WO2022205032A1 - Pièce polaire négative, dispositif électrochimique et dispositif électronique - Google Patents

Pièce polaire négative, dispositif électrochimique et dispositif électronique Download PDF

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WO2022205032A1
WO2022205032A1 PCT/CN2021/084276 CN2021084276W WO2022205032A1 WO 2022205032 A1 WO2022205032 A1 WO 2022205032A1 CN 2021084276 W CN2021084276 W CN 2021084276W WO 2022205032 A1 WO2022205032 A1 WO 2022205032A1
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based material
particle size
silicon
graphite
negative electrode
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PCT/CN2021/084276
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English (en)
Chinese (zh)
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贾彦龙
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宁德新能源科技有限公司
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Priority to PCT/CN2021/084276 priority Critical patent/WO2022205032A1/fr
Priority to CN202180004671.3A priority patent/CN114207873A/zh
Publication of WO2022205032A1 publication Critical patent/WO2022205032A1/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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • 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
    • 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 invention belongs to the field of electrochemical devices, and in particular relates to a negative electrode pole piece, an electrochemical device and an electronic device.
  • Silicon-based materials have the advantages of abundant reserves, ultra-high theoretical capacity (4200mAh/g), and environmental friendliness. They have good application prospects in anode materials, and have gradually attracted extensive attention and research. However, silicon-based materials are prone to volume expansion, have poor kinetic properties when used as negative electrode active materials, and have many side reactions with electrolytes, which easily lead to problems such as negative electrode structural damage and continuous formation of a passivation film (SEI) layer. This in turn affects the performance of the negative electrode structure, such as cyclability.
  • SEI passivation film
  • Common silicon-based materials mainly include nano-silicon, silicon-oxygen composite materials, silicon-carbon composite materials, etc. At present, this silicon-based material is generally used together with other negative electrode active materials such as graphite to improve the electrochemical performance of the negative electrode structure.
  • the silicon-based material is blended with graphite to form a negative electrode structure with a single-layer coating, or the silicon-based material and graphite are respectively formed into a negative electrode structure with different coatings, the silicon-based material in the negative electrode structure is easily affected. The improvement effect of defects such as volume expansion and easy side reactions with the electrolyte is limited.
  • the present invention provides a negative electrode pole piece, an electrochemical device and an electronic device, so as to at least solve the problems existing in the prior art such as poor structural stability of silicon negative electrodes, easy volume expansion, easy side reactions of silicon-based materials with electrolytes, and the resulting problems. Electrochemical devices have poor cyclability and other problems.
  • a negative electrode pole piece comprising a negative electrode current collector, a silicon-based material layer on at least one surface of the negative electrode current collector, and a solid electrolyte layer on the surface of the silicon-based material layer, wherein the silicon-based material layer contains a first
  • the negative electrode active material, the first negative electrode active material includes a silicon-based material, and the solid electrolyte layer contains a solid electrolyte.
  • the first negative electrode active material further includes a graphite-based material
  • the mass percentage of the silicon-based material is 1% to 40% based on the total mass of the first negative electrode active material.
  • the particle size of the graphite-based material satisfies 5 ⁇ m ⁇ Dv50 3 ⁇ 15 ⁇ m, and Dv99 3 ⁇ 25 ⁇ m, wherein Dv50 3 represents that in the particle size distribution based on the volume, the graphite-based material particles start from the small particle size side and reach the volume accumulation. 50% particle size, Dv99 3 represents the particle size of the graphite-based material particles from the small particle size side up to 99% by volume in the particle size distribution on a volume basis.
  • the silicon-based material layer further contains a binder and a conductive agent; the binder includes a water-based binder, and/or the conductive agent includes carbon nanotubes.
