にＳｉＯｘを使用する場合、ＳｉＯｘのみを用いてもよく、ＳｉＯｘと負極活物質とを併用してもよい。ＳｉＯｘと他の負極活物質とを併用する場合、前記他の負極活物質には、先に例示した各種負極活物質のうち、ＳｉＯｘ以外のものを使用することができるが、比較的容量が大きく、また、電池の充放電に伴う体積変化量がＳｉＯｘよりも小さいことから、高結晶の天然黒鉛、人造黒鉛といった黒鉛材料が好ましい。なお、天然黒鉛を使用する場合には、更に高温で熱処理を施したり、人造黒鉛の微粒子（粒状、扁平状など）を被覆させたり、樹脂などの有機物を被覆させて用いてもよい。
When SiO x is used for the negative electrode active material, only SiO x may be used, or SiO x and the negative electrode active material may be used in combination. When SiO x and other negative electrode active materials are used in combination, among the various negative electrode active materials exemplified above, materials other than SiO x can be used as the other negative electrode active materials. In addition, since the volume change due to charging / discharging of the battery is smaller than that of SiO x , graphite materials such as highly crystalline natural graphite and artificial graphite are preferable. When natural graphite is used, heat treatment may be performed at a higher temperature, artificial graphite fine particles (granular, flat, etc.) may be coated, or an organic substance such as a resin may be coated.
ＳｉＯｘと他の負極活物質とを併用する場合、全負極活物質の合計を１００質量％としたとき、ＳｉＯｘの割合は、電池をより高容量とする観点から、５質量％以上であることが好ましく、１０質量％以上であることがより好ましい。なお、このようにＳｉＯｘを比較的多くの割合で使用しても、正極が本発明の電極であるために、電池の充放電に伴う正極集電体の破断を抑制することができ、また、本発明の電極を負極として用いた場合には、電池の充放電に伴う負極集電体の破断を抑制することができる。
When SiO x and another negative electrode active material are used in combination, when the total of all negative electrode active materials is 100% by mass, the proportion of SiO x is 5% by mass or more from the viewpoint of increasing the capacity of the battery. It is preferably 10% by mass or more. Even when SiO x is used in a relatively large proportion as described above, since the positive electrode is the electrode of the present invention, it is possible to suppress breakage of the positive electrode current collector due to charge / discharge of the battery, When the electrode of the present invention is used as a negative electrode, breakage of the negative electrode current collector accompanying charging / discharging of the battery can be suppressed.
なお、負極活物質にはＳｉＯｘのみを使用してもよいため、全負極活物質の合計を１００質量％としたときのＳｉＯｘの割合は、１００質量％であってもよい。なお、前記の通り、黒鉛材料などを併用することで、電池の充放電サイクル特性を更に高めることもできるが、この場合、全負極活物質の合計を１００質量％としたときのＳｉＯｘの割合は、９５質量％以下であることが好ましく、８５質量％以下であることがより好ましい。
Since only the SiO x may be used as the negative electrode active material, the ratio of SiO x when the total of all the negative electrode active materials is 100% by mass may be 100% by mass. In addition, as described above, the charge / discharge cycle characteristics of the battery can be further enhanced by using a graphite material or the like in this case. In this case, the ratio of SiO x when the total of all the negative electrode active materials is 100% by mass. Is preferably 95% by mass or less, and more preferably 85% by mass or less.
負極合剤層に係るバインダには、ＰＶＤＦ、ＳＢＲ、カルボキシメチルセルロース（ＣＭＣ）、ポリビニルピロリドン（ＰＶＰ）、ポリアミドイミド、ポリイミド、ポリアミド、下記の式（１）で表されるユニットと式（２）で表されるユニットとを有する共重合体〔ただし、式（２）におけるＲは水素またはメチル基を表し、Ｍ１はナトリウム、カリウム、リチウムなどのアルカリ金属元素を表す〕などを使用することができる。
For the binder relating to the negative electrode mixture layer, PVDF, SBR, carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP), polyamideimide, polyimide, polyamide, a unit represented by the following formula (1) and formula (2) A copolymer having a unit represented by the formula (wherein R in the formula (2) represents hydrogen or a methyl group, and M 1 represents an alkali metal element such as sodium, potassium, or lithium) can be used. .
負極合剤層には導電助剤を含有させることもできる。負極合剤層に係る導電助剤には、正極合剤層に使用し得るものとして先に例示したものと同じものを用いることができる。
The negative electrode mixture layer can also contain a conductive additive. The same thing as what was illustrated previously as what can be used for a positive mix layer can be used for the conductive support agent which concerns on a negative mix layer.
負極合剤層の厚みは、例えば、集電体の片面あたり１０～１００μｍであることが好ましい。また、負極合剤層の組成としては、例えば、負極活物質の量が８５～９５質量％であることが好ましく、バインダの量が１～１５質量％であることが好ましく、導電助剤を使用する場合には、その量が１～１０質量％であることが好ましい。
The thickness of the negative electrode mixture layer is preferably, for example, 10 to 100 μm per one side of the current collector. As the composition of the negative electrode mixture layer, for example, the amount of the negative electrode active material is preferably 85 to 95% by mass, the amount of the binder is preferably 1 to 15% by mass, and a conductive assistant is used. In that case, the amount is preferably 1 to 10% by mass.
負極合剤層は、例えば、負極活物質およびバインダ、更には必要に応じて導電助剤などを、ＮＭＰなどの有機溶剤や水といった溶剤に分散させたペースト状やスラリー状の負極合剤含有組成物を調製し（ただし、バインダは溶剤に溶解していてもよい）、これを集電体の片面または両面に塗布し、乾燥した後に、必要に応じてカレンダー処理などのプレス処理を施す工程を経て形成することができる。
The negative electrode mixture layer is, for example, a paste-like or slurry-like negative electrode mixture-containing composition in which a negative electrode active material and a binder, and further a conductive auxiliary agent, if necessary, are dispersed in an organic solvent such as NMP or a solvent such as water. (However, the binder may be dissolved in a solvent), and this is applied to one or both sides of the current collector, dried, and then subjected to pressing treatment such as calendering as necessary. It can be formed through.
なお、本発明のリチウムイオン二次電池においては、ＳｉＯｘのような高容量で不可逆容量が大きい材料を負極活物質に使用した場合、電池の初期の充電で正極（正極活物質）から放出されたＬｉイオンのうちの比較的多くが次回の放電で正極に戻り得ないため、正極が本来備えている容量を十分に引き出すことができない虞がある。よって、本発明のリチウムイオン二次電池では、ＳｉＯｘのなどの不可逆容量が大きい負極活物質を使用する場合には、組み立て時において、その不可逆容量分を埋めるためのＬｉ供給源（プレドープ用Ｌｉ供給源）を、正極とは別に有していることが好ましい。
In the lithium ion secondary battery of the present invention, when a material having a high capacity and a large irreversible capacity such as SiO x is used for the negative electrode active material, it is released from the positive electrode (positive electrode active material) by the initial charge of the battery. Since relatively many of the Li ions cannot return to the positive electrode at the next discharge, there is a possibility that the capacity that the positive electrode originally has cannot be sufficiently extracted. Therefore, in the lithium ion secondary battery of the present invention, when a negative electrode active material having a large irreversible capacity such as SiO x is used, an Li supply source (Li for pre-doping) is used to fill the irreversible capacity during assembly. It is preferable to have a supply source) separately from the positive electrode.
Ｌｉ供給源としては、Ｌｉ金属箔、Ｌｉ合金箔（以下、両者を纏めて「Ｌｉ箔」と記載する）などが挙げられ、電池の外装体内のいずれかの箇所（非水電解液と接触可能な箇所）に、このＬｉ供給源を配置すればよい。具体的には、例えば、集電体となる銅箔などの金属箔に、Ｌｉ供給源となるＬｉ箔を貼り付けるなどして形成したＬｉ極を使用することができ、このＬｉ極を負極と電気的に接続しておくことで、Ｌｉ極のＬｉ箔がＬｉ供給源として機能する。また、負極の集電体の一部に負極合剤層を形成しない箇所を設け（例えばタブ部）、この箇所にＬｉ箔を貼り付けることで、Ｌｉ供給源を設けることもできる。
Examples of the Li supply source include Li metal foil and Li alloy foil (hereinafter collectively referred to as “Li foil”) and the like, and can be in contact with any part of the battery outer body (non-aqueous electrolyte solution). This Li supply source may be arranged at a certain point. Specifically, for example, a Li electrode formed by attaching a Li foil as a Li supply source to a metal foil such as a copper foil as a current collector can be used. By being electrically connected, the Li electrode Li foil functions as a Li supply source. Alternatively, a portion where the negative electrode mixture layer is not formed may be provided in a part of the current collector of the negative electrode (for example, a tab portion), and a Li supply source may be provided by attaching a Li foil to this portion.
負極活物質へのプレドープをするためのＬｉ供給源を設けた電池においては、導入するＬｉ供給源の量（Ｌｉ供給源に含まれるＬｉの量）を、電池の初回の充放電で、０．１Ｃ放電電流レートで電圧が２．０Ｖに達するまでの放電を行ったときに、正極活物質に含まれるＬｉと金属Ｍとのモル比Ｌｉ／Ｍが、０．９～１．０５となるようにすることが好ましい。
In a battery provided with a Li supply source for pre-doping the negative electrode active material, the amount of Li supply source to be introduced (the amount of Li contained in the Li supply source) is set to 0. When discharge is performed until the voltage reaches 2.0 V at a 1 C discharge current rate, the molar ratio Li / M of Li and metal M contained in the positive electrode active material is 0.9 to 1.05. It is preferable to make it.
