WO2014181447A1 - Accumulateur lithium-ion - Google Patents

Accumulateur lithium-ion Download PDF

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Publication number
WO2014181447A1
WO2014181447A1 PCT/JP2013/063099 JP2013063099W WO2014181447A1 WO 2014181447 A1 WO2014181447 A1 WO 2014181447A1 JP 2013063099 W JP2013063099 W JP 2013063099W WO 2014181447 A1 WO2014181447 A1 WO 2014181447A1
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negative electrode
battery
secondary battery
overcharge
active material
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PCT/JP2013/063099
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English (en)
Japanese (ja)
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斉景 田中
宏文 ▲高▼橋
山本　恒典
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株式会社 日立製作所
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Priority to PCT/JP2013/063099 priority Critical patent/WO2014181447A1/fr
Publication of WO2014181447A1 publication Critical patent/WO2014181447A1/fr

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    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • 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

Definitions

  • the present invention relates to a non-aqueous secondary battery, and in particular, a high energy density lithium ion secondary battery excellent in safety during overcharge and suitable for use in portable equipment, electric vehicles, power storage, and the like, and a battery module thereof. About.
  • Lithium ion secondary batteries (hereinafter referred to as lithium ion batteries) that use the insertion and release of lithium ions for charge / discharge reactions have higher energy density and output density than conventional lead batteries and nickel cadmium batteries. Application to portable devices, electric vehicles, and power storage is in progress.
  • One of the most important battery abnormalities is overcharge.
  • the battery When the battery is charged beyond an appropriate charge / discharge range, the battery may be heated, ruptured, or ignited due to decomposition of the positive electrode active material, deposition of metallic lithium on the negative electrode, decomposition of the electrolyte, or the like. Therefore, a safe battery is expected even if the control system falls into an abnormal state.
  • Patent Document 1 discloses, as a conventional technique for solving this problem, a negative electrode made of a carbon material and an additive made of a material containing Si or Sn, or a material containing these elements, which is known as a high capacity alloy negative electrode material. Is added to suppress the generation of Li dendrite and to selectively deposit the metal eluted from the positive electrode active material on the surface of the additive.
  • the alloy-based negative electrode material described in Patent Document 1 has problems such as a large volume change and a large irreversible capacity. If it is added in a large amount, it may cause a decrease in battery characteristics. On the other hand, when there is too little addition amount, there exists a subject by which the safety improvement effect at the time of overcharge is limited.
  • the purpose of the present invention is to solve such problems and problems.
  • an object of the present invention is to provide a secondary battery capable of suppressing deterioration of battery characteristics due to the alloy-based negative electrode material while suppressing generation of Li dendrite by adding the alloy-based negative electrode material as an overcharge preventing material. It is to provide.
  • the secondary battery according to the present invention is a secondary battery having a positive electrode having a Li-containing transition metal oxide as a main active material and a negative electrode having graphite as a main active material.
  • the negative electrode includes Si, Sn, Or an overcharge preventive material having a particle composed of either Al as a nucleus and a coating composed of SiO 2 or SiC provided on the outer periphery of the nucleus, and the thickness of the coating is 2 nm to 100 nm It is characterized by that.
  • the high-resistance barrier layer on which the surface of the alloy-based negative electrode material is formed can prevent charging and discharging of the alloy-based negative electrode material at normal times. It is possible to suppress deterioration in battery characteristics due to volume change and high irreversible capacity. Once overcharge occurs, lithium ions move through the barrier layer to prevent Li dendrite precipitation. Furthermore, since the alloy-based negative electrode material contributes to charging / discharging, the charging / discharging curve of the battery changes. From this change, it becomes possible to grasp the history of overcharging and the progress of overcharging.
  • the present invention detects battery overcharge and improves safety. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.
  • FIG. 2A is a diagram illustrating a schematic diagram of a Li ion battery according to the present embodiment, and FIG. It is a figure which shows the AA sectional drawing of Fig.1 (a).
  • A The figure which shows the overcharge prevention material 100
  • (b) The figure which shows the preparation method of the overcharge prevention material 100. It is a figure which shows the change (change of the reaction form with Li) of the charge curve by high resistance film provision. It is a figure which shows the change (change of the reaction form with Li) of the discharge curve by high resistance film provision.
