WO2022205032A1 - 负极极片、电化学装置及电子装置 - Google Patents

负极极片、电化学装置及电子装置 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)
French (fr)
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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/zh
Priority to CN202180004671.3A priority patent/CN114207873A/zh
Publication of WO2022205032A1 publication Critical patent/WO2022205032A1/zh

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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).

Abstract

本发明提供一种负极极片、电化学装置及电子装置，所述负极极片包括负极集流体、位于所述负极集流体至少一个表面的硅基材料层、位于所述硅基材料层表面的固态电解质层，所述硅基材料层中含有第一负极活性物质，所述第一负极活性物质包括硅基材料，所述固态电解质层中含有固态电解质。本发明的负极极片具有良好的结构稳定性，能够有效解决硅负极结构稳定性差、易发生体积膨胀及硅基材料易与电解液发生副反应以及由此导致的电化学装置循环性差等问题。

Description

负极极片、电化学装置及电子装置 技术领域
本发明属于电化学装置领域，具体涉及一种负极极片、电化学装置及电子装置。
背景技术
硅基材料具有丰富的储备、超高的理论容量(4200mAh/g)、环境友好等优点，在负极材料方面具有良好的应用前景，逐渐受到广泛关注和研究。然而，硅基材料容易发生体积膨胀，作为负极活性材料时的动力学性能较差，且与电解液的副反应较多，容易导致负极结构破坏以及钝化膜(SEI)层不断生成等问题，进而影响负极结构的循环性等性能。
常见的硅基材料主要有纳米硅、硅氧复合材料、硅碳复合材料等，目前，一般是将该硅基材料与石墨等其他负极活性材料一起使用，以改善负极结构的电化学性能，但现有技术中，无论是将硅基材料与石墨共混后形成单层涂层的负极结构，还是分别将硅基材料与石墨形成不同涂层的负极结构，均对负极结构中硅基材料易发生体积膨胀、易与电解液发生副反应等缺陷的改善效果有限。因此，如何提高含硅负极的结构稳定性，缓解硅负极的体积膨胀以及硅基材料易与电解液发生副反应等问题，进而提高电化学装置的循环性等性能，仍是本领域技术人员所面临的重要课题。
发明内容
本发明提供一种负极极片、电化学装置及电子装置，以至少解决现有技术存在的硅负极结构稳定性差、易发生体积膨胀及硅基材料易与电解液发生副反应以及由此导致的电化学装置循环性差等问题。
本发明的一方面，提供一种负极极片，包括负极集流体、位于负极集流体至少一个表面的硅基材料层、位于硅基材料层表面的固态电解质层，硅基材料层中含有第一负极活性物质，第一负极活性物质包括硅基材料，固态电解质层中含有固态电解质。
根据本发明的研究，在一些实施例中，第一负极活性物质还包含石墨基材料，基于第一负极活性物质的总质量，硅基材料的质量百分比为1％至40％。可选地，石墨基材料的粒径满足5μm≤Dv50 3≤15μm，Dv99 3<25μm，其中，Dv50 3表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 3表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积99％的粒径。可选地，硅基材料层还含有粘结剂和导电剂；粘结剂包括水系粘结剂，和/或，导电剂包括碳纳米管。可选地，硅基材料的粒径满足2μm≤Dv50 1≤5μm，1.2≤(Dv99 1-Dv10)/Dv50 1≤3，其中，Dv50 1表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 1表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积99％的粒径，Dv10表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积10％的粒径。可选地，硅基材料层的厚度为10μm至50μm，硅基材料层的压实密度为1.6g/cm 3至1.78g/cm 3。