Ｌｉ供給源（前記のＬｉ箔）は、前記の通り、そこから放出されるＬｉイオンが負極活物質の不可逆容量を埋めるために負極活物質に取り込まれるため、組み立てから時間が経過した電池内には存在していない場合があるが、前記のモル比Ｌｉ／Ｍが前記の値を満たす場合には、Ｌｉ供給源を導入して負極活物質にプレドープを行った電池であると判断できる。
As described above, the Li supply source (the Li foil) is incorporated into the negative electrode active material in order to fill the irreversible capacity of the negative electrode active material. However, when the molar ratio Li / M satisfies the above value, it can be determined that the battery is a battery in which a negative electrode active material is pre-doped by introducing a Li supply source.
なお、Ｌｉ供給源を導入した電池において、充放電を数十サイクル（１００サイクル以下）で繰り返した場合でも、前記のモル比Ｌｉ／Ｍは、初回の充放電における放電後から大きく変動しない。よって、１００サイクル以下程度の充放電サイクル数を経た電池において、モル比Ｌｉ／Ｍが前記の値を満たす場合には、電池の組み立て時にＬｉ供給源を導入し、負極活物質にプレドープをした電池とみなすことができる。
In addition, even when charging / discharging is repeated in several tens of cycles (100 cycles or less) in a battery into which a Li supply source is introduced, the molar ratio Li / M does not vary greatly after the discharge in the first charge / discharge. Therefore, in a battery that has passed the number of charge / discharge cycles of about 100 cycles or less, when the molar ratio Li / M satisfies the above value, a Li supply source is introduced at the time of battery assembly and the negative electrode active material is pre-doped. Can be considered.
図５に、本発明の電極（負極）の一例を模式的に表す平面図を示す。図５に示す電極（負極）２０は、集電体２２の表面に電極合剤層（負極合剤層）２１を有している。この電極合剤層２１を有する部分（図中、ドットを付して表示）が本体部である。また、電極（負極）２０には、集電体２２の両面に電極合剤層が形成されていない露出部からなるタブ部２３が設けられている。また、タブ部２３には負極タブ２４とＬｉ供給源２５とがそれぞれ設置されている。なお、図５に示す電極の本体部は、平面視で長方形である。
FIG. 5 is a plan view schematically showing an example of the electrode (negative electrode) of the present invention. The electrode (negative electrode) 20 shown in FIG. 5 has an electrode mixture layer (negative electrode mixture layer) 21 on the surface of the current collector 22. A portion having the electrode mixture layer 21 (shown with dots in the drawing) is a main body portion. The electrode (negative electrode) 20 is provided with a tab portion 23 formed of an exposed portion where the electrode mixture layer is not formed on both surfaces of the current collector 22. The tab portion 23 is provided with a negative electrode tab 24 and a Li supply source 25. Note that the electrode main body shown in FIG. 5 is rectangular in plan view.
図５に示すように、本発明の電極（負極）２０は、集電体２２の表面に電極合剤層（負極合剤層）２１を有する本体部と、タブ部とを有している。なお、図５においてはタブ部２３を電極（負極）２０の右端に設けているが、電極（負極）２０の中央付近に設けてもよい。
As shown in FIG. 5, the electrode (negative electrode) 20 of the present invention has a main body portion having an electrode mixture layer (negative electrode mixture layer) 21 on the surface of a current collector 22 and a tab portion. In FIG. 5, the tab portion 23 is provided at the right end of the electrode (negative electrode) 20, but may be provided near the center of the electrode (negative electrode) 20.
本発明の電池に係るセパレータには、例えば、ポリオレフィン、ポリエステル、ポリイミド、ポリアミド、ポリウレタンなどの樹脂で構成された多孔質膜を使用することができるが、セパレータにシャットダウン機能を持たせる観点から、ポリオレフィン製の多孔質膜を使用することが好ましい。
For the separator according to the battery of the present invention, for example, a porous film composed of a resin such as polyolefin, polyester, polyimide, polyamide, polyurethane can be used. From the viewpoint of providing the separator with a shutdown function, polyolefin is used. It is preferred to use a porous membrane made of
ポリオレフィンとしては、低密度ポリエチレン、高密度ポリエチレン、超高分子量ポリエチレンなどのポリエチレン（ＰＥ）；ポリプロピレン（ＰＰ）；などが挙げられ、これらのうちの１種のみを用いてもよく、２種以上を併用してもよい。例えば、２種以上のポリオレフィンを使用した多孔質膜としては、例えば、ＰＰ層上にＰＥ層を介してＰＰ層を積層した三層構造の多孔質膜が挙げられる。
Examples of the polyolefin include polyethylene (PE) such as low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene; polypropylene (PP); etc., and only one of these may be used. You may use together. For example, as a porous film using two or more kinds of polyolefin, for example, a porous film having a three-layer structure in which a PP layer is laminated on a PP layer via a PE layer can be mentioned.
これらのポリオレフィンの中でも、融点、すなわち、ＪＩＳ Ｋ ７１２１の規定に準じて、ＤＳＣを用いて測定される融解温度が、８０～１５０℃のものを使用することが好ましい。このような融点のポリオレフィンを含有する多孔質膜であれば、前記ポリオレフィンが軟化してセパレータの空孔が閉塞されるシャットダウン特性の開始温度が９０～１５０℃のセパレータとすることができるため、かかるセパレータを使用することで、電池の安全性を更に高めることが可能となる。
Among these polyolefins, those having a melting point, that is, a melting temperature measured by DSC of 80 to 150 ° C., in accordance with JIS K 7121 are preferably used. A porous film containing a polyolefin having such a melting point can be a separator having a shutdown characteristic starting temperature of 90 to 150 ° C. in which the polyolefin is softened and the pores of the separator are closed. By using the separator, it is possible to further improve the safety of the battery.
セパレータに使用する多孔質膜としては、例えば、従来から知られている溶剤抽出法や、乾式または湿式延伸法などにより形成された孔を多数有するイオン透過性の多孔質膜（電池のセパレータとして汎用されている微多孔膜）を用いることができる。
Examples of porous membranes used in separators include ion-permeable porous membranes having a large number of pores formed by a conventionally known solvent extraction method, dry type or wet drawing method (generally used as battery separators). A microporous film) can be used.
また、前記の多孔質膜（微多孔膜）の表面に、耐熱性の無機フィラーを含有する耐熱性の多孔質層を形成した積層型のセパレータを用いてもよい。このような積層型のセパレータを用いた場合には、電池内の温度が上昇してもセパレータの収縮が抑制されて、正極と負極との接触による短絡を抑えることができるため、より安全性の高い非水二次電池とすることができる。
Alternatively, a laminated separator in which a heat-resistant porous layer containing a heat-resistant inorganic filler is formed on the surface of the porous film (microporous film) may be used. When such a stacked separator is used, the shrinkage of the separator is suppressed even when the temperature in the battery rises, and a short circuit due to contact between the positive electrode and the negative electrode can be suppressed. A high non-aqueous secondary battery can be obtained.
耐熱性の多孔質層に含有させる無機フィラーとしては、ベーマイト、アルミナ、シリカ、酸化チタンなどが好ましく、これらのうちの１種または２種以上を使用することができる。
As the inorganic filler to be contained in the heat-resistant porous layer, boehmite, alumina, silica, titanium oxide and the like are preferable, and one or more of these can be used.
また、耐熱性の多孔質層には、前記の無機フィラー同士を結着したり、耐熱性の多孔質層と微多孔膜とを接着したりするためのバインダを含有させることが好ましい。バインダには、エチレン－酢酸ビニル共重合体（ＥＶＡ、酢酸ビニル由来の構造単位が２０～３５モル％のもの）、エチレン－エチルアクリレート共重合体などのエチレン－アクリル酸共重合体、フッ素系ゴム、ＳＢＲ、カルボキシメチルセルロース（ＣＭＣ）、ヒドロキシエチルセルロース（ＨＥＣ）、ポリビニルアルコール（ＰＶＡ）、ポリビニルブチラール（ＰＶＢ）、ポリビニルピロリドン（ＰＶＰ）、架橋アクリル樹脂、ポリウレタン、エポキシ樹脂などを用いることが好ましく、これらのうちの１種または２種以上を使用することができる。
Further, the heat-resistant porous layer preferably contains a binder for binding the inorganic fillers or bonding the heat-resistant porous layer and the microporous film. The binder includes an ethylene-vinyl acetate copolymer (EVA, having a structural unit derived from vinyl acetate of 20 to 35 mol%), an ethylene-acrylic acid copolymer such as an ethylene-ethyl acrylate copolymer, and a fluorine-based rubber. , SBR, carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), crosslinked acrylic resin, polyurethane, epoxy resin, etc. are preferably used. One or more of them can be used.
耐熱性の多孔質層における無機フィラーの含有量は、耐熱性の多孔質層を構成する成分の全体積中（空孔部分を除く全体積中）、５０体積％以上であることが好ましく、７０体積％以上であることがより好ましく、９９体積％以下であることがより好ましい（残部は、前記のバインダであればよい）。
The content of the inorganic filler in the heat-resistant porous layer is preferably 50% by volume or more in the entire volume of the components constituting the heat-resistant porous layer (in the entire volume excluding the pores), 70 It is more preferable that the volume is not less than volume%, and it is more preferable that the volume be not more than 99 volume% (the remainder may be the above binder).