  • 2 is a detailed view of a negative electrode 200.
  • FIG. It is a figure which shows the battery internal (positive / negative state) analysis result by battery measurement information. It is an experimental data of each Example and a comparative example.
  • FIG. 1A is a diagram showing a cylindrical Li ion battery 1 of the present embodiment.
  • the cylindrical Li-ion battery 1 is a wound battery in which an electrode group 3 wound with a positive electrode 200 and a negative electrode 300 facing each other through a separator 350 and an electrolyte solution are housed inside a battery can 4. It is.
  • the electrode group 3 has a shaft core 2 at the start of the electrode group 3, and the electrode group 3 is configured to be wound around the shaft core 2, and the electrode group 3 and the shaft core 2 are accommodated inside the battery can 4. It has become.
  • the upper and lower ends of the electrode group 3 are provided with electrical insulating plates 5 so that the electrode group 3 does not come into contact with the battery can 4 due to vibration or the like and is not short-circuited.
  • a positive conductive lead 7 is provided at the upper end of the electrode group 3, one end of the conductive lead 7 is electrically connected to the positive electrode 200 of the electrode group 3, and the other end of the conductive lead 7 is the battery lid 6. It is the structure electrically connected to.
  • a negative electrode conductive lead 8 is provided at the lower end of the electrode group 3, one end of the conductive lead 8 is electrically connected to the negative electrode 300 of the electrode group 3, and the other end of the conductive lead 8 is a battery can. 4 is joined to the bottom.
  • the electrolytic solution is injected into the battery can 4 when the dehumidifying atmosphere or the inert atmosphere is controlled.
  • a gasket 9 serving both as an electric insulator and a gas seal is disposed between the battery can 4 and the battery lid 6, and the battery can 4 and the battery lid 6 are integrated by caulking the battery can 4. 4 It is the structure which keeps the inside sealed.
  • FIG. 2 is a cross-sectional view of the Li ion battery of FIG. As described above, the shaft core 2 and the electrode group 3 are accommodated in the battery can 4.
  • the electrode group 3 has a structure in which the positive electrode 200 and the negative electrode 300 are wound through the separator 350 as described above.
  • the positive electrode 200 has a structure in which a positive electrode material 202 is provided on both surfaces of the positive electrode foil 201.
  • the negative electrode 300 has a structure in which the negative electrode material 302 is provided on both surfaces of the negative electrode foil 301.
  • the shaft core 2 may be any known one as long as it can carry the positive electrode, the separator, and the negative electrode. It is desirable to use an aluminum foil for the positive foil 202 and a copper foil for the negative foil 302, but any material may be used as long as it is chemically stable in the charge / discharge reaction of the lithium ion battery.
  • the battery which can be applied is not restricted to a cylindrical battery, It is possible to apply this invention also to a square battery and a laminate cell battery.
  • the electrode group 3 can have various shapes obtained by winding the positive electrode 200 and the negative electrode 300 into an arbitrary shape such as a flat shape.
  • the electrode group 3 may be produced by winding without using the shaft core 2, or a laminate in which a positive electrode and a negative electrode are laminated via a separator like a laminated cell battery may be used.
  • the shape of the battery can 4 may be selected from shapes such as a cylindrical shape, a flat oval shape, a flat oval shape, and a square shape according to the shape of the electrode group 3.
  • the material of the battery can 4 is selected from materials that are corrosion resistant to the nonaqueous electrolyte, such as aluminum, stainless steel, and nickel-plated steel. Further, when the battery can 4 is electrically connected to the positive electrode 200 or the negative electrode 300, the material is not deteriorated due to corrosion of the battery can 4 or alloying with lithium ions in the portion in contact with the nonaqueous electrolyte. Thus, the material of the battery can 4 is selected.
  • the electrolytic solution 3 may be injected directly into the electrode group with the battery lid 6 open, or from the injection port installed in the battery lid 20.
  • the positive electrode 200 includes a positive electrode active material, a conductive agent, a binder, and a positive electrode foil 201.