  • the particle size of the silicon-based material satisfies 2 ⁇ m ⁇ Dv50 1 ⁇ 5 ⁇ m, and 1.2 ⁇ (Dv99 1 -Dv10)/Dv50 1 ⁇ 3, wherein Dv50 1 indicates that in the particle size distribution based on the volume, the silicon-based material particles from small The particle size from the particle size side up to 50% of the cumulative volume, Dv99 1 represents the particle size distribution on the volume basis, the particle size of the silicon-based material particles from the small particle size side to the cumulative 99% of the volume, Dv10 represents the particle size on the volume basis In the particle size distribution, the silicon-based material particles reach a particle size of 10% by volume from the small particle size side.
  • the thickness of the silicon-based material layer is 10 ⁇ m to 50 ⁇ m, and the compaction density of the silicon-
  • the above-mentioned negative electrode pole piece further includes a graphite-based material layer located between the silicon-based material layer and the solid electrolyte layer, the graphite-based material layer contains a second negative electrode active material, and the second negative electrode active material includes a graphite-based material .
  • the particle size of the graphite-based material in the graphite-based material layer satisfies 3 ⁇ m ⁇ Dv50 2 ⁇ 10 ⁇ m, and Dv99 2 ⁇ 20 ⁇ m, wherein Dv50 2 indicates that in the particle size distribution based on volume, the graphite-based material particles are from small particles.
  • the particle size from the radial side up to 50% of the volume accumulation, Dv99 2 represents the particle size of the graphite-based material particles from the small particle size side up to 99% of the volume accumulation in the particle size distribution on a volume basis.
  • the Raman spectrum of the graphite-based material in the graphite-based material layer shows that the ratio of the peak height I 1350 at 1350 cm ⁇ 1 and the peak height I 1580 at 1580 cm ⁇ 1 satisfies I 1350 /I 1580 >0.3.
  • both the graphite-based material layer and the silicon-based material layer contain a binder, and the mass content of the binder in the silicon-based material layer is higher than the mass content of the binder in the graphite-based material layer.
  • the thickness of the graphite-based material layer is 10 ⁇ m to 40 ⁇ m, and the compaction density of the graphite-based material layer is 1.6 g/cm 3 to 1.78 g/cm 3 .
  • the solid electrolyte layer contains a binder and a solid electrolyte
  • the solid electrolyte includes a fast ion conductor with a conductivity of 10 -3 S/cm to 10 S/cm
  • the mass content of the solid electrolyte is 80% to 95%.
  • the thickness of the solid electrolyte layer is 1 ⁇ m to 10 ⁇ m
  • the compaction density of the solid electrolyte layer is 1.6 g/cm 3 to 1.75 g/cm 3 .
  • the present invention also provides an electrochemical device including the above-mentioned negative electrode plate and an electronic device including the electrochemical device.
  • the silicon-based material layer is used as the undercoat layer, and the solid electrolyte layer is arranged on the surface thereof.
  • the advantages of the silicon-based material layer such as high capacity can not only be effectively exerted, but also the advantages of the silicon-based material layer can be effectively exerted.
  • the solid electrolyte layer is arranged on the surface, which can reduce the contact between the silicon-based material and the electrolyte, thereby reducing the occurrence of side reactions and the corrosion of the silicon-based material.
  • the demand for electrolyte, thereby further reducing the contact between the silicon-based material and the electrolyte, and the solid electrolyte layer has higher strength, which can inhibit the volume expansion of the silicon-based material layer and protect the structure of the negative electrode from being damaged.
  • the pole piece structure exhibits good structural stability, and when applied to an electrochemical device, can effectively improve the cycle performance and other qualities of the electrochemical device.
  • FIG. 1 is a schematic structural diagram of a negative pole piece according to an embodiment of the present invention.
  • FIG. 2 is a capacity fading curve diagram of a battery during cycling according to an embodiment of the present invention.
  • the negative electrode sheet of the present invention includes a negative electrode current collector 1 , a silicon-based material layer 2 located on at least one surface of the negative electrode current collector 1 , a solid electrolyte layer 4 located on the surface of the silicon-based material layer 2 , and the silicon-based material layer.
  • 2 contains a first negative electrode active material
  • the first negative electrode active material contains a silicon-based material
  • the solid electrolyte layer 4 contains a solid electrolyte.
  • the silicon-based material layer 2 is the undercoat layer of the negative pole piece, and is also the active material layer of the negative pole piece.
