WO2022120833A1 - 一种电化学装置和电子装置 - Google Patents

一种电化学装置和电子装置 Download PDF

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WO2022120833A1
WO2022120833A1 PCT/CN2020/135882 CN2020135882W WO2022120833A1 WO 2022120833 A1 WO2022120833 A1 WO 2022120833A1 CN 2020135882 W CN2020135882 W CN 2020135882W WO 2022120833 A1 WO2022120833 A1 WO 2022120833A1
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Prior art keywords
coating
coating layer
electrochemical device
negative electrode
current collector
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PCT/CN2020/135882
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English (en)
French (fr)
Inventor
江兵
刘涛
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东莞新能源科技有限公司
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Application filed by 东莞新能源科技有限公司 filed Critical 东莞新能源科技有限公司
Priority to CN202080037773.0A priority Critical patent/CN113906597A/zh
Priority to EP20964769.2A priority patent/EP4207353A4/en
Priority to PCT/CN2020/135882 priority patent/WO2022120833A1/zh
Publication of WO2022120833A1 publication Critical patent/WO2022120833A1/zh
Priority to US18/192,939 priority patent/US20240079592A1/en

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    • H—ELECTRICITY
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    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/70—Additives characterised by shape, e.g. fibres, flakes or microspheres
    • H—ELECTRICITY
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    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
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    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
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    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/66—Additives characterised by particle size
    • C09D7/68—Particle size between 100-1000 nm
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    • 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
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    • 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
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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    • H01M4/623—Binders being polymers fluorinated polymers
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2227—Oxides; Hydroxides of metals of aluminium
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    • C08K3/00—Use of inorganic substances as compounding ingredients
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    • C08K2003/325—Calcium, strontium or barium phosphate
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2203/00—Applications
    • C08L2203/20—Applications use in electrical or conductive gadgets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H01G11/28—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
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    • H—ELECTRICITY
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    • 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 present application relates to the field of electrochemistry, in particular to an electrochemical device and an electronic device.
  • Lithium-ion batteries have the advantages of high energy storage density, high open circuit voltage, low self-discharge rate, long cycle life, and good safety. They are widely used in various fields such as electrical energy storage, mobile electronic equipment, electric vehicles, and aerospace equipment. With the rapid development of mobile electronic devices and electric vehicles, the market has put forward higher and higher requirements for the energy density, safety, cycle performance and service life of lithium-ion batteries.
  • the negative electrode current collector and the negative electrode active material layer are easily released from the mold.
  • a conductive coating layer including a conductive agent and a binder is generally provided in the prior art.
  • the force cannot meet the current needs, and the negative electrode active material layer still has a mold release phenomenon.
  • the copper foil is often broken due to the insufficient strength of the negative current collector (copper foil), which affects the production efficiency;
  • the expansion squeezes the positive pole piece, causing the inner ring of the positive pole piece to break, and the phenomenon of low capacity of the lithium ion battery occurs. Therefore, the strength of the negative electrode current collector and the bonding force between the negative electrode current collector and the negative electrode active material layer need to be improved.
  • the purpose of the present application is to provide an electrochemical device and an electronic device to improve the strength of the negative electrode current collector and the bonding force between the negative electrode current collector and the negative electrode active material layer.
  • the specific technical solutions are as follows:
  • the present application is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery.
  • a first aspect of the present application provides an electrochemical device, comprising a negative electrode, the negative electrode comprising a current collector, a first coating layer and a second coating layer, the second coating layer is provided on at least one surface of the current collector, the first coating layer A coating is disposed between the current collector and a second coating, the first coating comprising inorganic particles having a Mohs hardness of 2 to 7.
  • the second coating layer can also be understood as a negative electrode active material layer.
  • the first coating layer is disposed between the current collector and the second coating layer, the first coating layer contains inorganic particles, and the inorganic particles are wrapped by a binder to form a stronger High bonding unit, the strength of the bonding unit is affected by the Mohs hardness of the inorganic particles.
  • the hardness of the inorganic particles is too small, the cold pressing process is easy to deform, which will cause the internal structural stability of the first coating to deteriorate, making the bonding
  • the strength of the unit is affected, and the hardness of the inorganic particles is too large, which will cause greater wear and tear on the coating equipment.
  • the bonding unit with higher strength can increase the cohesion of the first coating, which can offset the tensile stress of part of the current collector, thereby increasing the strength of the current collector, making the current collector less likely to break during processing; on the other hand , the formation of the bonding unit increases the bonding strength and bonding sites of the first coating layer, thereby effectively improving the bonding force between the current collector and the second coating layer.
  • the improvement of the adhesion between the first coating and the second coating can reduce the content of the binder in the second coating and increase the proportion of the negative active material in the second coating, thereby improving the lithium-ion battery’s performance. Energy Density.
  • the negative electrode of the present application may have a first coating and a second coating on one surface thereof, or may have a first coating and a second coating on both surfaces thereof. You can choose according to actual needs.
  • the electrochemical device provided by the present application includes a negative electrode, the negative electrode includes a current collector, a first coating layer and a second coating layer, the first coating layer is arranged between the negative electrode current collector and the second coating layer, and the first coating layer Inorganic particles having a Mohs hardness of 2 to 7 are included in the first coating, which can effectively improve the strength of the current collector and the adhesion between the current collector and the second coating, thereby reducing the binder content of the second coating, Increasing the proportion of negative active materials in the negative electrode can effectively improve the energy density of the lithium-ion battery.
  • the types of inorganic particles are not particularly limited, as long as the Mohs hardness is within the range of 2 to 7, the purpose of the present application can be achieved.
  • the inorganic particles may contain at least one of boehmite, aluminum powder, quartz sand, apatite, zircon, and the like.
  • the average particle diameter Dv50 of the inorganic particles is 100 nm to 600 nm.
  • the average particle size Dv50 of the inorganic particles is greater than 100 nm, which can avoid the agglomeration of the inorganic particles; the average particle size Dv50 of the inorganic particles is greater than 600 nm, which will make the surface of the first coating uneven and affect the performance of the lithium-ion battery.
  • the thickness of the first coating layer can be maintained at the nanometer level, so that the thickness of the negative electrode will not be increased, and the volume energy density of the lithium-ion battery will be avoided. Ensure the flatness of the surface of the first coating to avoid affecting the performance of the lithium-ion battery.
  • the first coating further comprises a conductive agent, a binder and a dispersant, based on the total mass of the first coating, the mass of the inorganic particles, the conductive agent, the binder and the dispersant The percentages are (1%-10%): (14%-70%): (14%-70%): (2%-6%).
  • the ratio of the mass of the binder to the total mass of the first coating is less than 14%, the bonding effect is not obvious; when the mass of the binder accounts for more than 70% of the total mass of the first coating, the binder content Too much, easy to cause inorganic particle agglomeration;
  • the mass of the dispersant By controlling the mass of the dispersant to be 2% to 6% of the total mass of the first coating layer, the internal structure of the first coating layer can be made uniform and stable, and the agglomeration of inorganic particles can be effectively prevented;
  • the conductive agent may include at least one of a zero-dimensional conductive agent and a one-dimensional conductive agent.