  • the positive electrode active material include LiCoO 2 , LiNiO 2 , and LiMn 2 O 4 .
  • the particle size of the positive electrode active material is usually specified so as to be equal to or less than the thickness of the mixture layer formed of the positive electrode active material, the conductive agent, and the binder.
  • the coarse particles can be removed in advance by sieving classification, wind classification, etc. preferable.
  • the positive electrode active material is generally oxide-based and has high electric resistance
  • a conductive agent made of carbon powder for supplementing electric conductivity is used. Since both the positive electrode active material and the conductive agent are usually powders, a binder can be mixed with the powders, and the powders can be bonded together and simultaneously bonded to the positive electrode foil 201.
  • the positive electrode foil 201 an aluminum foil having a thickness of 10 to 100 ⁇ m, an aluminum perforated foil having a thickness of 10 to 100 ⁇ m and a pore diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, or the like is used.
  • materials such as stainless steel and titanium are also applicable.
  • any positive foil 201 can be used without being limited by the material, shape, manufacturing method and the like.
  • a positive electrode slurry in which a positive electrode active material, a conductive agent, a binder, and an organic solvent are mixed is attached to the positive electrode foil 201 by a doctor blade method, a dipping method, or a spray method, and then the organic solvent is dried and applied by a roll press.
  • a positive electrode can be produced by pressure forming.
  • a plurality of mixture layers can be laminated on the positive electrode foil 201 by performing a plurality of times from application to drying.
  • the negative electrode 300 includes a negative electrode active material, a binder, and a negative electrode foil 301.
  • a conductive agent may be added.
  • the negative electrode active material that can be used in the present invention include graphite, non-graphite carbon, metals such as aluminum, silicon, and tin, and alloys thereof, lithium-containing transition metal nitrides Li (3-X) M X N, silicon
  • the lower oxide Li x SiO y (0 ⁇ x, 0 ⁇ y ⁇ 2) and the tin lower oxide Li x SnO y are selected from materials that form an alloy with lithium or materials that form an intermetallic compound. be able to.
  • the material of the negative electrode active material is not particularly limited and can be used other than the above materials. However, when a part of the material such as a material having a large expansion and contraction is selected, if the range used by the negative electrode is too large, Resistance rise may be large. In this case, it is preferable to confirm whether or not the negative electrode potential is below a certain level as a condition for changing the battery voltage.
  • the graphite is included, and the graphite has a graphite interlayer distance (d002) of 0.335 nm or more and 0.338 nm or less.
  • d002 graphite interlayer distance
  • the potential curve of graphite has a stage structure, so that the cycle characteristics of the lithium ion secondary battery can be further improved.
  • the graphite used for the negative electrode is natural graphite that can occlude and release lithium ions, artificial graphite, mesophase carbon, expanded graphite, carbon fiber, vapor grown carbon fiber, pitch-based carbonaceous material, needle coke, Manufactured using petroleum coke and polyacrylonitrile-based carbon fiber as raw materials.
  • the graphite interlayer distance (d002) can be measured using XRD (X-Ray Diffraction Method) or the like.
  • the non-graphitic carbon used for the negative electrode 300 is a carbon material excluding the above-mentioned graphite, and can occlude or release lithium ions.
  • Amorphous carbon materials synthesized by pyrolysis of organic compounds are included.
  • a material that forms an alloy with lithium or a material that forms an intermetallic compound may be added as a third negative electrode active material to the negative electrode 300 having a voltage change rate different from that of the positive electrode 200.
  • the third negative electrode active material include metals such as aluminum, silicon, and tin and alloys thereof, lithium-containing transition metal nitrides Li (3-X) M X N, and lower oxides of silicon Li X SiO y ( 0 ⁇ x, 0 ⁇ y ⁇ 2), and the lower oxide of tin Li x SnO y .
  • the negative electrode active material generally used is a powder
  • a binder is mixed with the negative electrode active material, and the powders are bonded together and simultaneously bonded to the negative electrode foil 301.
  • the particle size of the negative electrode active material be equal to or less than the thickness of the mixture layer formed from the negative electrode active material and the binder.
  • the coarse particles may be removed in advance by sieving classification or wind classification, and particles having a thickness of the mixture layer thickness or less may be used. preferable.