在一些实施例中，上述负极极片还包括位于硅基材料层和固态电解质层之间的石墨基材料层，石墨基材料层中含有第二负极活性物质，第二负极活性物质包括石墨基材料。可选地，该石墨基材料层中的石墨基材料的粒径满足3μm≤Dv50 2≤10μm，Dv99 2＜20μm，其中，Dv50 2表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 2表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积99％的粒径。可选地，石墨基材料层中的石墨基材料的拉曼光谱显示，1350cm -1的峰高度I 1350和1580cm -1的峰高度I 1580的比值满足I 1350/I 1580＞0.3。可选地，石墨基材料层、硅基材料层中均含有粘结剂，硅基材料层中粘结剂的质量含量高于石墨基材料层中粘结剂的质量含量。可选地，石墨基材料层的厚度为10μm至40μm，石墨基材料层的压实密度为1.6g/cm 3至1.78g/cm 3。
在一些实施例中，固态电解质层中含有粘结剂和固态电解质，固态电解质包括电导率为10 -3S/cm至10S/cm的快离子导体，在固态电解质层中，固态电解质的质量含量为80％至95％。可选地，固态电解质层的厚度为1μm至10μm，固态电解质层的压实密度为1.6g/cm 3至1.75g/cm 3。
作为本发明思想的延伸，本发明还提供一种包括上述负极极片的电化学 装置和包括该电化学装置的电子装置。
本发明提供的负极极片，硅基材料层作为底涂层，在其表面设置固态电解质层，通过该多涂层结构设计，不仅能够有效发挥硅基材料层的高容量等优势，而且通过在其表面设置固态电解质层，可以减少硅基材料与电解液的接触，从而减少副反应的发生和对硅基材料的腐蚀，并且通过设置固态电解质层还可以提高负极极片的离子迁移能力，降低对电解液的需求，从而进一步减少硅基材料与电解液的接触，同时固态电解质层具有更高的强度，可以抑制硅基材料层的体积膨胀，保护负极极片结构不被破坏，从而使负极极片结构表现出良好的结构稳定性，在应用于电化学装置时，能够有效提高电化学装置的循环性能等品质。
附图说明
图1为本发明一实施方式的负极极片的结构示意图；
图2为本发明一实施例的电池循环过程中的容量衰减曲线图。
附图标记说明：1：负极集流体；2：硅基材料层；3：石墨基材料层；4：固态电解质层。
具体实施方式
为使本领域技术人员更好地理解本发明的方案，下面对本发明作进一步地详细说明。
如图1所示，本发明的负极极片包括负极集流体1、位于负极集流体1至少一个表面的硅基材料层2、位于硅基材料层2表面的固态电解质层4，硅基材料层2中含有第一负极活性物质，第一负极活性物质包含硅基材料，固态电解质层4中含有固态电解质。
具体来说，硅基材料层2是负极极片的底涂层，也是负极极片的活性物质层，采用硅基材料作为负极活性物质，能够保证负极极片具有高容量等优势，根据本发明的研究，同时在硅基材料层2中引入石墨基材料，对负极极片的导电性以及缓解负极极片的体积膨胀是有利的，兼顾考虑上述因素，在一些实施例中，第一负极活性物质还包含石墨基材料，基于第一负极活性物质的总质量，硅基材料的质量百分比可以为1％至40％(即第一负极活性物质 中硅基材料的质量含量为1％至40％)，例如1％、5％、10％、15％、20％、·125％、30％、35％、40％或其中的任意两者组成的范围，余量是石墨基材料。
进一步地，硅基材料层2中所引入的石墨基材料的粒径一般可以满足，5μm≤Dv50 3≤15μm，Dv99 3<25μm，其中，Dv50 3表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 3表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积99％的粒径。具体地，该石墨基材料可以包括石墨，例如包括人造石墨、天然石墨或中间相碳微球中的至少一种。
一般情况下，硅基材料层2还含有导电剂和粘结剂，举例来说，硅基材料层2中，硅基材料包括硅、硅氧材料或硅碳复合物中的至少一种，硅氧材料例如包括氧化亚硅；粘结剂包括水系粘结剂和/或非水系粘结剂，水系粘结剂例如包括聚丙烯酸(PAA)、聚丙烯酸酯、聚酰亚胺、聚酰胺、聚酰胺酰亚胺、丁苯橡胶(SBR)、海藻酸钠、聚乙烯醇、聚四氟乙烯、聚丙烯腈、羧甲基纤维素钾或羧甲基纤维素钠(CMC)中的至少一种，油系粘结剂包括聚偏氟乙烯(PVDF)，相对而言，水系粘结剂更利于与硅基材料配合，提高负极极片的稳定性等性能；导电剂可以包括碳纳米管(CNT)、导电炭黑(Super-P)、乙炔黑、科琴黑、导电石墨或石墨烯中的至少一种，相对而言，采用CNT利于提升负极极片的导电性等性能。