  • the types of zero-dimensional conductive agent and one-dimensional conductive agent are not particularly limited, as long as the purpose of the application can be achieved.
  • the zero-dimensional conductive agent may include conductive carbon black, acetylene black, superconducting carbon black, particle At least one of graphite or Ketjen black, etc., the average particle size Dv50 of the zero-dimensional conductive agent is less than 400nm;
  • the one-dimensional conductive agent can include at least one of conductive carbon tubes or conductive carbon rods, etc.
  • the diameter is less than 400nm.
  • the type of the binder is not particularly limited as long as the purpose of the present application can be achieved.
  • the binder may comprise styrene-butadiene rubber, polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyacrylate, polyvinylidene fluoride, polyvinyl chloride, formaldehyde resin, cyclodextrin or cyanoacrylate, etc. at least one.
  • the addition of the binder can improve the viscosity of the first coating layer, thereby increasing the binding force between the first coating layer and the negative electrode current collector, and between the first coating layer and the second coating layer respectively, and can also reduce the concentration of the second coating layer. Binder content.
  • the type of dispersant is not particularly limited as long as the purpose of the present application can be achieved.
  • the dispersing agent may comprise sodium carboxymethyl cellulose, lithium hydroxymethyl cellulose, sodium alginate, propylene glycol alginate, methyl cellulose, sodium starch phosphate, sodium carboxymethyl cellulose, sodium alginate , at least one of casein, sodium polyacrylate, polyoxyethylene or polyvinylpyrrolidone.
  • the addition of the dispersant can improve the uniformity and stability of the internal structure of the first coating layer and prevent the agglomeration of inorganic particles.
  • the tensile strength of the negative electrode is 200 MPa to 500 MPa, which is effectively improved.
  • the thickness of the first coating is 280 nm to 1500 nm.
  • the coating quality X of the first coating layer satisfies: 0.02 mg/cm 2 ⁇ X ⁇ 0.15 mg/cm 2 .
  • the coverage of the first coating is 50% to 100%.
  • the coverage rate of the first coating is more than 50%, the first coating can effectively play its role, so that the performance of the lithium ion battery can be improved.
  • the electronic resistance of the negative electrode is 30m ⁇ to 60m ⁇ , it can be seen that the electronic resistance of the negative electrode of the present application is relatively large, which can increase the polarization of the lithium ion battery and reduce the release of electric energy, thereby improving the lithium ion battery. security.
  • the elongation rate of the negative electrode is 0.05% to 1%, the elongation rate is relatively low, and the negative electrode structural state is stable.
  • the current collector is not particularly limited, and current collectors known in the art, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector, can be used.
  • the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material is not particularly limited, and a negative electrode active material known in the art can be used.
  • at least one of artificial graphite, natural graphite, mesocarbon microspheres, silicon, silicon carbon, silicon oxide, soft carbon, hard carbon, lithium titanate or niobium titanate, and the like may be included.
  • the thicknesses of the current collector and the negative electrode active material layer are not particularly limited as long as the purpose of the present application can be achieved.
  • the thickness of the current collector is 6 ⁇ m to 10 ⁇ m
  • the thickness of the negative electrode active material layer is 30 ⁇ m to 120 ⁇ m.
  • a positive electrode typically includes a current collector and a positive electrode active material layer.
  • the current collector is not particularly limited, and can be a positive electrode current collector known in the art, such as copper foil, aluminum foil, aluminum alloy foil, and composite current collector.
  • the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material is not particularly limited, and can be a positive electrode active material known in the art, for example, including nickel cobalt lithium manganate (811, 622, 523, 111), nickel cobalt lithium aluminate, At least one of lithium iron phosphate, lithium-rich manganese-based material, lithium cobaltate, lithium manganate, lithium iron manganese phosphate, or lithium titanate.
  • the thicknesses of the positive electrode current collector and the positive electrode active material layer are not particularly limited as long as the purpose of the present application can be achieved.
  • the thickness of the current collector of the positive electrode is 8 ⁇ m to 12 ⁇ m
  • the thickness of the positive electrode active material layer is 30 ⁇ m to 120 ⁇ m.
  • the positive electrode may further comprise a conductive layer located between the current collector and the positive electrode active material layer.
  • the composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art.
  • the conductive layer includes a conductive agent and a binder.
  • the lithium ion battery of the present application further includes a separator for separating the positive electrode and the negative electrode, preventing the internal short circuit of the lithium ion battery, allowing the free passage of electrolyte ions, and completing the role of the electrochemical charging and discharging process.
  • the separator is not particularly limited as long as the purpose of the present application can be achieved.
  • PET polyethylene terephthalate
  • cellulose films such as polyethylene terephthalate (PET) films
  • PET polyamide Imine film
  • PA polyamide film
  • spandex or aramid film woven film
  • non-woven film non-woven film (non-woven fabric)
  • microporous film composite film, diaphragm paper, laminated film, spinning film, etc. at least one of them.
  • the release film may include a substrate layer and a surface treatment layer.
  • the substrate layer can be a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer can include at least one of polyethylene, polypropylene, polyethylene terephthalate, polyimide, etc. kind.
  • polypropylene porous membranes, polyethylene porous membranes, polypropylene non-woven fabrics, polyethylene non-woven fabrics, or polypropylene-polyethylene-polypropylene porous composite membranes may be used.
  • at least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.
  • the inorganic substance layer includes inorganic particles and a binder
  • the inorganic particles are not particularly limited, for example, can be selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, At least one of zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium sulfate, and the like.
  • the binder is not particularly limited, for example, it can be selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyethylene pyrrolidine One or a combination of ketone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene) and the like.
  • the lithium ion battery of the present application further includes an electrolyte, and the electrolyte may be one or more of a gel electrolyte, a solid electrolyte, and an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2.
  • LiPF 6 can be chosen as the lithium salt because it can give high ionic conductivity and improve cycle characteristics.
  • the non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or a combination thereof.
  • the above-mentioned carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound, or a combination thereof.
  • Examples of the above-mentioned chain carbonate compound are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), carbonic acid Methyl ethyl ester (MEC) and combinations thereof.
  • Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), and combinations thereof.
  • fluorocarbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethyl carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-dicarbonate Fluoro-1-methylethylene, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Ethyl carbonate 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • 1,2-dicarbonate Fluoro-1-methylethylene 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethyl
  • carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , caprolactone, valerolactone, mevalonolactone, caprolactone, and combinations thereof.
  • ether compounds examples include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl ether Oxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
  • Examples of the above-mentioned other organic solvents are dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, Formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters and combinations thereof.
  • a second aspect of the present application provides an electronic device, including the electrochemical device provided in the first aspect of the present application.