  • a copper foil having a thickness of 10 to 100 ⁇ m, a copper perforated foil having a thickness of 10 to 100 ⁇ m and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam metal plate, or the like is used.
  • materials such as stainless steel, titanium, or nickel are also applicable.
  • any negative electrode foil 301 can be used without being limited by the material, shape, manufacturing method and the like.
  • a negative electrode slurry in which a negative electrode active material, a binder, and an organic solvent are mixed is attached to the negative electrode foil 301 by a doctor blade method, a dipping method, a spray method, or the like, and then the organic solvent is dried and pressure-molded by a roll press. Thereby, a negative electrode can be produced. Moreover, it is also possible to form a multilayer mixture layer on the negative electrode foil 301 by performing from application to drying a plurality of times.
  • a separator 350 is inserted between the positive electrode 200 and the negative electrode 300 manufactured by the above method to prevent a short circuit between the positive electrode and the negative electrode.
  • the separator 350 can be a polyolefin polymer sheet made of polyethylene, polypropylene, or the like, or a two-layer structure in which a polyolefin polymer and a fluorine polymer sheet typified by tetrafluoropolyethylene are welded. It is.
  • a mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator 350 so that the separator does not shrink when the battery temperature increases. Since these separators need to allow lithium ions to permeate during charge and discharge of the battery, they can be used for lithium ion batteries as long as the pore diameter is generally 0.01 to 10 ⁇ m and the porosity is 20 to 90%.
  • Electrolyte As a representative example of the electrolyte that can be used in an embodiment of the present invention, lithium hexafluorophosphate (LiPF 6 ) as an electrolyte, a solvent obtained by mixing dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate with ethylene carbonate, Alternatively, there is a solution in which lithium borofluoride (LiBF 4 ) is dissolved.
  • the present invention is not limited to the type of solvent and electrolyte, and the mixing ratio of solvents, and other electrolytes can be used.
  • non-aqueous solvents examples include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, ⁇ -butyrolactone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, 1,2-dimethoxyethane, -Methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, formamide, dimethylformamide, methyl propionate, ethyl propionate, phosphate triester, trimethoxymethane, dioxolane, diethyl ether, sulfolane, 3-methyl-2-
  • non-aqueous solvents such as oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane, chloroethylene carbonate, or chloropropylene carbonate.
  • Other solvents may be used as long as they do not decompose on the positive electrode or the negative electrode
  • examples of the electrolyte LiPF 6, LiBF 4, LiClO 4, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, or imide salts such as lithium represented by lithium trifluoromethane sulfonimide, multi
  • lithium salts A nonaqueous electrolytic solution obtained by dissolving these salts in the above-mentioned solvent can be used as a battery electrolytic solution.
  • An electrolyte other than this may be used as long as it does not decompose on the positive electrode and the negative electrode of the battery according to this embodiment.
  • ion conductive polymers such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, polyhexafluoropropylene, and polyethylene oxide can be used for the electrolyte.
  • polyethylene oxide polyacrylonitrile
  • polyvinylidene fluoride polymethyl methacrylate
  • polyhexafluoropropylene polyethylene oxide
  • an ionic liquid can be used.
  • EMI-BF4 1-ethyl-3-methylimidazole tetrafluoroborate
  • LiTFSI lithium salt LiN (SO 2 CF 3 ) 2
  • triglyme and tetraglyme a mixed salt of lithium salt LiN (SO 2 CF 3 ) 2
  • LiTFSI lithium salt LiN (SO 2 CF 3 ) 2
  • triglyme and tetraglyme LiN (SO 2 CF 3 ) 2
  • a cyclic quaternary ammonium cation N-methyl) -N-propylpyrrolidinium
  • an imide-based anion example is bis (fluorosulfonyl) imide
  • the overcharge prevention material 100 is a characteristic part of the present invention.
  • the overcharge prevention material 100 in the present invention is a high-capacity Li storage material 10 provided with a high resistance film.
  • the high-capacity Li storage material 10 is specifically Si, Sn, and Al particles. Since these materials have a Li storage capacity as high as 2 to 7 times that of graphite, the Li storage capacity of the negative electrode can be enhanced only by mixing a small amount.