具体地，在一些实施例中，硅基材料层2中，第一负极活性物质的质量含量为93％至97.5％，例如93％、94％、95％、96％、97％、97.5％或其中的任意两者组成的范围，粘结剂的质量含量为2％至5％，例如2％、2.5％、3％、3.5％、4％、4.5％、5％或其中的任意两者组成的范围，导电剂的质量含量为0.2％至2％，例如0.2％、0.5％、0.8％、1％、1.2％、1.5％、1.8％、2％或其中的任意两者组成的范围。
在一些实施例中，硅基材料的粒径满足：2μm≤Dv50 1≤5μm，1.2≤(Dv99 1-Dv10)/Dv50 1≤3，其中，Dv50 1表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 1表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积99％的粒径，Dv10表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积10％的粒径。Dv50 1例如为2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、 5μm或其中的任意两者组成的范围，(Dv99 1-Dv10)/Dv50 1例如为1.2、1.5、1.8、2、2.2、2.5、2.8、3或其中的任意两者组成的范围。
在一些实施例中，硅基材料层2的厚度为10μm至50μm，例如10μm、15μm、20μm、25μm、30μm、35μm、40μm、45μm、50μm或其中的任意两者组成的范围，利于进一步兼顾提高对负极极片的容量、导电性及抑制其体积膨胀的改善效果。进一步地，硅基材料层2的压实密度为1.6g/cm 3至1.78g/cm 3，例如1.6g/cm 3、1.65g/cm 3、1.68g/cm 3、1.7g/cm 3、1.75g/cm 3、1.78g/cm 3或其中的任意两者组成的范围。
根据本发明的进一步研究，负极极片还可以包括位于硅基材料层2和固态电解质层4之间的石墨基材料层3，石墨基材料层3中含有第二负极活性物质，第二负极活性物质包括石墨基材料，石墨基材料层3作为负极极片的中间层，可以进一步防止硅基材料层与电解液的解除，减少副反应的发生，降低负极极片的体积膨胀，同时还利于提升负极极片的导电能力，进一步保证负极极片的功能发挥。
在一些实施例中，石墨基材料层3中的石墨基材料的粒径满足3μm≤Dv50 2≤10μm，Dv99 2＜20μm，Dv50 2表示在体积基准的粒度分布中，石墨基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 2表示在体积基准的粒度分布中，石墨基材料颗粒从小粒径侧起、达到体积累积99％的粒径，利于进一步改善负极极片的性能。Dv50 2例如为3μm、4μm、5μm、6μm、7μm、8μm或其中的任意两者组成的范围。
进一步地，石墨基材料层3中的石墨基材料的拉曼光谱显示，1350cm -1的峰高度I 1350和1580cm -1的峰高度I 1580的比值满足I 1350/I 1580＞0.3，该石墨基材料可以是常规以石墨为基体的负极活性材料，例如是石墨，具体可以包括包括人造石墨、天然石墨或中间相碳微球中的至少一种。
一般情况下，石墨基材料层3中还含有粘结剂和导电剂，其中，第二负极活性物质的质量含量可以为96％至98％，粘结剂的质量含量为1％至2％，导电剂的质量含量为0.2％至2％，可选地，粘结剂可以包括聚丙烯酸(PAA)、聚丙烯酸酯、聚酰亚胺、聚酰胺、聚酰胺酰亚胺、聚偏氟乙烯(PVDF)、丁苯橡胶(SBR)、海藻酸钠、聚乙烯醇、聚四氟乙烯、聚丙烯腈、羧甲基纤维素钠或羧甲基纤维素钾中的至少一种，导电剂可以包括碳纳米管(CNT)、 导电炭黑(Super-P)、乙炔黑(AB)、科琴黑(KB)、导电石墨或石墨烯中的至少一种。
在一些实施例中，硅基材料层2中粘结剂的质量含量高于石墨基材料层3中粘结剂的质量含量，利于硅基材料层2与负极集流体1具有较强的接合力，提高负极极片的结构稳定性，同时使负极极片兼具低内阻、高容量等性能。
在一些实施例中，石墨基材料层3的厚度为10μm至40μm，例如10μm、15μm、20μm、25μm、30μm、35μm、40μm或其中的任意两者组成的范围，利于进一步兼顾负极极片的容量、导电性及结构稳定性等性能。进一步地，石墨基材料层3的压实密度可以为1.6g/cm 3至1.78g/cm 3，例如1.6g/cm 3、1.65g/cm 3、1.68g/cm 3、1.7g/cm 3、1.75g/cm 3、1.78g/cm 3或其中的任意两者组成的范围。
