WO2014020729A1 - 非水電解液二次電池 - Google Patents
非水電解液二次電池 Download PDFInfo
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- WO2014020729A1 WO2014020729A1 PCT/JP2012/069617 JP2012069617W WO2014020729A1 WO 2014020729 A1 WO2014020729 A1 WO 2014020729A1 JP 2012069617 W JP2012069617 W JP 2012069617W WO 2014020729 A1 WO2014020729 A1 WO 2014020729A1
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- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
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- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
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- 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
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- 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
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- 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
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
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- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/443—Particulate material
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- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
- H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
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- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
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- H01M2300/0028—Organic electrolyte characterised by the solvent
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- H01M2300/0028—Organic electrolyte characterised by the solvent
- H01M2300/0034—Fluorinated solvents
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- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
- H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
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- 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
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- 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
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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present invention relates to a non-aqueous electrolyte secondary battery. Specifically, the present invention relates to a lithium secondary battery and other nonaqueous electrolyte secondary batteries that can be applied to a vehicle-mounted power source.
- Secondary batteries such as lithium secondary batteries and nickel metal hydride batteries are used as in-vehicle power sources that use electricity as driving sources, or power sources that are installed in personal computers, portable terminals, and other electrical products.
- lithium secondary batteries and other non-aqueous electrolyte secondary batteries that are lightweight and obtain high energy density are suitable as high-output power sources for mounting on vehicles such as electric vehicles and hybrid vehicles.
- further performance improvement such as higher energy density is required.
- Patent Document 1 proposes a non-aqueous electrolyte secondary battery that uses a positive electrode active material that exhibits an operating voltage higher than 4.3 V on the basis of metallic lithium.
- the use of a positive electrode active material having a higher working potential can be an effective means for increasing the energy density.
- the metal element constituting the positive electrode active material may be eluted.
- the battery is charged under the condition that it is charged until the potential of the positive electrode is 4.5 V or higher with respect to metallic lithium (hereinafter, the potential based on metallic lithium may be expressed as “vs. Li / Li + ”).
- the discharge is repeated, the tendency of the metal element to elute from the positive electrode is increased, and the battery capacity may be deteriorated due to precipitation of the eluted metal on the negative electrode.
- the present invention relates to an improvement in a non-aqueous electrolyte secondary battery using a positive electrode having a high operating upper limit potential, and an object thereof is to provide a non-aqueous electrolyte secondary battery capable of suppressing deterioration of battery capacity. It is to be.
- the present invention provides a nonaqueous electrolyte secondary battery including an electrode body including a positive electrode and a negative electrode.
- the upper limit operating potential of the positive electrode is 4.5 V or more based on metallic lithium.
- the electrode body includes a lithium titanate-containing layer. The lithium titanate-containing layer is separated from the negative electrode.
- the lithium titanate-containing layer separated from the negative electrode captures the metal element eluted from the positive electrode. Thereby, the metal element is prevented from being deposited on the negative electrode, and the deterioration of the battery capacity is suppressed. It has been confirmed that when the lithium titanate-containing layer is in contact with the negative electrode, the capacity deterioration is rather increased.
- the positive electrode includes a lithium transition metal composite oxide having a spinel structure as a positive electrode active material, and the lithium transition metal composite oxide is a transition metal. It contains at least nickel and manganese as elements. Since this positive electrode active material has a high operating potential, a secondary battery constructed using the positive electrode active material can be charged to a higher potential. Therefore, it can be said that a transition metal (typically manganese (Mn)) is eluted from the positive electrode by high potential charge / discharge, and an event in which the eluted metal element is deposited on the negative electrode tends to occur.
- Mn manganese
- the effect of the present invention that is, the effect of suppressing the deterioration of the battery capacity by capturing the eluted transition metal before reaching the negative electrode can be suitably exhibited.
- the lithium titanate-containing layer is disposed between the positive electrode and the negative electrode.
- the lithium titanate can appropriately capture the metal element.
- the separator is arrange
- the lithium titanate-containing layer contains 50% by mass or more of lithium titanate. Thereby, the lithium titanate-containing layer can appropriately capture the metal element.
- the thickness of the lithium titanate-containing layer is 5 to 15 ⁇ m. If the lithium titanate-containing layer is too thin, the metal element capturing ability tends to decrease, and the strength of the layer itself tends to decrease. On the other hand, if the lithium titanate-containing layer is too thick, the battery characteristics may be lowered, for example, the energy density is lowered.
- the non-aqueous electrolyte constituting the non-aqueous electrolyte secondary battery contains a fluorinated carbonate. Under the condition that the secondary battery is charged to 4.5 V or more, the nonaqueous electrolytic solution tends to be oxidatively decomposed. By applying a nonaqueous electrolytic solution containing a fluorinated carbonate having excellent oxidation resistance to such a secondary battery, oxidative decomposition of the nonaqueous electrolytic solution is suppressed.
- a non-aqueous electrolyte is suitable as a non-aqueous electrolyte for a secondary battery using a positive electrode having an operating upper limit potential of 4.5 V or more (vs. Li / Li + ).
- non-aqueous electrolyte secondary battery disclosed here, deterioration of the battery capacity is suppressed. Therefore, taking advantage of this feature, it can be suitably used as a drive power source for vehicles such as hybrid vehicles (HV), plug-in hybrid vehicles (PHV), electric vehicles (EV) and the like. That is, according to the present invention, there is provided a vehicle equipped with any of the nonaqueous electrolyte secondary batteries disclosed herein (which may be in the form of an assembled battery in which a plurality of batteries are connected).
- FIG. 2 is a cross-sectional view taken along line II-II in FIG. It is a perspective view which shows typically the state which winds and produces the electrode body which concerns on one Embodiment. It is a figure which expands and shows a part of cross section between positive and negative electrodes in the example of 1 structure of the winding electrode body of FIG.
- FIG. 5 is a diagram corresponding to FIG. 4 and an enlarged cross-sectional view between positive and negative electrodes in another configuration example of a wound electrode body. It is a graph which shows the relationship between the cycle number in a durability test, and a capacity
- the “secondary battery” means a general battery that can be repeatedly charged and discharged, and includes a storage battery such as a lithium secondary battery.
- the “non-aqueous electrolyte secondary battery” refers to a battery including a non-aqueous electrolyte (typically, an electrolyte containing a supporting salt in a non-aqueous solvent).
- lithium secondary battery refers to a secondary battery that uses lithium ions (Li ions) as electrolyte ions and can be charged and discharged by the movement of charges associated with Li ions between the positive and negative electrodes.
- Li ions lithium ions
- a battery generally called a lithium ion secondary battery is a typical example included in the lithium secondary battery in this specification.
- the lithium secondary battery 100 includes a rectangular box-shaped battery case 10 and a wound electrode body 20 accommodated in the battery case 10.
- the battery case 10 has an opening 12 on the upper surface.
- the opening 12 is sealed by the lid 14 after the wound electrode body 20 is accommodated in the battery case 10 from the opening 12.
- a non-aqueous electrolyte solution 25 is also accommodated in the battery case 10.
- the lid body 14 is provided with an external positive terminal 38 and an external negative terminal 48 for external connection, and a part of the terminals 38 and 48 protrudes to the surface side of the lid body 14.
- a part of the external positive terminal 38 is connected to the internal positive terminal 37 inside the battery case 10, and a part of the external negative terminal 48 is connected to the internal negative terminal 47 inside the battery case 10.
- the wound electrode body 20 includes a long sheet-like positive electrode (positive electrode sheet) 30 and a long sheet-like negative electrode (negative electrode sheet) 40.
- the positive electrode sheet 30 includes a long positive electrode current collector 32 and a positive electrode mixture layer 34 formed on at least one surface (typically both surfaces) thereof.
- the negative electrode sheet 40 includes a long negative electrode current collector 42 and a negative electrode mixture layer 44 formed on at least one surface (typically both surfaces) thereof.
- the wound electrode body 20 also includes two long sheet-like separators (separator sheets) 50A and 50B.
- the positive electrode sheet 30 and the negative electrode sheet 40 are laminated via two separator sheets 50A and 50B, and the positive electrode sheet 30, the separator sheet 50A, the negative electrode sheet 40, and the separator sheet 50B are laminated in this order.
- the laminated body is formed into a wound body by being wound in the longitudinal direction, and is further formed into a flat shape by crushing the rolled body from the side surface direction and causing it to be ablated.
- the electrode body is not limited to a wound electrode body. Depending on the shape of the battery and the purpose of use, an appropriate shape and configuration, such as a laminate mold, can be employed as appropriate.
- the positive electrode mixture layer 34 formed on the surface of the positive electrode current collector 32 and the surface of the negative electrode current collector 42 are formed at the center of the wound electrode body 20 in the width direction (direction orthogonal to the winding direction). A portion in which the negative electrode composite material layer 44 thus overlapped and densely stacked is formed. Further, at one end in the width direction of the positive electrode sheet 30, a portion where the positive electrode current collector layer 34 is not formed and the positive electrode current collector 32 is exposed (positive electrode mixture layer non-forming portion 36) is provided. .
- the positive electrode mixture layer non-forming portion 36 is in a state of protruding from the separator sheets 50 ⁇ / b> A and 50 ⁇ / b> B and the negative electrode sheet 40.
- the positive electrode current collector laminated portion 35 in which the positive electrode mixture layer non-forming portion 36 of the positive electrode current collector 32 overlaps is formed at one end in the width direction of the wound electrode body 20. Further, similarly to the case of the positive electrode sheet 30 at one end, the negative electrode current collector stack in which the negative electrode mixture layer non-forming portion 46 of the negative electrode current collector 42 is overlapped with the other end in the width direction of the wound electrode body 20. A portion 45 is formed.
- the separator sheets 50 ⁇ / b> A and 50 ⁇ / b> B have a width that is larger than the width of the laminated portion of the positive electrode mixture layer 34 and the negative electrode mixture layer 44 and smaller than the width of the wound electrode body 20.
