WO2023184227A1 - Electrochemical device and electronic device using safety coating - Google Patents

Electrochemical device and electronic device using safety coating Download PDF

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Publication number
WO2023184227A1
WO2023184227A1 PCT/CN2022/084041 CN2022084041W WO2023184227A1 WO 2023184227 A1 WO2023184227 A1 WO 2023184227A1 CN 2022084041 W CN2022084041 W CN 2022084041W WO 2023184227 A1 WO2023184227 A1 WO 2023184227A1
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WIPO (PCT)
Prior art keywords
protective layer
active material
positive electrode
electrochemical device
lithium
Prior art date
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PCT/CN2022/084041
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French (fr)
Chinese (zh)
Inventor
刘晓欠
张青文
韩冬冬
陈梅锋
Original Assignee
宁德新能源科技有限公司
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Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to PCT/CN2022/084041 priority Critical patent/WO2023184227A1/en
Priority to CN202280010595.1A priority patent/CN117015866A/en
Publication of WO2023184227A1 publication Critical patent/WO2023184227A1/en

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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
    • 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
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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

  • This application relates to the field of energy storage, and specifically to an electrochemical device and an electronic device using a safety coating.
  • the present application relates to an electrochemical device, which includes: a positive electrode including a positive current collector, a protective layer and a positive active material layer.
  • the protective layer is disposed between the positive current collector and the positive active material layer, wherein X g of the protective layer is dispersed in 50X g of water at 25°C to 35°C, and a dispersion disk with a diameter of 50mm to 80mm is used.
  • the stirrer is stirred at a stirring speed of 1200r/min. After filtering and drying using a 100-mesh filter, the weight of the protective layer on the filter is W g, where W/X ⁇ 10%.
  • the most dangerous short circuit between the positive electrode current collector and the negative electrode active material layer can be suppressed during impact or puncture by external forces, thereby improving electrochemical performance.
  • the safety performance of the device on the other hand, the overall tendency of the protective layer that satisfies W/X ⁇ 10% is hydrophilic rather than lipophilic, which can avoid the large-area loss of adhesive force of the protective layer due to swelling in the oily electrolyte. This maintains the bonding effect and inhibits the growth of internal resistance in high-temperature storage.
  • the infrared spectrum of the protective layer has characteristic peaks in the range of 1400 cm -1 to 1700 cm -1 and/or 2100 cm -1 to 2300 cm -1 .
  • the protective layer contains polar functional groups such as carbonyl and/or cyano groups, which can enhance its adhesion to the positive electrode current collector, thereby improving the high-temperature storage internal resistance growth rate of the electrochemical device.
  • the resistance of the positive electrode is R ⁇ , 1.5 ⁇ R ⁇ 5.
  • controlling R to be greater than or equal to 1.5 ⁇ can significantly improve the central nail penetration rate of the electrochemical device; on the other hand, controlling R to be less than or equal to 5 ⁇ can further improve the high-temperature storage process of the electrochemical device.
  • the internal resistance increases.
  • the thickness of the protective layer is T ⁇ m, T ⁇ 0.5.
  • the thickness of the protective layer T ⁇ 0.5 ⁇ m can effectively suppress the short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external forces, and improve the safety of the electrochemical device.
  • the protective layer includes a first active material, a first binder, and a first conductive agent.
  • the protective layer further includes a leveling agent.
  • the mass percentage of the first conductive agent is 0.5% to 15%
  • the mass percentage of the first active material is 60% to 98.5%
  • the first The mass percentage of binder is 1% to 20%.
  • the leveling agent includes silicone compounds, silicone derivatives, oxygen-containing olefin polymers, acrylate polymers, acrylate polymers, alcohol compounds, ethers At least one of compounds or fluorocarbons.
  • the mass percentage of the leveling agent is 0.01% to 5% based on the mass of the protective layer.
  • the first binder meets at least one of the following characteristics: (a) includes a polymer formed from at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylate; ( b) Contains at least one of carboxymethyl cellulose salt or nitrile rubber.
  • the first adhesive is an aqueous adhesive.
  • the first binder has a weight average molecular weight of 200,000 to 2,000,000.
  • the first active material includes at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, or lithium nickel cobalt manganate.
  • the first conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
  • the positive active material layer includes a second active material, a second binder, and a second conductive agent.
  • the mass percentage of the second active material is 91.5% to 99%, and the mass percentage of the second binder is 0.5% to 5%, so The mass percentage of the second conductive agent is 0.5% to 3.5%.
  • the second active material includes at least one of lithium cobalt oxide, lithium manganate, or lithium nickel cobalt manganate.
  • the second binder includes at least one of polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene-hexafluoropropylene, sodium polyacrylate, nitrile rubber, or polyacrylate.
  • the second conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
  • the present application relates to an electronic device comprising an electrochemical device according to any of the preceding embodiments.
  • a list of items connected by the term "at least one of,” “at least one of,” “at least one of,” or other similar terms may mean that the listed items any combination of.
  • the phrase “at least one of A and B” means only A; only B; or A and B.
  • the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B and C.
  • Project A can contain a single component or multiple components.
  • Project B can contain a single component or multiple components.
  • Project C may contain a single component or multiple components.
  • the present application relates to an electrochemical device, which includes a positive electrode including a positive current collector, a protective layer and a positive active material layer.
  • the protective layer is disposed between the cathode current collector and the cathode active material layer.
  • the protective layer satisfies: W/X ⁇ 10%, where The mass of the protective layer remaining on the filter (unit: g) after stirring with a mixer of 50mm to 80mm at a stirring speed of 1200r/min, filtering and drying through a 100-mesh screen.
  • the protective layer can inhibit the most dangerous short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external forces, improving the safety performance of the electrochemical device; at the same time, by meeting the protection requirement of W/X ⁇ 10%
  • the layer can control the high-temperature storage internal resistance growth rate of the lithium-ion battery below 40%, where, in some embodiments, high-temperature storage refers to storage of the electrochemical device at 85° C. for 6 hours. This is because the overall protective layer tends to be hydrophilic rather than lipophilic, which can avoid large-area loss of adhesive force due to swelling of the protective layer in the oily electrolyte, thereby maintaining the adhesive effect and inhibiting the growth of internal resistance in high-temperature storage. .
  • the value of X is 20-80 g.
  • the infrared spectrum of the protective layer has characteristic peaks in the range of 1400 cm -1 to 1700 cm -1 - and/or 2100 cm -1 to 2300 cm -1 .
  • the protective layer contains polar functional groups such as carbonyl and/or cyano groups, which can enhance its adhesion to the positive electrode current collector, thereby improving the high-temperature storage internal resistance growth rate of the electrochemical device.
  • the protective layer includes a first active material, a first binder, and a first conductive agent.
  • the mass percentage of the first active material is 60% to 98.5%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 65% to 96%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 70% to 95%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 75% to 95%.
  • the mass percentage of the first active material is 60%, 65%, 70%, 75%, 77%, 78%, 80%, 82%, 84%, 85%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 98.5% or the range between any two of the aforementioned values.
  • the first active material includes at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, or lithium nickel cobalt manganate.
  • the mass percentage of the first binder is 1% to 20% based on the mass of the protective layer. In some embodiments, the mass percentage of the first binder is 1%, 2%, 3%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% , 8.5%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or the range between any two of the aforementioned values.
  • the first binder is an aqueous binder.
  • the first binder satisfies at least one of the following characteristics: (a) includes a polymer formed from at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylate; (b) Contains at least one of carboxymethyl cellulose salt or nitrile rubber.
  • the first adhesive is a polymer composed of acrylate. In this case, the first adhesive has good hydrophilic and oleophobic properties, so that the protective layer has excellent adhesion and stability. This can then improve the nail penetration safety performance and high-temperature storage internal resistance growth rate of the electrochemical device.
  • the first binder has a weight average molecular weight of 200,000 to 2,000,000. In some embodiments, the first binder has a weight average molecular weight of 200,000 to 1.8 million. In some embodiments, the first binder has a weight average molecular weight of 200,000 to 1.6 million.