本发明中，固态电解质层4一般是作为负极极片的顶层(即负极极片的表面为固态电解质层4)，负极极片的活性物质层(如上述硅基材料层2和石墨基材料层4)位于负极集流体1表面和固态电解质层4之间，通过设置电解质层3，可以增强负极极片的导离子能力，同时降低对电解液的需求，进而提升负极极片的循环性及快充能力等性能。固态电解质层4具体可以是由快离子导体与粘结剂混合形成，例如是将含有快离子导体和粘结剂的电解质浆料涂布在活性物质层表面后再经过加热定型形成，涂布方式可以是刮涂或喷涂等，对此不作特别限制。
具体地，在一些实施例中，固态电解质层4包括粘结剂和电导率为0.001S/cm至10S/cm的快离子导体，其中，固态电解质的质量含量可以为80％至95％，例如80％、82％、85％、88％、90％、92％、95％或其中的任意两者组成的范围，余量为粘结剂，利于进一步优化负极极片的性能。快离子导体的电导率例如为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或其中的任意两者组成的范围，快离子导体可以包括有机类快离子导体和/或无机类快离子导体，例如包括LiNbO 3、Li 4Ti 5O 4、Li 3PO 4或LiTFSI中的至少一种，粘结剂例如包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)或丙烯腈多元共聚物(LA133)中的至少一种。
在一些实施例中，固态电解质层4的厚度为1μm至10μm，例如1μm、2μm、3μm、4μm、5μm或其中的任意两者组成的范围，更利于其功能发挥。固态电解质层4的压实密度一般可以为1.6g/cm 3至1.75g/cm 3，例如1.6g/cm 3、1.65g/cm 3、1.68g/cm 3、1.7g/cm 3、1.75g/cm 3或其中的任意两者组成的范围。
本发明的负极极片可以通过涂覆法制得，但不局限于此，在一些实施例中，其制备过程可以包括：(1)将含有硅基材料层原料的第一负极浆料涂敷于负极集流体的至少一个表面，经烘干、辊压等处理后，在集流体表面形成硅基材料层；(2)再将含有石墨基材料层原料的第二负极浆料涂敷于硅基材料层表面，经干燥、辊压等处理后，在硅基材料层表面形成石墨基材料层；(3)将再将含有固态电解质层原料的浆料涂布于石墨基材料层表面，经烘干(加热定型)、辊压等处理后，在石墨基材料层表面形成固态电解质层；其中，步骤(1)和(2)中，所述烘干的温度一般不超过120℃，例如可以是60℃、70℃、90℃、110℃、120℃或其中的任意两者组成的范围，步骤(3)中，加热定型的温度可以为60℃至140℃，时间一般可以为5秒(s)至60秒；所用负极集流体可以是铜箔等本领域常规负极集流体，具体的涂覆、烘干、辊压等过程均是本领域常规工序，不再赘述。
本发明中，涂层的压实密度是指涂层质量与涂层厚度的比值，例如，上述硅基材料层的压实密度是指硅基材料层的质量与硅基材料层体积的比值。
本发明中，可以只在负极集流体的一个表面设置上述硅基材料层、固态电解质层等涂层，也可以在负极集流体的正反两个表面均设置上述硅基材料层、固态电解质层等涂层，相对而言，后者更利于提高负极极片的容量等特性，具体实施时可以根据需要选择。
本发明的电化学装置包括上述负极极片，该电化学装置可以是发生电化学反应的任何装置，尤其可以是具备具有能够吸留、放出金属离子的正极活性物质的正极以及具有能够吸留、放出金属离子的负极活性物质的负极的电化学装置，其具体实例可以是包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容器，特别地，该电化学装置可以是锂电池，如锂金属电池或锂离子电池等，例如包括软包锂离子聚合物电池等。
具体来说，上述电化学装置还包括正极极片、以及位于负极极片和正极极片之间的隔离膜，示例性地，正极极片包括正极集流体和位于正极集流体 至少一个表面的正极活性物质层，正极活性物质层包括正极活性物质、导电剂和粘结剂，正极活性物质例如包括钴酸锂(LiCoO 2)、磷酸铁锂、镍钴锰三元材料(NCM)或镍钴铝三元材料(NCA)中的至少一种，正极集流体可以是铝箔等；隔离膜用于间隔正极极片和负极极片，其可以包括聚乙烯(PE)多孔聚合薄膜等。