  • electronic devices may include, but are not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, assisted bicycles, bicycles, Lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large-scale household storage batteries and lithium-ion capacitors, etc.
  • electrochemical devices can be manufactured by the following process: the positive electrode and the negative electrode are overlapped through a separator, and they are wound, folded, etc., as required, and placed in a case, and the electrolyte is injected into the case and sealed.
  • an overcurrent preventing element, a guide plate, etc. can be placed in the case to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the application provides an electrochemical device and an electronic device, the electrochemical device includes a negative electrode, the negative electrode includes a current collector, a first coating and a second coating, the second coating is provided on at least one surface of the current collector, the The first coating layer is arranged between the current collector and the second coating layer, the first coating layer contains inorganic particles with a Mohs hardness of 2 to 7, so that the strength of the current collector is improved, and the current collector and the second coating layer are located between the current collector and the second coating layer.
  • the binding force of the anode is improved, and the content of the binder in the second coating layer is reduced, thereby increasing the proportion of the anode active material in the anode, and effectively improving the energy density of the electrochemical device.
  • FIG. 1 is a schematic structural diagram of a negative pole piece according to an embodiment of the present application.
  • the present application is explained by taking a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present application is not limited to a lithium ion battery.
  • FIG. 1 shows a schematic structural diagram of a negative electrode in an embodiment of the present application.
  • the first coating layer 20 is disposed between the current collector 10 and the second coating layer 30 .
  • the first coating 20 and the second coating 30 may also be disposed on the other side of the current collector 10 .
  • the average particle size Dv50 of the inorganic particles was measured using a Malvern laser particle sizer MS3000.
  • Dv50 refers to the particle size at which the inorganic particles reach 50% of the cumulative volume from the small particle size side in the volume-based particle size distribution, that is, the volume of the inorganic particles smaller than this particle size accounts for 50% of the total volume of the inorganic particles.
  • SOC refers to the state of charge of the negative electrode, also known as the remaining power, which represents the ratio of the remaining dischargeable power after the negative electrode is used for a period of time or left for a long time to the power in the fully charged state. 100% SOC represents the negative state of full charge, and 0% SOC represents the negative state of zero charge.
  • the recorded data is the tensile strength.
  • the test temperature is 25/45°C, charge to 4.4V with 0.7C constant current, charge to 0.025C with constant voltage, and discharge to 3.0V with 0.5C after standing for 5 minutes.
  • the capacity obtained in this step was taken as the initial capacity, and 0.7C charge/0.5C discharge was carried out for cycle test, and the capacity decay curve was obtained by taking the ratio of the capacity in each step to the initial capacity.
  • the room temperature cycle performance of the lithium-ion battery was recorded as the number of cycles from 25°C to 90% of the capacity retention rate, and the high-temperature cycle performance of the lithium-ion battery was recorded as the number of cycles from 45°C to 80%.
  • the cycle performance of the material is obtained by the number of cycles in this case.
  • discharge at 0.2C to 3.0V let stand for 5 minutes, charge at 0.5C to 4.45V, charge at constant voltage to 0.05C, and then let stand for 5 minutes, adjust the discharge rate, respectively, at 0.2C, 0.5C, 1C , 1.5C, 2.0C for discharge test, respectively, to obtain the discharge capacity, compare the capacity obtained at each rate with the capacity obtained at 0.2C, and compare the rate performance by comparing the ratio of 2C and 0.2C.
  • the prepared first coating slurry was coated on the surface of the negative electrode current collector copper foil to obtain a first coating with a thickness of 280 nm, the coverage of the first coating was 50%, and the coating quality of the first coating was 0.02 mg /cm 2 ;
  • the negative electrode active material graphite, styrene-butadiene polymer and sodium carboxymethyl cellulose are mixed according to the weight ratio of 97.5:1.3:1.2, and deionized water is added as a solvent to prepare a slurry with a solid content of 70%. and stir well.
  • the slurry was uniformly coated on the first coating layer, dried at 110°C, and after cold pressing, a negative electrode pole piece with a single-sided coating of the first coating layer and the negative electrode active material layer with a negative electrode active material layer thickness of 150 ⁇ m was obtained.
  • these steps are also completed on the back side of the negative electrode pole piece by the same method, that is, the negative pole piece with double-sided coating is obtained.
  • the negative pole pieces are cut into sheets with a size of 76mm ⁇ 851mm, and the tabs are welded for use.
  • the positive active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) was added as a solvent. , prepare a slurry with a solid content of 75%, and stir evenly. The slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10 ⁇ m, and dried at 90° C. to obtain a positive electrode sheet with a coating thickness of 110 ⁇ m. After the above steps are completed, the single-side coating of the positive electrode sheet is completed. After that, the above steps are repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet coated with positive active material on both sides. After the coating is completed, the pole piece is cut into a size of 38mm ⁇ 58mm for use.
  • NMP N-methylpyrrolidone
  • Lithium hexafluorophosphate was dissolved and mixed uniformly to obtain an electrolyte solution with a lithium salt concentration of 1.15 mol/L.
  • Alumina and polyvinylidene fluoride were mixed in a mass ratio of 90:10 and dissolved in deionized water to form a ceramic slurry with a solids content of 50%. Then, the ceramic slurry was uniformly coated on one side of the porous substrate (polyethylene, thickness 7 ⁇ m, average pore size 0.073 ⁇ m, porosity 26%) by gravure coating, and dried to obtain a ceramic coating
  • the bilayer structure with the porous substrate, the thickness of the ceramic coating is 50 ⁇ m.
  • PVDF Polyvinylidene fluoride
  • polyacrylate was mixed in a mass ratio of 96:4 and dissolved in deionized water to form a polymer slurry with a solids content of 50%. Then, the polymer slurry is uniformly coated on both surfaces of the above-mentioned double-layer structure of the ceramic coating layer and the porous substrate by the gravure coating method, and is subjected to drying treatment to obtain a separator, wherein the single layer formed by the polymer slurry is The coating thickness is 2 ⁇ m.
  • the above-prepared positive electrode, separator, and negative electrode are stacked in sequence, so that the separator is in the middle of the positive and negative electrodes for isolation, and the electrode assembly is obtained by winding.
  • the electrode assembly is put into an aluminum-plastic film packaging bag, and the moisture is removed at 80°C, and the prepared electrolyte is injected.
  • Example 2 The rest is the same as Example 1, except that in ⁇ Preparation of First Coating Slurry>, the Mohs hardness of 3 boehmite is replaced by the Mohs hardness of 7 quartz sand.
  • Example 2 The rest is the same as Example 1, except that in ⁇ Preparation of First Coating Slurry>, boehmite with a Mohs hardness of 3 is replaced by zircon with a Mohs hardness of 6.5.
  • Example 2 The rest is the same as Example 1 except that in ⁇ Preparation of First Coating Slurry>, boehmite with a Mohs hardness of 3 is replaced by apatite with a Mohs hardness of 5.