- the separator sheets 50A and 50B are each a three-layered sheet made of polypropylene (PP) / polyethylene (PE) / polypropylene (PP).
- a lithium titanate-containing layer (hereinafter also referred to as LTO layer) 51 is formed on the surface of the separator sheet 50A on the positive electrode sheet 30 side so as to cover the entire surface.
- the LTO layer 51 is separated from the negative electrode sheet 40.
- metal elements typically transition metals such as Mn
- Mn transition metals
- the eluted metal element is irreversibly deposited on the negative electrode surface. It is considered that the lithium that can contribute to charge / discharge is deactivated by this precipitation, and the battery capacity is deteriorated.
- the separator 50B can have the same configuration as that of the separator 50A, and an LTO layer may be provided similarly to the separator 50A.
- the LTO layer may be included in the electrode body and separated from the negative electrode, and there is no limitation on the configuration or arrangement as long as it is. If the LTO layer is in contact with the negative electrode, the capacity deterioration tends to increase.
- two separator sheets 50a and 50b are disposed between the positive electrode sheet 30 and the negative electrode sheet 40, and the LTO layer 51 is disposed between the two separator sheets 50a and 50b. It may be.
- the separator sheets 50a and 50b can be independently a single layer or a multilayer sheet.
- the LTO layer may be provided on the surface of the positive electrode.
- the positive electrode (typically the positive electrode mixture layer) can also function as the LTO layer by including lithium titanate in the positive electrode (typically the positive electrode mixture layer). Or you may exclude the aspect whose LTO layer is a positive mix layer.
- a separator (for example, at least one layer of a separator having a multilayer structure) may contain lithium titanate, and the separator containing lithium titanate may be used as the LTO layer.
- the LTO layer is preferably disposed between the positive electrode and the negative electrode in consideration of the ability to capture the eluted metal element. From the same viewpoint, the LTO layer is particularly preferably face-to-face with the surface of the positive and negative electrodes between the positive and negative electrodes. Since the LTO layer can be distinguished from the LTO layer used as the reference electrode, the LTO layer disclosed here may be excluded from the LTO layer containing lithium titanate as the reference electrode.
- the LTO layer may be provided only in a partial region between the positive electrode and the negative electrode.
- the LTO layer can be provided only in a partial region rather than the entire separator surface.
- an LTO layer is provided only in the outer region of the wound electrode body (typically, a partial region including the outermost peripheral portion of the positive electrode sheet). Also good. Since elution of the metal element is likely to occur in the vicinity of the outermost periphery of the wound electrode body, it is possible to suitably prevent the eluted metal element from being deposited on the negative electrode surface by configuring as described above.
- a positive electrode current collector constituting a positive electrode (for example, a positive electrode sheet) of a lithium secondary battery a conductive member made of a metal having good conductivity is preferably used.
- a conductive member for example, aluminum or an alloy containing aluminum as a main component can be used.
- the shape of the positive electrode current collector can be different depending on the shape of the battery and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape.
- the thickness of the positive electrode current collector is not particularly limited, and can be, for example, 8 ⁇ m to 30 ⁇ m.
- the positive electrode mixture layer may contain additives such as a conductive material and a binder (binder) as necessary.
- an operating potential (vs. Li / Li + ) in at least a part of SOC (State of Charge) 0% to 100% is a general lithium secondary battery (upper limit of operating potential). Is higher than about 4.2V).
- a positive electrode active material having an upper limit (operating upper limit potential) of the operating potential of 4.5 V (vs. Li / Li + ) or more can be preferably used.
- a positive electrode active material having a maximum operating potential of 4.5 V (vs. Li / Li + ) or more at SOC 0 % to 100% can be preferably used.
- the upper limit operating potential (vs. Li / Li + ) of the positive electrode active material is preferably higher than 4.5 V, and is preferably 4.6 V or higher (typically 4.7 V or higher).
- the upper limit of the operating potential (vs. Li / Li + ) is not particularly limited, but may be 5.5 V or lower (for example, 5.3 V or lower, typically 5.1 V or lower).
- the value measured as follows can be adopted as the operating potential of the positive electrode active material. That is, using a positive electrode containing a positive electrode active material to be measured as a working electrode (WE), metallic lithium as a counter electrode (CE), metallic lithium as a reference electrode (RE), and ethylene carbonate (EC): dimethyl carbonate
- WE working electrode
- CE counter electrode
- RE metallic lithium as a reference electrode
- EC ethylene carbonate
- the SOC can be adjusted, for example, by performing constant current charging between WE and CE using a general charging / discharging device or a potentiostat. Then, the potential between WE and RE after the cells adjusted to the respective SOC values are left for 1 hour is measured, and the potential is determined based on the operating potential (vs. Li / Li + ) of the positive electrode active material at the SOC value. And it is sufficient.
- the operating potential of the positive electrode active material is the highest between SOC 0% and 100% in a range including SOC 100%. Therefore, the operating potential of the positive electrode active material is normally 100% SOC (that is, fully charged).
- the upper limit (typically, whether it is 4.5 V or higher) of the working potential of the positive electrode active material can be grasped.
- the working potential (upper working potential) of the positive electrode active material at 100% SOC is more preferably higher than 4.4 V, 4.5 V or higher (eg, 4.6 V or higher, typically 4 More preferably, it is 0.7V or more.
- the operating potential (operating upper limit potential) (vs.
- Li / Li + of the positive electrode active material at 100% SOC is 7.0 V or less (typically 6.0 V or less, For example, it is preferably applied to a non-aqueous electrolyte secondary battery having a voltage of 5.5 V or less.
- the positive electrode active material one or more of various materials known to be usable as a positive electrode active material of a lithium secondary battery can be used without particular limitation.
- the positive electrode active material can typically be in the form of particles having an average particle size of about 1 to 20 ⁇ m (eg, 2 to 10 ⁇ m).
- the “average particle diameter” means a median diameter (D 50 ) in a volume-based particle size distribution obtained by a general laser diffraction particle size distribution measuring device unless otherwise specified.
- a lithium transition metal composite oxide or the like can be used.
- the spinel structure lithium transition metal composite oxide examples include a spinel structure lithium manganese composite oxide containing at least manganese (Mn) as a transition metal. More specifically, a lithium manganese composite oxide having a spinel structure represented by a general formula: Li p Mn 2 -q M q O 4 + ⁇ can be given. Where p is 0.9 ⁇ p ⁇ 1.2; q is 0 ⁇ p ⁇ 2, typically 0 ⁇ q ⁇ 1 (eg 0.2 ⁇ q ⁇ 0.6). ⁇ is a value determined to satisfy the charge neutrality condition with ⁇ 0.2 ⁇ ⁇ ⁇ 0.2.
- M may be one or more selected from any metal element or nonmetal element other than Mn. More specifically, Na, Mg, Ca, Sr, Ti, Zr, V, Nb, Cr, Mo, Fe, Co, Rh, Ni, Pd, Pt, Cu, Zn, B, Al, Ga, In, It can be Sn, La, Ce or the like. Especially, at least 1 sort (s) of transition metal elements, such as Fe, Co, and Ni, can be employ
- the positive electrode active material having such a composition mainly uses Mn, which is an abundant and inexpensive metal resource, it is preferable from the viewpoint of reducing raw material costs and raw material supply risks.
- a positive electrode active material containing Mn for example, a lithium manganese composite oxide having a spinel structure
- the technique disclosed here can be preferably applied.
- a compound (lithium nickel manganese composite oxide) in which M in the above general formula contains at least Ni can be given. More specifically, the general formula: Li x lithium-nickel-manganese composite oxide of (Ni y Mn 2-y- z M 1 z) spinel structure represented by O 4 + beta and the like.
- M 1 may be any transition metal element or typical metal element other than Ni and Mn (for example, one or more selected from Fe, Co, Cu, Cr, Zn, and Al). Of these, M 1 is preferably contains at least one trivalent Fe and Co. Alternatively, it may be a metalloid element (for example, one or more selected from B, Si and Ge) and a nonmetallic element.
- x is 0.9 ⁇ x ⁇ 1.2; y is 0 ⁇ y; z is 0 ⁇ z; y + z ⁇ 2 (typically y + z ⁇ 1); ⁇ can be the same as ⁇ described above.
- y is 0.2 ⁇ y ⁇ 1.0 (more preferably 0.4 ⁇ y ⁇ 0.6, such as 0.45 ⁇ y ⁇ 0.55); z is 0 ⁇ z ⁇ 1.0 (for example, 0 ⁇ z ⁇ 0.3).
- Specific examples include LiNi 0.5 Mn 1.5 O 4 and the like.
- Li / Li + ) Li / Li +
- 5 V-class lithium A secondary battery can be constructed.
- the compound having the above composition is also excellent in durability.
- whether or not the compound (oxide) has a spinel structure can be determined by X-ray structural analysis (preferably single crystal X-ray structural analysis). More specifically, it can be determined by measurement using an X-ray diffractometer (for example, “single crystal automatic X-ray structure analyzer” manufactured by Rigaku Corporation) using CuK ⁇ rays (wavelength 0.154051 nm).
- Such a lithium manganese composite oxide can be prepared and prepared by a conventionally known method.
- a raw material compound selected according to the target composition for example, a lithium source and a transition metal element source containing nickel and manganese
- the target composition for example, a lithium source and a transition metal element source containing nickel and manganese
- the target composition for example, a lithium source and a transition metal element source containing nickel and manganese
- the target composition for example, a lithium source and a transition metal element source containing nickel and manganese
- the positive electrode active material may be the following compound.
- a lithium transition metal composite oxide typically represented by a general formula LiMO 2 and having a layered structure.
- M includes at least one transition metal element such as Ni, Co, and Mn, and may further include another metal element or a non-metal element. Specific examples include LiNiO 2 and LiNi 1/3 Co 1/3 Mn 1/3 O 2 .