  • the weight average molecular weight of the first binder is 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 75
  • the weight average molecular weight of the first binder is within the above range, which can achieve both film-forming property and adhesive force, and improve the uniformity and stability of the protective layer.
  • the mass percentage of the first conductive agent is 0.5% to 15%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first conductive agent is 0.5% to 10%. In some embodiments, the mass percentage of the first conductive agent is 0.5% to 8% based on the mass of the protective layer. In some embodiments, the mass percentage of the first conductive agent is 1% to 7% based on the mass of the protective layer.
  • the mass percentage of the first conductive agent is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.2%, 2.3%, 2.4%, 2.5%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4% , 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or the range between any two of the aforementioned values.
  • the first conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
  • the protective layer further includes a leveling agent.
  • the leveling agent includes silicone compounds, silicone derivatives, oxygen-containing olefin polymers, acrylate polymers, acrylate polymers, alcohol compounds, ether compounds or fluorine compounds. At least one of the carbon compounds.
  • the mass percentage of the leveling agent is 0.01% to 5% based on the mass of the protective layer. In some embodiments, the mass percentage of the leveling agent is 0.03% to 4% based on the mass of the protective layer. In some embodiments, the mass percentage of the leveling agent is 0.05% to 4% based on the mass of the protective layer.
  • the mass percentage of the leveling agent is 0.08% to 4% based on the mass of the protective layer. In some embodiments, based on the quality of the protective layer, the mass percentage of the leveling agent is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or The range between any two values mentioned above.
  • the addition of the above-mentioned leveling agent is conducive to forming a uniform and smooth protective layer, increasing the contact area between the protective layer and the current collector and the positive active material layer, improving the conductivity, and improving the internal resistance growth during high-temperature storage.
  • the resistance of the positive electrode is R ⁇ .
  • R is from 1 to 10.
  • R is from 1.5 to 9.
  • R is from 1.5 to 5.
  • R is 1, 1.5, 2, 2.1, 2.3, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or The range between any two values mentioned above. . When R is within this range, the electrochemical device can maintain a high nail penetration rate while having a low high-temperature storage internal resistance growth rate.
  • the thickness of the protective layer is T ⁇ m, T ⁇ 0.5. In some embodiments, T is 0.5 to 10. In some embodiments, T ranges from 1 to 9. In some embodiments, T is 1.5 to 8.5. In some embodiments, T is from 2 to 8. In some embodiments, T is 2.5 to 7.5. In some embodiments, T is 1.5 to 5. In some embodiments, T is 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or any of the foregoing The range between two values.
  • the thickness of the protective layer is within the above range, which can effectively suppress the short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external force, and improve the safety of the electrochemical device.
  • the positive active material layer includes a second active material, a second binder, and a second conductive agent.
  • the mass percentage of the second active material is 91.5% to 99%
  • the mass percentage of the second binder is 0.5% to 5%
  • the mass percentage of the second conductive agent is 0.5% to 3.5%.
  • the second active material includes at least one of lithium cobalt oxide, lithium manganate, or lithium nickel cobalt manganate.
  • the second binder includes at least one of polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene-hexafluoropropylene, sodium polyacrylate, nitrile rubber, or polyacrylate.
  • the second conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
  • this application can suppress the most dangerous short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external forces, and improve the performance of the electrochemical device.
  • Safety performance at the same time, this application recognizes that by controlling the material of the protective layer so that W/X ⁇ 10% (where After the protective layer is dispersed in water under the aforementioned conditions, use a stirrer with a dispersion disk diameter of 50mm to 80mm to stir at a stirring speed of 1200r/min. Use a 100-mesh filter to filter and dry the remaining protective layer on the filter.
  • the protective layer when the protective layer tends to be hydrophilic rather than lipophilic, it can avoid large-area loss of adhesive force due to swelling of the protective layer in the oily electrolyte, thereby maintaining the bonding effect and inhibiting high-temperature storage Growth of internal resistance. For example, it can control the growth rate of high-temperature storage internal resistance below 40%.
  • the electrochemical device of the present application also includes a separator, an electrolyte and a negative electrode.
  • electrochemical devices of the present application include primary or secondary batteries.
  • the electrochemical device is a lithium secondary battery.
  • lithium secondary batteries include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries, sodium ion batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.
  • the preparation method of the electrochemical device of the present application is described in detail below by taking a lithium-ion battery as an example.
  • Preparation of the negative electrode Disperse the negative electrode active material (at least one of carbon material, silicon material or lithium titanate), negative electrode binder, and optional conductive material in the solvent system according to a certain mass ratio, and stir thoroughly to mix evenly. Then, it is coated on the negative electrode current collector, dried and cold pressed to obtain the negative electrode.
  • the negative electrode active material at least one of carbon material, silicon material or lithium titanate
  • the negative electrode binder at least one of carbon material, silicon material or lithium titanate
  • optional conductive material in the solvent system according to a certain mass ratio
  • Preparation of the positive electrode (1) Add the first active material, the first conductive agent, the first binder, and the optional leveling agent to the solvent and mix evenly to obtain a protective layer slurry (hereinafter referred to as "first slurry”); (2) apply the first slurry in step (1) to the target area of the positive electrode current collector; (3) apply the positive electrode containing the first slurry obtained in step (2) The current collector is dried to remove the solvent, and a positive electrode current collector coated with a protective layer is obtained; (4) The second active material, the second conductive agent, and the second binder are dispersed in the solvent system according to a certain mass ratio and stirred thoroughly Mix evenly to obtain a slurry of positive active material (hereinafter referred to as "second slurry”); (5) Coat the second slurry on the positive electrode current collector coated with a protective layer obtained in step (3). Target area; (6) Dry the positive electrode current collector containing the second slurry in step (5) to remove the solvent, thereby obtaining the desired positive electrode.
  • the types of the first active material, the first conductive agent, the first binder, the leveling agent, the second active material, the second conductive agent and the second binder are as described above.
  • examples of the solvent include, but are not limited to, N-methylpyrrolidone, acetone, or water. In some embodiments, the amount of solvent can be adjusted appropriately.
  • the current collector has a thickness in the range of 3 microns to 20 microns, although the disclosure is not limited thereto.
  • the current collector is not particularly limited as long as the current collector is conductive without causing adverse chemical changes in the manufactured battery.
  • Examples of the current collector include copper, stainless steel, aluminum, nickel, titanium, or alloys (eg, homo-nickel alloys), but the disclosure is not limited thereto.
  • fine irregularities eg, surface roughness
  • the current collector can be used in various forms, and examples thereof include films, sheets, foils, meshes, porous structures, foams, or similar materials, but the disclosure is not limited thereto.
  • Isolation film In some embodiments, a polyethylene (abbreviated as PE) porous polymer film is used as the isolation film.
  • the material of the isolation membrane may include fiberglass, polyester, polyethylene, polypropylene, polytetrafluoroethylene or combinations thereof.
  • the pores in the isolation film have a diameter in the range of 0.01 micron to 1 micron, and the thickness of the isolation film ranges from 5 microns to 500 microns.
  • the electrolyte includes an organic solvent, a lithium salt, and additives.
  • the organic solvent includes ethylene carbonate (abbreviated as EC), propylene carbonate (abbreviated as PC), diethyl carbonate (abbreviated as DEC), ethyl methyl carbonate (abbreviated as EMC), dimethyl carbonate At least one of ester (abbreviated as DMC), propylene carbonate, ethyl acetate, ethyl propionate or propyl propionate.
  • EC ethylene carbonate
  • PC propylene carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • ester abbreviated as DMC
  • propylene carbonate ethyl acetate, ethyl propionate or propyl propionate.
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • lithium salts include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium bistrifluoromethanesulfonimide LiN (CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bis(fluorosulfonyl)borate LiB(C 2 O 4 ) 2 (LiBOB) or lithium difluoroxalatoborate At least one of LiBF 2 (C 2 O 4 ) (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiN CF 3 SO 2 ) 2
  • LiTFSI lithium bis(fluorosulfonyl)imide Li(N
  • the content of the lithium salt is 8%-30% based on the quality of the electrolyte. In some embodiments, the lithium salt content is 8%, 9%, 10%, 11%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% or any of the foregoing. The range between two values.