  • silicon-based material as the negative electrode active material can ensure that the negative pole piece has the advantages of high capacity and the like.
  • the introduction of a graphite-based material into the silicon-based material layer 2 is beneficial to the conductivity of the negative electrode pole piece and alleviating the volume expansion of the negative electrode pole piece.
  • the first negative electrode active The material also includes a graphite-based material, and based on the total mass of the first negative electrode active material, the mass percentage of the silicon-based material can be 1% to 40% (that is, the mass content of the silicon-based material in the first negative electrode active material is 1% to 40% ), such as a range of 1%, 5%, 10%, 15%, 20%, 125%, 30%, 35%, 40% or any two thereof, the balance being graphite based material.
  • the particle size of the graphite-based material introduced into the silicon-based material layer 2 can generally satisfy, 5 ⁇ m ⁇ Dv50 3 ⁇ 15 ⁇ m, and Dv99 3 ⁇ 25 ⁇ m, wherein Dv50 3 indicates that in the particle size distribution based on the volume, the graphite-based material
  • Dv50 3 indicates that in the particle size distribution based on the volume
  • Dv99 3 represents the particle size of the graphite-based material particles from the small particle size side up to 99% by volume in the volume-based particle size distribution.
  • the graphite-based material may include graphite, for example, including at least one of artificial graphite, natural graphite, or mesocarbon microspheres.
  • the silicon-based material layer 2 also contains a conductive agent and a binder.
  • the silicon-based material includes at least one of silicon, a silicon-oxygen material, or a silicon-carbon composite.
  • Oxygen materials include, for example, silicon oxide; binders include water-based binders and/or non-aqueous binders, and water-based binders include, for example, polyacrylic acid (PAA), polyacrylate, polyimide, polyamide, polyamide, etc.
  • the oil-based binder includes polyvinylidene fluoride (PVDF).
  • the water-based binder is more conducive to cooperating with silicon-based materials to improve the stability of the negative electrode and other properties;
  • the conductive agent can include carbon nanotubes (CNTs). ), conductive carbon black (Super-P), at least one of acetylene black, Ketjen black, conductive graphite or graphene, relatively speaking, the use of CNT is beneficial to improve the conductivity and other properties of the negative pole piece.
  • the mass content of the first negative electrode active material is 93% to 97.5%, such as 93%, 94%, 95%, 96%, 97%, 97.5% or In the range of any two of them, the mass content of the binder is 2% to 5%, such as 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or any two of them.
  • the mass content of the conductive agent is 0.2% to 2%, such as 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2% or any two of them.
  • the particle size of the silicon-based material satisfies: 2 ⁇ m ⁇ Dv50 1 ⁇ 5 ⁇ m, 1.2 ⁇ (Dv99 1 -Dv10)/Dv50 1 ⁇ 3, wherein Dv50 1 represents that in the particle size distribution based on volume, the silicon-based material The particle size of the material particles from the small particle size side up to 50% of the volume accumulation, Dv99 1 represents the particle size distribution on the volume basis, the particle size of the silicon-based material particles from the small particle size side to the volume accumulation 99%, Dv10 represents in the In the particle size distribution on a volume basis, the silicon-based material particles reach a particle size of 10% by volume from the small particle size side.
  • Dv50 1 is, for example, a range of 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m or any two thereof, and (Dv99 1 -Dv10)/Dv50 1 is, for example, 1.2, 1.5, 1.8, 2, 2.2 , 2.5, 2.8, 3, or a range of any two of them.
  • the thickness of the silicon-based material layer 2 is 10 ⁇ m to 50 ⁇ m, for example, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m, or a range composed of any two thereof, which is beneficial to further improve the The effect of improving the capacity, conductivity and inhibiting volume expansion of the negative pole piece.
  • the compaction density of the silicon-based material layer 2 is 1.6g/cm 3 to 1.78g/cm 3 , such as 1.6g/cm 3 , 1.65g/cm 3 , 1.68g/cm 3 , 1.7g/cm 3 , 1.75g/cm 3 , 1.78g/cm 3 or a range of any two of them.