- M includes at least one transition metal element such as Mn, Fe, and Co, and may further include another metal element or a nonmetal element. Specific examples include Li 2 MnO 3 and Li 2 PtO 3 .
- M includes at least one transition metal element such as Mn, Fe, Ni, and Co, and may further include another metal element or a nonmetal element.
- Specific examples include LiMnPO 4 and LiFePO 4 .
- M includes at least one transition metal element such as Mn, Ni, and Co, and may further include another metal element or a non-metal element.
- Specific examples include LiMnPO 4 F.
- (5) a solid solution of LiMO 2 and Li 2 MO 3.
- LiMO 2 refers to the composition represented by the general formula described in (1) above
- Li 2 MO 3 refers to the composition represented by the general formula described in (2) above.
- a specific example is a solid solution represented by 0.5LiNiMnCoO 2 -0.5Li 2 MnO 3 .
- the positive electrode active material can be used singly or in combination of two or more.
- the positive electrode active material is 50% by mass or more (typically 50% by mass) of the above-mentioned spinel structure lithium manganese composite oxide (preferably lithium nickel manganese composite oxide) in the total positive electrode active material used.
- the positive electrode active material is 50% by mass or more (typically 50% by mass) of the above-mentioned spinel structure lithium manganese composite oxide (preferably lithium nickel manganese composite oxide) in the total positive electrode active material used.
- a proportion of ⁇ 100% by mass for example, 70% by mass to 100% by mass, preferably 80% by mass to 100% by mass. It is more preferably made of a lithium nickel manganese composite oxide).
- the lithium transition metal composite oxide (layered compound) having a layered structure described above has a high potential of 4.5 V (vs. Li / Li + ) or more, the crystal structure collapses, and the transition metal (for example, Mn) constituting the compound is electrolyzed. There is a tendency to elute gradually in the liquid. Therefore, when charging and discharging are repeated, the battery capacity gradually decreases, and the durability may be deteriorated.
- the positive electrode active material may be substantially free of a layered compound. More specifically, the ratio of the layered compound to the total positive electrode active material is 5% by mass or less, typically 2% by mass or less, preferably 1% by mass or less (more preferably 0.1% by mass or less). Preferably there is.
- various carbon materials can be preferably used. More specifically, for example, one or more selected from carbon materials such as various carbon blacks, cokes, activated carbon, graphite (natural graphite, artificial graphite), carbon fibers, carbon nanotubes, fullerene, graphene, etc. possible.
- carbon black typically acetylene black
- metal powders such as copper and nickel and organic conductive materials such as polyphenylene derivatives may be used. These can be used alone or as a mixture of two or more.
- Bind materials include various polymer materials.
- an aqueous composition a composition using water or a mixed solvent containing water as a main component as a dispersion medium of active material particles
- water-soluble or water-dispersible these polymer materials can be preferably employed as the binder.
- water-soluble or water-dispersible polymer materials include cellulose polymers such as carboxymethyl cellulose (CMC); polyvinyl alcohol (PVA); fluorine resins such as polytetrafluoroethylene (PTFE); vinyl acetate polymers; styrene butadiene rubber Rubbers such as (SBR) and acrylic acid-modified SBR resin (SBR latex);
- cellulose polymers such as carboxymethyl cellulose (CMC); polyvinyl alcohol (PVA); fluorine resins such as polytetrafluoroethylene (PTFE); vinyl acetate polymers; styrene butadiene rubber Rubbers such as (SBR) and acrylic acid-modified SBR resin (SBR latex);
- a solvent-based composition a composition in which the dispersion medium of active material particles is mainly an organic solvent
- PVdF polyvinylidene fluoride
- PVdC polyvinylidene chloride
- Polymer materials such as vinyl halide resins such as poly
- the proportion of the positive electrode active material in the positive electrode mixture layer is preferably more than about 50% by mass, and preferably about 70% to 97% by mass (for example, 75% to 95% by mass).
- the ratio of the additive to the positive electrode mixture layer is not particularly limited, but the ratio of the conductive material is about 1 to 20 parts by mass (for example, 2 to 15 parts by mass with respect to 100 parts by mass of the positive electrode active material). (Typically 3 to 12 parts by mass).
- the ratio of the binder is about 0.8 to 10 parts by mass (for example, 1 to 7 parts by mass, typically 2 to 5 parts by mass) with respect to 100 parts by mass of the positive electrode active material. It is preferable.
- the method for producing the positive electrode as described above is not particularly limited, and a conventional method can be appropriately employed.
- a positive electrode active material, if necessary, a conductive material, a binder, etc. are mixed with an appropriate solvent (aqueous solvent, non-aqueous solvent or a mixed solvent thereof) to form a paste-like or slurry-like positive electrode mixture layer
- a composition is prepared.
- the mixing operation can be performed using, for example, a suitable kneader (a planetary mixer or the like).
- a solvent used for preparing the composition both an aqueous solvent and a non-aqueous solvent can be used.
- the aqueous solvent is not particularly limited as long as it is water-based as a whole, and water or a mixed solvent mainly composed of water can be preferably used.
- Preferable examples of the non-aqueous solvent include N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone, toluene and the like.
- the composition thus prepared is applied to the positive electrode current collector, and the solvent is evaporated by drying, followed by compression (pressing).
- a technique similar to a conventionally known method can be appropriately employed.
- the composition can be suitably applied to the positive electrode current collector by using an appropriate application device such as a die coater.
- drying a solvent it can be satisfactorily dried by using natural drying, hot air, low-humidity air, vacuum, infrared rays, far-infrared rays and an electron beam alone or in combination.
- a conventionally known compression method such as a roll press method or a flat plate press method can be employed.
- the thickness may be measured with a film thickness measuring instrument, and the press pressure may be adjusted to compress the film a plurality of times until a desired thickness is obtained. In this way, a positive electrode in which the positive electrode mixture layer is formed on the positive electrode current collector is obtained.
- the basis weight per unit area of the positive electrode mixture layer on the positive electrode current collector (the coating amount in terms of solid content of the composition for forming the positive electrode mixture layer) is not particularly limited, but a sufficient conductive path From the viewpoint of securing a (conduction path), it is 3 mg / cm 2 or more (for example, 5 mg / cm 2 or more, typically 6 mg / cm 2 or more) per side of the positive electrode current collector, and 45 mg / cm 2 or less (for example, 28 mg / cm 2 or less, typically 15 mg / cm 2 or less).
- the density of the positive-electrode mixture layer is not particularly limited, 1.0g / cm 3 ⁇ 3.8g / cm 3 ( e.g., 1.5g / cm 3 ⁇ 3.5g / cm 3, typically 2.0 g / cm 3 to 3.0 g / cm 3 ).
- a conductive member made of a highly conductive metal is preferably used as in the case of the conventional lithium secondary battery.
- a conductive member for example, copper or an alloy containing copper as a main component can be used.
- the shape of the negative electrode current collector can be different depending on the shape of the battery and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape.
- the thickness of the negative electrode current collector is not particularly limited, and can be, for example, about 8 ⁇ m to 30 ⁇ m.
- the negative electrode mixture layer includes a negative electrode active material that can occlude and release Li ions serving as charge carriers.
- a negative electrode active material that can occlude and release Li ions serving as charge carriers.
- the 1 type (s) or 2 or more types of the material conventionally used for a lithium secondary battery can be used.
- the negative electrode active material can typically be in the form of particles having an average particle size of about 1 to 20 ⁇ m (eg, 4 to 10 ⁇ m). Examples of such a negative electrode active material include carbon materials that are generally used in lithium secondary batteries. Representative examples of the carbon material include graphite carbon (graphite) and amorphous carbon. A particulate carbon material (carbon particles) containing a graphite structure (layered structure) at least partially is preferably used.
- the use of a carbon material mainly composed of natural graphite is preferred.
- the natural graphite may be a spheroidized graphite.
- a carbonaceous powder having a graphite surface coated with amorphous carbon may be used.
- the negative electrode active material it is also possible to use oxides such as lithium titanate, simple substances such as silicon materials and tin materials, alloys, compounds, and composite materials using the above materials in combination.
- vs. Li / Li + reduction potential
- the negative electrode active material having the reduction potential By using the negative electrode active material having the reduction potential, a high energy density can be realized. Examples of the material that can be at such a low potential include graphite-based carbon materials (typically graphite particles).
- the negative electrode mixture layer requires one or more binders, thickeners, and other additives that can be blended in the negative electrode mixture layer of a typical lithium secondary battery. It can be contained accordingly.
- the binder include various polymer materials.
- what can be contained in the positive electrode mixture layer can be preferably used for an aqueous composition or a solvent-based composition.
- Such a binder may be used as a thickener and other additives in the composition for forming a negative electrode mixture layer, in addition to being used as a binder.
- the proportion of the negative electrode active material in the negative electrode mixture layer exceeds about 50% by mass, and is about 90% to 99% by mass (eg, 95% to 99% by mass, typically 97% to 99% by mass). Preferably there is.
- the ratio of the additive in the negative electrode mixture layer is not particularly limited, but is approximately 0.8% by mass to 10% by mass (for example, approximately 1% by mass to 5% by mass, typically 1% by mass to 3% by mass). ) Is preferable.
- the method for producing the negative electrode is not particularly limited, and a conventional method can be adopted.
- a negative electrode active material is mixed with a binder or the like in the appropriate solvent (aqueous solvent, organic solvent, or mixed solvent thereof) to prepare a paste or slurry-like composition for forming a negative electrode mixture layer.
- the composition prepared in this manner is applied to the negative electrode current collector, the solvent is volatilized by drying, and then compressed (pressed).
- a negative electrode mixture layer can be formed on a negative electrode current collector using the composition, and a negative electrode provided with the negative electrode mixture layer can be obtained.
- the mixing, coating, drying, and compression methods can employ the same means as in the above-described production of the positive electrode.