セパレータ（ポリオレフィン製の微多孔膜からなるセパレータや、前記積層型のセパレータ）の厚みは、電池反応に関与しない成分の電池内容積の占有率を低減して正負極の活物質量を多くすることを可能にすることで、電池の設計容量や出力密度を高める観点から、３０μｍ以下であることが好ましく、１６μｍ以下であることがより好ましい。ただし、セパレータの強度を十分に保つ観点からは、セパレータの厚みは、５μｍ以上であることが好ましく、１０μｍ以上であることがより好ましい。
The thickness of the separator (a separator made of a microporous membrane made of polyolefin, or the laminated separator) is to reduce the occupancy of the battery internal volume of components that are not involved in the battery reaction and increase the amount of active material of the positive and negative electrodes From the viewpoint of increasing the design capacity and output density of the battery, it is preferably 30 μm or less, and more preferably 16 μm or less. However, from the viewpoint of sufficiently maintaining the strength of the separator, the thickness of the separator is preferably 5 μm or more, and more preferably 10 μm or more.
また、前記積層型のセパレータの場合、耐熱性の多孔質層の厚みは、３～８μｍであることが好ましい。また、耐熱性の多孔質層の空孔率は、４０～７０％であることが好ましい。
In the case of the laminated separator, the heat-resistant porous layer preferably has a thickness of 3 to 8 μm. The porosity of the heat resistant porous layer is preferably 40 to 70%.
本発明の電池に係る非水電解液には、下記の非水系溶媒中に、リチウム塩を溶解させることで調製した溶液が使用できる。
For the non-aqueous electrolyte solution according to the battery of the present invention, a solution prepared by dissolving a lithium salt in the following non-aqueous solvent can be used.
溶媒としては、例えば、エチレンカーボネート（ＥＣ）、プロピレンカーボネート（ＰＣ）、ブチレンカーボネート（ＢＣ）、ジメチルカーボネート（ＤＭＣ）、ジエチルカーボネート（ＤＥＣ）、メチルエチルカーボネート（ＭＥＣ）、γ－ブチロラクトン（γ-
ＢＬ）、１，２－ジメトキシエタン(ＤＭＥ)、テトラヒドロフラン(ＴＨＦ)、２－メチルテトラヒドロフラン、ジメチルスルフォキシド(ＤＭＳＯ)、１，３－ジオキソラン、ホルムアミド、ジメチルホルムアミド(ＤＭＦ)、ジオキソラン、アセトニトリル、ニトロメタン、蟻酸メチル、酢酸メチル、燐酸トリエステル、トリメトキシメタン、ジオキソラン誘導体、スルホラン、３－メチル－２－オキサゾリジノン、プロピレンカーボネート誘導体、テトラヒドロフラン誘導体、ジエチルエーテル、１，３－プロパンサルトンなどの非プロトン性有機溶媒を１種単独で、または２種以上を混合した混合溶媒として用いることができる。 Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), γ-butyrolactone (γ-
BL), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO), 1,3-dioxolane, formamide, dimethylformamide (DMF), dioxolane, acetonitrile, nitromethane Aprotic such as methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3-propane sultone The organic solvent can be used alone or as a mixed solvent in which two or more are mixed.
ＢＬ）、１，２－ジメトキシエタン(ＤＭＥ)、テトラヒドロフラン(ＴＨＦ)、２－メチルテトラヒドロフラン、ジメチルスルフォキシド(ＤＭＳＯ)、１，３－ジオキソラン、ホルムアミド、ジメチルホルムアミド(ＤＭＦ)、ジオキソラン、アセトニトリル、ニトロメタン、蟻酸メチル、酢酸メチル、燐酸トリエステル、トリメトキシメタン、ジオキソラン誘導体、スルホラン、３－メチル－２－オキサゾリジノン、プロピレンカーボネート誘導体、テトラヒドロフラン誘導体、ジエチルエーテル、１，３－プロパンサルトンなどの非プロトン性有機溶媒を１種単独で、または２種以上を混合した混合溶媒として用いることができる。 Examples of the solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), γ-butyrolactone (γ-
BL), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO), 1,3-dioxolane, formamide, dimethylformamide (DMF), dioxolane, acetonitrile, nitromethane Aprotic such as methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, diethyl ether, 1,3-propane sultone The organic solvent can be used alone or as a mixed solvent in which two or more are mixed.
非水電解液に係るリチウム塩としては、例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、Ｌｉ２Ｃ２Ｆ４（ＳＯ３）２、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣｎＦ２ｎ＋１ＳＯ３（ｎ≧２）、ＬｉＮ（ＲｆＯＳＯ２）２〔ここでＲｆはフルオロアルキル基〕などから選ばれる少なくとも１種が挙げられる。これらのリチウム塩の非水電解液中の濃度としては、０．６～１．８ｍｏｌ／ｌとすることが好ましく、０．９～１．６ｍｏｌ／ｌとすることがより好ましい。
The lithium salt according to the non-aqueous electrolyte solution, for example, LiClO 4, LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, Li 2 C 2 F 4 (SO 3) 2, At least selected from LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (n ≧ 2), LiN (RfOSO 2 ) 2 [where Rf is a fluoroalkyl group] One type is mentioned. The concentration of these lithium salts in the non-aqueous electrolyte is preferably 0.6 to 1.8 mol / l, and more preferably 0.9 to 1.6 mol / l.
また、非水電解液には、充放電サイクル特性の更なる改善や、高温貯蔵性や過充電防止などの安全性を向上させる目的で、ビニレンカーボネート、ビニルエチレンカーボネート、無水酸、スルホン酸エステル、ジニトリル、１，３－プロパンサルトン、ジフェニルジスルフィド、シクロヘキシルベンゼン、ビフェニル、フルオロベンゼン、ｔ－ブチルベンゼンなどの添加剤（これらの誘導体も含む）を適宜加えることもできる。
In addition, in the non-aqueous electrolyte, vinylene carbonate, vinyl ethylene carbonate, acid anhydride, sulfonic acid ester, for the purpose of improving the safety such as further improvement of charge / discharge cycle characteristics and high temperature storage property and prevention of overcharge, Additives (including these derivatives) such as dinitrile, 1,3-propane sultone, diphenyl disulfide, cyclohexylbenzene, biphenyl, fluorobenzene, and t-butylbenzene can be added as appropriate.
更に、非水電解液には、ポリマーなどの公知のゲル化剤を添加してゲル化したもの（ゲル状電解質）を用いることもできる。
Furthermore, as the non-aqueous electrolyte, a gel (gel electrolyte) obtained by adding a known gelling agent such as a polymer can be used.
本発明のリチウムイオン二次電池は、扁平形状または円柱形状であるスチール缶やアルミニウム缶などを外装缶として使用したり、金属を蒸着したラミネートフィルムを外装体としたソフトパッケージ電池としたりすることができる。
The lithium ion secondary battery of the present invention may be a flat or cylindrical steel can or aluminum can used as an outer can, or may be a soft package battery using a metal-deposited laminated film as an outer package. it can.
以下、実施例に基づいて本発明を詳細に述べる。ただし、下記実施例は、本発明を制限するものではない。
Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.
実施例１
＜正極の作製＞
正極活物質であるＬｉＣｏＯ２：９６．５質量部と、バインダであるＰＶＤＦを１０質量％の濃度で含むＮＭＰ溶液：２０質量部と、導電助剤であるアセチレンブラック：１．５質量部とを、二軸混練機を用いて混練し、更にＮＭＰを加えて粘度を調節して、正極合剤含有ペーストを調製した。このペーストを、後述するように複数の貫通孔を有する厚みが１５μｍで長方形のアルミニウム箔の両面に、本体部の長辺方向へテンションを掛けながら連続的に間欠塗布し、乾燥を行って、アルミニウム箔の片面または両面に正極合剤層を形成し、本体部の長辺方向へテンションを掛けながら連続的にプレス処理を行い、合剤層の塗膜密度が３．８０ｇ／ｃｍ３となるように正極合剤層の厚みを調整し、本体部の短辺方向が５２ｍｍ、長辺方向が７０５ｍｍになるように切断した。切断後、アルミニウム箔が露出したタブ部に、正極タブ（アルミニウム製）を溶接して図１に示すものと、各構成要素のサイズを除いて同様の構造の正極を作製した。 Example 1
<Preparation of positive electrode>
LiCoO 2 as a positive electrode active material: 96.5 parts by mass, NMP solution containing PVDF as a binder at a concentration of 10% by mass: 20 parts by mass, and acetylene black as a conductive auxiliary agent: 1.5 parts by mass The mixture was kneaded using a twin-screw kneader, and NMP was added to adjust the viscosity to prepare a positive electrode mixture-containing paste. As will be described later, this paste is intermittently applied to both sides of a rectangular aluminum foil having a plurality of through-holes and having a thickness of 15 μm while applying tension in the long side direction of the main body portion, and then dried to obtain aluminum. A positive electrode mixture layer is formed on one or both sides of the foil, and press treatment is continuously performed while applying tension in the long side direction of the main body so that the coating film density of the mixture layer is 3.80 g / cm 3. The thickness of the positive electrode mixture layer was adjusted, and the main body was cut so that the short side direction was 52 mm and the long side direction was 705 mm. After cutting, a positive electrode tab (made of aluminum) was welded to the tab portion where the aluminum foil was exposed to produce a positive electrode having the same structure as that shown in FIG. 1 except for the size of each component.