  • the negative electrode sheet can also include a graphite-based material layer 3 located between the silicon-based material layer 2 and the solid electrolyte layer 4, and the graphite-based material layer 3 contains a second negative electrode active material, and the second negative electrode active material
  • the material includes graphite-based material, and the graphite-based material layer 3 is used as the middle layer of the negative electrode, which can further prevent the release of the silicon-based material layer and the electrolyte, reduce the occurrence of side reactions, reduce the volume expansion of the negative electrode, and also facilitate the improvement of The conductivity of the negative pole piece further ensures the function of the negative pole piece.
  • the particle size of the graphite-based material in the graphite-based material layer 3 satisfies 3 ⁇ m ⁇ Dv50 2 ⁇ 10 ⁇ m, Dv99 2 ⁇ 20 ⁇ m, and Dv50 2 indicates that in the particle size distribution based on the volume, the graphite-based material particles range from a small particle size to a smaller particle size.
  • the particle size from the side up to 50% of the volume accumulation, Dv99 2 indicates that in the particle size distribution of the volume basis, the graphite-based material particles start from the small particle size side and reach the particle size of 99% of the volume accumulation, which is beneficial to further improve the performance of the negative electrode sheet .
  • Dv50 2 is, for example, a range of 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, or any two of them.
  • the Raman spectrum of the graphite-based material in the graphite-based material layer 3 shows that the ratio of the peak height I 1350 at 1350 cm ⁇ 1 and the peak height I 1580 at 1580 cm ⁇ 1 satisfies I 1350 /I 1580 >0.3, and the graphite base
  • the material may be a conventional negative electrode active material based on graphite, such as graphite, and may specifically include at least one of artificial graphite, natural graphite or mesocarbon microspheres.
  • the graphite-based material layer 3 also contains a binder and a conductive agent, wherein the mass content of the second negative electrode active material can be 96% to 98%, and the mass content of the binder is 1% to 2%, The mass content of the conductive agent is 0.2% to 2%, optionally, the binder may include polyacrylic acid (PAA), polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride ( At least one of PVDF), styrene-butadiene rubber (SBR), sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose or potassium carboxymethyl cellulose, the conductive agent may include At least one of carbon nanotubes (CNT), conductive carbon black (Super-P), acetylene black (AB), ketjen black (KB), conductive graphite or graphene.
  • PAA polyacrylic acid
  • the binder may include polyacrylic acid (PAA),
  • the mass content of the binder in the silicon-based material layer 2 is higher than the mass content of the binder in the graphite-based material layer 3 , which is beneficial for the silicon-based material layer 2 to have a stronger bonding force with the negative electrode current collector 1 , improve the structural stability of the negative pole piece, and at the same time make the negative pole piece have both low internal resistance, high capacity and other properties.
  • the thickness of the graphite-based material layer 3 is 10 ⁇ m to 40 ⁇ m, such as 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m or any two of them. , conductivity and structural stability.
  • the compaction density of the graphite-based material layer 3 may be 1.6 g/cm 3 to 1.78 g/cm 3 , such as 1.6 g/cm 3 , 1.65 g/cm 3 , 1.68 g/cm 3 , 1.7 g/cm 3 , 1.75g/cm 3 , 1.78g/cm 3 or a range of any two of them.
  • the solid electrolyte layer 4 is generally used as the top layer of the negative pole piece (that is, the surface of the negative pole piece is the solid electrolyte layer 4), and the active material layer of the negative pole piece (such as the above-mentioned silicon-based material layer 2 and graphite-based material layer 4) It is located between the surface of the negative electrode current collector 1 and the solid electrolyte layer 4.
  • the electrolyte layer 3 By arranging the electrolyte layer 3, the ion-conducting ability of the negative electrode pole piece can be enhanced, and the demand for electrolyte solution can be reduced at the same time, thereby improving the cyclability and speed of the negative electrode pole piece. charging capacity and other performance.