- the basis weight per unit area of the negative electrode composite material layer on the negative electrode current collector (the coating amount in terms of solid content of the composition for forming the negative electrode composite material layer) is not particularly limited, but sufficient conductive paths From the viewpoint of securing a (conduction path), it is 2 mg / cm 2 or more (for example, 3 mg / cm 2 or more, typically 4 mg / cm 2 or more) per side of the negative electrode current collector, and 40 mg / cm 2 or less (for example, 22 mg / cm 2 or less, typically 10 mg / cm 2 or less).
- the density of the negative electrode mixture layer is not particularly limited, but is 1.0 g / cm 3 to 3.0 g / cm 3 (for example, 1.2 g / cm 3 to 2.0 g / cm 3 , typically 1.3 g / cm 3) . 3 to 1.5 g / cm 3 ).
- the separator (separator sheet) disposed so as to separate the positive electrode and the negative electrode may be a member that insulates the positive electrode mixture layer and the negative electrode mixture layer and allows the electrolyte to move.
- a separator the thing similar to the sheet
- a member include a porous body, a nonwoven fabric, and a cloth.
- the porous sheet (porous resin sheet) which consists of resin can be used preferably.
- the porous resin sheet include a sheet mainly composed of a thermoplastic resin such as polyolefin (polyethylene (PE), polypropylene (PP), etc.), polyester or polyamide.
- a sheet having a single-layer structure or a multilayer structure mainly composed of one or more kinds of polyolefin-based resins can be given.
- a PE sheet, a PP sheet, a sheet having a three-layer structure (PP / PE / PP structure) in which a PP layer is laminated on both sides of the PE layer can be suitably used.
- the PE may be any polyethylene generally referred to as high-density polyethylene (HDPE), low-density polyethylene (LDPE), or linear (linear) low-density polyethylene (LLDPE), or a mixture thereof. May be.
- the said separator can also contain additives, such as various plasticizers and antioxidant, as needed.
- a resin sheet constituting a separator having a single layer structure or a multilayer structure for example, a uniaxially stretched or biaxially stretched porous resin sheet can be suitably used.
- a porous resin sheet uniaxially stretched in the longitudinal direction is particularly preferable because it has an appropriate strength and has little heat shrinkage in the width direction.
- thermal contraction in the longitudinal direction can be suppressed in a mode in which the separator is wound together with a long sheet-like positive electrode and negative electrode. Therefore, the porous resin sheet uniaxially stretched in the longitudinal direction is particularly suitable as one element of the separator constituting the wound electrode body.
- the thickness of the separator is not particularly limited, but is preferably about 5 to 40 ⁇ m (for example, 10 to 30 ⁇ m, typically 15 to 25 ⁇ m). When the thickness of the separator is within the above range, the ion permeability of the separator becomes better and film breakage is less likely to occur.
- the separator may be formed with a heat resistant layer.
- a solid (gel-like) electrolyte in which a polymer is added to the electrolyte for example, instead of a liquid electrolyte, the electrolyte itself can function as a separator, so that a separator is not necessary. There can be.
- the electrode body disclosed here may include an LTO layer.
- the LTO layer may be any layer containing lithium titanate (hereinafter also referred to as LTO) and separated from the negative electrode, and there is no particular limitation as long as it is.
- the average particle diameter of LTO (the above-mentioned average particle diameter D 50 ) is not particularly limited, but is preferably about 0.5 ⁇ m to 3 ⁇ m (for example, 0.8 ⁇ m to 2.5 ⁇ m, typically 1 ⁇ m to 2 ⁇ m).
- the potential of the LTO layer (typically LTO) may be adjusted (for example, adjusted to about 1.5 V (vs. Li / Li + )), or the potential may not be adjusted.
- the potential can be adjusted by inserting Li.
- the potential of LTO is about 3 V (vs. Li / Li + ).
- LTO contained in the LTO layer is an oxide containing lithium (Li) and titanium (Ti).
- a compound represented by Li x Ti y O z (0 ⁇ x ⁇ 4, 1 ⁇ y ⁇ 5, 2 ⁇ z ⁇ 12) may be used. Specific examples include Li 4 Ti 5 O 12 and Li 2 Ti 3 O 7 . Typically, it may be LTO having a spinel structure represented by Li 4 Ti 5 O 12 .
- the LTO may be ramsdelite type LiTiO 4 or anatase type Li 0.5 TiO 2 .
- the method for producing the LTO is not particularly limited.
- lithium hydroxide and titanium dioxide are mixed so that the molar ratio of Li and Ti is within a predetermined range, and after drying, the temperature is 600 ° C. to 1200 ° C. (preferably It can be produced by heating (firing) at 700 ° C. to 1000 ° C. for 5 hours to 20 hours (preferably 7 hours to 14 hours).
- LTO may also contain hydrogen (H). Hydrogen (H) may be included in the form of substitution for part of lithium (Li). Furthermore, the LTO has the formula: Li a Ti 5- b MbO 12 + c Wherein M is from the group consisting of V, Mn, Fe, Co, Ni, Cu, Zn, Al, B, Mg, Ca, Sr, Ba, Zr, Nb, Mo, W, Bi, Na and Ga. At least one selected, a being 3 to 5, b being 0.005 to 1.5, and c being -1 to 1. M is preferably at least one selected from the group consisting of Mn, Fe, Co, Ni, Cu, Al, B, Mg, Zr, Nb and W. The above LTO can be used alone or in combination of two or more.
- the LTO layer preferably contains an additive such as a binder.
- the binder is dispersed or dissolved in the aqueous solvent.
- Polymers can be used. Examples of the polymer that is dispersed or dissolved in the aqueous solvent include acrylic resins. Acrylic resins include acrylic acid, methacrylic acid, acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methyl methacrylate, 2-ethylhexyl acrylate and butyl acrylate. Coalescence is preferably used.
- polymerized 2 or more types of the said monomer may be sufficient. Further, a mixture of two or more of the above homopolymers and copolymers may be used.
- SBR styrene butadiene rubber
- SBR latex acrylic acid-modified SBR resin
- rubber such as gum arabic
- polyolefin resin such as polyethylene (PE); carboxymethylcellulose (CMC), Cellulose polymers such as methyl cellulose (MC); polyvinyl alcohol (PVA); fluorine resins such as polytetrafluoroethylene (PTFE); vinyl acetate polymers; polyalkylene oxides such as polyethylene oxide (PEO); it can.
- SBR styrene butadiene rubber
- SBR latex acrylic acid-modified SBR resin
- rubber such as gum arabic
- polyolefin resin such as polyethylene (PE); carboxymethylcellulose (CMC), Cellulose polymers such as methyl cellulose (MC); polyviny
- the binder When the composition for forming the LTO layer is a solvent-based solvent (a solution in which the binder dispersion medium is mainly an organic solvent), the binder should be a polymer that is dispersed or dissolved in the solvent-based solvent. Can do.
- the polymer dispersed or dissolved in the solvent-based solvent include, for example, vinyl halide resins such as polyvinylidene fluoride (PVdF).
- PVdF polyvinylidene fluoride
- the polyvinylidene fluoride a homopolymer of vinylidene fluoride is preferably used.
- the polyvinylidene fluoride may be a copolymer of a vinyl monomer copolymerizable with vinylidene fluoride.
- vinyl monomers copolymerizable with vinylidene fluoride examples include hexafluoropropylene, tetrafluoroethylene, and ethylene trichloride fluoride.
- PTFE polytetrafluoroethylene
- polyacrylonitrile polymethyl methacrylate, or the like is preferably used as a polymer that is dispersed or dissolved in a solvent-based solvent. These may be used alone or in combination of two or more.
- the form of the binder is not particularly limited, and a particulate (powdered) form may be used as it is, or a solution or emulsion prepared may be used. Two or more binders may be used in different forms.
- the average particle size (the above-mentioned average particle size D 50 ) is, for example, about 0.09 ⁇ m to 0.15 ⁇ m.
- the said binder may be used in order to exhibit the function as a thickener other additives of the composition for LTO layer formation besides the function as a binder.
- the ratio of LTO in the entire LTO layer is not particularly limited, but is approximately 50% by mass or more (for example, 70% by mass or more, typically 80% by mass or more). This is because as the LTO content increases, the trapped amount of the metal element eluted from the positive electrode tends to increase, so that the LTO content is 90 mass% or more (eg, 92 mass% to 99.5 mass%).
- the LTO layer contains an additive such as a binder or a thickener, the additive occupying the LTO layer is more preferably 95% by mass, typically 95% by mass to 99% by mass.
- the ratio is preferably about 0.1 to 10% by mass (for example, 0.5% to 8% by mass, typically 1% to 5% by mass).
- Strength of the layer itself is improved. In the case of forming the LTO layer on the surface of the separator is likely to adjust the strength and elongation of the separator in a suitable range.
- the method for forming the LTO layer disclosed herein is not particularly limited, and can be formed by the following method, for example.
- Mixing and dispersing operations can be performed using an appropriate kneader such as a disper mill, a clear mix, a fill mix, a ball mill, a homodisper, or an ultrasonic disperser.
- the LTO in the obtained paste-like or slurry-like composition for forming an LTO layer, the blending ratio of the binder and other additives added as necessary are each in the above-mentioned LTO layer in terms of solid content. It can be the same as the proportion of the components.
- Examples of the solvent used in the composition for forming an LTO layer include water or a mixed solvent mainly composed of water.
- the solvent other than water constituting the mixed solvent one or more organic solvents (lower alcohol such as ethanol, lower ketone, etc.) that can be uniformly mixed with water can be appropriately selected and used.
- one organic solvent such as N-methyl-2-pyrrolidone (NMP), pyrrolidone, methyl ethyl ketone, methyl isobutyl ketone, ixahexanone, toluene, dimethylformamide, dimethylacetamide, or a combination of two or more thereof. It may be used.
- the content of the solvent in the composition for forming an LTO layer is not particularly limited, but may be 30% by mass to 90% by mass (for example, 40% by mass to 60% by mass) of the entire composition.
- an appropriate amount of the obtained paste-form or slurry-form composition for forming an LTO layer is applied to the surface of at least one of the separator and the positive electrode, and further dried to form an LTO layer.