  • the high resistance film 11 is specifically made of SiO 2 or SiC.
  • the volume resistivity of SiO 2 is about 10 6 to 10 10 ⁇ cm, and SiC is 10 6 ⁇ cm. Therefore, a value higher than the volume resistivity of Si or the like is shown, and it becomes possible to function as a high resistance film.
  • the thickness of the SiO 2 or SiC coating 11 is preferably 2 nm to 100 nm.
  • the reason why the thickness of the coating 11 is required to be 2 nm or more is that when the thickness of the coating 11 is less than 2 nm, dielectric breakdown occurs even at a low potential, and even when no overvoltage actually occurs, an overcharge prevention material This is because there is a risk that the performance of the Li-ion battery may deteriorate. Moreover, when it becomes a thin film, the influence of the resistance value resulting from crystallinity will become large, and it will operate
  • the reason why the thickness of the coating film 11 must be 100 nm or less is that when the thickness of the coating film 11 exceeds 100 nm, the electronic conductivity of the overvoltage prevention material 100 becomes too low, and a considerable overvoltage is not applied. This is because the overvoltage prevention material 100 does not work.
  • the resistance value of the film is 10 ⁇ 1 to 10 3 ⁇ . In this case, charging starts near 0 V at the Li / Li + potential, and the high-capacity Li storage material 10 can absorb Li ions.
  • the overvoltage prevention material 100 Inside the battery, at a potential at which Li does not precipitate, the resistance of the negative electrode active material is lower than that of the overcharge preventing material 100, so that a current flows into the negative electrode active material and a charging reaction is performed. However, in the vicinity of 0 V at which Li is deposited, the amount of Li ions that can be occluded in the negative electrode active material is almost in a limit state (a state in which charging is impossible any more), and the mobility of Li ions becomes small. As a result, the resistance of the negative electrode active material itself increases, and the overcharge preventing material 100 is also put in a voltage state. In this state, Li ions are inserted into the overcharge prevention material 100 and function as an overcharge prevention material.
  • the overvoltage prevention material 100 is used by being added to the negative electrode material 302.
  • the overvoltage prevention material 100 has an increased electrical resistance due to the formation of the coating 11, and the high-capacity Li storage material 10 (for example, Si) and Li at the time of overvoltage generation. It becomes possible to reduce the initial reaction potential.
  • Li ions are inserted into the high-capacity Li storage material 10 having a higher reaction potential with Li than the negative electrode active material such as graphite (that is, the high-capacity Li storage material 10 is present before the graphite or the like). To react).
  • the overvoltage prevention material 100 When the overvoltage prevention material 100 is used for the above reason, it has the effect of suppressing the occurrence of overvoltage in addition to the overcharge prevention effect.
  • the electric resistance and the Li diffusion resistance can be further increased, and the high-capacity Li storage material 10
  • the overvoltage required for the initial reaction between (for example, Si) and Li can be increased, and the overvoltage prevention material can be reliably operated.
  • the Li reaction potential can be lowered to the vicinity of the Li deposition potential.
  • the negative electrode active material such as graphite
  • Si is not included in the SiO 2 matrix, but the volume of the high-capacity Li absorbing material 10 (for example, Si) is larger than that of the coating film 11 (for example, SiO 2 ). Is a point. This is because the structure in which Si is included in the SiO 2 matrix does not sufficiently function as an overvoltage prevention material because the resistance is too high and the amount of Si is small.
  • the coating 11 provided on the high-capacity Li absorbent material 10 must cover the entire surface of the high-capacity Li absorbent material 10. If the high-capacity Li-occlusion material 10 (for example, Si) is exposed, the resistance of the exposed surface is low, so that a conduction path to Si can be made directly. Therefore, conduction to Si through the SiO 2 coating 11 is performed. This is because there is no phenomenon that a pass can be made, that is, an insulation pass is made due to dielectric breakdown at the time of overvoltage, and the function as an overvoltage prevention material is not exhibited unless a very large overvoltage prevention occurs.