  • Example 2 The rest is the same as Example 1, except that in ⁇ Preparation of First Coating Slurry>, the boehmite with a Mohs hardness of 3 is replaced by a nano-ceramic with a Mohs hardness of 7.
  • Example 2 The same as in Example 1, except that the thickness of the first coating layer was 520 nm in ⁇ Preparation of Negative Electrode Plate Containing First Coating Layer>.
  • Example 7 The same as in Example 7, except that the thickness of the first coating layer was 520 nm in ⁇ Preparation of Negative Electrode Pole Sheet Containing First Coating Layer>.
  • Example 9 The same as Example 9, except that the thickness of the first coating layer was 520 nm in ⁇ Preparation of Negative Electrode Plate Containing First Coating Layer>.
  • the thickness of the first coating layer was 380 nm, the rest was the same as that of Example 8.
  • the thickness of the first coating layer is 1000 nm, the rest is the same as that of Example 8.
  • the thickness of the first coating layer was 1200 nm, the rest was the same as that of Example 8.
  • the coating mass of the first coating layer is 0.05 mg/cm 2 .
  • the coating mass of the first coating layer is 0.08 mg/cm 2 .
  • the coating mass of the first coating layer is 0.1 mg/cm 2 .
  • the coating mass of the first coating layer is 0.13 mg/cm 2 .
  • the coating mass of the first coating layer is 0.14 mg/cm 2 .
  • Example 2 The rest is the same as Example 1, except that in ⁇ Preparation of Negative Electrode Plate Containing First Coating Layer>, the coating mass of the first coating layer is 0.06 mg/cm 2 .
  • Example 2 The rest is the same as Example 1, except that in ⁇ Preparation of Negative Electrode Plate Containing First Coating Layer>, the coating mass of the first coating layer is 0.15 mg/cm 2 .
  • Example 1 and Examples 7-11 the average particle size Dv50 of the inorganic particles of the present application has a significant impact on the thickness and tensile strength of the first coating.
  • the increase of Dv50 increases the thickness of the first coating.
  • the Dv50 is in the range of 200nm to 300nm, and the tensile strength of the negative electrode is above 400MPa.
  • Example 8 and Examples 12-14 it can be seen from Example 8 and Examples 12-14 that the change of the Dv50 of the inorganic particles will affect the tensile strength of the negative electrode and the cycle performance of the lithium ion battery. As long as the Dv50 of the inorganic particles is within the scope of the application, it can be effectively Improve the tensile strength of anodes and the cycling performance of lithium-ion batteries.
  • Example 8 and Examples 15-17 the change in the thickness of the first coating will affect the tensile strength of the negative electrode and the cycle performance of the lithium ion battery, as long as the thickness of the first coating is within the scope of the application , which can effectively improve the tensile strength of the negative electrode and the cycle performance of the lithium-ion battery.
  • Example 1 It can be seen from Example 1, Examples 18-25 and Comparative Examples 1-2 that the introduction of the first coating of the present application can significantly improve the tensile strength of the negative electrode, the cycle performance or rate performance of the lithium ion battery, and improve the Energy density of lithium-ion batteries.
  • the contents of inorganic particles, binders, dispersants, and conductive agents in the first coating changed, the tensile strength of the negative electrode, the cycle performance and the rate performance of the lithium-ion battery changed.