- the operation of applying the composition for forming an LTO layer to at least one surface of the separator and the positive electrode can be employed without any particular limitation on conventional general application means.
- a suitable coating apparatus gravure coater, slit coater, die coater, comma coater, dip coat, etc.
- a predetermined amount of the composition for forming the LTO layer is applied to at least one surface of the separator and the positive electrode. Apply to a uniform thickness.
- the solvent in the composition for LTO layer formation is removed by drying a coated material with a suitable drying means.
- a drying method natural drying, hot air, low-humidity air, vacuum, infrared rays, far-infrared rays, and an electron beam can be used alone or in combination.
- the drying can be performed at a temperature lower than the melting point of the material constituting the separator, for example, 110 ° C. or less (typically 30 to 80 ° C.). Or you may hold
- the LTO layer can be formed by removing the solvent from the composition for forming the LTO layer.
- the thickness of the LTO layer is not particularly limited, but is preferably about 1 ⁇ m to 18 ⁇ m (eg, 3 ⁇ m to 15 ⁇ m, typically 5 ⁇ m to 12 ⁇ m).
- the thickness of the LTO layer is within the above range, the metal element eluted from the positive electrode can be suitably captured without impairing the energy density.
- strength and elongation rate of a separator can be obtained by analyzing an image photographed by SEM (Scanning Electron Microscope).
- LTO is applied to a layer (typically an intermediate resin layer) located in the center of a separator having a three-layer structure or a layer located on the positive electrode side (typically a resin layer facing the positive electrode). Can be blended. Further, LTO may be contained in a layer (typically a resin layer) located on the negative electrode side of the separator having a multilayer structure. In that case, an additional layer such as a heat-resistant layer may be provided on the negative electrode side surface of the separator so that the LTO layer and the negative electrode are separated from each other. It is also possible to mix LTO into a single layer structure separator by the same method.
- the thickness of the LTO layer is 5 ⁇ m to 40 ⁇ m (for example, from the viewpoint of capturing the metal element eluted from the positive electrode without impairing the function as the separator) It is preferably about 10 ⁇ m to 30 ⁇ m, typically 15 ⁇ m to 25 ⁇ m.
- the thickness of the LTO layer is preferably about 3 to 20 ⁇ m (for example, 5 to 15 ⁇ m, typically 7 to 12 ⁇ m).
- the amount of LTO blended in the separator is not particularly limited, but is preferably 5% by mass or more (for example, 10% by mass or more, typically 30% by mass or more) from the viewpoint of capturing the metal element eluted from the positive electrode. . Furthermore, it is good also as 50 mass% or more (for example, 70 mass% or more, typically 80 mass% or more and 90 mass% or less). Further, from the viewpoint of not impairing the function of the separator (for example, insulation, ion permeability, electrolyte solution retention, etc.), it should be 50% by mass or less (for example, 30% by mass or less, typically 15% by mass or less). Is preferred. Furthermore, it is good also as 10 mass% or less (for example, 8 mass% or less, typically 1 mass% or more and 5 mass% or less).
- LTO may be blended in the positive electrode (typically, the positive electrode mixture layer).
- the positive electrode can function as an LTO layer.
- the amount of LTO blended into the positive electrode is 100 parts by mass of the total amount of conventionally known positive electrode mixture layer components (positive electrode active material, conductive material, binder, etc.).
- it is preferably 3 parts by mass or more (for example, 5 parts by mass or more, typically 8 parts by mass or more).
- 15 parts by mass or less for example, 12 parts by mass or less, typically 10 parts by mass or less
- the non-aqueous electrolyte injected into the secondary battery can include at least a non-aqueous solvent and a supporting salt.
- the electrolytic solution has a composition in which a supporting salt is contained in a suitable nonaqueous solvent.
- non-aqueous solvent examples include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), 1,2-dimethoxyethane, 1,2- Diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxane, 1,3-dioxolane, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, acetonitrile, propionitrile, nitromethane, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, ⁇ -butyrolactone
- EC ethylene carbonate
- PC propylene carbonate
- DEC diethyl carbonate
- DMC dimethyl carbonate
- EMC ethyl methyl carbonate
- 1,2-dimethoxyethane 1,2- Diethoxyethane
- tetrahydrofuran 2-
- fluorinated carbonates for example, fluorinated products of carbonates as described above
- a fluorinated cyclic carbonate or a fluorinated chain carbonate can be preferably used.
- fluorinated carbonate having one carbonate structure in one molecule it is preferable to use a fluorinated carbonate having one carbonate structure in one molecule.
- the fluorine substitution rate of the fluorinated carbonate is usually suitably 10% or more, and can be, for example, 20% or more (typically 20% or more and 100% or less, such as 20% or more and 80% or less).
- the fluorinated carbonate preferably exhibits an oxidation potential equivalent to or higher than the operating potential (upper limit operating potential) (vs. Li / Li + ) of the positive electrode active material.
- the difference from the upper limit operating potential (vs. Li / Li + ) of the positive electrode active material is larger than 0 V (typically about 0.1 V to 3.0 V, preferably about 0.1 V).
- the above difference is about 0V to 0.3V, the above difference is 0.3V or more (typically 0.3V to Those having a voltage of about 3.0 V, preferably about 0.3 V to 2.0 V, for example about 0.3 V to 1.5 V can be preferably used.
- the oxidation potential (vs. Li / Li + ) of the electrolytic solution can be measured by the following method.
- a working electrode (WE) is produced using LiNi 0.5 Mn 1.5 O 4 in the same manner as the positive electrode of the example described later.
- a tripolar cell is constructed using the produced WE, metallic lithium as a counter electrode (CE), metallic lithium as a reference electrode (RE), and an electrolyte to be measured.
- the triode cell is completely desorbed from WE. Specifically, at a temperature of 25 ° C., constant current charging is performed up to 4.5 V at a current value that is 1/5 of the battery capacity (Ah) predicted from the theoretical capacity of the WE, and the current value at 4.5 V is the initial current.
- the constant voltage charging is performed until it becomes 1/50 of the value (that is, the current value of 1/5 of the battery capacity).
- constant voltage charging for a predetermined time for example, 10 hours is performed at an arbitrary voltage in a voltage range (typically a voltage range higher than 4.5 V) that is predicted to include the oxidation potential of the electrolyte to be measured. And measure the current value. More specifically, the voltage is increased stepwise (for example, in steps of 0.2 V) within the above voltage range, and constant voltage charging is performed for a predetermined time (for example, about 10 hours) at each step. Measure the current value. What is necessary is just to let the electric potential when the electric current value at the time of constant voltage charge becomes larger than 0.1 mA be the oxidation potential (oxidation decomposition potential) of the said electrolyte solution.
- fluorinated cyclic carbonate those having 2 to 8 carbon atoms (more preferably 2 to 6, for example 2 to 4, typically 2 or 3) are preferable. When there are too many carbon atoms, the viscosity of a non-aqueous electrolyte may become high or ion conductivity may fall.
- a fluorinated cyclic carbonate represented by the following formula (C1) can be preferably used.
- R 11 , R 12 and R 13 in the above formula (C1) are each independently a hydrogen atom, a fluorine atom or an alkyl group having 1 to 4 carbon atoms (more preferably 1 to 2, typically 1). And a haloalkyl group, and a halogen atom other than fluorine (preferably a chlorine atom).
- the haloalkyl group may be a group having a structure in which one or more hydrogen atoms of the alkyl group are substituted with a halogen atom (for example, a fluorine atom or a chlorine atom, preferably a fluorine atom).
- a compound in which one or two of R 11 , R 12 and R 13 are fluorine atoms is preferred.
- a compound in which at least one of R 12 and R 13 is a fluorine atom is preferable.
- R 11 , R 12 and R 13 are all fluorine atoms or hydrogen atoms.
- fluorinated cyclic carbonate represented by the above formula (C1) include monofluoroethylene carbonate (MFEC), difluoroethylene carbonate (DFEC), 4,4-difluoroethylene carbonate, trifluoroethylene carbonate, perfluoroethylene.
- MFEC and DFEC are preferable.
- a fluorinated chain carbonate represented by the following formula (C2) can be used as the nonaqueous electrolytic solution in the technology disclosed herein.
- At least one (preferably both) of R 21 and R 22 in the formula (C2) is an organic group containing fluorine, and may be, for example, a fluorinated alkyl group or a fluorinated alkyl ether group. It may be a fluorinated alkyl group or a fluorinated alkyl ether group further substituted with a halogen atom other than fluorine.
- One of R 21 and R 22 may be an organic group that does not contain fluorine (for example, an alkyl group or an alkyl ether group).
- Each of R 21 and R 22 is preferably an organic group having 1 to 6 carbon atoms (more preferably 1 to 4, for example 1 to 3, typically 1 or 2).
- R 21 and R 22 are linear, more preferably R 21 and R 22 are both linear.
- R 21 and R 22 are both fluorinated alkyl groups and the total number of carbon atoms thereof is 1 or 2.
- fluorinated chain carbonate represented by the above formula (C2) include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, fluoromethyl difluoromethyl carbonate, bis (fluoromethyl) carbonate, bis (Difluoromethyl) carbonate, bis (trifluoromethyl) carbonate, (2-fluoroethyl) methyl carbonate, ethylfluoromethyl carbonate, (2,2-difluoroethyl) methyl carbonate, (2-fluoroethyl) fluoromethyl carbonate, ethyl Difluoromethyl carbonate, (2,2,2-trifluoroethyl) methyl carbonate, (2,2-difluoroethyl) fluoromethyl carbonate, (2-fluoro Ethyl) difluoromethyl carbonate, ethyl trifluoromethyl carbonate, ethyl- (2-fluoroethyl) carbon
- the amount of the fluorinated carbonate is, for example, 5% by volume or more (for example, 10% by volume or more, typically) among all components excluding the supporting salt from the non-aqueous electrolyte (hereinafter also referred to as “component other than the supporting salt”). Is preferably 20% by volume or more.