＜正極の作製＞
正極活物質であるＬｉＣｏＯ２：９６．５質量部と、バインダであるＰＶＤＦを１０質量％の濃度で含むＮＭＰ溶液：２０質量部と、導電助剤であるアセチレンブラック：１．５質量部とを、二軸混練機を用いて混練し、更にＮＭＰを加えて粘度を調節して、正極合剤含有ペーストを調製した。このペーストを、後述するように複数の貫通孔を有する厚みが１５μｍで長方形のアルミニウム箔の両面に、本体部の長辺方向へテンションを掛けながら連続的に間欠塗布し、乾燥を行って、アルミニウム箔の片面または両面に正極合剤層を形成し、本体部の長辺方向へテンションを掛けながら連続的にプレス処理を行い、合剤層の塗膜密度が３．８０ｇ／ｃｍ３となるように正極合剤層の厚みを調整し、本体部の短辺方向が５２ｍｍ、長辺方向が７０５ｍｍになるように切断した。切断後、アルミニウム箔が露出したタブ部に、正極タブ（アルミニウム製）を溶接して図１に示すものと、各構成要素のサイズを除いて同様の構造の正極を作製した。 Example 1
<Preparation of positive electrode>
LiCoO 2 as a positive electrode active material: 96.5 parts by mass, NMP solution containing PVDF as a binder at a concentration of 10% by mass: 20 parts by mass, and acetylene black as a conductive auxiliary agent: 1.5 parts by mass The mixture was kneaded using a twin-screw kneader, and NMP was added to adjust the viscosity to prepare a positive electrode mixture-containing paste. As will be described later, this paste is intermittently applied to both sides of a rectangular aluminum foil having a plurality of through-holes and having a thickness of 15 μm while applying tension in the long side direction of the main body portion, and then dried to obtain aluminum. A positive electrode mixture layer is formed on one or both sides of the foil, and press treatment is continuously performed while applying tension in the long side direction of the main body so that the coating film density of the mixture layer is 3.80 g / cm 3. The thickness of the positive electrode mixture layer was adjusted, and the main body was cut so that the short side direction was 52 mm and the long side direction was 705 mm. After cutting, a positive electrode tab (made of aluminum) was welded to the tab portion where the aluminum foil was exposed to produce a positive electrode having the same structure as that shown in FIG. 1 except for the size of each component.
また、正極集電体には、孔径が１５０μｍの貫通孔が図２に示す千鳥配列（以下、「パターンＡ」と記載する）で設けられており、正極集電体の空孔率は１７％で、１つの貫通孔１２０と、これに最も近接する６つの貫通孔との間の距離が４００μｍである。そして、この正極集電体を、図２において一点鎖線で示す各直線のうち、図中斜めの２つの直線が、それぞれ本体部の短辺に平行な方向から３０°となり、図中左右方向の直線が、本体部の短辺に平行な方向から９０°となるように配置した。
Further, the positive electrode current collector is provided with through holes having a hole diameter of 150 μm in a staggered arrangement shown in FIG. 2 (hereinafter referred to as “pattern A”), and the positive electrode current collector has a porosity of 17%. Thus, the distance between one through hole 120 and the six through holes closest to the through hole 120 is 400 μm. In the positive electrode current collector, among the straight lines indicated by the alternate long and short dash line in FIG. 2, two diagonal lines in the figure are 30 ° from the direction parallel to the short side of the main body, respectively, It arrange | positioned so that a straight line may become 90 degrees from the direction parallel to the short side of a main-body part.
＜負極の作製＞
平均粒子径Ｄ５０％が２２μｍ、ｄ００２が０．３３８ｎｍで、ＢＥＴ法による比表面積が３．８ｍ２／ｇである黒鉛Ａ（表面を非晶質炭素で被覆していない黒鉛）と、平均粒子径Ｄ５０％が１０μｍ、ｄ００２が０．３３６ｎｍで、ＢＥＴ法による比表面積が３．９ｍ２／ｇである黒鉛Ｂ（黒鉛からなる母粒子の表面を非晶質炭素で被覆した黒鉛）と、ＳｉＯの表面を炭素で被覆した複合体（平均粒子径８μｍ、複合体における炭素の量が２０質量％。以下、「ＳｉＯ／炭素複合体」と記載する。）とを、４７．５：４７．５：５の比率（質量比）で混合した混合物：９３質量部、前記式（１）で表わされるユニットと前記（２）式で表わされるユニットとを有し、前記式（２）におけるＲが水素でＭ１がカリウムであり、前記式（１）で表わされるユニットと前記式（２）で表わされるユニットとのモル比が６／４である共重合体（Ａ）：５質量部、並びに導電助剤であるケッチェンブラック：２質量部をイオン交換水と混合して、水系の負極合剤含有ペーストを調製した。 <Production of negative electrode>
The average particle diameter D50% is 22 .mu.m, with d 002 is 0.338 nm, the graphite BET specific surface area is 3.8m 2 / g A (graphite no surface coating with amorphous carbon), the average particle diameter D50% is 10 [mu] m, with d 002 is 0.336 nm, the graphite BET specific surface area is 3.9m2 / g B (graphite covering the surface of the mother particle made of graphite with amorphous carbon), SiO 47.5: 47.5 is a composite in which the surface is coated with carbon (average particle size 8 μm, the amount of carbon in the composite is 20 mass%, hereinafter referred to as “SiO / carbon composite”). : A mixture mixed at a ratio (mass ratio) of 5: 93 parts by mass, a unit represented by the formula (1) and a unit represented by the formula (2), and R in the formula (2) is hydrogen in M 1 is potassium, the above formula (1) Copolymer (A) having a molar ratio of the unit represented to the unit represented by the formula (2) of 6/4: 5 parts by mass, and ketjen black as a conductive auxiliary agent: 2 parts by mass A water-based negative electrode mixture-containing paste was prepared by mixing with water.
平均粒子径Ｄ５０％が２２μｍ、ｄ００２が０．３３８ｎｍで、ＢＥＴ法による比表面積が３．８ｍ２／ｇである黒鉛Ａ（表面を非晶質炭素で被覆していない黒鉛）と、平均粒子径Ｄ５０％が１０μｍ、ｄ００２が０．３３６ｎｍで、ＢＥＴ法による比表面積が３．９ｍ２／ｇである黒鉛Ｂ（黒鉛からなる母粒子の表面を非晶質炭素で被覆した黒鉛）と、ＳｉＯの表面を炭素で被覆した複合体（平均粒子径８μｍ、複合体における炭素の量が２０質量％。以下、「ＳｉＯ／炭素複合体」と記載する。）とを、４７．５：４７．５：５の比率（質量比）で混合した混合物：９３質量部、前記式（１）で表わされるユニットと前記（２）式で表わされるユニットとを有し、前記式（２）におけるＲが水素でＭ１がカリウムであり、前記式（１）で表わされるユニットと前記式（２）で表わされるユニットとのモル比が６／４である共重合体（Ａ）：５質量部、並びに導電助剤であるケッチェンブラック：２質量部をイオン交換水と混合して、水系の負極合剤含有ペーストを調製した。 <Production of negative electrode>
The average particle diameter D50% is 22 .mu.m, with d 002 is 0.338 nm, the graphite BET specific surface area is 3.8m 2 / g A (graphite no surface coating with amorphous carbon), the average particle diameter D50% is 10 [mu] m, with d 002 is 0.336 nm, the graphite BET specific surface area is 3.9m2 / g B (graphite covering the surface of the mother particle made of graphite with amorphous carbon), SiO 47.5: 47.5 is a composite in which the surface is coated with carbon (average particle size 8 μm, the amount of carbon in the composite is 20 mass%, hereinafter referred to as “SiO / carbon composite”). : A mixture mixed at a ratio (mass ratio) of 5: 93 parts by mass, a unit represented by the formula (1) and a unit represented by the formula (2), and R in the formula (2) is hydrogen in M 1 is potassium, the above formula (1) Copolymer (A) having a molar ratio of the unit represented to the unit represented by the formula (2) of 6/4: 5 parts by mass, and ketjen black as a conductive auxiliary agent: 2 parts by mass A water-based negative electrode mixture-containing paste was prepared by mixing with water.
前記負極合剤含有ペーストを後述するように複数の貫通孔を有する厚みが１０μｍで長方形の銅箔の両面に本体部の長辺方向へテンションを掛けながら連続的に間欠塗布し乾燥を行って、銅箔の両面に負極合剤層を形成し、本体部の長辺方向へテンションを掛けながら連続的にプレス処理を行って負極合剤層の密度を１．５６ｇ／ｃｍ３に調整した後に、本体部の短辺方向が５３ｍｍ、長辺方向が６８５ｍｍになるように切断した。切断後、銅箔が露出したタブ部に、負極タブを溶接した。更に、銅箔の露出したタブ部に厚み３００μmのＬｉ箔（負極へのＬｉプレドープ用）を圧着して図５に示すものと、各構成要素のサイズを除いて同様の構造の負極を作製した。
As described later, the negative electrode mixture-containing paste has a thickness of 10 μm and has a thickness of 10 μm, and is continuously applied intermittently while applying tension to the long side direction of the main body on both sides of the rectangular copper foil. After forming the negative electrode mixture layer on both sides of the copper foil and adjusting the density of the negative electrode mixture layer to 1.56 g / cm 3 by continuously pressing while applying tension in the long side direction of the main body, The main body was cut so that the short side direction was 53 mm and the long side direction was 685 mm. After cutting, a negative electrode tab was welded to the tab portion where the copper foil was exposed. Further, a 300 μm thick Li foil (for Li pre-doping to the negative electrode) was pressure-bonded to the exposed tab portion of the copper foil to produce a negative electrode having the same structure as that shown in FIG. 5 except for the size of each component. .