  • the solid electrolyte layer 4 can be specifically formed by mixing a fast ion conductor and a binder.
  • the electrolyte slurry containing the fast ion conductor and the binder is coated on the surface of the active material layer, and then formed by heating and setting. It may be blade coating or spray coating, etc., which is not particularly limited.
  • the solid electrolyte layer 4 includes a binder and a fast ion conductor with a conductivity of 0.001 S/cm to 10 S/cm, wherein the mass content of the solid electrolyte may be 80% to 95%, for example The range of 80%, 82%, 85%, 88%, 90%, 92%, 95% or any two of them, and the balance is the binder, which is beneficial to further optimize the performance of the negative pole piece.
  • the conductivity of the fast ionic conductor is, for example, 0.001S/cm, 0.01S/cm, 0.1S/cm, 1S/cm, 2S/cm, 3S/cm, 4S/cm, 5S/cm, 6S/cm, 7S/cm , 8S/cm, 9S/cm, 10S/cm or any two of them
  • the fast ion conductor can include organic fast ion conductors and/or inorganic fast ion conductors, such as LiNbO 3 , Li 4 Ti 5 At least one of O 4 , Li 3 PO 4 or LiTFSI
  • the binder includes, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) or acrylonitrile multipolymer (LA133).
  • the thickness of the solid electrolyte layer 4 is 1 ⁇ m to 10 ⁇ m, such as a range of 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m or any two thereof, which is more conducive to its function.
  • the compacted density of the solid electrolyte layer 4 may generally be 1.6 g/cm 3 to 1.75 g/cm 3 , such as 1.6 g/cm 3 , 1.65 g/cm 3 , 1.68 g/cm 3 , 1.7 g/cm 3 , 1.75 g /cm 3 or a range of any two of them.
  • the negative pole piece of the present invention may be prepared by a coating method, but is not limited thereto.
  • the preparation process may include: (1) coating the first negative electrode slurry containing the silicon-based material layer raw material on a At least one surface of the negative electrode current collector is dried, rolled, etc., to form a silicon-based material layer on the surface of the current collector; (2) the second negative electrode slurry containing the raw material of the graphite-based material layer is coated on the silicon-based material layer.
  • the surface of the material layer is processed by drying, rolling, etc., to form a graphite-based material layer on the surface of the silicon-based material layer; (3) The slurry containing the solid electrolyte layer raw material is then coated on the surface of the graphite-based material layer, and after drying After drying (heat-setting), rolling and other treatments, a solid electrolyte layer is formed on the surface of the graphite-based material layer; wherein, in steps (1) and (2), the drying temperature generally does not exceed 120 ° C, for example, it can be 60 °C, 70 °C, 90 °C, 110 °C, 120 °C or the range of any two of them, in step (3), the temperature of heating and setting can be 60 °C to 140 °C, and the time can generally be 5 seconds (s). ) to 60 seconds; the negative electrode current collector used can be a conventional negative electrode current collector in the field such as copper foil, and the processes such as concrete coating, drying, and rolling are all conventional procedures in the field, and will not
  • the compaction density of the coating refers to the ratio of the mass of the coating to the thickness of the coating.
  • the compaction density of the silicon-based material layer refers to the ratio of the mass of the silicon-based material layer to the volume of the silicon-based material layer.
  • coatings such as the above-mentioned silicon-based material layer and solid electrolyte layer may be provided only on one surface of the negative electrode current collector, or the above-mentioned silicon-based material layer and solid electrolyte layer may be provided on both the positive and negative surfaces of the negative electrode current collector. Relatively speaking, the latter is more conducive to improving the capacity and other characteristics of the negative pole piece, and can be selected according to needs in the specific implementation.
  • the electrochemical device of the present invention includes the above-mentioned negative electrode, and the electrochemical device can be any device that undergoes an electrochemical reaction, especially a positive electrode having a positive active material capable of occluding and releasing metal ions, and a positive electrode having a positive electrode capable of occluding and releasing metal ions.