  • the additives include fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), vinyl sulfate ( DTD), at least one of succinonitrile (SN), adiponitrile (ADN), 1,3,6-hexanetrinitrile (HTCN), and succinic anhydride (SA).
  • FEC fluoroethylene carbonate
  • VC vinylene carbonate
  • VEC vinyl ethylene carbonate
  • PS 1,3-propane sultone
  • DTD vinyl sulfate
  • SN succinonitrile
  • ADN adiponitrile
  • HTCN 1,3,6-hexanetrinitrile
  • SA succinic anhydride
  • the bare cell obtained by winding is placed in an outer package, electrolyte is injected and packaged, and a lithium-ion battery is obtained through processes such as formation, degassing, and trimming.
  • the present application provides an electronic device comprising the electrochemical device according to the foregoing content.
  • the electronic devices 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, head-mounted Stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles , bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries or lithium/sodium ion capacitors, etc.
  • Step (1) Add the first active material, the first conductive agent, the first binder, and the optional leveling agent to water and mix evenly to obtain a protective layer slurry (hereinafter referred to as "first slurry”). material”);
  • Step (2) Coating the first slurry in step (1) on the target area of the positive electrode current collector;
  • Step (3) drying the positive electrode current collector containing the first slurry obtained in step (2) to remove the solvent to obtain a positive electrode current collector coated with a protective layer;
  • Step (4) Combine the second active material (lithium cobalt oxide, 97.3% by mass), the second conductive agent (0.6% by mass of conductive carbon (trade name: Super P)) and 0.5% by mass of carbon nanotubes (abbreviated as CNT) and the second binder (polyvinylidene fluoride (abbreviated as PVDF) with a mass percentage of 1.6%) are dispersed in the N-methylpyrrolidone solvent system and stirred thoroughly to obtain a slurry of the positive electrode active material (hereinafter referred to as as "second slurry");
  • Step (5) applying the second slurry to the target area of the positive electrode current collector coated with the protective layer obtained in step (3);
  • Step (6) Drying the positive electrode current collector containing the second slurry in step (5) to remove the solvent, thereby obtaining the desired positive electrode.
  • Table 1 below specifically shows the differences in protective layers in the positive electrodes in Examples 1 to 33 and Comparative Examples 1 to 2.
  • the positive electrode of the electrochemical device was fabricated as described above.
  • Negative electrode Combine the active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (abbreviated as SBR), and thickener sodium carboxymethylcellulose (abbreviated as CMC) in a mass ratio of 95:2:2:1 After thoroughly stirring and mixing in water, it is coated on Cu foil, dried, and cold pressed to obtain a negative electrode.
  • SBR binder styrene-butadiene rubber
  • CMC thickener sodium carboxymethylcellulose
  • Electrolyte In an argon atmosphere glove box with a water content of ⁇ 10ppm, mix ethylene carbonate (abbreviated as EC), diethyl carbonate (abbreviated as DEC), and propylene carbonate (abbreviated as PC) according to 2:6: Mix evenly at a mass ratio of 2, then dissolve the fully dried lithium salt LiPF 6 in the above solvent, and then add 1,3-propane sultone, fluoroethylene carbonate and adiponitrile.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • the content of LiPF 6 is 12.5%
  • the content of 1,3-propane sultone is 1.5%
  • the content of fluoroethylene carbonate is 3%
  • the content of adiponitrile is 2%
  • the rest are EC and DEC and PC, where the content of each substance is based on the total weight of the electrolyte.
  • Isolation film Polyethylene (abbreviated as PE) porous polymer film is used as the isolation film.
  • Table 2 below shows various properties of Examples 1 to 33 and Comparative Examples 1 to 2.
  • Example 15 From the comparison between Example 15 and Example 16, it can be found that when the W/X of the protective layer becomes smaller (that is, when the water solubility of the binder is better), it can improve the central nail penetration rate of the electrochemical device. At the same time, the effect of improving the growth rate of high-temperature storage internal resistance is more obvious.
  • Example 1 to 33 it can be found that the center nail penetration rate (throughput/total test amount) of Examples 1 to 32 that satisfies R ⁇ 1.5 is significantly better than that of Example 33. It can be seen that by controlling the full-charge positive electrode resistance R ⁇ 1.5 by adding a protective layer, the center nail penetration rate of lithium-ion batteries can be significantly improved. At the same time, the high-temperature storage internal resistance growth rate of Examples 1 to 31 satisfying R ⁇ 5 is also significantly better than that of Example 32. It can be seen that by controlling 1.5 ⁇ R ⁇ 5, a lithium-ion battery with both a higher nail penetration rate and a lower high-temperature storage internal resistance growth rate can be obtained.
  • the thickness of the protective layer T ⁇ 0.5 ⁇ m can effectively improve the center nail penetration rate of the lithium-ion battery, and at the same time, the improvement effect of high-temperature storage internal resistance growth rate is also more obvious.
  • the conductive agent used in the protective layer in Examples 1 to 33 of the present application includes at least one of carbon nanotubes (abbreviated as CNT), conductive carbon (abbreviated as SP), Ketjen black, graphene (abbreviated as GN), and graphite fiber. kind.
  • CNT carbon nanotubes
  • SP conductive carbon
  • GN graphene
  • GN graphite fiber
  • the binder used for the protective layer in Examples 1 to 33 of the present application may include acrylonitrile, acrylate, acrylamide polymer, polyacrylic acid, sodium carboxymethyl cellulose, sodium polyacrylate, polyacrylate, polyacrylonitrile or At least one type of nitrile rubber.
  • the adhesive used in the protective layer of the present application is not limited to the types listed in the specific embodiments. It may include a polymer formed from at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylic ester, or Contains its analogues.
  • Examples 17 to 20 show that when the binder includes at least one selected from the group consisting of sodium polyacrylate, polyacrylate, polyacrylonitrile, and nitrile rubber, it is possible to improve the center penetration of the electrochemical device. At the same time, it improves the growth rate of high-temperature storage internal resistance.
  • the leveling agent used for the protective layer in Examples 1 to 33 of the present application may include at least one of oxygen-containing olefin polymers, ethanol, silicone compounds, acrylate polymers, acrylate polymers, diethyl ether or ethanol.
  • the leveling agent used in the protective layer of the present application is not limited to the types listed in the specific embodiments, and may include analogs thereof.
  • the electrochemical device of the present application can have improved high-temperature storage internal resistance growth rate and a higher center penetration rate.
  • references throughout this specification to “some embodiments,” “partial embodiments,” “one embodiment,” “another example,” “example,” “specific example,” or “partial example” mean the following: At least one embodiment or example in this application includes a specific feature, structure, material or characteristic described in the embodiment or example. Accordingly, phrases such as “in some embodiments,” “in an embodiment,” “in one embodiment,” “in another example,” “in one example,” etc. may appear in various places throughout this specification. "in”, “in a particular example” or “for example” do not necessarily refer to the same embodiment or example in this application. Furthermore, the specific features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.

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Abstract

The present application relates to an electrochemical device. The electrochemical device comprises: a positive electrode, wherein the positive electrode comprises a positive electrode current collector, a protective layer and a positive electrode active material layer. The protective layer is arranged between the positive electrode current collector and the positive electrode active material layer, wherein X g of the protective layer is dispersed in 50X g of water at 25°C to 35°C, is stirred at a stirring speed of 1200 r/min by using a stirrer with a dispersion disc diameter of 50 to 80 mm, and is filtered by using a filter screen with a 100-mesh sieve and then dried, after which the weight of the protective layer on the filter screen is then W g, wherein W/X is less than or equal to 10%.

Description

一种使用安全涂层的电化学装置及电子装置Electrochemical device and electronic device using safety coating 技术领域Technical field
本申请涉及储能领域，具体涉及一种使用安全涂层的电化学装置及电子装置。This application relates to the field of energy storage, and specifically to an electrochemical device and an electronic device using a safety coating.