また、負極集電体には、孔径が１５０μｍの貫通孔がパターンＡの配置で設けられており（ただし、図５では、集電体２２の露出部であるタブ部２３において、貫通孔を示していない）、負極集電体の空孔率は１７％で、１つの貫通孔１２０と、これに最も近接する６つの貫通孔との間の距離が１８０μｍである。そして、この負極集電体を、図２において一点鎖線で示す各直線のうち、図中斜めの２つの直線が、それぞれ本体部の短辺に平行な方向から３０°となり、図中左右方向の直線が、本体部の短辺に平行な方向から９０°となるように配置した。
Further, the negative electrode current collector is provided with through holes having a hole diameter of 150 μm in the pattern A arrangement (however, in FIG. 5, the through holes are shown in the tab portion 23 which is the exposed portion of the current collector 22). The porosity of the negative electrode current collector is 17%, and the distance between one through hole 120 and the six through holes closest to it is 180 μm. In the negative electrode current collector, among the straight lines indicated by the alternate long and short dash line in FIG. 2, two diagonal lines in the figure are 30 ° from the direction parallel to the short side of the main body, respectively, It arrange | positioned so that a straight line may become 90 degrees from the direction parallel to the short side of a main-body part.
＜セパレータの作製＞
二次凝集体ベーマイト５ｋｇにイオン交換水５ｋｇと分散剤（水系ポリカルボン酸アンモニウム塩、固形分濃度４０％）０．５ｋｇとを加え、内容積２０Ｌ、転回数４０回／分のボールミルで１０時間解砕処理をして分散液を調製した。処理後の分散液を１２０℃で真空乾燥し、ＳＥＭ観察をしたところ、ベーマイトの形状はほぼ板状であった。また、レーザー散乱粒度分布計（ＨＯＲＩＢＡ社製「ＬＡ－９２０」）を用い、屈折率１．６５としてベーマイトの平均粒子径（Ｄ５０％）を測定したところ、１．０μｍであった。 <Preparation of separator>
Add 5 kg of ion-exchanged water and 0.5 kg of a dispersant (aqueous polycarboxylic acid ammonium salt, solid content concentration 40%) to 5 kg of secondary aggregate boehmite, and use a ball mill for 20 hours with an internal volume of 20 L and a rotation speed of 40 times / minute for 10 hours. A dispersion was prepared by crushing treatment. The treated dispersion was vacuum-dried at 120 ° C. and observed by SEM. As a result, the shape of boehmite was almost plate-like. Further, when the average particle diameter (D50%) of boehmite was measured with a refractive index of 1.65 using a laser scattering particle size distribution analyzer (“LA-920” manufactured by HORIBA), it was 1.0 μm.
二次凝集体ベーマイト５ｋｇにイオン交換水５ｋｇと分散剤（水系ポリカルボン酸アンモニウム塩、固形分濃度４０％）０．５ｋｇとを加え、内容積２０Ｌ、転回数４０回／分のボールミルで１０時間解砕処理をして分散液を調製した。処理後の分散液を１２０℃で真空乾燥し、ＳＥＭ観察をしたところ、ベーマイトの形状はほぼ板状であった。また、レーザー散乱粒度分布計（ＨＯＲＩＢＡ社製「ＬＡ－９２０」）を用い、屈折率１．６５としてベーマイトの平均粒子径（Ｄ５０％）を測定したところ、１．０μｍであった。 <Preparation of separator>
Add 5 kg of ion-exchanged water and 0.5 kg of a dispersant (aqueous polycarboxylic acid ammonium salt, solid content concentration 40%) to 5 kg of secondary aggregate boehmite, and use a ball mill for 20 hours with an internal volume of 20 L and a rotation speed of 40 times / minute for 10 hours. A dispersion was prepared by crushing treatment. The treated dispersion was vacuum-dried at 120 ° C. and observed by SEM. As a result, the shape of boehmite was almost plate-like. Further, when the average particle diameter (D50%) of boehmite was measured with a refractive index of 1.65 using a laser scattering particle size distribution analyzer (“LA-920” manufactured by HORIBA), it was 1.0 μm.
前記分散液５００ｇに、増粘剤としてキサンタンガムを０．５ｇ、バインダとして樹脂バインダーディスパージョン（変性ポリブチルアクリレート、固形分含量４５質量％）を１７ｇ加え、スリーワンモーターで３時間攪拌して均一なスラリー〔多孔質層（II）形成用スラリーａ、固形分比率５０質量％〕を調製した。
To 500 g of the above dispersion, 0.5 g of xanthan gum as a thickener and 17 g of a resin binder dispersion (modified polybutyl acrylate, solid content 45% by mass) as a binder are added and stirred with a three-one motor for 3 hours to form a uniform slurry. [Porous layer (II) forming slurry a, solid content ratio 50 mass%] was prepared.
リチウムイオン二次電池用ＰＥ製微多孔質セパレータ〔多孔質層（I）：厚み８μｍ、空孔率４０％、平均孔径０．０２μｍ、ＰＥの融点１３５℃〕の片面にコロナ放電処理（放電量４０Ｗ・ｍｉｎ／ｍ２）を施し、この処理面に多孔質層（II）形成用スラリーａをマイクログラビアコーターによって塗布し、乾燥して多孔質層（II）を形成してセパレータを得た。なお、多孔質層（II）の厚みは、４μｍに調整した。また、多孔質層（II）の構成成分の全体積中におけるベーマイトの含有量は、８８体積％であった。
PE microporous separator for lithium ion secondary battery [Porous layer (I): thickness 8 μm, porosity 40%, average pore diameter 0.02 μm, PE melting point 135 ° C.] on one side corona discharge treatment (discharge amount) 40 W · min / m 2 ) was applied, and the slurry a for forming the porous layer (II) was applied to the treated surface with a microgravure coater and dried to form a porous layer (II) to obtain a separator. The thickness of the porous layer (II) was adjusted to 4 μm. The boehmite content in the total volume of the constituent components of the porous layer (II) was 88% by volume.
＜電池の組み立て＞
前記の正極と負極とセパレータとを用いて巻回電極体を作製した。図６に、巻回電極体を作製する際の正極、負極およびセパレータの配置を模式的に表す平面図を示している。なお、図６は、巻回電極体作製時の正極、負極およびセパレータの配置を説明するためのものであって、各構成要素のサイズは正確ではない。この図６に示す通り、正極１０および負極２０を、セパレータ３を介して重ね合わせた状態〔ただし、セパレータ３の多孔質層（II）は正極１０側に向くように重ねる〕とした。なお、図６では、負極のＬｉ供給源は示していない。 <Battery assembly>
A wound electrode body was prepared using the positive electrode, the negative electrode, and the separator. FIG. 6 is a plan view schematically showing the arrangement of the positive electrode, the negative electrode, and the separator when the wound electrode body is manufactured. In addition, FIG. 6 is for demonstrating arrangement | positioning of the positive electrode, negative electrode, and separator at the time of winding electrode body manufacture, Comprising: The size of each component is not exact. As shown in FIG. 6, thepositive electrode 10 and the negative electrode 20 were overlapped via the separator 3 (however, the porous layer (II) of the separator 3 was overlapped so as to face the positive electrode 10). In FIG. 6, the Li supply source of the negative electrode is not shown.
前記の正極と負極とセパレータとを用いて巻回電極体を作製した。図６に、巻回電極体を作製する際の正極、負極およびセパレータの配置を模式的に表す平面図を示している。なお、図６は、巻回電極体作製時の正極、負極およびセパレータの配置を説明するためのものであって、各構成要素のサイズは正確ではない。この図６に示す通り、正極１０および負極２０を、セパレータ３を介して重ね合わせた状態〔ただし、セパレータ３の多孔質層（II）は正極１０側に向くように重ねる〕とした。なお、図６では、負極のＬｉ供給源は示していない。 <Battery assembly>
A wound electrode body was prepared using the positive electrode, the negative electrode, and the separator. FIG. 6 is a plan view schematically showing the arrangement of the positive electrode, the negative electrode, and the separator when the wound electrode body is manufactured. In addition, FIG. 6 is for demonstrating arrangement | positioning of the positive electrode, negative electrode, and separator at the time of winding electrode body manufacture, Comprising: The size of each component is not exact. As shown in FIG. 6, the
次に正極１０、負極２０およびセパレータ３を、図６の左側の電極短辺端を巻芯側として渦巻き状に巻回し、更に扁平状に押しつぶして巻回電極体を得た。得られた巻回電極体を模式的に表す斜視図を図７に示す。図７に示す通り、巻回電極体３０の正極タブ１４および負極タブ２４は、巻回電極体の最外周側に位置している。
Next, the positive electrode 10, the negative electrode 20, and the separator 3 were wound in a spiral shape with the short electrode end on the left side in FIG. 6 as the winding core side, and further crushed into a flat shape to obtain a wound electrode body. A perspective view schematically showing the obtained wound electrode body is shown in FIG. As shown in FIG. 7, the positive electrode tab 14 and the negative electrode tab 24 of the wound electrode body 30 are located on the outermost peripheral side of the wound electrode body.