上述电化学装置还包括电解液，举例来说，电解液包括有机溶剂、锂盐和添加剂，有机溶剂包括碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚丙酯或丙酸乙酯中的至少一种，锂盐包括有机锂盐和/或无机锂盐，例如包括六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)中的至少一种，添加剂包括冠醚类化合物、硼基化合物、无机纳米氧化物、碳酸酯类化合物或酰胺类化合物中的至少一种，例如可以包括12-冠-4醚、硼基阴离子受体三(五氟苯基)硼烷(TFPB)、三(五氟苯基)硼酸盐、亚乙烯碳酸酯(VC)或乙酰胺及其衍生物中的至少一种。在一些实施例中，电解液中锂盐的含量为0.5mol/L至1.5mol/L，比如可以为0.7mol/L至1.3mol/L或0.9mol/L至1.1mol/L。
本发明的电化学装置可以按照本领域常规方法制得，例如，在一些实施例中，该电化学装置具体为卷绕式锂离子电池，其制备过程可以包括：将正极极片、隔离膜、负极极片层叠设置后，卷绕形成裸电芯，然后经封装(例如采用铝塑膜封装)、真空状态下烘烤去除水分、注液(即注入电解液)、化成、分选等工序后得到电池；上述卷绕、封装、烘烤、注液、化成、分选等工序均为本领域常规操作，不再赘述。
本发明的电子装置包括上述电化学装置，既可以是上述任一实施例的电化学装置，也可以是不脱离本发明主旨范围内的其他实施方式的电化学装置。
为使本发明的目的、技术方案和优点更加清楚，下面将结合具体实施例对本发明的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本 领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
如无特别说明，以下实施例和对比例中，电池性能测试均为本领域常规方法，相关测试过程简述如下：
(1)电池循环性能测试：在25℃的测试温度下，将电池以0.5C恒流充电到4.45V，恒压充电到0.025C，静置5分钟后以0.5C放电到3.0V，以此步骤得到的容量为初始容量；然后进行0.5C充电/0.5C放电进行循环测试，每一循环圈数对应的容量与初始容量的比值即为该循环圈数对应的容量保持率，进而获得容量衰减曲线(即容量保持率与循环圈数的关系曲线)；
(2)电池膨胀率测试：用螺旋千分尺测试初始时电池的厚度d 0，循环至600圈时，再用螺旋千分尺测试此时电池的厚度d x，与初始半充时电池的厚度d 0对比，即可得循环600圈时电池的膨胀率(即该膨胀率＝d 0/d x)。
实施例1
(1)负极极片的制备
将硅氧材料氧化亚硅、人造石墨、CNT、SBR按照质量比15：80：1.5：3.5置于搅拌罐中，搅拌均匀后制成第一负极浆料，将第一负极浆料涂覆于铜箔的正反两个表面，经烘干、辊压后，在铜箔的正反两个表面形成硅基材料层；
将石墨、Super-P、SBR按照质量比96.5:1.5:2置于搅拌罐中，搅拌均匀后制成第二负极浆料，将第二负极浆料涂覆于铜箔正反两个表面的硅基材料层的表面，经烘干、辊压后形成石墨基材料层；
将LiNbO 3和PTFE按照质量比9:1置于搅拌罐中，搅拌均匀后制成电解质浆料，将电解质浆料涂敷于铜箔正反两个表面的石墨基材料层的表面，经烘干、辊压后形成固态电解质层，得到负极极片。
(2)正极极片及电池的制备
将LiCoO 2、导电炭黑、PVDF按重量比96.7：1.7：1.6置于N-甲基吡咯烷酮中，搅拌均匀后制成正极浆料，将正极浆料涂覆于铝箔的表面，经烘干、辊压后形成正极活性物质层，得到正极极片；
以PE多孔聚合薄膜作为隔离膜，将上述正极极片、隔离膜、负极极片按顺序叠放后卷绕形成裸电芯，采用铝塑膜对裸电芯进行封装，然后在真空状态下烘烤去除水分，经注液(即注入电解液)、化成、分选等工序后制成软包锂离子聚合物电池；其中，电解液由LiPF 6、有机溶剂和添加剂组成，有机溶剂由EC、DMC、DEC、FEC等组成，其中，有机溶剂中EC、DMC、DEC的体积百分比(vol％)的比例可以为EC:DMC:DEC＝1:1:1，电解液中FEC的质量含量为5％，电解液中LiPF 6的浓度为1mol/L，添加剂包括TFPB、12-冠-4醚、VC，电解液中TFPB的浓度为0.1mol/L，电解液中12-冠-4醚的浓度为0.05mol/L，电解液中VC的浓度为0.1mol/L。
参照实施例1的过程，制得实施例1至实施例10及对比例1至对比例4的电池，各实施例中，硅基材料层的原料组成、石墨基材料层的原料组成、固体电解质层的原料组成见表1；硅基材料的粒径(Dv50 1、Dv99 1、Dv10 1)、硅基材料层中所用石墨的粒径(Dv50 3、Dv99 3)、硅基材料层厚度及其压实密度、石墨基材料层中所用石墨的粒径(Dv50 2、Dv99 2)及其I 1350/I 1580比值、石墨基材料层的厚度及其压实密度、固态电解质层的厚度及其压实密度、负极极片的结构(两层/三层)见表2；电池性能测试结果见表3。除表1与表2示出的区别外，各实施例及对比例的其余条件基本相同。