  • Example 1 Examples 26-30 and Comparative Examples 1-2 that with the increase of the coverage of the first coating, the tensile strength of the negative electrode and the cycle performance of the lithium ion battery are improved.
  • Example 1 Examples 31-37 and Comparative Examples 1-2 that the negative electrode comprising the first coating of the present application has a lower elongation rate, the lithium ion battery has a higher rate performance, and the lithium ion battery has a higher rate capability.
  • the energy density of the battery It can be seen from Example 1, Examples 31-37 and Comparative Examples 1-2 that the negative electrode comprising the first coating of the present application has a lower elongation rate, the lithium ion battery has a higher rate performance, and the lithium ion battery has a higher rate capability.
  • the energy density of the battery is not limited to the battery.

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Abstract

一种电化学装置和电子装置，电化学装置包括负极，负极包括集流体（10）、第一涂层（20）和第二涂层（30），第二涂层（30）设置在集流体（10）的至少一个表面，第一涂层（20）设置于集流体（10）和第二涂层（30）之间，第一涂层（20）包含莫氏硬度为2至7的无机粒子，使得集流体（10）强度提高，且集流体（10）与第二涂层（30）之间的粘结力提高，降低了第二涂层（30）中粘结剂的含量，从而提高负极中负极活性物质的占比，有效提高了电化学装置的能量密度。

Description

一种电化学装置和电子装置 技术领域
本申请涉及电化学领域，具体涉及一种电化学装置和电子装置。
背景技术
锂离子电池具有储能密度大、开路电压高、自放电率低、循环寿命长、安全性好等优点，广泛应用于电能储存、移动电子设备、电动汽车和航天航空设备等各个领域。随着移动电子设备和电动汽车进入高速发展阶段，市场对锂离子电池的能量密度、安全性、循环性能和使用寿命等都提出了越来越高的要求。
锂离子电池在循环过程中，负极集流体与负极活性物质层之间易脱模，为解决该问题，现有技术一般设置一层包括导电剂和粘结剂的导电涂层，但其粘结力无法满足当前需要，负极活性物质层仍然存在脱模现象。再者，在冷压过程中，经常容易由于负极集流体(铜箔)强度不够造成铜箔断带，影响生产效率；同时，由于铜箔强度不够，在锂离子电池循环过程中，负极极片膨胀挤压到正极极片，造成正极极片内圈断裂，出现锂离子电池低容的现象。因此，负极集流体的强度、及其与负极活性物质层之间的粘结力亟需提高。
发明内容
本申请的目的在于提供一种电化学装置和电子装置，以提高负极集流体的强度、及其与负极活性物质层之间的粘结力。具体技术方案如下：
需要说明的是，在以下内容中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
本申请的第一方面提供了一种电化学装置，包括负极，该负极包括集流体、第一涂层和第二涂层，该第二涂层设置在集流体的至少一个表面，该第一涂层设置在集流体和第二涂层之间，该第一涂层包含无机粒子，该无机粒子的莫氏硬度为2至7。
本申请中，第二涂层也可以理解为负极活性物质层。
在本申请的一种实施方案的电化学装置中，将第一涂层设置于集流体和第二涂层之间，该第一涂层包含无机粒子，无机粒子被粘结剂包裹形成强度更高的粘接单元，该粘结单元 的强度受无机粒子莫氏硬度的影响，当无机粒子硬度过小，冷压过程容易变形，会造成第一涂层内部结构稳定性变差，使得粘结单元强度受影响，而无机粒子硬度过大，对涂覆设备磨损较大。一方面，强度更高的粘结单元可以使得第一涂层内聚力增加，该内聚力能抵消部分集流体的拉伸应力，从而增加集流体的强度，使得集流体在加工过程不易断裂；另一方面，粘结单元的形成使得第一涂层的的粘结强度和粘结位点增加，从而有效提升集流体与第二涂层之间的粘结力。而第一涂层与第二涂层之间粘结力的提升，能够减少第二涂层中粘结剂的含量、提高第二涂层中负极活性物质的占比，从而提高锂离子电池的能量密度。
本领域技术人员应当理解，本申请的负极可以在其一个表面具有第一涂层和第二涂层，也可以在其两个表面均具有第一涂层和第二涂层，本领域技术人员根据实际需要进行选择即可。
本申请提供的电化学装置，包括负极，该负极包括集流体、第一涂层和第二涂层，该第一涂层设置于负极集流体和第二涂层之间，该第一涂层包含莫氏硬度2至7的无机粒子，该第一涂层能够有效提升集流体的强度、及其与第二涂层之间的粘结力，从而降低第二涂层的粘结剂含量，提高负极中负极活性物质的占比，使锂离子电池的能量密度得到有效提高。
在本申请中，对无机粒子的种类没有特别限制，只要满足莫氏硬度在2至7的范围内，能实现本申请目的即可。例如，无机粒子可以包含勃姆石、铝粉、石英砂、磷灰石或锆石等中的至少一种。
在本申请的一种实施方案中，无机粒子的平均粒径Dv50为100nm至600nm。无机粒子的平均粒径Dv50大于100nm，能够避免无机粒子出现团聚；无机粒子的平均粒径Dv50大于600nm，会使第一涂层表面凹凸不平而影响锂离子电池的性能发挥。通过将无机粒子的平均粒径Dv50控制在上述范围内，能够确保第一涂层厚度维持在纳米级别，从而不会增加负极的厚度，避免锂离子电池的体积能量密度受到损失，同时纳米颗粒能够确保第一涂层表面的平整性，避免影响锂离子电池的性能发挥。
在本申请的一种实施方案中，第一涂层还包括导电剂、粘结剂和分散剂，基于该第一涂层的总质量，无机粒子、导电剂、粘结剂和分散剂的质量百分比为(1％～10％)：(14％～70％)：(14％～70％)：(2％～6％)。
其中，当无机粒子质量占第一涂层总质量的比例小于1％时，体现不出无机粒子的高强度作用，当无机粒子质量占第一涂层总质量的比例大于10％时，容易出现无机粒子难以分散、颗粒团聚的现象；
当粘结剂的质量占第一涂层总质量的比例小于14％时，粘结作用不明显；当粘结剂的质量占第一涂层总质量的比例大于70％时，粘结剂含量过多，易造成无机粒子团聚；
通过将分散剂质量控制在第一涂层总质量的2％至6％，能够使第一涂层的内部结构均匀、稳定，有效防止无机粒子的团聚；
通过将导电剂质量控制在第一涂层总质量的14％至70％，使负极的导电性能得以提升。在本申请的一种实施方案中，导电剂可以包含零维导电剂和一维导电剂中的至少一种。
在本申请中，对零维导电剂和一维导电剂的种类没有特别限制，能够实现本申请目的即可，例如，零维导电剂可以包含导电碳黑、乙炔黑、超导碳黑、颗粒石墨或科琴黑等中的至少一种，零维导电剂的平均粒径Dv50小于400nm；一维导电剂可以包含导电碳管或导电碳棒等中的至少一种，一维导电剂的平均直径小于400nm。通过导电剂的加入，能够提升负极的导电性能。通过将导电剂的平均粒径或平均直径控制在上述范围内，能够有效控制第一涂层的厚度，避免锂离子电池体积能量密度的损失。
在本申请中，对粘结剂的种类没有特别限制，只要能够实现本申请目的即可。例如，粘结剂可以包含丁苯橡胶、聚丙烯酸、聚乙烯醇、聚乙二醇、聚丙烯酸酯、聚偏氟乙烯、聚氯乙烯、甲醛树脂、环糊精或氰基丙烯酸酯等中的至少一种。粘结剂的加入能够提高第一涂层的粘性，从而分别提高第一涂层与负极集流体间、第一涂层与第二涂层间的粘结力，也能够减少第二涂层中粘结剂的含量。