そして、前記巻回電極体が収まるように窪みを形成した厚み：０．１５ｍｍ、幅：６１ｍｍ、高さ：６８ｍｍのアルミニウムラミネートフィルムの、前記窪みに前記巻回電極体を挿入し、その上に前記と同じサイズのアルミニウムラミネートフィルムを置いて、両アルミニウムラミネートフィルムの３辺を熱溶着した。そして、両アルミニウムラミネートフィルムの残りの１辺から非水電解液〔エチレンカーボネートとエチルメチルカーボネートとジエチルカーボネートとを体積比＝１：１：１で混合した溶媒に、ＬｉＰＦ６を１．１ｍｏｌ／ｌの濃度になるように溶解させ、４－フルオロ－１，３－ジオキソラン－２－オンを１．５質量％、ビニレンカーボネートを２．０質量％、および２－プロピニル２－（ジエトキシホスホリル）アセテートを１．５質量％となる量で添加した溶液〕を注入し、その後、両アルミニウムラミネートフィルムの前記残りの１辺を真空熱封止して、図８に示す外観で、図９に示す断面構造のリチウムイオン二次電池を作製した。
And the said winding electrode body is inserted in the said hollow of the aluminum laminate film of thickness: 0.15mm, width: 61mm, and height: 68mm which formed the hollow so that the said winding electrode body might be accommodated, and on it An aluminum laminate film of the same size as described above was placed, and three sides of both aluminum laminate films were thermally welded. Then, from the remaining one side of both aluminum laminate films, non-aqueous electrolyte [LiPF6 was added at 1.1 mol / l in a solvent in which ethylene carbonate, ethylmethyl carbonate and diethyl carbonate were mixed at a volume ratio = 1: 1: 1. Dissolved to a concentration, 1.5% by mass of 4-fluoro-1,3-dioxolan-2-one, 2.0% by mass of vinylene carbonate, and 2-propynyl 2- (diethoxyphosphoryl) acetate Solution added in an amount of 1.5% by mass], and then the remaining one side of both aluminum laminate films is vacuum heat sealed to obtain the cross-sectional structure shown in FIG. A lithium ion secondary battery was prepared.
図８および図９について説明すると、図８はリチウムイオン二次電池を模式的に表す平面図であり、図９は、図８のＩ－Ｉ線断面図である。リチウムイオン二次電池１００は、２枚のアルミニウムラミネートフィルムで構成したアルミニウムラミネートフィルム外装体１０１内に、正極と負極とをセパレータを介して積層し、渦巻状に巻回して構成した巻回電極体３０と、非水電解液（図示しない）とを収容しており、アルミニウムラミネートフィルム外装体１０１は、その外周部において、上下のアルミニウムラミネートフィルムを熱融着することにより封止されている。なお、図９では、図面が煩雑になることを避けるために、アルミニウムラミネートフィルム外装体１０１を構成している各層や、巻回電極体を構成している正極、負極およびセパレータを区別して示していない。
8 and 9, FIG. 8 is a plan view schematically showing a lithium ion secondary battery, and FIG. 9 is a cross-sectional view taken along the line II of FIG. A lithium ion secondary battery 100 includes a wound electrode body in which a positive electrode and a negative electrode are laminated via a separator in an aluminum laminate film outer package 101 composed of two aluminum laminate films and wound in a spiral shape. 30 and a non-aqueous electrolyte (not shown) are accommodated, and the aluminum laminate film exterior body 101 is sealed by heat-sealing the upper and lower aluminum laminate films at the outer peripheral portion thereof. In FIG. 9, in order to avoid making the drawing complicated, each layer constituting the aluminum laminate film outer package 101 and the positive electrode, the negative electrode and the separator constituting the wound electrode body are shown separately. Absent.
巻回電極体３０の有する正極の正極タブ１４、および負極の負極タブ２４は、外部の機器などと接続可能なように、片端側をアルミニウムラミネートフィルム外装体１０１の外側に引き出している。
The positive electrode tab 14 of the positive electrode and the negative electrode tab 24 of the negative electrode of the wound electrode body 30 are drawn out to the outside of the aluminum laminate film exterior body 101 so that they can be connected to an external device or the like.
実施例２
正極集電体を、孔径が１５０μｍの貫通孔が図３に示す千鳥配列（以下、「パターンＢ」と記載する）で設けられており、空孔率が１７％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が３８０μｍであるものに変更し、この正極集電体を、図中の一点鎖線で示す直線が、本体部の短辺に平行な方向から９０°となるように配置した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 2
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm in the staggered arrangement shown in FIG. 3 (hereinafter referred to as “pattern B”), and the porosity is 17%. The distance between the through hole closest to this is changed to 380 μm, and the positive electrode current collector is changed from the direction in which the straight line indicated by the alternate long and short dash line in the figure is parallel to the short side of the main body portion. A positive electrode for a battery was produced in the same manner as in Example 1 except that the positive electrode for a battery was arranged so as to be at 0 °. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体を、孔径が１５０μｍの貫通孔が図３に示す千鳥配列（以下、「パターンＢ」と記載する）で設けられており、空孔率が１７％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が３８０μｍであるものに変更し、この正極集電体を、図中の一点鎖線で示す直線が、本体部の短辺に平行な方向から９０°となるように配置した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 2
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm in the staggered arrangement shown in FIG. 3 (hereinafter referred to as “pattern B”), and the porosity is 17%. The distance between the through hole closest to this is changed to 380 μm, and the positive electrode current collector is changed from the direction in which the straight line indicated by the alternate long and short dash line in the figure is parallel to the short side of the main body portion. A positive electrode for a battery was produced in the same manner as in Example 1 except that the positive electrode for a battery was arranged so as to be at 0 °. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
実施例３
正極集電体を、孔径が１５０μｍの貫通孔が図３に示す並列配列（以下、「パターンＣ」と記載する）で設けられており、空孔率が１７％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が３７０μｍであるものに変更し、この正極集電体を、図中の一点鎖線で示す２本の直線が、それぞれ本体部の短辺に平行な方向から４５°となるように配置した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 3
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm in the parallel arrangement shown in FIG. 3 (hereinafter referred to as “pattern C”), and the porosity is 17%. The distance between the through hole closest to this is changed to 370 μm, and the two straight lines indicated by the alternate long and short dash line in the figure of this positive electrode current collector are parallel to the short side of the main body part, respectively. A positive electrode for a battery was produced in the same manner as in Example 1 except that it was disposed at 45 ° from the right direction. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体を、孔径が１５０μｍの貫通孔が図３に示す並列配列（以下、「パターンＣ」と記載する）で設けられており、空孔率が１７％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が３７０μｍであるものに変更し、この正極集電体を、図中の一点鎖線で示す２本の直線が、それぞれ本体部の短辺に平行な方向から４５°となるように配置した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 3
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm in the parallel arrangement shown in FIG. 3 (hereinafter referred to as “pattern C”), and the porosity is 17%. The distance between the through hole closest to this is changed to 370 μm, and the two straight lines indicated by the alternate long and short dash line in the figure of this positive electrode current collector are parallel to the short side of the main body part, respectively. A positive electrode for a battery was produced in the same manner as in Example 1 except that it was disposed at 45 ° from the right direction. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
実施例４
正極集電体を、孔径が１５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が３５％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が１８０μｍであるものに変更した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 4
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm arranged in the pattern A, the porosity is 35%, and the distance between one throughhole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Example 1 except that the thickness was changed to 180 μm. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体を、孔径が１５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が３５％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が１８０μｍであるものに変更した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 4
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm arranged in the pattern A, the porosity is 35%, and the distance between one through
実施例５
負極集電体の向きを、図２中の３本の一点鎖線で示した直線のうちの１本が、本体部の短辺に平行な方向となり、残りの２本が、本体部の短辺に平行な方向から３０°となるように配置した以外は、実施例１と同様にして電池用負極を作製した。そして、前記電池用負極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 5
The direction of the negative electrode current collector is such that one of the three straight lines shown in FIG. 2 is parallel to the short side of the main body, and the other two are the short sides of the main body. A negative electrode for a battery was produced in the same manner as in Example 1 except that it was arranged at 30 ° from a direction parallel to the negative electrode. And the lithium ion secondary battery was produced like Example 1 except having used the said negative electrode for batteries.
負極集電体の向きを、図２中の３本の一点鎖線で示した直線のうちの１本が、本体部の短辺に平行な方向となり、残りの２本が、本体部の短辺に平行な方向から３０°となるように配置した以外は、実施例１と同様にして電池用負極を作製した。そして、前記電池用負極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 5
The direction of the negative electrode current collector is such that one of the three straight lines shown in FIG. 2 is parallel to the short side of the main body, and the other two are the short sides of the main body. A negative electrode for a battery was produced in the same manner as in Example 1 except that it was arranged at 30 ° from a direction parallel to the negative electrode. And the lithium ion secondary battery was produced like Example 1 except having used the said negative electrode for batteries.