背景技术Background technique
随着电子产品如笔记本电脑、手机、掌上游戏机和平板电脑等的普及，人们对电化学装置(例如，锂离子电池)的安全性和稳定性要求也越来越高。然而，目前锂离子电池在使用过程中，仍然存在由于外力撞击或穿刺等原因造成的着火、***等安全事故，且在高温下电池阻抗增长严重，限制了锂离子电池的广泛应用。因此，亟需一种能够改善锂离子电池安全性能和高温稳定性的技术手段。With the popularity of electronic products such as laptops, mobile phones, handheld game consoles, and tablet computers, people have increasingly higher requirements for the safety and stability of electrochemical devices (such as lithium-ion batteries). However, during the current use of lithium-ion batteries, there are still safety accidents such as fires and explosions caused by external impacts or punctures, and the battery impedance increases seriously at high temperatures, which limits the wide application of lithium-ion batteries. Therefore, a technical means that can improve the safety performance and high-temperature stability of lithium-ion batteries is urgently needed.
发明内容Contents of the invention
根据本申请的一方面，本申请涉及一种电化学装置，其包括：正极，所述正极包括正极集流体、保护层和正极活性材料层。所述保护层设置于所述正极集流体与所述正极活性材料层之间，其中，取X g所述保护层在25℃至35℃分散于50X g水中，并用分散盘直径为50mm至80mm的搅拌器在1200r/min的搅拌速度下搅拌，采用100目筛子的滤网过滤、干燥后，所述滤网上的所述保护层的重量为W g，其中W/X≤10％。一方面，通过在正极集流体与正极活性材料层之间设置保护层，能够抑制在受到外力撞击或穿刺过程中，发生最危险的正极集流体与负极活性材料层之间的短路，提高电化学装置的安全性能；另一方面，满足W/X≤10％的保护层整体倾向为亲水性而非亲油性，从而可以避免保护层在油性电解液中由于溶胀而大面积损失粘结力，从而保持粘结作用，抑制高温存储内阻的增长。According to one aspect of the present application, the present application relates to an electrochemical device, which includes: a positive electrode including a positive current collector, a protective layer and a positive active material layer. The protective layer is disposed between the positive current collector and the positive active material layer, wherein X g of the protective layer is dispersed in 50X g of water at 25°C to 35°C, and a dispersion disk with a diameter of 50mm to 80mm is used. The stirrer is stirred at a stirring speed of 1200r/min. After filtering and drying using a 100-mesh filter, the weight of the protective layer on the filter is W g, where W/X ≤ 10%. On the one hand, by providing a protective layer between the positive electrode current collector and the positive electrode active material layer, the most dangerous short circuit between the positive electrode current collector and the negative electrode active material layer can be suppressed during impact or puncture by external forces, thereby improving electrochemical performance. The safety performance of the device; on the other hand, the overall tendency of the protective layer that satisfies W/X ≤ 10% is hydrophilic rather than lipophilic, which can avoid the large-area loss of adhesive force of the protective layer due to swelling in the oily electrolyte. This maintains the bonding effect and inhibits the growth of internal resistance in high-temperature storage.
在一些实施例中，所述保护层的红外光谱在1400cm -1至1700cm -1和/或2100cm-1至2300cm-1范围内具有特征峰。此时，保护层中具有羰基和/或氰基等极性官能团，能够增强其对正极集流体的粘结力，进而改善电化学装置的高温存储内阻增 长率。 In some embodiments, the infrared spectrum of the protective layer has characteristic peaks in the range of 1400 cm -1 to 1700 cm -1 and/or 2100 cm -1 to 2300 cm -1 . At this time, the protective layer contains polar functional groups such as carbonyl and/or cyano groups, which can enhance its adhesion to the positive electrode current collector, thereby improving the high-temperature storage internal resistance growth rate of the electrochemical device.
在一些实施例中，在所述电化学装置处于满充状态时，所述正极的电阻为RΩ，1.5≤R≤5。一方面，将R控制在大于或等于1.5Ω，可以显着提高电化学装置的中心穿钉通过率；另一方面，将R控制在小于或等于5Ω，可以进一步改善电化学装置在高温存储过程中的内阻增长。In some embodiments, when the electrochemical device is in a fully charged state, the resistance of the positive electrode is RΩ, 1.5≤R≤5. On the one hand, controlling R to be greater than or equal to 1.5Ω can significantly improve the central nail penetration rate of the electrochemical device; on the other hand, controlling R to be less than or equal to 5Ω can further improve the high-temperature storage process of the electrochemical device. The internal resistance increases.
在一些实施例中，所述保护层的厚度为Tμm，T≥0.5。保护层的厚度T≥0.5μm，能够有效抑制在受到外力撞击或穿刺过程中正极集流体与负极活性材料层之间的短路，提高电化学装置的安全性。In some embodiments, the thickness of the protective layer is Tμm, T≥0.5. The thickness of the protective layer T ≥ 0.5 μm can effectively suppress the short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external forces, and improve the safety of the electrochemical device.
在一些实施例中，所述保护层包含第一活性物质、第一粘结剂和第一导电剂。In some embodiments, the protective layer includes a first active material, a first binder, and a first conductive agent.
在一些实施例中，所述保护层还包含流平剂。In some embodiments, the protective layer further includes a leveling agent.
在一些实施例中，基于所述保护层的质量，所述第一导电剂的质量百分比为0.5％至15％，所述第一活性物质的质量百分比为60％至98.5％，所述第一粘结剂的质量百分比为1％至20％。In some embodiments, based on the quality of the protective layer, the mass percentage of the first conductive agent is 0.5% to 15%, the mass percentage of the first active material is 60% to 98.5%, and the first The mass percentage of binder is 1% to 20%.
在一些实施例中，所述流平剂包含包括硅氧烷类化合物、硅氧烷类衍生物、含氧烯烃聚合物、丙烯酸酯类聚合物、丙烯酸盐类聚合物、醇类化合物、醚类化合物或氟碳化合物中的至少一种。在一些实施例中，基于所述保护层的质量，所述流平剂的质量百分比为0.01％至5％。In some embodiments, the leveling agent includes silicone compounds, silicone derivatives, oxygen-containing olefin polymers, acrylate polymers, acrylate polymers, alcohol compounds, ethers At least one of compounds or fluorocarbons. In some embodiments, the mass percentage of the leveling agent is 0.01% to 5% based on the mass of the protective layer.
在一些实施例中，所述第一粘结剂满足如下特征中的至少一者：(a)包含丙烯酸、丙烯酰胺、丙烯酸盐、丙烯腈或丙烯酸酯中的至少一种形成的聚合物；(b)包含羧甲基纤维素盐或丁腈橡胶中的至少一者。In some embodiments, the first binder meets at least one of the following characteristics: (a) includes a polymer formed from at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylate; ( b) Contains at least one of carboxymethyl cellulose salt or nitrile rubber.
在一些实施例中，所述第一粘结剂为水性粘结剂。In some embodiments, the first adhesive is an aqueous adhesive.
在一些实施例中，所述第一粘结剂的重量平均分子量为20万至200万。In some embodiments, the first binder has a weight average molecular weight of 200,000 to 2,000,000.
在一些实施例中，所述第一活性物质包含磷酸铁锂、磷酸锰铁锂、锰酸锂或镍钴锰酸锂中的至少一种。在一些实施例中，所述第一导电剂包含石墨烯、石墨纤维、碳纳米管、科琴黑或导电碳中的至少一种。In some embodiments, the first active material includes at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, or lithium nickel cobalt manganate. In some embodiments, the first conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
在一些实施例中，所述正极活性材料层包含第二活性物质、第二粘结剂和第二导电剂。在一些实施例中，基于所述正极活性材料层的质量，所述第二活性物质的质量百分比为91.5％至99％，所述第二粘结剂的质量百分比为0.5％至5％，所述第二导电剂的质量百分比为0.5％至3.5％。In some embodiments, the positive active material layer includes a second active material, a second binder, and a second conductive agent. In some embodiments, based on the mass of the cathode active material layer, the mass percentage of the second active material is 91.5% to 99%, and the mass percentage of the second binder is 0.5% to 5%, so The mass percentage of the second conductive agent is 0.5% to 3.5%.