- the fluorinated carbonate may be substantially 100% by volume (typically 99% by volume or more) of the components other than the supporting salt.
- the amount of fluorinated carbonate is 90% by volume or less (for example, 70% by volume or less, typically, other than the above-mentioned supporting salt). 60% by volume or less) is preferable.
- dialkyl carbonate having an alkyl group having 1 to 4 carbon atoms for example, EMC
- fluorinated carbonate for example, MFEC
- EMC alkyl group having 1 to 4 carbon atoms
- MFEC fluorinated carbonate
- the total amount thereof is 50% by volume or more (for example, 70% by volume or more, typically 90 volume% or more and 100 volume% or less) nonaqueous electrolyte solution containing the nonaqueous solvent is mentioned.
- the supporting salt examples include LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiI. 1 type, or 2 or more types of lithium compounds (lithium salt), such as these, can be used.
- the concentration of the supporting salt is not particularly limited, but is about 0.1 mol / L to 5 mol / L (for example, 0.5 mol / L to 3 mol / L, typically 0.8 mol / L to 1.5 mol / L). Concentration.
- the non-aqueous electrolyte may contain an optional additive as necessary as long as the object of the present invention is not significantly impaired.
- the additive may be used for the purpose of, for example, improving the output performance of the battery, improving the storage stability (suppressing the decrease in capacity during storage, etc.), improving the cycle characteristics, and improving the initial charge / discharge efficiency.
- preferable additives include fluorophosphate (preferably difluorophosphate, for example, lithium difluorophosphate represented by LiPO 2 F 2 ), lithium bisoxalate borate (LiBOB), and the like.
- additives such as cyclohexylbenzene and biphenyl that can be used as a countermeasure against overcharge may be used.
- the lithium secondary battery 100 is mounted on a vehicle 1 such as an automobile and can be suitably used as a power source for a drive source such as a motor that drives the vehicle 1.
- a vehicle typically an automobile, particularly a hybrid automobile (HV), a plug-in hybrid automobile (PHV), which includes the lithium secondary battery (typically, a plurality of series assembled batteries) 100 as a power source.
- An electric vehicle (EV), a vehicle equipped with an electric motor such as a fuel cell vehicle) 1 can be provided.
- Example 1 [Preparation of positive electrode sheet] A lithium nickel manganese composite oxide having a spinel structure (LiNi 0.5 Mn 1.5 O 4 ) as a positive electrode active material, acetylene black as a conductive material, PVdF as a binder, and a mass ratio of these materials of 85 was mixed with NMP so as to be 10: 5 to prepare a paste-like composition for forming a positive electrode mixture layer.
- a paste-like composition for forming a positive electrode mixture layer By applying this composition uniformly on both sides of an aluminum foil (positive electrode current collector: thickness 15 ⁇ m) so that the total coating amount is 30 mg / cm 2 (based on solid content), drying, and then compressing A sheet-like positive electrode (positive electrode sheet) was produced.
- the density of the positive electrode mixture layer was 2.8 g / cm 3 .
- Graphite powder as a negative electrode active material, PVdF as a binder, and carboxymethyl cellulose (CMC) as a thickener are mixed with ion-exchanged water so that the mass ratio of these materials is 98: 1: 1.
- CMC carboxymethyl cellulose
- a paste-like composition for forming a negative electrode mixture layer was prepared.
- the composition was uniformly applied to a copper foil (thickness: 14 ⁇ m) so that the application amount was 17 mg / cm 2 (solid content basis), dried and then compressed, whereby a sheet-like negative electrode (negative electrode) Sheet).
- the density of the negative electrode mixture layer was 1.4 g / cm 3 .
- separator sheet with LTO layer As a separator sheet, a three-layered separator sheet (thickness: 20 ⁇ m) made of PP / PE / PP was prepared. The thickness of each layer was 7 ⁇ m for each PP layer and 6 ⁇ m for the PE layer. An LTO layer was formed on one side of this separator sheet. Specifically, a composition for forming an LTO layer in a slurry state by mixing lithium titanate (LTO: Li 4 Ti 5 O 12 ) and PVdF with NMP so that the mass ratio thereof is 95: 5. was prepared. Mixing was performed using an ultrasonic disperser “CLEAMIX” manufactured by M Technique Co., Ltd.
- the obtained composition for forming an LTO layer was applied by a gravure coating method so as to cover the entire surface of the separator sheet, and dried at a temperature of 70 ° C. to form an LTO layer.
- surface was produced.
- an electrolyte obtained by dissolving about 1 mol / L LiPF 6 as a supporting salt in a 1: 1 (volume ratio) mixed solvent of monofluoroethylene carbonate (MFEC) and ethyl methyl carbonate (EMC) is used.
- MFEC monofluoroethylene carbonate
- EMC ethyl methyl carbonate
- a laminated battery was fabricated by thermally welding the aluminum laminate film and the seal portion attached to the lead while vacuuming the inside of the bag to seal (seal) the inside.
- Example 2 In addition to the separator sheet with an LTO layer, a single separator sheet (thickness: 10 ⁇ m) made of PE is prepared. Between the positive electrode sheet and the negative electrode sheet, the separator sheet with an LTO layer and the separator sheet (LTO Layered). At this time, the separator sheet with the LTO layer was disposed so that the LTO layer was opposed to the separator sheet (without the LTO layer). Otherwise, in the same manner as in Example 1, an electrode body having a configuration in which the cross section between the positive and negative electrodes was as shown in FIG. 5 was produced. A laminated battery according to Example 2 was produced in the same manner as Example 1 except that this electrode body was used.
- Example 3 A laminated battery according to Example 3 was produced in the same manner as in Example 1 except that the separator sheet with the LTO layer was disposed so that the LTO layer was opposed to the negative electrode sheet.
- Example 4 The laminate type battery according to Example 4 is the same as Example 1 except that a separator sheet with a three-layer structure (thickness: 20 ⁇ m) made of PP / PE / PP is used as the separator sheet instead of the separator sheet with an LTO layer. Produced.
- Example 4 After the durability test, the laminate type batteries according to Example 1 and Example 4 were disassembled, the negative electrode sheets of Examples 1 and 4 and the separator sheet with the LTO layer of Example 1 were taken out, and deposited on the negative electrode sheet and the LTO layer. The amount of manganese (Mn) was measured. Specifically, the negative electrode sheet and the LTO layer taken out are lightly washed 2 to 3 times with a non-aqueous solvent used as a non-aqueous electrolyte, and then the negative electrode sheet and the LTO layer are punched out to an arbitrary size. A measurement sample for Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was obtained.
- ICP-AES Inductively Coupled Plasma Atomic Emission Spectroscopy
- Example 1 and Example 2 in which the LTO layer is spaced from the negative electrode and disposed in the electrode body, the capacity retention rate is improved over Example 4 in which the LTO layer is not provided.
- Example 3 in which the LTO layer was disposed so as to be in contact with the negative electrode, the capacity retention rate was significantly reduced.
- the LTO layer is in contact with the negative electrode, the potential of the LTO layer is lowered to the potential of the negative electrode, and Li is absorbed in the LTO layer, thereby causing capacity deterioration. Is done. Further, as shown in FIG.
- Example 7 the amount of Mn deposited on the negative electrode in Example 1 is smaller than that in Example 4, and the total amount of Mn deposited in the negative electrode of Example 1 and the LTO layer is the negative electrode of Example 4. This approximates the amount of precipitated Mn. That is, in Example 1, it is recognized that Mn was deposited on the LTO layer so as to correspond to the decrease in Mn deposition on the negative electrode. From these results, it can be seen that in Example 1, the MTO eluted from the positive electrode was captured by the LTO layer, and the amount of Mn deposited on the negative electrode was reduced accordingly. As a result, it is considered that deterioration of the battery capacity due to metal deposition on the negative electrode was suppressed.