実施例６
正極集電体を、孔径が１５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が５０％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が１００μｍであるものに変更した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 6
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm arranged in the pattern A, the porosity is 50%, and the distance between one throughhole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Example 1 except that the thickness was changed to 100 μm. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体を、孔径が１５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が５０％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が１００μｍであるものに変更した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 6
The positive electrode current collector is provided with through holes having a hole diameter of 150 μm arranged in the pattern A, the porosity is 50%, and the distance between one through
実施例７
正極集電体を、孔径が４５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が２５％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が８００μｍであるものに変更した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 7
The positive electrode current collector is provided with through holes having a hole diameter of 450 μm arranged in the pattern A, the porosity is 25%, and the distance between one throughhole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Example 1 except that the thickness was changed to 800 μm. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体を、孔径が４５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が２５％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が８００μｍであるものに変更した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Example 7
The positive electrode current collector is provided with through holes having a hole diameter of 450 μm arranged in the pattern A, the porosity is 25%, and the distance between one through
比較例１
正極集電体の向きを、図２中の３本の一点鎖線で示した直線のうちの１本が、本体部の短辺に平行な方向となり、残りの２本が、本体部の短辺に平行な方向から３０°となるように配置した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 1
As for the direction of the positive electrode current collector, one of the three straight lines shown in FIG. 2 is parallel to the short side of the main body, and the other two are the short sides of the main body. A positive electrode for a battery was produced in the same manner as in Example 1 except that it was arranged at 30 ° from a direction parallel to the positive electrode. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体の向きを、図２中の３本の一点鎖線で示した直線のうちの１本が、本体部の短辺に平行な方向となり、残りの２本が、本体部の短辺に平行な方向から３０°となるように配置した以外は、実施例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 1
As for the direction of the positive electrode current collector, one of the three straight lines shown in FIG. 2 is parallel to the short side of the main body, and the other two are the short sides of the main body. A positive electrode for a battery was produced in the same manner as in Example 1 except that it was arranged at 30 ° from a direction parallel to the positive electrode. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
比較例２
正極集電体を、孔径が３５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が１７％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が９００μｍであるものに変更した以外は、比較例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 2
The positive electrode current collector is provided with through holes having a hole diameter of 350 μm arranged in the pattern A, the porosity is 17%, and the distance between one throughhole 120 and the closest through hole A positive electrode for a battery was produced in the same manner as in Comparative Example 1 except that the thickness was changed to 900 μm. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体を、孔径が３５０μｍの貫通孔がパターンＡの配置で設けられており、空孔率が１７％で、１つの貫通孔１２０と、これに最も近接する貫通孔との間の距離が９００μｍであるものに変更した以外は、比較例１と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 2
The positive electrode current collector is provided with through holes having a hole diameter of 350 μm arranged in the pattern A, the porosity is 17%, and the distance between one through
比較例３
正極集電体の向きを、図３中の一点鎖線で示した直線が、本体部の短辺に平行な方向となるように配置した以外は、実施例２と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 3
A positive electrode for a battery was produced in the same manner as in Example 2 except that the direction of the positive electrode current collector was arranged so that the straight line indicated by the alternate long and short dash line in FIG. 3 was parallel to the short side of the main body. did. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体の向きを、図３中の一点鎖線で示した直線が、本体部の短辺に平行な方向となるように配置した以外は、実施例２と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 3
A positive electrode for a battery was produced in the same manner as in Example 2 except that the direction of the positive electrode current collector was arranged so that the straight line indicated by the alternate long and short dash line in FIG. 3 was parallel to the short side of the main body. did. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
比較例４
正極集電体の向きを、図４中の２本の一点鎖線で示した直線のうちの１本が、本体部の短辺に平行な方向となり、残りの１本が、本体部の短辺に平行な方向から９０°となるように配置した以外は、実施例３と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 4
In the direction of the positive electrode current collector, one of the two straight lines shown in FIG. 4 is a direction parallel to the short side of the main body, and the other one is the short side of the main body. A positive electrode for a battery was produced in the same manner as in Example 3, except that it was disposed at 90 ° from a direction parallel to the positive electrode. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
正極集電体の向きを、図４中の２本の一点鎖線で示した直線のうちの１本が、本体部の短辺に平行な方向となり、残りの１本が、本体部の短辺に平行な方向から９０°となるように配置した以外は、実施例３と同様にして電池用正極を作製した。そして、前記電池用正極を用いた以外は、実施例１と同様にしてリチウムイオン二次電池を作製した。 Comparative Example 4
In the direction of the positive electrode current collector, one of the two straight lines shown in FIG. 4 is a direction parallel to the short side of the main body, and the other one is the short side of the main body. A positive electrode for a battery was produced in the same manner as in Example 3, except that it was disposed at 90 ° from a direction parallel to the positive electrode. And the lithium ion secondary battery was produced like Example 1 except having used the said battery positive electrode.
実施例および比較例のリチウムイオン二次電池について、以下の各評価を行った。
The following evaluations were performed on the lithium ion secondary batteries of Examples and Comparative Examples.
＜巻回電極体作製時の溶接の際の正極および負極のタブ部の破断・亀裂の有無＞
実施例および比較例の各電池に使用した巻回電極体を作製したときの、各正極のタブを正極集電体上に溶接した際、並びに各負極のタブを負極集電体上に溶接した際に、タブ部の溶接部分を目視観察し、破断や亀裂の有無を確認した。 <Presence / absence of fracture / cracking of the tab portions of the positive electrode and the negative electrode during welding during the production of the wound electrode body>
When the wound electrode bodies used in the batteries of Examples and Comparative Examples were prepared, the tabs of the respective positive electrodes were welded onto the positive electrode current collector, and the negative electrode tabs were welded onto the negative electrode current collector. At that time, the welded portion of the tab portion was visually observed to confirm the presence or absence of breakage or cracks.
実施例および比較例の各電池に使用した巻回電極体を作製したときの、各正極のタブを正極集電体上に溶接した際、並びに各負極のタブを負極集電体上に溶接した際に、タブ部の溶接部分を目視観察し、破断や亀裂の有無を確認した。 <Presence / absence of fracture / cracking of the tab portions of the positive electrode and the negative electrode during welding during the production of the wound electrode body>
When the wound electrode bodies used in the batteries of Examples and Comparative Examples were prepared, the tabs of the respective positive electrodes were welded onto the positive electrode current collector, and the negative electrode tabs were welded onto the negative electrode current collector. At that time, the welded portion of the tab portion was visually observed to confirm the presence or absence of breakage or cracks.
評価は、実施例および比較例のそれぞれにおいて、１０個ずつの巻回電極体について実施し、そのうちの全てにおいて破断や亀裂が生じなかった場合を◎、１個でも亀裂が生じたものの、破断は生じなかった場合を○、１個でも破断が生じたものを×とした。
Evaluation was carried out for each of the 10 wound electrode bodies in each of the examples and comparative examples, and in all cases where no breaks or cracks occurred, even if one crack occurred, the break was The case where it did not occur was marked with ○, and the case where even one piece was broken was marked with ×.
＜リチウムイオン二次電池の充放電サイクル後における正極集電体の破断・亀裂の有無＞
実施例および比較例の各電池について、組立後室温で２週間経過したのち、０．５Ｃの電流値で電圧が４．４Ｖになるまで定電流で充電を行い、引き続いて４．４Ｖの定電圧充電を、電流値が０．０５Ｃになるまで行った後に、０．２Ｃの電流値で電圧が２．０Ｖになるまで定電流放電を行う一連の操作を１サイクルとして、これらを５０サイクル実施した。その後、各電池を分解して、電極の状態を目視観察した。 <Presence or absence of fracture / crack of positive electrode current collector after charge / discharge cycle of lithium ion secondary battery>
About each battery of an Example and a comparative example, after assembly for 2 weeks at room temperature, it charged with a constant current until the voltage became 4.4V with the electric current value of 0.5C, and was followed by the constant voltage of 4.4V A series of operations in which charging was performed until the current value reached 0.05 C and then constant current discharging was performed until the voltage reached 2.0 V at a current value of 0.2 C was performed as 50 cycles. . Then, each battery was disassembled and the state of the electrode was visually observed.
実施例および比較例の各電池について、組立後室温で２週間経過したのち、０．５Ｃの電流値で電圧が４．４Ｖになるまで定電流で充電を行い、引き続いて４．４Ｖの定電圧充電を、電流値が０．０５Ｃになるまで行った後に、０．２Ｃの電流値で電圧が２．０Ｖになるまで定電流放電を行う一連の操作を１サイクルとして、これらを５０サイクル実施した。その後、各電池を分解して、電極の状態を目視観察した。 <Presence or absence of fracture / crack of positive electrode current collector after charge / discharge cycle of lithium ion secondary battery>
About each battery of an Example and a comparative example, after assembly for 2 weeks at room temperature, it charged with a constant current until the voltage became 4.4V with the electric current value of 0.5C, and was followed by the constant voltage of 4.4V A series of operations in which charging was performed until the current value reached 0.05 C and then constant current discharging was performed until the voltage reached 2.0 V at a current value of 0.2 C was performed as 50 cycles. . Then, each battery was disassembled and the state of the electrode was visually observed.
評価は、実施例および比較例のそれぞれにおいて、１０個ずつの電池について実施し、正極または負極の集電体において、破断や亀裂が生じなかった場合を◎、１個でも亀裂が生じたものの、破断は生じなかった場合を○、１個でも破断が生じたものを×とした。
Evaluation was carried out for each of the 10 batteries in each of the examples and comparative examples, and in the positive electrode or negative electrode current collector, no break or crack occurred. Even if one crack occurred, A case where no breakage occurred was marked with ○, and a case where even one breakage occurred was marked with ×.