  • the high-capacity Li-occlusion material 10 for example, Si
  • all the overvoltage preventions 100 in all the negative electrode materials 301 have a structure in which the entire surface of the high-capacity Li storage material 10 is covered with the coating 11.
  • the film 11 is formed on the entire surface of most particles (50% or more) in the overvoltage prevention material 100.
  • the overvoltage prevention material 100 of the present invention has the high voltage Li storage material 10 larger than the volume of the coating 11, so that the dielectric breakdown of the coating 11 occurs at an appropriate voltage. It is possible to function as.
  • the coating 11 is formed on the entire surface of the majority (50% or more) of the particles in the overvoltage prevention material 100, it can function as an overvoltage prevention material.
  • the film 11 is formed on the entire surface of 95% or more of the particles in the overvoltage preventing material 100.
  • FIG. 3A is a diagram illustrating the overcharge preventing material 100 according to the present embodiment. It has a core-shell structure in which particles of a high-capacity Li-absorbing material 10 (Si, Al, Sn) capable of storing Li are used as a core layer and a coating 11 (shell layer) having a high resistivity is formed on the surface thereof.
  • a high-capacity Li-absorbing material 10 Si, Al, Sn
  • a coating 11 shell layer having a high resistivity
  • the overvoltage prevention material 100 has an arbitrary thickness by placing Si particles in a high-temperature firing furnace and firing in an Ar / O 2 mixed gas at a temperature of 900 to 1200 ° C. for a predetermined time.
  • SiO 2 layer can be applied (range 5-100 nm). Also, these oxide films can be produced by high-pressure steam oxidation.
  • the overvoltage prevention material 100 When a SiC layer is formed as a coating, it is possible to prepare the overvoltage prevention material 100 by mixing Si particles with tar pitch and a carbon-containing organic substance and firing in an inert atmosphere at 1300 ° C. or higher.
  • FIG. 4 shows characteristics at the time of charging of the overvoltage prevention material 100 in which Si is used as the high-capacity Li storage material 10 and a high-resistance coating (SiO 2) is applied around the Si.
  • the solid line shown in FIG. 4 is a charge curve of Si using Si with no surface coating applied as an active material. As shown by the solid line, it can be seen that the capacity increases from 0.4 V (at Li / Li + potential) when Si with no surface coating is used as the active material. This means that Si reacts with Li from 0.4 V at the Li / Li + potential.
  • the broken line in FIG. 4 is a charging curve of the Si surface provided with the SiO 2 coating 11. From this data, it can be seen that Si to which the SiO 2 coating 11 is applied does not start the reaction with Li unless an overvoltage is applied until it reaches around 0V.
  • the reaction start potential can be lowered.
  • This overvoltage decrease in reaction initiation potential
  • the electrical resistance of the coating on the surface is higher. More specifically, for example, increasing the thickness of the coating 11 can be mentioned.
  • the electric resistance of the coating layer is too large, the overvoltage for initiating the reaction is too large, and it may not operate even at the Li deposition potential.
  • FIG. 5 shows a discharge curve curve of Si coated with a SiO 2 layer (shown by a dotted line), a discharge curve of Si not coated (shown by a broken line), and a discharge curve of graphite (shown by a solid line). Indicated).
  • the mixing ratio of the overcharge prevention material is desirably 5 to 15 wt% or less with respect to the main active material.
  • the mixing ratio of the overcharge prevention material is lower than 5 wt%, the amount of Li absorption is small and the effect becomes minute.
  • the mixing ratio is higher than 15 wt%, the overcharge prevention material 100 dispersed in the main active material is connected. This is because the electric conduction path of the main active material is obstructed and the electric resistance of the negative electrode mixture layer is increased.
  • FIG. 6 shows a cross-sectional view of the negative electrode 300 in the present embodiment.
  • the graphite 110 and the overvoltage preventing material 100 are applied.
  • the overcharge prevention material may be mixed with the main active material so as to be uniform, or a concentration gradient may be provided so that the abundance ratio is increased in a portion where Li is likely to precipitate, for example, in the vicinity of the surface.
  • the overcharge prevention material 100 mixed with the main active material is not limited to a single form, and may have a plurality of forms.
  • the thickness and material of the high resistance film or the material of the Li storage material may be different.