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Abstract
Description
図1および図2に示すように、リチウム二次電池100は、角型箱状の電池ケース10と、電池ケース10内に収容される捲回電極体20とを備える。電池ケース10は上面に開口部12を有している。この開口部12は、捲回電極体20を開口部12から電池ケース10内に収容した後、蓋体14によって封止される。電池ケース10内にはまた、非水電解液25が収容されている。蓋体14には、外部接続用の外部正極端子38と外部負極端子48とが設けられており、それら端子38,48の一部は蓋体14の表面側に突出している。また、外部正極端子38の一部は電池ケース10内部で内部正極端子37に接続されており、外部負極端子48の一部は電池ケース10内部で内部負極端子47に接続されている。
次に、上述のリチウム二次電池を構成する各構成要素について説明する。リチウム二次電池の正極(例えば正極シート)を構成する正極集電体としては、導電性の良好な金属からなる導電性部材が好ましく用いられる。そのような導電性部材としては、例えば、アルミニウムまたはアルミニウムを主成分とする合金を用いることができる。正極集電体の形状は、電池の形状等に応じて異なり得るため、特に制限はなく、棒状、板状、シート状、箔状、メッシュ状等の種々の形態であり得る。正極集電体の厚さも特に限定されず、例えば8μm~30μmとすることができる。正極合材層は、正極活物質の他、必要に応じて導電材、結着材(バインダ)等の添加材を含有してもよい。
(1)一般式LiMO2で表される、典型的には層状構造のリチウム遷移金属複合酸化物。ここで、Mは、Ni,Co,Mn等の遷移金属元素の少なくとも1種を含み、他の金属元素または非金属元素をさらに含んでよい。具体例としては、LiNiO2、LiNi1/3Co1/3Mn1/3O2等が挙げられる。
(2)一般式Li2MO3で表されるリチウム遷移金属複合酸化物。ここで、Mは、Mn,Fe,Co等の遷移金属元素の少なくとも1種を含み、他の金属元素または非金属元素をさらに含んでよい。具体例としては、Li2MnO3,Li2PtO3等が挙げられる。
(3)一般式LiMPO4で表されるリチウム遷移金属化合物(リン酸塩)。ここで、Mは、Mn,Fe,Ni,Co等の遷移金属元素の少なくとも1種を含み、他の金属元素または非金属元素をさらに含んでよい。具体例としては、LiMnPO4,LiFePO4等が挙げられる。
(4)一般式Li2MPO4Fで表されるリチウム遷移金属化合物(リン酸塩)。ここで、Mは、Mn,Ni,Co等の遷移金属元素の少なくとも1種を含み、他の金属元素または非金属元素をさらに含んでよい。具体例としては、LiMnPO4F等が挙げられる。
(5)LiMO2とLi2MO3との固溶体。ここで、LiMO2は上記(1)に記載の一般式で表される組成を指し、Li2MO3は上記(2)に記載の一般式で表される組成を指す。具体例としては、0.5LiNiMnCoO2-0.5Li2MnO3で表される固溶体が挙げられる。
負極(例えば負極シート)を構成する負極集電体としては、従来のリチウム二次電池と同様に、導電性の良好な金属からなる導電性部材が好ましく用いられる。そのような導電性部材としては、例えば銅または銅を主成分とする合金を用いることができる。負極集電体の形状は、電池の形状等に応じて異なり得るため特に制限はなく、棒状、板状、シート状、箔状、メッシュ状等の種々の形態であり得る。負極集電体の厚さも特に限定されず、例えば8μm~30μm程度とすることができる。
正極と負極とを隔てるように配置されるセパレータ(セパレータシート)は、正極合材層と負極合材層とを絶縁するとともに、電解質の移動を許容する部材であればよい。上記セパレータとしては、従来のリチウム二次電池においてセパレータとして用いられるシートと同様のものを用いることができる。そのような部材としては、例えば、多孔質体や不織布状体、布状体等が挙げられる。なかでも、樹脂からなる多孔性シート(多孔性樹脂シート)を好ましく用いることができる。
また、ここで開示される電極体はLTO層を含み得る。LTO層は、チタン酸リチウム(以下、LTOともいう)を含有し、負極から離隔している層であればよく、その限りにおいて特に制限はない。LTOの平均粒径(上述の平均粒径D50)は特に限定されないが、凡そ0.5μm~3μm(例えば0.8μm~2.5μm、典型的には1μm~2μm)であることが好ましい。また、LTO層(典型的にはLTO)の電位は調整(例えば1.5V(vs.Li/Li+)程度に調整)されていてもよく、電位未調整であってもよい。いずれの場合でも、正極から溶出した金属元素(典型的にはMn等の遷移金属)を捕捉することが可能である。なお、電位の調整はLiを吸蔵させることによって行うことができる。電位未調整の場合、LTOの電位は凡そ3V(vs.Li/Li+)程度である。
LiaTi5-bMbO12+c
(式中、Mは、V、Mn、Fe、Co、Ni、Cu、Zn、Al、B、Mg、Ca、Sr、Ba、Zr、Nb、Mo、W、Bi、NaおよびGaからなる群から選ばれる少なくとも1種であり、aは3~5、bは0.005~1.5、cは-1~1を満たす。)で表されるものであってもよい。Mは、Mn、Fe、Co、Ni、Cu、Al、B、Mg、Zr、NbおよびWからなる群から選ばれる少なくとも1種であることが好ましい。上述のLTOは、1種を単独でまたは2種以上を混合して用いることができる。
二次電池に注入される非水電解液は、少なくとも非水溶媒と支持塩とを含み得る。典型的には、適当な非水溶媒に支持塩を含有させた組成を有する電解液である。上記非水溶媒としては、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)、ジエチルカーボネート(DEC)、ジメチルカーボネート(DMC)、エチルメチルカーボネート(EMC)、1,2-ジメトキシエタン、1,2-ジエトキシエタン、テトラヒドロフラン、2-メチルテトラヒドロフラン、ジオキサン、1,3-ジオキソラン、ジエチレングリコールジメチルエーテル、エチレングリコールジメチルエーテル、アセトニトリル、プロピオニトリル、ニトロメタン、N,N-ジメチルホルムアミド、ジメチルスルホキシド、スルホラン、γ-ブチロラクトンが挙げられ、これらは1種を単独でまたは2種以上を混合して用いることができる。なかでも、EC、DMCおよびEMCの混合溶媒が好ましい。
このようにして構築されたリチウム二次電池は、正極から溶出した金属元素の負極上での析出が抑制されているので、電池容量の劣化が抑制されている。したがって、各種用途の二次電池として利用可能である。例えば、図8に示すように、リチウム二次電池100は、自動車等の車両1に搭載され、車両1を駆動するモータ等の駆動源用の電源として好適に利用することができる。本発明は、上記リチウム二次電池(典型的には複数直列接続してなる組電池)100を電源として備える車両(典型的には自動車、特にハイブリッド自動車(HV)、プラグインハイブリッド自動車(PHV)、電気自動車(EV)、燃料電池自動車のような電動機を備える自動車)1を提供することができる。
[正極シートの作製]
正極活物質としてスピネル構造のリチウムニッケルマンガン複合酸化物(LiNi0.5Mn1.5O4)と、導電材としてアセチレンブラックと、結着材としてPVdFとを、これらの材料の質量比が85:10:5となるようにNMPで混合して、ペースト状の正極合材層形成用組成物を調製した。この組成物をアルミニウム箔(正極集電体:厚さ15μm)の両面に合計塗付量が30mg/cm2(固形分基準)となるように均一に塗付し、乾燥後、圧縮することによってシート状の正極(正極シート)を作製した。正極合材層の密度は2.8g/cm3であった。
負極活物質としてグラファイト粉末と、結着材としてのPVdFと、増粘材としてカルボキシメチルセルロース(CMC)とを、これらの材料の質量比が98:1:1となるようにイオン交換水で混合して、ペースト状の負極合材層形成用組成物を調製した。この組成物を、塗付量が17mg/cm2(固形分基準)となるように銅箔(厚さ14μm)に均一に塗付し、乾燥後、圧縮することによって、シート状の負極(負極シート)を作製した。負極合材層の密度は1.4g/cm3であった。
セパレータシートとして、PP/PE/PPからなる3層構造のセパレータシート(厚さ:20μm)を用意した。各層の厚さはPPの各層が7μm、PE層が6μmであった。このセパレータシートの片面にLTO層を形成した。具体的には、チタン酸リチウム(LTO:Li4Ti5O12)とPVdFとを、これらの質量比が95:5となるようにNMPで混合することによってスラリー状のLTO層形成用組成物を調製した。混合は、エム・テクニック(株)製の超音波分散機「クレアミックス」を用いて行った。得られたLTO層形成用組成物を、セパレータシートの片面全体を覆うようにグラビア塗工方法により塗付し、温度70℃で乾燥させてLTO層を形成した。このようにして厚さ10μmのLTO層が片面に形成されたLTO層付きセパレータシートを作製した。
上記のようにして作製した正極シートと負極シートとを、それぞれ4.4cm角となり、かつタブを有するように切断し、タブ部の合材層を剥がしとって、シール付きリードを取り付けた。正極シート1枚に対し、LTO層付きセパレータシートを介して2枚の負極シートを重ね合わせた。LTO層付きセパレータシートは、LTO層が正極シートに対向するように配置した。このようにして、正負極間の断面が図4に示すような構成の電極体を作製した。この電極体をアルミラミネートフィルム製の袋に収容し、非水電解液を袋内に注入した。非水電解液としては、モノフルオロエチレンカーボネート(MFEC)とエチルメチルカーボネート(EMC)との1:1(体積比)混合溶媒に、支持塩として約1mol/LのLiPF6を溶解した電解液を用いた。袋内を真空にひきながらアルミラミネートフィルムとリードに取り付けられたシール部とを熱溶着して内部を封止(密封)することにより、ラミネート型電池を作製した。
LTO層付きセパレータシートの他に、PEからなる単層のセパレータシート(厚さ:10μm)を1枚用意し、正極シートと負極シートとの間に、LTO層付きセパレータシートと上記セパレータシート(LTO層なし)を重ね合わせた。このとき、LTO層付きセパレータシートは、LTO層が上記セパレータシート(LTO層なし)と対向するように配置した。その他は例1と同様にして、正負極間の断面が図5に示すような構成の電極体を作製した。この電極体を用いた他は例1と同様にして例2に係るラミネート型電池を作製した。
LTO層付きセパレータシートを、LTO層が負極シートに対向するように配置した他は例1と同様にして例3に係るラミネート型電池を作製した。
セパレータシートとして、LTO層付きセパレータシートに代えてPP/PE/PPからなる3層構造のセパレータシート(厚さ:20μm)を用いた他は例1と同様にして例4に係るラミネート型電池を作製した。
[耐久試験]
各電池に対し、温度25℃にて、1/3Cレートで4.9Vまで定電流(CC)充電した後、10分間休止し、次いで1/3Cレートで3.5VまでCC放電した後、10分間休止する充放電操作を3サイクル繰り返し(コンディショニング)、3サイクル目の放電容量を測定し、これを初期容量(初期放電容量)とした(初期容量測定)。
その後、温度60℃に設定された恒温槽内に2時間以上静置した後、以下の充放電操作(1)~(4)を200サイクル繰り返した(耐久試験)。
(1)2Cのレートで4.9VまでCC充電する。
(2)10分間休止する。
(3)2Cのレートで3.5VまでCC放電する。
(4)10分間休止する。
50サイクル後、100サイクル後、200サイクル後の放電容量を上記初期容量と同様の方法により測定した(サイクル後容量測定)。容量維持率(%)は、初期容量に対する各サイクル(50サイクル、100サイクル、200サイクル)後の容量の割合((各サイクル後の容量/初期容量)×100(%))として算出した。得られた値(容量維持率)を、例4の結果を100とする相対値に換算した。結果を図6に示す。
上記耐久試験の後、例1および例4に係るラミネート型電池を解体し、例1および例4の負極シートと、例1のLTO層付きセパレータシートを取り出し、負極シートおよびLTO層上に析出したマンガン(Mn)量を測定した。具体的には、取り出した負極シートとLTO層とを、非水電解液として用いた非水溶媒で2~3回軽く洗浄した後、この負極シートとLTO層とを任意の大きさに打ち抜いて誘導結合プラズマ発光分光分析(Inductively Coupled Plasma Atomic Emission Spectroscopy:ICP‐AES)用の測定用試料を得た。この試料を酸溶媒中(ここでは硫酸を用いた。)に加熱溶解させ、この溶液をICP-AESで分析することによって、Mn原子の量(μg)を測定した。得られた測定値は、例4の負極シートにおけるMn量を100とする相対値に換算した。結果を図7に示す。