  • the electrochemical device of the negative electrode of the negative electrode active material that emits metal ions a specific example of which may be a primary battery, a secondary battery, a fuel cell, a solar cell or a capacitor including all kinds, in particular, the electrochemical device may be a lithium battery, Such as lithium metal batteries or lithium ion batteries, for example, including soft pack lithium ion polymer batteries and the like.
  • the above-mentioned electrochemical device further includes a positive electrode plate and a separator between the negative electrode electrode plate and the positive electrode electrode plate.
  • the positive electrode electrode plate includes a positive electrode current collector and a positive electrode located on at least one surface of the positive electrode current collector.
  • the positive active material layer includes a positive active material, a conductive agent and a binder, and the positive active material includes, for example, lithium cobalt oxide (LiCoO 2 ), lithium iron phosphate, nickel-cobalt-manganese ternary material (NCM) or nickel-cobalt-aluminum At least one of ternary materials (NCA), the positive current collector can be aluminum foil, etc.; the separator is used to separate the positive electrode and the negative electrode, which can include polyethylene (PE) porous polymer film and the like.
  • PE polyethylene
  • the above electrochemical device further includes an electrolyte, for example, the electrolyte includes an organic solvent, a lithium salt and an additive, and the organic solvent includes ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), carbonic acid At least one of methyl ethyl ester (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate, and lithium salts include organic lithium salts and/or inorganic lithium salts, such as lithium hexafluorophosphate (LiPF6), Lithium Tetrafluoroborate (LiBF 4 ), Lithium Difluorophosphate (LiPO 2 F 2 ), Lithium Bistrifluoromethanesulfonimide LiN(CF 3 SO 2 ) 2 (LiTFSI), Lithium Bis(fluorosulfonyl)imide At least one of Li(N(SO 2 F) 2 ) (LiFSI), Lithium Bisox
  • the electrochemical device of the present invention can be prepared according to conventional methods in the art.
  • the electrochemical device is specifically a wound lithium-ion battery, and the preparation process may include: a positive pole piece, a separator, a After the negative pole pieces are stacked and arranged, they are wound to form a bare cell, which is then packaged (for example, packaged with aluminum-plastic film), baked under vacuum to remove moisture, injected (that is, injected with electrolyte), chemically formed, and sorted.
  • the battery is obtained; the above-mentioned processes such as winding, packaging, baking, liquid injection, chemical formation, and sorting are all routine operations in the art, and will not be repeated here.
  • the electronic device of the present invention includes the above-mentioned electrochemical device, and may be the electrochemical device of any of the above-described embodiments, or may be an electrochemical device of other embodiments without departing from the spirit and scope of the present invention.
  • Battery cycle performance test At a test temperature of 25°C, charge the battery to 4.45V at a constant current of 0.5C, charge it to 0.025C at a constant voltage, and discharge it to 3.0V at 0.5C after standing for 5 minutes.
  • the capacity obtained in the steps is the initial capacity; then 0.5C charge/0.5C discharge is carried out for cycle test, the ratio of the capacity corresponding to each cycle number to the initial capacity is the capacity retention rate corresponding to the cycle number, and then the capacity decay is obtained Curve (that is, the relationship between the capacity retention rate and the number of cycles);
  • the silicon-oxygen material silicon oxide, artificial graphite, CNT, and SBR were placed in a stirring tank according to the mass ratio of 15:80:1.5:3.5, and after stirring evenly, the first negative electrode slurry was prepared, and the first negative electrode slurry was coated on the The front and back surfaces of the copper foil are dried and rolled to form a silicon-based material layer on the front and back surfaces of the copper foil;
  • LiNbO 3 and PTFE were placed in a stirring tank according to the mass ratio of 9:1, and the electrolyte slurry was prepared after stirring evenly. After drying and rolling, a solid electrolyte layer is formed to obtain a negative pole piece.
  • LiCoO 2 , conductive carbon black, and PVDF were placed in N-methylpyrrolidone in a weight ratio of 96.7:1.7:1.6, stirred evenly, and made into a positive electrode slurry.