在一些实施例中，所述第二活性物质包含钴酸锂、锰酸锂或镍钴锰酸锂中的至少一种。在一些实施例中，所述第二粘结剂包含聚丙烯酸、聚偏氟乙烯、聚四氟乙烯-六氟丙烯、聚丙烯酸钠、丁腈橡胶或聚丙烯酸酯中的至少一种。在一些实施例中，所述第二导电剂包含石墨烯、石墨纤维、碳纳米管、科琴黑或导电碳中的至少一种。In some embodiments, the second active material includes at least one of lithium cobalt oxide, lithium manganate, or lithium nickel cobalt manganate. In some embodiments, the second binder includes at least one of polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene-hexafluoropropylene, sodium polyacrylate, nitrile rubber, or polyacrylate. In some embodiments, the second conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
根据本申请的另一方面，本申请涉及包含根据前述任一实施例所述的电化学装置的电子装置。According to another aspect of the present application, the present application relates to an electronic device comprising an electrochemical device according to any of the preceding embodiments.
具体实施方式Detailed ways
下文中，对本申请进行详细说明。应当理解，在说明书和所附权利要求中使用的术语不应被解释为限于一般和词典的含义，而是在发明人被允许适当定义术语以进行最佳解释的原则的基础上基于与本申请的技术方面相对应的含义和概念来解释。因此，说明书中所述的实施方案中所示的描述仅仅是用于说明的目的的具体实例，而不旨在显示本申请的所有技术方面，并且应当理解，在提交本申请时可以对其完成多种可选等价体和变体。Hereinafter, the present application is described in detail. It is to be understood that the terms used in the specification and appended claims should not be construed to be limited to their ordinary and dictionary meanings, but rather on the basis that the inventor is allowed to appropriately define the terms for the best interpretation based on the principles associated with this application. The corresponding meanings and concepts of the technical aspects are explained. Accordingly, the descriptions shown in the embodiments described in the specification are specific examples for illustrative purposes only and are not intended to demonstrate all technical aspects of the application, and it will be understood that they may be completed by the time this application is filed. Many optional equivalents and variants.
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个组件或多个组件。项目B可包含单个组件或多个组件。项目C可包含单个组件或多个组件。In the detailed description and claims, a list of items connected by the term "at least one of," "at least one of," "at least one of," or other similar terms may mean that the listed items any combination of. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if the items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B and C. Project A can contain a single component or multiple components. Project B can contain a single component or multiple components. Project C may contain a single component or multiple components.
另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的 数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。Additionally, quantities, ratios, and other numerical values are sometimes presented herein in range format. It should be understood that such range formats are for convenience and brevity, and should be flexibly construed to include not only the values expressly designated as range limits, but also all individual values or subranges encompassed within the stated range, as if expressly Specify each value and subrange individually.
一、电化学装置1. Electrochemical device
本申请涉及一种电化学装置，其包括：正极，所述正极包括正极集流体、保护层和正极活性材料层。所述保护层设置于所述正极集流体与所述正极活性材料层之间。保护层满足：W/X≤10％，其中X表示取X g保护层在25℃至35℃分散于50X g水中，W表示X g保护层在前述条件下分散于水中后，用分散盘直径为50mm至80mm的搅拌器在1200r/min的搅拌速度下搅拌，采用100目筛子的滤网过滤、干燥后，滤网上剩余的保护层的质量(单位为g)。The present application relates to an electrochemical device, which includes a positive electrode including a positive current collector, a protective layer and a positive active material layer. The protective layer is disposed between the cathode current collector and the cathode active material layer. The protective layer satisfies: W/X≤10%, where The mass of the protective layer remaining on the filter (unit: g) after stirring with a mixer of 50mm to 80mm at a stirring speed of 1200r/min, filtering and drying through a 100-mesh screen.
保护层可以抑制在受到外力撞击或穿刺过程中，发生最危险的正极集流体与负极活性材料层之间的短路，提高电化学装置的安全性能；同时，通过满足W/X≤10％的保护层可以将锂离子电池的高温存储内阻增长率控制在40％以下，其中，在一些实施例中，高温存储指的是所述电化学装置在85℃放置6小时的条件下存储。这是由于，保护层整体倾向为亲水性而非亲油性，从而可以避免保护层在油性电解液中由于溶胀而大面积损失粘结力，从而保持粘结作用，抑制高温存储内阻的增长。在一些实施例中，W/X≤9％。在一些实施例中，W/X≤8％。在一些实施例中，W/X≤7％。在一些实施例中，W/X≤6％。在一些实施例中，W/X≤5％。在一些实施例中，W/X的值为1％、2％、3％、4％、5％、6％、7％、8％、9％、10％等。The protective layer can inhibit the most dangerous short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external forces, improving the safety performance of the electrochemical device; at the same time, by meeting the protection requirement of W/X ≤ 10% The layer can control the high-temperature storage internal resistance growth rate of the lithium-ion battery below 40%, where, in some embodiments, high-temperature storage refers to storage of the electrochemical device at 85° C. for 6 hours. This is because the overall protective layer tends to be hydrophilic rather than lipophilic, which can avoid large-area loss of adhesive force due to swelling of the protective layer in the oily electrolyte, thereby maintaining the adhesive effect and inhibiting the growth of internal resistance in high-temperature storage. . In some embodiments, W/X ≤ 9%. In some embodiments, W/X ≤ 8%. In some embodiments, W/X ≤ 7%. In some embodiments, W/X ≤ 6%. In some embodiments, W/X ≤ 5%. In some embodiments, the value of W/X is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.
在一些实施例中，X的值为20～80g。In some embodiments, the value of X is 20-80 g.
在一些实施例中，保护层的红外光谱在1400cm -1至1700cm -1-和/或2100cm -1至2300cm -1范围内具有特征峰。此时，保护层中具有羰基和/或氰基等极性官能团，能够增强其对正极集流体的粘结力，进而改善电化学装置的高温存储内阻增长率。 In some embodiments, the infrared spectrum of the protective layer has characteristic peaks in the range of 1400 cm -1 to 1700 cm -1 - and/or 2100 cm -1 to 2300 cm -1 . At this time, the protective layer contains polar functional groups such as carbonyl and/or cyano groups, which can enhance its adhesion to the positive electrode current collector, thereby improving the high-temperature storage internal resistance growth rate of the electrochemical device.
在一些实施例中，保护层包含第一活性物质、第一粘结剂和第一导电剂。In some embodiments, the protective layer includes a first active material, a first binder, and a first conductive agent.
在一些实施例中，基于保护层的质量，第一活性物质的质量百分比为60％至98.5％。在一些实施例中，基于保护层的质量，第一活性物质的质量百分比为65％至96％。在一些实施例中，基于保护层的质量，第一活性物质的质量百分比为70％至 95％。在一些实施例中，基于保护层的质量，第一活性物质的质量百分比为75％至95％。在一些实施例中，基于保护层的质量，第一活性物质的质量百分比为60％、65％、70％、75％、77％、78％、80％、82％、84％、85％、87％、88％、89％、90％、91％、92％、93％、94％、95％、96％、97％、98％、98.5％或前述任意两数值之间的范围。In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 60% to 98.5%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 65% to 96%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 70% to 95%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first active material is 75% to 95%. In some embodiments, based on the quality of the protective layer, the mass percentage of the first active material is 60%, 65%, 70%, 75%, 77%, 78%, 80%, 82%, 84%, 85%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 98.5% or the range between any two of the aforementioned values.
在一些实施例中，第一活性物质包含磷酸铁锂、磷酸锰铁锂、锰酸锂或镍钴锰酸锂中的至少一种。In some embodiments, the first active material includes at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate, or lithium nickel cobalt manganate.