10 電池ケース
12 開口部
14 蓋体
20 捲回電極体
25 非水電解液
30 正極(正極シート)
32 正極集電体
34 正極合材層
35 正極集電体積層部
36 正極合材層非形成部
37 内部正極端子
38 外部正極端子
40 負極(負極シート)
42 負極集電体
44 負極合材層
45 負極集電体積層部
46 負極合材層非形成部
47 内部負極端子
48 外部負極端子
50A,50B,50a,50b セパレータ(セパレータシート)
51 チタン酸リチウム含有層(LTO層)
100 リチウム二次電池
Claims (8)
- 正極と負極とを含む電極体を備える非水電解液二次電池であって、
前記正極の作動上限電位は、金属リチウム基準で4.5V以上であり、
前記電極体はチタン酸リチウム含有層を含み、該チタン酸リチウム含有層は前記負極と離隔している、非水電解液二次電池。 - 前記正極は、正極活物質としてスピネル構造のリチウム遷移金属複合酸化物を含み、該リチウム遷移金属複合酸化物は、遷移金属元素として少なくともニッケルとマンガンとを含有する、請求項1に記載の非水電解液二次電池。
- 前記チタン酸リチウム含有層は、前記正極と前記負極との間に配置されている、請求項1または2に記載の非水電解液二次電池。
- 前記正極と前記負極との間にはセパレータが配置されており、
前記チタン酸リチウム含有層は、前記セパレータの正極側表面に設けられている、請求項3に記載の非水電解液二次電池。 - 前記チタン酸リチウム含有層は、チタン酸リチウムを50質量%以上含む、請求項1~4のいずれかに記載の非水電解液二次電池。
- 前記チタン酸リチウム含有層の厚さは5~15μmである、請求項1~5のいずれかに記載の非水電解液二次電池。
- 前記非水電解液二次電池を構成する非水電解液は、フッ素化カーボネートを含む、請求項1~6のいずれかに記載の非水電解液二次電池。
- 請求項1~7のいずれかに記載の非水電解液二次電池を備える車両。
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US14/417,975 US9543572B2 (en) | 2012-08-01 | 2012-08-01 | Non-aqueous electrolyte secondary battery |
JP2014527899A JP6011888B2 (ja) | 2012-08-01 | 2012-08-01 | 非水電解液二次電池 |
EP12882113.9A EP2882012B1 (en) | 2012-08-01 | 2012-08-01 | Non-aqueous electrolyte secondary battery |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105449139A (zh) * | 2015-03-27 | 2016-03-30 | 万向A一二三***有限公司 | 一种解决钛酸锂负极锂离子电池高温胀气的方法 |
JP2016149200A (ja) * | 2015-02-10 | 2016-08-18 | トヨタ自動車株式会社 | 非水電解質二次電池 |
JP2019046587A (ja) * | 2017-08-30 | 2019-03-22 | 旭化成株式会社 | 非水電解質電池用吸着層並びにこれを用いた非水電解質電池用セパレータ及び非水電解質電池 |
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Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001052704A (ja) * | 1999-08-10 | 2001-02-23 | Hitachi Ltd | リチウム二次電池 |
JP2002343363A (ja) * | 2001-05-17 | 2002-11-29 | Toshiba Battery Co Ltd | 非水電解質二次電池 |
JP2007305352A (ja) * | 2006-05-10 | 2007-11-22 | Gs Yuasa Corporation:Kk | 非水電解液二次電池 |
JP2008210573A (ja) | 2007-02-23 | 2008-09-11 | Sanyo Electric Co Ltd | 非水電解質二次電池 |
JP2009190954A (ja) * | 2008-02-18 | 2009-08-27 | Toyota Central R&D Labs Inc | リチウムチタン鉄複合酸化物、その使用方法、リチウムイオン二次電池、及びリチウムチタン鉄複合酸化物の製造方法 |
JP2010192230A (ja) * | 2009-02-18 | 2010-09-02 | Murata Mfg Co Ltd | 非水電解液二次電池 |
JP2011503828A (ja) * | 2007-11-19 | 2011-01-27 | エルジー・ケム・リミテッド | 多孔性コーティング層が形成されたセパレータ及びこれを備えた電気化学素子 |
JP2012059486A (ja) * | 2010-09-08 | 2012-03-22 | Konica Minolta Holdings Inc | リチウムイオン二次電池及びリチウムイオン二次電池用多孔質絶縁層 |
JP2012138359A (ja) * | 2010-12-27 | 2012-07-19 | Ind Technol Res Inst | リチウム電池および電極板構造 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5962166A (en) * | 1997-08-18 | 1999-10-05 | Covalent Associates, Inc. | Ultrahigh voltage mixed valence materials |
JPH11219722A (ja) * | 1998-02-03 | 1999-08-10 | Matsushita Electric Ind Co Ltd | リチウム二次電池 |
JP2001210325A (ja) | 2000-01-25 | 2001-08-03 | Toshiba Battery Co Ltd | 非水電解液二次電池 |
JP4973826B2 (ja) | 2000-11-14 | 2012-07-11 | 戸田工業株式会社 | 非水電解質二次電池用正極活物質の製造法、非水電解質二次電池 |
WO2007129839A1 (en) | 2006-05-04 | 2007-11-15 | Lg Chem, Ltd. | Lithium secondary battery and method for producing the same |
JP4765955B2 (ja) | 2007-02-22 | 2011-09-07 | 三菱電機株式会社 | 電気二重層キャパシタ用圧延電極シートの製造方法 |
CN104103851B (zh) | 2007-09-14 | 2018-10-09 | A123***有限责任公司 | 具有用于健康状态监视的参考电极的锂可再充电电池 |
CN104409710A (zh) * | 2009-01-06 | 2015-03-11 | 株式会社Lg化学 | 锂二次电池用正极活性材料 |
-
2012
- 2012-08-01 US US14/417,975 patent/US9543572B2/en active Active
- 2012-08-01 JP JP2014527899A patent/JP6011888B2/ja active Active
- 2012-08-01 KR KR1020157004779A patent/KR101671131B1/ko active IP Right Grant
- 2012-08-01 CN CN201280074968.8A patent/CN104508869B/zh active Active
- 2012-08-01 WO PCT/JP2012/069617 patent/WO2014020729A1/ja active Application Filing
- 2012-08-01 EP EP12882113.9A patent/EP2882012B1/en active Active
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001052704A (ja) * | 1999-08-10 | 2001-02-23 | Hitachi Ltd | リチウム二次電池 |
JP2002343363A (ja) * | 2001-05-17 | 2002-11-29 | Toshiba Battery Co Ltd | 非水電解質二次電池 |
JP2007305352A (ja) * | 2006-05-10 | 2007-11-22 | Gs Yuasa Corporation:Kk | 非水電解液二次電池 |
JP2008210573A (ja) | 2007-02-23 | 2008-09-11 | Sanyo Electric Co Ltd | 非水電解質二次電池 |
JP2011503828A (ja) * | 2007-11-19 | 2011-01-27 | エルジー・ケム・リミテッド | 多孔性コーティング層が形成されたセパレータ及びこれを備えた電気化学素子 |
JP2009190954A (ja) * | 2008-02-18 | 2009-08-27 | Toyota Central R&D Labs Inc | リチウムチタン鉄複合酸化物、その使用方法、リチウムイオン二次電池、及びリチウムチタン鉄複合酸化物の製造方法 |
JP2010192230A (ja) * | 2009-02-18 | 2010-09-02 | Murata Mfg Co Ltd | 非水電解液二次電池 |
JP2012059486A (ja) * | 2010-09-08 | 2012-03-22 | Konica Minolta Holdings Inc | リチウムイオン二次電池及びリチウムイオン二次電池用多孔質絶縁層 |
JP2012138359A (ja) * | 2010-12-27 | 2012-07-19 | Ind Technol Res Inst | リチウム電池および電極板構造 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2882012A4 |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2016149200A (ja) * | 2015-02-10 | 2016-08-18 | トヨタ自動車株式会社 | 非水電解質二次電池 |
CN105449139A (zh) * | 2015-03-27 | 2016-03-30 | 万向A一二三***有限公司 | 一种解决钛酸锂负极锂离子电池高温胀气的方法 |
JP2019046587A (ja) * | 2017-08-30 | 2019-03-22 | 旭化成株式会社 | 非水電解質電池用吸着層並びにこれを用いた非水電解質電池用セパレータ及び非水電解質電池 |
JP7053192B2 (ja) | 2017-08-30 | 2022-04-12 | 旭化成株式会社 | 非水電解質電池用吸着層並びにこれを用いた非水電解質電池用セパレータ及び非水電解質電池 |
JP2020068303A (ja) * | 2018-10-25 | 2020-04-30 | テイカ株式会社 | 蓄電デバイス用出力向上剤、及び該出力向上剤を含む蓄電デバイス用正極又はセパレータ、並びにそれらを含む蓄電デバイス |
JP7224850B2 (ja) | 2018-10-25 | 2023-02-20 | テイカ株式会社 | 蓄電デバイス用出力向上剤を含む蓄電デバイス用正極又はセパレータ、並びにそれらを含む蓄電デバイス |
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CN104508869B (zh) | 2017-05-17 |
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