  • the positive electrode slurry was coated on the surface of the aluminum foil. After drying, After rolling, a positive electrode active material layer is formed to obtain a positive electrode plate;
  • the above-mentioned positive electrode, separator and negative electrode are stacked in order and then wound to form a bare cell.
  • Bake to remove moisture, and after liquid injection (ie, electrolyte injection), chemical formation, sorting and other procedures, a soft-pack lithium-ion polymer battery is made; wherein the electrolyte is composed of LiPF 6 , an organic solvent and additives, and the organic solvent is composed of EC, DMC, DEC, FEC, etc., wherein, the ratio of the volume percentage (vol%) of EC, DMC, DEC in the organic solvent can be EC:DMC:DEC 1:1:1, and the mass content of FEC in the electrolyte is 5 %, the concentration of LiPF 6 in the electrolyte is 1mol/L, the additives include TFPB, 12-crown-4 ether, VC, the concentration of TFPB in the electrolyte is 0.1mol/L, the concentration of 12-crown-4
  • the batteries of Example 1 to Example 10 and Comparative Example 1 to Comparative Example 4 were prepared.
  • the raw material composition of the silicon-based material layer, the raw material composition of the graphite-based material layer, the solid electrolyte The raw material composition of the layer is shown in Table 1; the particle size of the silicon-based material (Dv50 1 , Dv99 1 , Dv10 1 ), the particle size of the graphite used in the silicon-based material layer (Dv50 3 , Dv99 3 ), the thickness of the silicon-based material layer and its thickness.
  • Compaction density, particle size (Dv50 2 , Dv99 2 ) of graphite used in the graphite-based material layer and its I 1350 /I 1580 ratio, thickness of the graphite-based material layer and its compaction density, and solid electrolyte layer thickness and its compaction The solid density and the structure of the negative pole piece (two layers/three layers) are shown in Table 2; the battery performance test results are shown in Table 3. Except for the differences shown in Table 1 and Table 2, the remaining conditions of the Examples and Comparative Examples are basically the same.
  • Table 3 shows the measured first coulombic efficiency of the batteries in each embodiment and the comparative example, the capacity retention rate of the battery when the battery is cycled for 600 cycles, and the expansion rate of the battery when the battery is cycled for 600 cycles.
  • the capacity fading curves during the battery cycle in Example 1 and Comparative Example 3 were measured as shown in Figure 3 ( Figure 3 shows the results of about 4 measurements in Example 1 and Comparative Example 1, and it can be seen that Example 1 with better stability).

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Abstract

La présente invention concerne une pièce polaire négative, un dispositif électrochimique et un dispositif électronique. La pièce polaire négative comprend un collecteur de courant d'électrode négative, une couche de matériau à base de silicium située sur au moins une surface du collecteur de courant d'électrode négative, et une couche d'électrolyte solide située sur la surface de la couche de matériau à base de silicium. La couche de matériau à base de silicium contient un premier matériau actif d'électrode négative, le premier matériau actif d'électrode négative comprend un matériau à base de silicium, et la couche d'électrolyte solide contient un électrolyte solide. La pièce polaire négative de la présente invention présente une excellente stabilité structurelle, et peut résoudre efficacement des problèmes tels qu'une mauvaise stabilité d'une structure d'électrode négative en silicium, une forte probabilité d'expansion de volume, et une réaction latérale entre un matériau à base de silicium et un électrolyte se produisant facilement et la performance de cycle médiocre d'un dispositif électrochimique résultant de celle-ci.
PCT/CN2021/084276 2021-03-31 2021-03-31 Pièce polaire négative, dispositif électrochimique et dispositif électronique WO2022205032A1 (fr)

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CN202180004671.3A CN114207873A (zh) 2021-03-31 2021-03-31 负极极片、电化学装置及电子装置

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CN116888751A (zh) * 2023-01-03 2023-10-13 宁德时代新能源科技股份有限公司 负极极片以及包含其的电极组件、电池单体、电池和用电装置
CN116404101A (zh) * 2023-06-08 2023-07-07 深圳海辰储能控制技术有限公司 一种负极极片、电池、电池包及用电设备
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