在一些实施例中，基于保护层的质量，第一粘结剂的质量百分比为1％至20％。在一些实施例中，第一粘结剂的质量百分比为1％、2％、3％、4％、4.5％、5％、5.5％、6％、6.5％、7％、7.5％、8％、8.5％、9％、10％、11％、12％、13％、14％、15％、16％、17％、18％、19％、20％或前述任意两数值之间的范围。通过控制第一粘结剂在保护层中的质量百分比在上述范围内，可以保证正极活性材料层、保护层和集流体之间具有较好的结合力，减少在跌落、针刺、撞击等异常情况下，保护层和正极活性材料层的松动乃至脱落，从而可以改善电化学装置的穿钉安全性能和高温存储内阻增长率。In some embodiments, the mass percentage of the first binder is 1% to 20% based on the mass of the protective layer. In some embodiments, the mass percentage of the first binder is 1%, 2%, 3%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8% , 8.5%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or the range between any two of the aforementioned values. By controlling the mass percentage of the first binder in the protective layer to be within the above range, it is possible to ensure a good bonding force between the positive electrode active material layer, the protective layer and the current collector, and to reduce abnormalities such as drops, needle sticks, and impacts. In this case, the protective layer and the cathode active material layer loosen or even fall off, which can improve the nail penetration safety performance and high-temperature storage internal resistance growth rate of the electrochemical device.
在一些实施例中，第一粘结剂为水性粘结剂。在一些实施例中，第一粘结剂满足如下特征中的至少一者：(a)包含丙烯酸、丙烯酰胺、丙烯酸盐、丙烯腈或丙烯酸酯中的至少一种形成的聚合物；(b)包含羧甲基纤维素盐或丁腈橡胶中的至少一者。在一些实施例中，第一粘结剂为包含丙烯酸盐形成的聚合物，此时，第一粘结剂具有较好的亲水疏油性，使得保护层具有优异的粘结性和稳定性，进而可以改善电化学装置的穿钉安全性能和高温存储内阻增长率。In some embodiments, the first binder is an aqueous binder. In some embodiments, the first binder satisfies at least one of the following characteristics: (a) includes a polymer formed from at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylate; (b) Contains at least one of carboxymethyl cellulose salt or nitrile rubber. In some embodiments, the first adhesive is a polymer composed of acrylate. In this case, the first adhesive has good hydrophilic and oleophobic properties, so that the protective layer has excellent adhesion and stability. This can then improve the nail penetration safety performance and high-temperature storage internal resistance growth rate of the electrochemical device.
在一些实施例中，第一粘结剂的重量平均分子量为20万至200万。在一些实施例中，第一粘结剂的重量平均分子量为20万至180万。在一些实施例中，第一粘结剂的重量平均分子量为20万至160万。在一些实施例中，第一粘结剂的重量平均分子量为20万、25万、30万、35万、40万、45万、50万、55万、60万、65万、70万、75万、80万、90万、95万、100万、110万、120万、120万、130万、140万、150万、160万、170万、180万、190万、200万或前述任意两数值之间的范 围。第一粘结剂的重量平均分子量在上述范围内，能够兼顾成膜性和粘结力，提高保护层的均匀性和稳定性。In some embodiments, the first binder has a weight average molecular weight of 200,000 to 2,000,000. In some embodiments, the first binder has a weight average molecular weight of 200,000 to 1.8 million. In some embodiments, the first binder has a weight average molecular weight of 200,000 to 1.6 million. In some embodiments, the weight average molecular weight of the first binder is 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 75 Ten thousand, 800,000, 900,000, 950,000, 1 million, 1.1 million, 1.2 million, 1.2 million, 1.3 million, 1.4 million, 1.5 million, 1.6 million, 1.7 million, 1.8 million, 1.9 million, 2 million or any two of the above The range between values. The weight average molecular weight of the first binder is within the above range, which can achieve both film-forming property and adhesive force, and improve the uniformity and stability of the protective layer.
在一些实施例中，基于保护层的质量，第一导电剂的质量百分比为0.5％至15％。在一些实施例中，基于保护层的质量，第一导电剂的质量百分比为0.5％至10％。在一些实施例中，基于保护层的质量，第一导电剂的质量百分比为0.5％至8％。在一些实施例中，基于保护层的质量，第一导电剂的质量百分比为1％至7％。在一些实施例中，基于保护层的质量，第一导电剂的质量百分比为0.5％、0.6％、0.7％、0.8％、0.9％、1％、1.1％、1.2％、1.3％、1.4％、1.5％、1.6％、1.7％、1.8％、1.9％、2％、2.2％、2.3％、2.4％、2.5％、2.8％、3％、3.2％、3.4％、3.6％、3.8％、4％、5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％或前述任意两数值之间的范围。In some embodiments, based on the mass of the protective layer, the mass percentage of the first conductive agent is 0.5% to 15%. In some embodiments, based on the mass of the protective layer, the mass percentage of the first conductive agent is 0.5% to 10%. In some embodiments, the mass percentage of the first conductive agent is 0.5% to 8% based on the mass of the protective layer. In some embodiments, the mass percentage of the first conductive agent is 1% to 7% based on the mass of the protective layer. In some embodiments, based on the quality of the protective layer, the mass percentage of the first conductive agent is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.2%, 2.3%, 2.4%, 2.5%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4% , 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or the range between any two of the aforementioned values.
在一些实施例中，所述第一导电剂包含石墨烯、石墨纤维、碳纳米管、科琴黑或导电碳中的至少一种。In some embodiments, the first conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
在一些实施例中，保护层还包含流平剂。在一些实施例中，流平剂包括硅氧烷类化合物、硅氧烷类衍生物、含氧烯烃聚合物、丙烯酸酯类聚合物、丙烯酸盐类聚合物、醇类化合物、醚类化合物或氟碳化合物中的至少一种。在一些实施例中，基于保护层的质量，流平剂的质量百分比为0.01％至5％。在一些实施例中，基于保护层的质量，流平剂的质量百分比为0.03％至4％。在一些实施例中，基于保护层的质量，流平剂的质量百分比为0.05％至4％。在一些实施例中，基于保护层的质量，流平剂的质量百分比为0.08％至4％。在一些实施例中，基于保护层的质量，流平剂的质量百分比为0.01％、0.02％、0.03％、0.04％、0.05％、0.06％、0.07％、0.08％、0.09％、0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％或前述任意两数值之间的范围。上述流平剂的加入，有利于形成均匀、平滑的保护层，增加保护层和集流体以及正极活性材料层的接触面积，提高导电性，改善高温存储时的内阻增长。In some embodiments, the protective layer further includes a leveling agent. In some embodiments, the leveling agent includes silicone compounds, silicone derivatives, oxygen-containing olefin polymers, acrylate polymers, acrylate polymers, alcohol compounds, ether compounds or fluorine compounds. At least one of the carbon compounds. In some embodiments, the mass percentage of the leveling agent is 0.01% to 5% based on the mass of the protective layer. In some embodiments, the mass percentage of the leveling agent is 0.03% to 4% based on the mass of the protective layer. In some embodiments, the mass percentage of the leveling agent is 0.05% to 4% based on the mass of the protective layer. In some embodiments, the mass percentage of the leveling agent is 0.08% to 4% based on the mass of the protective layer. In some embodiments, based on the quality of the protective layer, the mass percentage of the leveling agent is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or The range between any two values mentioned above. The addition of the above-mentioned leveling agent is conducive to forming a uniform and smooth protective layer, increasing the contact area between the protective layer and the current collector and the positive active material layer, improving the conductivity, and improving the internal resistance growth during high-temperature storage.