在本申请中，对分散剂的种类没有特别限制，只要能够实现本申请目的即可。例如，分散剂可以包含羟甲基纤维素钠、羟甲基纤维素锂、海藻酸钠、丙二醇藻蛋白酸酯、甲基纤维素、淀粉磷酸钠、羧甲基纤维素钠、藻蛋白酸钠、酪蛋白、聚丙烯酸钠、聚氧乙烯或聚乙烯吡咯烷酮等中的至少一种。分散剂的加入能够提高第一涂层内部结构的均匀、稳定性，防止无机粒子的团聚。
在本申请中，通过第一涂层的设置，负极的拉伸强度为200MPa至500MPa，得到有效提高。
在本申请的一种实施方案中，第一涂层的厚度为280nm至1500nm。通过将第一涂层 的厚度控制在上述范围内，能够有效控制负极厚度的增加，从而改善锂离子电池的能量密度。
在本申请的一种实施方案中，第一涂层的涂覆质量X满足：0.02mg/cm 2≤X≤0.15mg/cm 2。通过将第一涂层的涂覆质量控制在上述范围内，能够有效控制第一涂层的厚度和涂覆均匀性，能够使第一涂层的性能得到有效发挥，从而提升锂离子电池的能量密度。
在本申请的一种实施方案中，第一涂层的覆盖率为50％至100％。通过控制第一涂层的覆盖率在50％以上，使第一涂层有效发挥其作用，使锂离子电池的性能得以改善。
在本申请的一种实施方案中，负极的电子电阻为30mΩ至60mΩ，可见本申请负极的电子电阻较大，能够增大锂离子电池的极化、减小电能的释放，从而提高锂离子电池的安全性。
在本申请的一种实施方案中，负极的延展率为0.05％至1％，其延展率较低，负极结构状态稳定。
本申请的负极中，集流体没有特别限制，可以使用本领域公知的集流体，例如铜箔、铝箔、铝合金箔以及复合集电体等。负极活性物质层包括负极活性物质，负极活性物质没有特别限制，可以使用本领域公知的负极活性物质。例如，可以包括人造石墨、天然石墨、中间相碳微球、硅、硅碳、硅氧化合物、软碳、硬碳、钛酸锂或钛酸铌等中的至少一种。在本申请中，集流体和负极活性物质层的厚度没有特别限制，只要能够实现本申请目的即可。例如，集流体的厚度为6μm至10μm，负极活性物质层的厚度为30μm至120μm。
本申请中的正极没有特别限制，只要能够实现本申请目的即可。例如，正极通常包含集流体和正极活性物质层。其中，集流体没有特别限制，可以为本领域公知的正极集流体，例如铜箔、铝箔、铝合金箔以及复合集流体等。正极活性物质层包括正极活性物质，正极活性物质没有特别限制，可以为本领域公知的正极活性物质，例如，包括镍钴锰酸锂(811、622、523、111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。在本申请中，正极集流体和正极活性物质层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极的集流体的厚度为8μm至12μm，正极活性物质层的厚度为30μm至120μm。
任选地，正极还可以包含导电层，该导电层位于集流体和正极活性物质层之间。导电层的组成没有特别限制，可以是本领域常用的导电层。该导电层包括导电剂和粘结剂。
本申请的锂离子电池还包括隔离膜，用以分隔正极和负极，防止锂离子电池内部短路，允许电解质离子自由通过，完成电化学充放电过程的作用。在本申请中，隔离膜没有特别限制，只要能够实现本申请目的即可。
例如，聚乙烯(PE)、聚丙烯(PP)为主的聚烯烃(PO)类隔离膜，聚酯膜(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素膜、聚酰亚胺膜(PI)、聚酰胺膜(PA)，氨纶或芳纶膜、织造膜、非织造膜(无纺布)、微孔膜、复合膜、隔膜纸、碾压膜、纺丝膜等中的至少一种。
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺等中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
例如，无机物层包括无机颗粒和粘结剂，该无机颗粒没有特别限制，例如可以选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡等中的至少一种。粘结剂没有特别限制，例如可以选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的一种或几种的组合。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)等中的至少一种。
本申请的锂离子电池还包括电解质，电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。
在本申请一些实施方案中，锂盐选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB和二氟硼酸锂中的一种或多种。举例来说，锂盐可以选用LiPF 6，因为它可以给出高的离子导电率并改善循环特性。
非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。
上述碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。
上述链状碳酸酯化合物的实例为碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)及其组合。环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)及其组合。氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯、碳酸三氟甲基亚乙酯及其组合。
上述羧酸酯化合物的实例为甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯、己内酯及其组合。
上述醚化合物的实例为二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃、四氢呋喃及其组合。
上述其它有机溶剂的实例为二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯、和磷酸酯及其组合。
本申请的第二方面提供了一种电子装置，包括本申请第一方面提供的电化学装置。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制。例如电化学装置可以通过以下过程制造：将正极和负极经由隔离膜重叠，并根据需要将其卷绕、折叠等操作后放入壳体内，将电解液注入壳体并封口。此外，也可以根据需要将防过电流 元件、导板等置于壳体中，从而防止电化学装置内部的压力上升、过充放电。
本申请提供了一种电化学装置和电子装置，电化学装置包括负极，该负极包括集流体、第一涂层和第二涂层，该第二涂层设置在集流体的至少一个表面，该第一涂层设置于集流体和第二涂层之间，该第一涂层包含莫氏硬度为2至7的无机粒子，使得该集流体强度提高，且集流体与第二涂层之间的粘结力提高，降低了第二涂层中粘结剂的含量，从而提高负极中负极活性物质的占比，有效提高了电化学装置的能量密度。
附图说明
为了更清楚地说明本申请和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例。
图1为本申请的一种实施方案的负极极片的结构示意图。
附图标记：10.集流体，20.第一涂层，30.第二涂层。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图和实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他技术方案，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
图1示出了本申请一种实施方案中的负极的结构示意图，第一涂层20设置于集流体10和第二涂层30之间。当然，第一涂层20和第二涂层30也可以设置于集流体10的另一侧。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
无机粒子平均粒径Dv50的测试方法：
使用马尔文激光粒度仪MS3000测试无机粒子平均粒径Dv50。
Dv50是指，无机粒子在体积基准的粒度分布中从小粒径侧起达到体积累积50％的粒径，即，小于此粒径的无机粒子的体积占无机粒子总体积的50％。
第一涂层和第二涂层的厚度测试：
1)将涂有第一涂层和第二涂层的负极极片从成品锂离子电池中拆出；
2)使用等离子体切割技术，沿负极极片厚度方向切割1)中所得负极极片，得到第一涂层和第二涂层的横截面；
3)在SEM(电子显微镜)下，观察2)中所得第一涂层和第二涂层的横截面(要求所观察的横截面长度需不少于2cm)，在SEM下分别测试第一涂层、第二涂层的厚度，每层需测试不少于15个不同的位置，记各层所有测试位置的厚度均值为对应层的厚度值。