  • Si particles having different SiO 2 layer thicknesses, SiO 2 and SiC Si particles on the surface, SiO 2 on the surface layer, and Si and Sn particles mixed therein may be used.
  • FIG. 7 shows a charge / discharge curve when the above-described overvoltage prevention material 100 is used.
  • the reaction potential between the core material of the overcharge prevention material 100 (inside the coating) and Li takes a value specific to the substance.
  • the lower diagram in FIG. 7 shows data when the reaction amount of the overcharge prevention material 100 is larger than that in the upper diagram in FIG.
  • LiFePO4 as positive electrode active material 88 parts by mass (active material and mixing ratio may be changed), artificial graphite as conductive aid: 1 part by mass, Ketjen black: 1 part by mass, and PVDF as binder: 10 parts by mass
  • NMP as a solvent
  • the positive electrode mixture-containing paste is intermittently applied to both surfaces of an aluminum foil (thickness: 15 ⁇ m) by adjusting the thickness, dried, and then subjected to a calendering process, so that the total thickness of the positive electrode mixture layer is 183 ⁇ m. Was adjusted to produce a positive electrode.
  • the Si particles coated with SiO 2 are placed in a high-temperature firing furnace with Si particles having an average particle diameter D50 of 1 ⁇ m, fired in an Ar / O 2 mixed gas at a temperature of 900 to 1200 ° C. for a predetermined time, and then crushed and coated.
  • the thickness was made in the range of 2 to 100 nm.
  • ⁇ Production of negative electrode> Mixture of SiO2 coated Si particles and graphite having an average particle diameter D50 of 20 ⁇ m mixed at a mass ratio of 15:85: 98 parts by mass, CMC aqueous solution adjusted to have a viscosity of 1500 to 5000 mPa ⁇ s (concentration: 1 mass%): 1 mass part and SBR: 1 mass part were mixed, and the aqueous negative mix containing paste was prepared.
  • the negative electrode mixture-containing paste is intermittently applied on both sides of a current collector made of copper foil with a thickness of 8 ⁇ m while adjusting the thickness, dried, and then calendered to give a total thickness of 108 ⁇ m.
  • a negative electrode was prepared by adjusting the thickness of the mixture layer.
  • LiPF 6 as a lithium salt was dissolved at a concentration of 1 mol / l in a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate in a volume ratio of 1: 1: 1 to prepare a non-aqueous electrolyte.
  • ⁇ Battery assembly> The positive electrode and the negative electrode were cut into a predetermined size, and a wound electrode body was produced through a separator made of a microporous polyethylene film having a thickness of 30 ⁇ m and a porosity of 50%. This wound electrode body was inserted into a cylindrical battery can, and then the non-aqueous electrolyte was poured into the can and sealed to produce a cylindrical non-aqueous secondary battery.
  • Example 2 A cylindrical non-aqueous secondary battery was fabricated in the same manner as in Experimental Example 1 except that the overcharge prevention material was changed to 5 parts by mass (Experimental Example 3). A cylindrical non-aqueous secondary battery was produced in the same manner as in Experimental Example 1 except that the overcharge prevention material was changed to 15 parts by mass (Comparative Example 1). A cylindrical non-aqueous secondary battery was produced in the same manner as in Example 1 except that the overcharge prevention material was changed to 0 part by mass (Comparative Example 2). A cylindrical non-aqueous secondary battery was produced in the same manner as in Example 1 except that the overcharge prevention material was changed to 20 parts by mass.
  • ⁇ Overcharge detection test> The amount of current discharged in 1 hour is 1 C with respect to the initial discharge capacity of the manufactured battery, and the capacity change width is centered on a voltage at which the capacity is exactly half of the discharge capacity at a discharge current of 0.2 C.
  • the constant current charge / discharge cycle test was carried out in a thermostatic bath maintained at 25 ° C. with a charge / discharge current of 2C within a range of 80%.
  • the lower limit value of the discharge termination condition was that the battery voltage reached 1.5V.
  • constant current / constant voltage charging was performed at a predetermined voltage (3.8 V in the process) every 200 cycles, and constant current discharging was performed at a current amount of 0.1C.