実施例および比較例の各リチウムイオン二次電池における正極集電体の構成を表１に、負極集電体の構成を表２に示し、前記の各評価結果を表３に示す。なお、表１および表２における「角度」は、１つの貫通孔と、これに最も近接する他の貫通孔との間の直線の、本体部の短辺に平行な方向からの角度（集電体の短辺に平行な方向からの角度）を意味している。
Table 1 shows the configuration of the positive electrode current collector in each lithium ion secondary battery of Examples and Comparative Examples, Table 2 shows the configuration of the negative electrode current collector, and Table 3 shows the evaluation results. The “angle” in Tables 1 and 2 is the angle from the direction parallel to the short side of the main body of the straight line between one through hole and the other through hole closest to the through hole (current collection). Angle from a direction parallel to the short side of the body).
表１から表３に示す通り、集電体における貫通孔の配置が適正な正極を使用した実施例１～７のリチウムイオン二次電池は、充放電サイクル後における正極の本体部での集電体の破断の発生が抑制されており、高い信頼性を有していた。また、実施例１～７のリチウムイオン二次電池に使用した正極は、正極タブの溶接時タブ部の破断の発生が良好に抑制されていたが、貫通孔の平均径や正極集電体の空孔率がより好適な実施例１～５に係る正極は、タブ部の亀裂の発生も良好に抑制されていた。他方、負極に関しては、正極よりも破断が生じ難いため、集電体における貫通孔の配置が不適な実施例５に係る負極においても、例えば、負極タブの溶接の際には、特に問題は生じなかったが、電池の充放電サイクル後においては、集電体に亀裂の発生が認められ、これらの配置が適正な実施例１～４、６、７に係る負極よりも信頼性が劣っていた。
As shown in Tables 1 to 3, the lithium ion secondary batteries of Examples 1 to 7 using the positive electrode with the proper arrangement of the through-holes in the current collector are current collectors in the main body of the positive electrode after the charge / discharge cycle. The occurrence of breakage of the body was suppressed, and it had high reliability. In addition, in the positive electrodes used in the lithium ion secondary batteries of Examples 1 to 7, the occurrence of breakage of the tab portion during welding of the positive electrode tab was well suppressed, but the average diameter of the through holes and the positive electrode current collector In the positive electrodes according to Examples 1 to 5 having more preferable porosity, the occurrence of cracks in the tab portion was well suppressed. On the other hand, since the negative electrode is less likely to break than the positive electrode, even in the negative electrode according to Example 5 in which the arrangement of the through holes in the current collector is inappropriate, for example, when the negative electrode tab is welded, a problem particularly occurs. However, after the charge / discharge cycle of the battery, cracks were observed in the current collector, and the reliability was inferior to the negative electrodes according to Examples 1 to 4, 6, and 7 in which these arrangements were appropriate. .
これに対し、集電体における貫通孔の配置が不適な正極を使用した比較例１～４の電池は、充放電サイクル後に正極の集電体で破断が生じており、信頼性が劣っていた。また、これらの電池に使用した正極は、巻回電極体作製時の溶接の際にも集電体に破断の発生が認められ、信頼性が劣っていた。
On the other hand, the batteries of Comparative Examples 1 to 4 using the positive electrode in which the arrangement of the through holes in the current collector was inadequate were inferior in reliability because the positive electrode current collector was broken after the charge / discharge cycle. . In addition, the positive electrode used in these batteries was inferior in reliability due to the occurrence of breakage in the current collector during welding during the production of the wound electrode body.
本発明は、その趣旨を逸脱しない範囲で、前記以外の形態としても実施が可能である。本出願に開示された実施形態は一例であって、本発明は、これらの実施形態には限定されない。本発明の範囲は、前記の明細書の記載よりも、添付されている請求の範囲の記載を優先して解釈され、請求の範囲と均等の範囲内での全ての変更は、請求の範囲に含まれる。
The present invention can be implemented in other forms as long as it does not depart from the spirit of the present invention. The embodiments disclosed in the present application are examples, and the present invention is not limited to these embodiments. The scope of the present invention is construed in preference to the description of the appended claims rather than the description of the above specification, and all modifications within the scope equivalent to the claims are construed in the scope of the claims. included.
本発明のリチウムイオン二次電池は、従来から知られているリチウムイオン二次電池が適用されている各種用途と同じ用途に適用することができる。
The lithium ion secondary battery of the present invention can be applied to the same applications as various applications to which conventionally known lithium ion secondary batteries are applied.
１０ 正極
１１ 正極合剤層
１２ 正極集電体
１３ タブ部
１４ 正極タブ
２０ 負極
２１ 負極合剤層
２２ 負極集電体
２３ タブ部
２４ 負極タブ
２５ Ｌｉ供給源
１２０ 貫通孔 DESCRIPTION OFSYMBOLS 10 Positive electrode 11 Positive electrode mixture layer 12 Positive electrode collector 13 Tab part 14 Positive electrode tab 20 Negative electrode 21 Negative electrode mixture layer 22 Negative electrode collector 23 Tab part 24 Negative electrode tab 25 Li supply source 120 Through-hole
１１ 正極合剤層
１２ 正極集電体
１３ タブ部
１４ 正極タブ
２０ 負極
２１ 負極合剤層
２２ 負極集電体
２３ タブ部
２４ 負極タブ
２５ Ｌｉ供給源
１２０ 貫通孔 DESCRIPTION OF
Claims (10)
- 正極および負極がセパレータを介して巻回されてなる巻回電極体を有する電気化学素子の、前記正極または前記負極に使用される電気化学素子用電極であって、
電極活物質を含有する電極合剤層を集電体の片面または両面に有する本体部と、前記集電体の両面に電極合剤層を有しないタブ部とを有しており、
前記本体部は、平面視で、１対の短辺と１対の長辺とを有する長方形であり、
前記集電体は、片面から他面に貫通する複数の貫通孔を有しており、かつ前記複数の貫通孔は規則的に配置されており、
１つの貫通孔と、前記１つの貫通孔と最も近接する他の貫通孔とを結ぶ直線が、前記本体部の短辺に平行な方向から０°±２０°の範囲内に存在していないことを特徴とする電気化学素子用電極。 An electrochemical element electrode used for the positive electrode or the negative electrode of an electrochemical element having a wound electrode body in which a positive electrode and a negative electrode are wound through a separator,
A main body having an electrode mixture layer containing an electrode active material on one or both sides of the current collector, and a tab portion having no electrode mixture layer on both sides of the current collector;
The main body is a rectangle having a pair of short sides and a pair of long sides in plan view,
The current collector has a plurality of through holes penetrating from one surface to the other surface, and the plurality of through holes are regularly arranged;
A straight line connecting one through hole and the other through hole closest to the one through hole does not exist within a range of 0 ° ± 20 ° from a direction parallel to the short side of the main body. An electrode for an electrochemical element characterized by the above. - 前記複数の貫通孔は、特定のパターンの繰り返しによって配置されている請求項１に記載の電気化学素子用電極。 The electrode for an electrochemical element according to claim 1, wherein the plurality of through holes are arranged by repeating a specific pattern.
- 前記複数の貫通孔は、千鳥配列によって配置されている請求項１または２に記載の電気化学素子用電極。 The electrode for an electrochemical element according to claim 1 or 2, wherein the plurality of through holes are arranged in a staggered arrangement.
- 前記複数の貫通孔の平均径が１～４００μｍである請求項１～３のいずれかに記載の電気化学素子用電極。 4. The electrode for an electrochemical element according to claim 1, wherein an average diameter of the plurality of through holes is 1 to 400 μm.
- 前記集電体の空孔率が３～５０％である請求項１～４のいずれかに記載の電気化学素子用電極。 The electrode for an electrochemical element according to any one of claims 1 to 4, wherein the current collector has a porosity of 3 to 50%.
- リチウムイオン二次電池の正極に使用される請求項１～５のいずれかに記載の電気化学素子用電極。 The electrode for an electrochemical element according to any one of claims 1 to 5, which is used for a positive electrode of a lithium ion secondary battery.
- 正極および負極がセパレータを介して巻回されてなる巻回電極体と、非水電解液とを有するリチウムイオン二次電池であって、
少なくとも前記正極が、請求項１～６のいずれかに記載の電気化学素子用電極であることを特徴とするリチウムイオン二次電池。 A lithium ion secondary battery having a wound electrode body in which a positive electrode and a negative electrode are wound through a separator, and a non-aqueous electrolyte,
A lithium ion secondary battery, wherein at least the positive electrode is an electrode for an electrochemical element according to any one of claims 1 to 6. - 前記正極および前記負極の両方が、請求項１～６のいずれかに記載の電気化学素子用電極である請求項７に記載のリチウムイオン二次電池。 The lithium ion secondary battery according to claim 7, wherein both the positive electrode and the negative electrode are electrodes for electrochemical devices according to any one of claims 1 to 6.
- 前記負極は、Ｓｉを構成元素に含む材料Ｓを負極活物質とし、前記負極が含有する全負極活物質の合計を１００質量％としたとき、前記材料Ｓの割合が５質量％以上である請求項７または８に記載のリチウムイオン二次電池。 The negative electrode has a material S containing Si as a constituent element as a negative electrode active material, and the total amount of all negative electrode active materials contained in the negative electrode is 100% by mass, and the ratio of the material S is 5% by mass or more. Item 9. The lithium ion secondary battery according to Item 7 or 8.
- 前記材料Ｓは、ＳｉとＯとを構成元素に含む材料（ただし、Ｓｉに対するＯの原子比ｘは、０．５≦ｘ≦１．５である）である請求項９に記載のリチウムイオン二次電池。 10. The material according to claim 9, wherein the material S is a material containing Si and O as constituent elements (provided that the atomic ratio x of O to Si is 0.5 ≦ x ≦ 1.5). Next battery.
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