第一涂层覆盖率测试方法：
1)将极片的实际面积计为S1；
2)将上述极片放入去离子水中浸泡2h后，将极片上层的石墨层擦去，露出的第一涂层面积计为S2；
3)通过以下表达式计算第一涂层的覆盖率B:B＝S2/S1×100％
负极延展率测试方法：
1)将放电至0％SOC的锂离子电池进行拆解，取出负极极片，测试负极极片宽度L1；
2)将锂离子电池充电至100％SOC，对锂离子电池进行拆解。取出负极极片，测试负极极片宽度L2；
3)负极延展率计算方法：(L2-L1)/L1×100％。
其中，SOC是指负极的电荷状态，也可称为剩余电量，代表负极使用一段时间或长期搁置后的剩余可放电电量与其完全充电状态的电量的比值。100％SOC表示负极满电荷状态，0％SOC表示负极零电荷状态。
负极拉伸强度测试方法：
1)制备150×20mm的负极极片；
2)将较窄的两端分别置于高铁拉力机两头，并固定；
3)启动高铁拉力机，对1)所得负极极片进行拉伸。
当负极极片断裂时，记录下数据即为拉伸强度。
循环性能测试：
测试温度为25/45℃，以0.7C恒流充电到4.4V，恒压充电到0.025C，静置5分钟后以0.5C放电到3.0V。以此步得到的容量为初始容量，进行0.7C充电/0.5C放电进行循环测试，以每一步的容量与初始容量做比值，得到容量衰减曲线。以25℃循环截至到容量保持率为90％的圈数记为锂离子电池的室温循环性能，以45℃循环截至到80％的圈数记为锂离子电池的高温循环性能，通过比较上述两种情况下的循环圈数而得到材料的循环性能。
放电倍率测试：
在25℃下，以0.2C放电到3.0V，静置5min，以0.5C充电到4.45V，恒压充电到0.05C后静置5分钟，调整放电倍率，分别以0.2C、0.5C、1C、1.5C、2.0C进行放电测试，分别得到放电容量，以每个倍率下得到的容量与0.2C得到的容量对比，通过比较2C与0.2C下的比值比较倍率性能。
实施例1
<第一涂层浆料的制备>
将导电碳和羟甲基纤维素钠放置搅拌罐中分散均匀，加入一定量的去离子水加速分散，待羟甲基纤维素钠完全溶解无胶块呈现后，将一定量的勃姆石倒入其中，三者再次混合分散，最后将丁苯橡胶加入，再次分散，即得。其中导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为44:4:2:50，勃姆石的莫氏硬度为3、Dv50为100nm。
<含有第一涂层的负极极片的制备>
将制得的第一涂层浆料涂覆在负极集流体铜箔表面，得到厚度为280nm的第一涂层，第一涂层覆盖率50％，第一涂层的涂覆质量为0.02mg/cm 2；
将负极活性物质石墨、苯乙烯-丁二烯聚合物和羧甲基纤维素钠按照重量比97.5:1.3:1.2进行混合，加入去离子水作为溶剂，调配成为固含量为70％的浆料，并搅拌均匀。将浆料均匀涂覆在第一涂层上，110℃条件下烘干，冷压后得到负极活性物质层厚度为150μm的 单面涂覆第一涂层和负极活性物质层的负极极片。
以上步骤完成后，采用同样的方法在该负极极片背面也完成这些步骤，即得到双面涂布完成的负极极片。涂布完成后，将负极极片裁切成规格为76mm×851mm的片材并焊接极耳待用。
<正极极片的制备>
将正极活性材料钴酸锂(LiCoO 2)、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97.5:1.0:1.5进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75％的浆料，并搅拌均匀。将浆料均匀涂覆在厚度为10μm的正极集流体铝箔的一个表面上，90℃条件下烘干，得到涂层厚度为110μm的正极极片。以上步骤完成后，即完成正极极片的单面涂布。之后，在该正极极片的另一个表面上重复以上步骤，即得到双面涂布正极活性材料的正极极片。涂布完成后，将极片裁切成38mm×58mm的规格待用。
<电解液的制备>
在干燥氩气气氛中，将有机溶剂碳酸乙烯酯、碳酸甲乙酯和碳酸二乙酯以质量比EC:EMC:DEC＝30:50:20混合得到有机溶液，然后向有机溶剂中加入锂盐六氟磷酸锂溶解并混合均匀，得到锂盐的浓度为1.15Mol/L的电解液。
<隔离膜的制备>
将氧化铝与聚偏氟乙烯依照质量比90:10混合并将其溶入到去离子水中以形成固含量为50％的陶瓷浆料。随后采用微凹涂布法将陶瓷浆料均匀涂布到多孔基材(聚乙烯，厚度7μm，平均孔径为0.073μm，孔隙率为26％)的其中一面上，经过干燥处理以获得陶瓷涂层与多孔基材的双层结构，陶瓷涂层的厚度为50μm。
将聚偏二氟乙烯(PVDF)与聚丙烯酸酯依照质量比96:4混合并将其溶入到去离子水中以形成固含量为50％的聚合物浆料。随后采用微凹涂布法将聚合物浆料均匀涂布到上述陶瓷涂层与多孔基材双层结构的两个表面上，经过干燥处理以获得隔离膜，其中聚合物浆料形成的单层涂层厚度为2μm。
<锂离子电池的制备>
将上述制备的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极极片中间起到隔离的作用，并卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下 脱去水分，注入配好的电解液，经过真空封装、静置、化成、整形等工序得到锂离子电池。
实施例2
除了在<第一涂层浆料的制备>中，将莫氏硬度为3的勃姆石替换为莫氏硬度为2的铝粉以外，其余与实施例1相同。
实施例3
除了在<第一涂层浆料的制备>中，将莫氏硬度为3的勃姆石替换为莫氏硬度为7的石英砂以外，其余与实施例1相同。
实施例4
除了在<第一涂层浆料的制备>中，将莫氏硬度为3的勃姆石替换为莫氏硬度为6.5的锆石以外，其余与实施例1相同。
实施例5
除了在<第一涂层浆料的制备>中，将莫氏硬度为3的勃姆石替换为莫氏硬度为5的磷灰石以外，其余与实施例1相同。
实施例6
除了在<第一涂层浆料的制备>中，将莫氏硬度为3的勃姆石替换为莫氏硬度为7的纳米陶瓷以外，其余与实施例1相同。
实施例7
除了在<第一涂层浆料的制备>中勃姆石的Dv50为200nm、在<含有第一涂层的负极极片的制备>中第一涂层的厚度为380nm以外，其余与实施例1相同。
实施例8
除了在<第一涂层浆料的制备>中勃姆石的Dv50为300nm、在<含有第一涂层的负极极片的制备>中第一涂层的厚度为520nm以外，其余与实施例1相同。
实施例9
除了在<第一涂层浆料的制备>中勃姆石的Dv50为400nm、在<含有第一涂层的负极极片的制备>中第一涂层的厚度为1000nm以外，其余与实施例1相同。
实施例10
除了在<第一涂层浆料的制备>中勃姆石的Dv50为500nm、在<含有第一涂层的负极极片的制备>中第一涂层的厚度为1200nm以外，其余与实施例1相同。
实施例11
除了在<第一涂层浆料的制备>中勃姆石的Dv50为600nm、在<含有第一涂层的负极极片的制备>中第一涂层的厚度为1500nm以外，其余与实施例1相同。
实施例12
除了在<含有第一涂层的负极极片的制备>中，第一涂层的厚度为520nm以外，其余与实施例1相同。
实施例13
除了在<含有第一涂层的负极极片的制备>中，第一涂层的厚度为520nm以外，其余与实施例7相同。
实施例14
除了在<含有第一涂层的负极极片的制备>中，第一涂层的厚度为520nm以外，其余与实施例9相同。
实施例15
除了在<含有第一涂层的负极极片的制备>中，第一涂层的厚度为380nm以外，其余与实施例8相同。
实施例16
除了在<含有第一涂层的负极极片的制备>中，第一涂层的厚度为1000nm以外，其余与实施例8相同。
实施例17
除了在<含有第一涂层的负极极片的制备>中，第一涂层的厚度为1200nm以外，其余与实施例8相同。
实施例18
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为44:4:3:49以外，其余与实施例1相同。
实施例19
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为44:4:4:48以外，其余与实施例1相同。
实施例20
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为44:4:5:47以外，其余与实施例1相同。
实施例21
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为44:4:6:46以外，其余与实施例1相同。
实施例22