  • the first signal is detected at the stage where the reaction between Si and Li, which are overcharge prevention materials, is detected, and the capacity of the overcharge prevention material (the peak derived from Si and the rising peak at the end of discharge in the differential curve)
  • the second signal is different from the first signal when the charged overcharge prevention material has completely reacted, and the overcharge prevention material capacity is 3/4 or more. In some cases, the test was terminated after 5 cycles after emitting a signal different from the first and second signals.
  • the first signal was emitted in 2200 cycles
  • the second signal was emitted in 2600
  • the third signal was emitted in 2800 cycles.
  • the first signal is 2000 cycles
  • the second signal is 2200
  • the third signal is 2400.
  • the number of cycles at the time of signal generation is faster, and the interval between each signal Also became shorter.
  • Comparative Example 1 the test was terminated when the discharge termination condition of 1.5 V was reached without observing a signal, and Li deposition was observed on the negative electrode in the decomposition observation.

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Abstract

L'objet de la présente invention est de produire un accumulateur selon lequel, tout en supprimant la formation de dendrites de lithium via l'addition d'un matériau d'électrode négative en alliage comme matériau de prévention de surcharge, la réduction des caractéristiques de batterie causée par ledit matériau d'électrode négative en alliage peut être réduite au minimum. Le présent accumulateur comporte : une électrode positive dont le matériau actif primaire est un oxyde de métal de transition contenant du lithium ; et une électrode négative dont le matériau actif primaire est du graphite. Ledit accumulateur est caractérisé en ce que : son électrode négative contient un matériau de prévention de surcharge dans lequel des particules noyaux comprenant du silicium, de l'étain ou de l'aluminium sont chacune recouvertes d'une pellicule comprenant du SiO2 ou du SiC ; et en ce que l'épaisseur desdites pellicules est comprise entre 2 et 100 nm inclus.
PCT/JP2013/063099 2013-05-10 2013-05-10 Accumulateur lithium-ion WO2014181447A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019188757A1 (fr) * 2018-03-29 2019-10-03 パナソニックＩｐマネジメント株式会社 Dispositif électrochimique
CN111244410A (zh) * 2020-01-16 2020-06-05 兰溪致德新能源材料有限公司 锂电池负极材料及其制备方法
US20210143411A1 (en) * 2019-11-07 2021-05-13 Samsung Sdi Co., Ltd. Negative active material for rechargeable lithium battery and rechargeable lithium battery including the same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005294078A (ja) * 2004-03-31 2005-10-20 Nec Corp 二次電池用負極及び二次電池
JP2007172858A (ja) * 2005-12-19 2007-07-05 Matsushita Electric Ind Co Ltd 非水電解質二次電池用負極材料及びその製造方法
JP2011076822A (ja) * 2009-09-30 2011-04-14 Hitachi Vehicle Energy Ltd リチウムイオン二次電池
JP2012084426A (ja) * 2010-10-13 2012-04-26 Hitachi Maxell Energy Ltd 非水電解質二次電池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005294078A (ja) * 2004-03-31 2005-10-20 Nec Corp 二次電池用負極及び二次電池
JP2007172858A (ja) * 2005-12-19 2007-07-05 Matsushita Electric Ind Co Ltd 非水電解質二次電池用負極材料及びその製造方法
JP2011076822A (ja) * 2009-09-30 2011-04-14 Hitachi Vehicle Energy Ltd リチウムイオン二次電池
JP2012084426A (ja) * 2010-10-13 2012-04-26 Hitachi Maxell Energy Ltd 非水電解質二次電池

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019188757A1 (fr) * 2018-03-29 2019-10-03 パナソニックＩｐマネジメント株式会社 Dispositif électrochimique
US20210143411A1 (en) * 2019-11-07 2021-05-13 Samsung Sdi Co., Ltd. Negative active material for rechargeable lithium battery and rechargeable lithium battery including the same
CN111244410A (zh) * 2020-01-16 2020-06-05 兰溪致德新能源材料有限公司 锂电池负极材料及其制备方法
CN111244410B (zh) * 2020-01-16 2022-05-27 兰溪致德新能源材料有限公司 锂电池负极材料及其制备方法

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