在电化学装置处于满充状态时，正极的电阻RΩ。在一些实施例中，R为1至10。在一些实施例中，R为1.5至9。在一些实施例中，R为1.5至5。在一些实施例中，R为1、1.5、2、2.1、2.3、2.5、3、3.5、4、4.5、5、5.5、6、6.5、7、7.5、 8、8.5、9、9.5、10或前述任意两数值之间的范围。。当R在此范围内，能够使电化学装置在保持较高的穿钉通过率的同时，具有较低的高温存储内阻增长率。When the electrochemical device is fully charged, the resistance of the positive electrode is RΩ. In some embodiments, R is from 1 to 10. In some embodiments, R is from 1.5 to 9. In some embodiments, R is from 1.5 to 5. In some embodiments, R is 1, 1.5, 2, 2.1, 2.3, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or The range between any two values mentioned above. . When R is within this range, the electrochemical device can maintain a high nail penetration rate while having a low high-temperature storage internal resistance growth rate.
在一些实施例中，保护层的厚度为Tμm，T≥0.5。在一些实施例中，T为0.5至10。在一些实施例中，T为1至9。在一些实施例中，T为1.5至8.5。在一些实施例中，T为2至8。在一些实施例中，T为2.5至7.5。在一些实施例中，T为1.5至5。在一些实施例中，T为0.5、1、1.5、2、2.5、3、3.5、4、4.5、5、5.5、6、6.5、7、7.5、8、8.5、9、9.5、10或前述任意两数值之间的范围。保护层的厚度在上述范围内，能够有效抑制在受到外力撞击或穿刺过程中正极集流体与负极活性材料层之间的短路，提高电化学装置的安全性。In some embodiments, the thickness of the protective layer is Tμm, T≥0.5. In some embodiments, T is 0.5 to 10. In some embodiments, T ranges from 1 to 9. In some embodiments, T is 1.5 to 8.5. In some embodiments, T is from 2 to 8. In some embodiments, T is 2.5 to 7.5. In some embodiments, T is 1.5 to 5. In some embodiments, T is 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or any of the foregoing The range between two values. The thickness of the protective layer is within the above range, which can effectively suppress the short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external force, and improve the safety of the electrochemical device.
在一些实施例中，所述正极活性材料层包含第二活性物质、第二粘结剂和第二导电剂。在一些实施例中，基于正极活性材料层的质量，第二活性物质的质量百分比为91.5％至99％，第二粘结剂的质量百分比为0.5％至5％，第二导电剂的质量百分比为0.5％至3.5％。In some embodiments, the positive active material layer includes a second active material, a second binder, and a second conductive agent. In some embodiments, based on the mass of the cathode active material layer, the mass percentage of the second active material is 91.5% to 99%, the mass percentage of the second binder is 0.5% to 5%, and the mass percentage of the second conductive agent is 0.5% to 3.5%.
在一些实施例中，所述第二活性物质包含钴酸锂、锰酸锂或镍钴锰酸锂中的至少一种。在一些实施例中，所述第二粘结剂包含聚丙烯酸、聚偏氟乙烯、聚四氟乙烯-六氟丙烯、聚丙烯酸钠、丁腈橡胶或聚丙烯酸酯中的至少一种。在一些实施例中，所述第二导电剂包含石墨烯、石墨纤维、碳纳米管、科琴黑或导电碳中的至少一种。In some embodiments, the second active material includes at least one of lithium cobalt oxide, lithium manganate, or lithium nickel cobalt manganate. In some embodiments, the second binder includes at least one of polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene-hexafluoropropylene, sodium polyacrylate, nitrile rubber, or polyacrylate. In some embodiments, the second conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
本申请通过在正极集流体与正极活性材料层之间设置保护层可以抑制在受到外力撞击或穿刺过程中，发生最危险的正极集流体与负极活性材料层之间的短路，提高电化学装置的安全性能；同时，本申请认识到，藉由控制保护层的材料使W/X≤10％时(其中X表示取X g保护层在25℃至35℃分散于50X g水中，W表示X g保护层在前述条件下分散于水中后，用分散盘直径为50mm至80mm的搅拌器在1200r/min的搅拌速度下搅拌，采用100目筛子的滤网过滤、干燥后，滤网上剩余的保护层的质量(单位为g))，保护层倾向为亲水性而非亲油性时，可以避免保护层在油性电解液中由于溶胀而大面积损失粘结力，从而保持粘结作用，抑制高温存储内阻的增长。举例而言，其可将高温存储内阻增长率控制在40％以下。By arranging a protective layer between the positive electrode current collector and the positive electrode active material layer, this application can suppress the most dangerous short circuit between the positive electrode current collector and the negative electrode active material layer during impact or puncture by external forces, and improve the performance of the electrochemical device. Safety performance; at the same time, this application recognizes that by controlling the material of the protective layer so that W/X ≤ 10% (where After the protective layer is dispersed in water under the aforementioned conditions, use a stirrer with a dispersion disk diameter of 50mm to 80mm to stir at a stirring speed of 1200r/min. Use a 100-mesh filter to filter and dry the remaining protective layer on the filter. mass (unit: g)), when the protective layer tends to be hydrophilic rather than lipophilic, it can avoid large-area loss of adhesive force due to swelling of the protective layer in the oily electrolyte, thereby maintaining the bonding effect and inhibiting high-temperature storage Growth of internal resistance. For example, it can control the growth rate of high-temperature storage internal resistance below 40%.
本申请的电化学装置还包括隔离膜、电解液和负极。The electrochemical device of the present application also includes a separator, an electrolyte and a negative electrode.
在一些实施例中，本申请的电化学装置包括一次电池或二次电池。在一些实施例中，所述电化学装置是锂二次电池。在一些实施例中，锂二次电池包括，但不限于：锂金属二次电池、锂离子二次电池、钠离子电池、锂聚合物二次电池或锂离子聚合物二次电池。In some embodiments, electrochemical devices of the present application include primary or secondary batteries. In some embodiments, the electrochemical device is a lithium secondary battery. In some embodiments, lithium secondary batteries include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries, sodium ion batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.
二、一种制备前述电化学装置的方法2. A method of preparing the aforementioned electrochemical device
如下以锂离子电池为例详细描述了本申请的电化学装置的制备方法。The preparation method of the electrochemical device of the present application is described in detail below by taking a lithium-ion battery as an example.
负极的制备：将负极活性物质(碳材料、硅材料或钛酸锂中的至少一种)和负极粘结剂，以及可选的导电材料按一定的质量比分散于溶剂体系中充分搅拌混合均匀后，涂覆于负极集流体上，经过烘干、冷压，得到负极。Preparation of the negative electrode: Disperse the negative electrode active material (at least one of carbon material, silicon material or lithium titanate), negative electrode binder, and optional conductive material in the solvent system according to a certain mass ratio, and stir thoroughly to mix evenly. Then, it is coated on the negative electrode current collector, dried and cold pressed to obtain the negative electrode.
正极的制备：(1)将第一活性物质、第一导电剂、第一粘结剂，以及可选的流平剂，加入溶剂中混合均匀，获得保护层的浆料(在后称作“第一浆料”)；(2)将步骤(1)中的第一浆料涂覆在正极集流体的目标区域；(3)将步骤(2)中的获得的含有第一浆料的正极集流体进行烘干以去除溶剂，得到涂有保护层的正极集流体；(4)将第二活性物质、第二导电剂、第二粘结剂按一定的质量比分散于溶剂体系中充分搅拌混合均匀，得到正极活性物质的浆料(在后称作“第二浆料”)；(5)将第二浆料涂覆在步骤(3)中得到的涂有保护层的正极集流体的目标区域；(6)将步骤(5)中的含有第二浆料的正极集流体进行烘干以去除溶剂，从而得到所要正极。Preparation of the positive electrode: (1) Add the first active material, the first conductive agent, the first binder, and the optional leveling agent to the solvent and mix evenly to obtain a protective layer slurry (hereinafter referred to as " first slurry"); (2) apply the first slurry in step (1) to the target area of the positive electrode current collector; (3) apply the positive electrode containing the first slurry obtained in step (2) The current collector is dried to remove the solvent, and a positive electrode current collector coated with a protective layer is obtained; (4) The second active material, the second conductive agent, and the second binder are dispersed in the solvent system according to a certain mass ratio and stirred thoroughly Mix evenly to obtain a slurry of positive active material (hereinafter referred to as "second slurry"); (5) Coat the second slurry on the positive electrode current collector coated with a protective layer obtained in step (3). Target area; (6) Dry the positive electrode current collector containing the second slurry in step (5) to remove the solvent, thereby obtaining the desired positive electrode.