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为70:6:10:14以外，其余与实施例1相同。
实施例23
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为25:4:1:70以外，其余与实施例1相同。
实施例24
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为14:6:10:70以外，其余与实施例1相同。
实施例25
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、勃姆石和丁苯橡胶的质量比为55:2:4:39以外，其余与实施例1相同。
实施例26
除了在<含有第一涂层的负极极片的制备>中，第一涂层覆盖率为60％以外，其余与实 施例1相同。
实施例27
除了在<含有第一涂层的负极极片的制备>中，第一涂层覆盖率为70％以外，其余与实施例1相同。
实施例28
除了在<含有第一涂层的负极极片的制备>中，第一涂层覆盖率为80％以外，其余与实施例1相同。
实施例29
除了在<含有第一涂层的负极极片的制备>中，第一涂层覆盖率为90％以外，其余与实施例1相同。
实施例30
除了在<含有第一涂层的负极极片的制备>中，第一涂层覆盖率为100％以外，其余与实施例1相同。
实施例31
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.05mg/cm 2以外，其余与实施例1相同。
实施例32
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.08mg/cm 2以外，其余与实施例1相同。
实施例33
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.1mg/cm 2以外，其余与实施例1相同。
实施例34
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.13mg/cm 2以外，其余与实施例1相同。
实施例35
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.14mg/cm 2以外，其余与实施例1相同。
实施例36
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.06mg/cm 2以外，其余与实施例1相同。
实施例37
除了在<含有第一涂层的负极极片的制备>中，第一涂层的涂覆质量为0.15mg/cm 2以外，其余与实施例1相同。
对比例1
除了在<第一涂层浆料的制备>中：将莫氏硬度为3的勃姆石替换为莫氏硬度为9的氧化铝、其中导电碳、羟甲基纤维素钠、氧化铝和丁苯橡胶的质量比为44:4:4:48；在<含有第一涂层的负极极片的制备>中：第一涂层覆盖率为90％，第一涂层的涂覆质量为0.08mg/cm 2以外；其余与实施例1相同。
对比例2
除了在<第一涂层浆料的制备>中，导电碳、羟甲基纤维素钠、氧化铝和丁苯橡胶的质量比为44:4:0:52以外，其余与对比例1相同。
各实施例和对比例的制备参数及测试结果如下表1-5所示。
表1 实施例1-6和对比例1-2的制备参数和测试结果
Figure PCTCN2020135882-appb-000001
表2 实施例1、实施例7-17的制备参数和测试结果
Figure PCTCN2020135882-appb-000002
表3 实施例1、实施例18-25和对比例1-2的制备参数和测试结果
Figure PCTCN2020135882-appb-000003
Figure PCTCN2020135882-appb-000004
表4 实施例1、实施例26-30和对比例1-2的制备参数和测试结果
Figure PCTCN2020135882-appb-000005
Figure PCTCN2020135882-appb-000006
表5 实施例1、实施例31-37和对比例1-2的制备参数和测试结果
Figure PCTCN2020135882-appb-000007
注：表1-5中的“/”表示无制备参数或测试结果。
从实施例1-6和对比例1-2可以看出，本申请第一涂层的引入，明显降低了负极的延伸率，同时显著提升锂离子电池的循环性能和倍率性能，提高了锂离子电池的能量密度。
从实施例1、实施例7-11可以看出，本申请无机粒子的平均粒径Dv50对第一涂层厚度和拉伸强度有着明显的影响，Dv50的增大，使第一涂层厚度增大，Dv50在200nm至300nm的范围内，负极的拉伸强度在400MPa以上。
从实施例8、实施例12-14可以看出，无机粒子的Dv50的变化会影响负极的拉伸强度和锂离子电池的循环性能，只要使得无机粒子的Dv50在本申请范围内，就能够有效提升负极的拉伸强度和锂离子电池的循环性能。
从实施例8、实施例15-17可以看出，第一涂层的厚度的变化会影响负极的拉伸强度和锂离子电池的循环性能，只要使得第一涂层的厚度在本申请范围内，就能够有效提升负极的拉伸强度和锂离子电池的循环性能。
从实施例1、实施例18-25和对比例1-2可以看出，本申请第一涂层的引入，能够显著提升负极的拉伸强度、锂离子电池的循环性能或倍率性能，提高了锂离子电池的能量密度。随着第一涂层中无机粒子、粘结剂、分散剂和导电剂含量的变化，负极的拉伸强度、锂离子电池的循环性能和倍率性能发生变化。
从实施例1、实施例26-30和对比例1-2可以看出，随着第一涂层覆盖率的提高，负极的拉伸强度和锂离子电池的循环性能得到提高。
从实施例1、实施例31-37和对比例1-2可以看出，包含本申请第一涂层的负极具有更低的延展率、锂离子电池具有更高的倍率性能，提高了锂离子电池的能量密度。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (15)

  1. 一种电化学装置，包括负极，所述负极包括集流体、第一涂层和第二涂层，所述第二涂层设置在所述集流体的至少一个表面，所述第一涂层设置在所述集流体和所述第二涂层之间，所述第一涂层包括无机粒子，所述无机粒子的莫氏硬度为2至7。
  2. 根据权利要求1所述的电化学装置，其中，所述无机粒子包含勃姆石、铝粉、石英砂、磷灰石、纳米陶瓷或锆石中的至少一种。
  3. 根据权利要求1所述的电化学装置，其中，所述无机粒子的平均粒径Dv50为100nm至600nm。
  4. 根据权利要求1所述的电化学装置，其中，所述第一涂层还包括导电剂、粘结剂和分散剂，基于所述第一涂层的总质量，所述无机粒子、导电剂、粘结剂和分散剂的质量百分比为(1％～10％)：(14％～70％)：(14％～70％)：(2％～6％)。
  5. 根据权利要求4所述的电化学装置，其中，所述导电剂包括零维导电剂或一维导电剂中的至少一种。
  6. 根据权利要求5所述的电化学装置，其中，满足以下特征中的至少一者：
    所述零维导电剂包括导电碳黑、乙炔黑或科琴黑中的至少一种，所述零维导电剂的Dv50小于400nm；
    所述一维导电剂包括导电碳管或导电碳棒中的至少一种，所述一维导电剂的平均直径小于400nm。
  7. 根据权利要求4所述的电化学装置，其中，所述粘结剂包括丁苯橡胶、聚丙烯酸、聚乙烯醇、聚乙二醇、聚丙烯酸酯、聚偏氟乙烯、聚氯乙烯、甲醛树脂、环糊精或氰基丙烯酸酯中的至少一种。
  8. 根据权利要求4所述的电化学装置，其中，所述分散剂包括羟甲基纤维素钠、羟甲基纤维素锂、海藻酸钠、丙二醇藻蛋白酸酯、甲基纤维素、淀粉磷酸钠、羧甲基纤维素钠、藻蛋白酸钠、酪蛋白、聚丙烯酸钠、聚氧乙烯或聚乙烯吡咯烷酮中的至少一种。
  9. 根据权利要求1所述的电化学装置，其中，所述负极的拉伸强度为200MPa至500MPa。
  10. 根据权利要求1所述的电化学装置，其中，所述第一涂层的厚度为280nm至1500nm。
  11. 根据权利要求1所述的电化学装置，其中，所述第一涂层的涂覆质量X满足：0.02mg/cm 2≤X≤0.15mg/cm 2。
  12. 根据权利要求1所述的电化学装置，其中，所述第一涂层的覆盖率为50％至100％。
  13. 根据权利要求1所述的电化学装置，其中，所述负极的电子电阻为30mΩ至60mΩ。
  14. 根据权利要求1所述的电化学装置，其中，所述负极的延展率为0.05％至1％。
  15. 一种电子装置，其包含权利要求1至14任意一项所述的电化学装置。
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