测得各实施例及对比例中电池的首次库伦效率、电池循环600圈时的容量保持率、电池循环600圈时的膨胀率见表3。另测得实施例1与对比例3中电池循环过程中的容量衰减曲线见图3(图3示出了实施例1与对比例1中各测定4次左右的结果，可以看到实施例1具有更好的稳定性)。
表1各实施例及对比例涂层原料组成
Figure PCTCN2021084276-appb-000001
Figure PCTCN2021084276-appb-000002
表3电池性能测试结果
Figure PCTCN2021084276-appb-000003
以上，对本发明的实施方式进行了说明。但是，本发明不限定于上述实施方式。凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种负极极片，其特征在于，包括负极集流体、位于所述负极集流体至少一个表面的硅基材料层、位于所述硅基材料层表面的固态电解质层，所述硅基材料层中含有第一负极活性物质，所述第一负极活性物质包括硅基材料，所述固态电解质层中含有固态电解质。
  2. 根据权利要求1所述的负极极片，其特征在于，所述第一负极活性物质还包含石墨基材料，基于所述第一负极活性物质的总质量，所述硅基材料的质量百分比为1％至40％。
  3. 根据权利要求2所述的负极极片，其特征在于，所述石墨基材料的粒径满足5μm≤Dv50 3≤15μm，Dv99 3<25μm，其中，Dv50 3表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 3表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积99％的粒径。
  4. 根据权利要求1或2所述的负极极片，其特征在于，所述硅基材料层还含有粘结剂和导电剂；所述粘结剂包括水系粘结剂，和/或，所述导电剂包括碳纳米管。
  5. 根据权利要求1所述的负极极片，其特征在于，所述硅基材料的粒径满足2μm≤Dv50 1≤5μm，1.2≤(Dv99 1-Dv10)/Dv50 1≤3，其中，Dv50 1表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 1表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积99％的粒径，Dv10表示在体积基准的粒度分布中，硅基材料颗粒从小粒径侧起、达到体积累积10％的粒径。
  6. 根据权利要求1或5所述的负极极片，其特征在于，满足如下特征中的至少一种：
    所述硅基材料层的厚度为10μm至50μm，
    所述硅基材料层的压实密度为1.6g/cm 3至1.78g/cm 3；
    所述固态电解质层的厚度为1μm至10μm；
    所述固态电解质层的压实密度为1.6g/cm 3至1.75g/cm 3。
  7. 根据权利要求1所述的负极极片，其特征在于，满足如下特征中的至 少一种：
    还包括位于所述硅基材料层和所述固态电解质层之间的石墨基材料层，所述石墨基材料层中含有第二负极活性物质，所述第二负极活性物质包括石墨基材料；
    所述石墨基材料层中的石墨基材料的粒径满足3μm≤Dv50 2≤10μm，Dv99 2＜20μm，其中，Dv50 2表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积50％的粒径，Dv99 2表示在体积基准的粒度分布中，该石墨基材料颗粒从小粒径侧起、达到体积累积99％的粒径；
    所述石墨基材料层中的石墨基材料的拉曼光谱显示，1350cm -1的峰高度I 1350和1580cm -1的峰高度I 1580的比值满足I 1350/I 1580＞0.3；
    所述石墨基材料层、所述硅基材料层中均含有粘结剂，所述硅基材料层中粘结剂的质量含量高于所述石墨基材料层中粘结剂的质量含量；
    所述石墨基材料层的厚度为10μm至40μm；
    所述石墨基材料层的压实密度为1.6g/cm 3至1.78g/cm 3。
  8. 根据权利要求1或7所述的负极极片，其特征在于，所述固态电解质层中含有粘结剂和所述固态电解质，所述固态电解质包括电导率为10 -3S/cm至10S/cm的快离子导体，在所述固态电解质层中，所述固态电解质的质量含量为80％至95％。
  9. 一种电化学装置，其特征在于，包括权利要求1-8任一项所述的负极极片。
  10. 一种电子装置，其特征在于，包括权利要求9所述的电化学装置。
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