第一活性物质、第一导电剂、第一粘结剂、流平剂、第二活性物质、第二导电剂和第二粘结剂的种类如前述。The types of the first active material, the first conductive agent, the first binder, the leveling agent, the second active material, the second conductive agent and the second binder are as described above.
在一些实施例中，所述溶剂的示例包括但不限于N-甲基吡咯烷酮、丙酮或水。在一些实施例中，可适当的调节溶剂的量。In some embodiments, examples of the solvent include, but are not limited to, N-methylpyrrolidone, acetone, or water. In some embodiments, the amount of solvent can be adjusted appropriately.
在一些实施例中，所述集流体具有3微米至20微米范围内的厚度，但本公开内容不限于此。所述集流体没有特别的限制，只要所述集流体是导电的，而不在所制造的电池中引起不利的化学变化。所述集流体的实施例包括铜、不锈钢、 铝、镍、钛或合金(例如同-镍合金)，但公开内容不限于此。在一些实施例中，所述集流体的表面上可包括细小的不规则物(例如，表面粗糙度)以增强所述集流体的表面对活性物质的粘合。在一些实施例中，集流体可以多种形式使用，其实施例包括膜、片、箔、网、多孔结构体、泡沫体或无妨物，但本公开内容不限于此。In some embodiments, the current collector has a thickness in the range of 3 microns to 20 microns, although the disclosure is not limited thereto. The current collector is not particularly limited as long as the current collector is conductive without causing adverse chemical changes in the manufactured battery. Examples of the current collector include copper, stainless steel, aluminum, nickel, titanium, or alloys (eg, homo-nickel alloys), but the disclosure is not limited thereto. In some embodiments, fine irregularities (eg, surface roughness) may be included on the surface of the current collector to enhance adhesion of the surface of the current collector to the active material. In some embodiments, the current collector can be used in various forms, and examples thereof include films, sheets, foils, meshes, porous structures, foams, or similar materials, but the disclosure is not limited thereto.
隔离膜：在一些实施例中，以聚乙烯(简写为PE)多孔聚合薄膜作为隔离膜。在一些实施例中，所述隔离膜的材质可包括玻璃纤维，聚酯，聚乙烯，聚丙烯，聚四氟乙烯或其组合。在一些实施例中，所述隔离膜中的孔具有在0.01微米至1微米范围的直径，所述隔离膜的厚度在5微米至500微米范围内。Isolation film: In some embodiments, a polyethylene (abbreviated as PE) porous polymer film is used as the isolation film. In some embodiments, the material of the isolation membrane may include fiberglass, polyester, polyethylene, polypropylene, polytetrafluoroethylene or combinations thereof. In some embodiments, the pores in the isolation film have a diameter in the range of 0.01 micron to 1 micron, and the thickness of the isolation film ranges from 5 microns to 500 microns.
电解液：在一些实施例中，所述电解液包括有机溶剂、锂盐和添加剂。Electrolyte: In some embodiments, the electrolyte includes an organic solvent, a lithium salt, and additives.
在一些实施例中，有机溶剂包括碳酸乙烯酯(简写为EC)、碳酸丙烯酯(简写为PC)、碳酸二乙酯(简写为DEC)、碳酸甲乙酯(简写为EMC)、碳酸二甲酯(简写为DMC)、碳酸亚丙酯、乙酸乙酯、丙酸乙酯或丙酸丙酯中的至少一种。In some embodiments, the organic solvent includes ethylene carbonate (abbreviated as EC), propylene carbonate (abbreviated as PC), diethyl carbonate (abbreviated as DEC), ethyl methyl carbonate (abbreviated as EMC), dimethyl carbonate At least one of ester (abbreviated as DMC), propylene carbonate, ethyl acetate, ethyl propionate or propyl propionate.
在一些实施例中，锂盐包括有机锂盐或无机锂盐中的至少一种。In some embodiments, the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
在一些实施例中，锂盐包括六氟磷酸锂(LiPF 6)、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。 In some embodiments, lithium salts include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium bistrifluoromethanesulfonimide LiN (CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bis(fluorosulfonyl)borate LiB(C 2 O 4 ) 2 (LiBOB) or lithium difluoroxalatoborate At least one of LiBF 2 (C 2 O 4 ) (LiDFOB).
在一些实施例中，基于所述电解液的质量，所述锂盐的含量为8％-30％。在一些实施例中，所述锂盐含量为8％、9％、10％、11％、12％、15％、18％、20％、23％、25％、28％、30％或前述任意两数值之间的范围。In some embodiments, the content of the lithium salt is 8%-30% based on the quality of the electrolyte. In some embodiments, the lithium salt content is 8%, 9%, 10%, 11%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% or any of the foregoing. The range between two values.
在一些实施例中，添加剂包含氟代碳酸乙烯酯(FEC)、碳酸亚乙烯酯(VC)、乙烯基碳酸乙烯酯(VEC)、1，3-丙烷磺内酯(PS)、硫酸乙烯酯(DTD)、丁二腈(SN)、己二腈(ADN)、1，3，6-己烷三腈(HTCN)、琥珀酸酐(SA)中的至少一种。In some embodiments, the additives include fluoroethylene carbonate (FEC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), vinyl sulfate ( DTD), at least one of succinonitrile (SN), adiponitrile (ADN), 1,3,6-hexanetrinitrile (HTCN), and succinic anhydride (SA).
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正负极中间起到隔离的作 用，并卷绕得到裸电芯。将经卷绕所得裸电芯置于外包装中，注入电解液并封装，经过化成、脱气、切边等工艺流程得到锂离子电池。Stack the positive electrode, isolation film, and negative electrode in order so that the isolation film is between the positive and negative electrodes for isolation, and wind them to obtain a bare cell. The bare cell obtained by winding is placed in an outer package, electrolyte is injected and packaged, and a lithium-ion battery is obtained through processes such as formation, degassing, and trimming.
三、电子装置3. Electronic devices
本申请提供了一种电子装置，其包含根据前述内容所述的电化学装置。The present application provides an electronic device comprising the electrochemical device according to the foregoing content.
根据本申请的一些实施例，所述电子装置包括，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、家庭用大型蓄电池或锂/钠离子电容器等。According to some embodiments of the present application, the electronic devices 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, head-mounted Stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles , bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries or lithium/sodium ion capacitors, etc.
四、具体的实施例4. Specific Examples
下面结合实施例，对本申请做进一步详细的描述。然而，应理解，以下实施例仅是示例，本申请的实施例方式不限于此。The present application will be described in further detail below with reference to examples. However, it should be understood that the following embodiments are only examples, and the embodiments of the present application are not limited thereto.
实施例1至33和对比例1至2Examples 1 to 33 and Comparative Examples 1 to 2
正极的制作Production of positive electrode
步骤(1)：将第一活性物质、第一导电剂、第一粘结剂，以及可选的流平剂，加入水中混合均匀，获得保护层的浆料(在后称作“第一浆料”)；Step (1): Add the first active material, the first conductive agent, the first binder, and the optional leveling agent to water and mix evenly to obtain a protective layer slurry (hereinafter referred to as "first slurry"). material");
步骤(2)将步骤(1)中的第一浆料涂覆在正极集流体的目标区域；Step (2) Coating the first slurry in step (1) on the target area of the positive electrode current collector;
步骤(3)将步骤(2)中的获得的含有第一浆料的正极集流体进行烘干以去除溶剂，得到涂有保护层的正极集流体；Step (3) drying the positive electrode current collector containing the first slurry obtained in step (2) to remove the solvent to obtain a positive electrode current collector coated with a protective layer;
步骤(4)将第二活性物质(钴酸锂，质量百分比97.3％)、第二导电剂(质量百分比0.6％的导电碳(商品名Super P)和质量百分比0.5％的碳纳米管(简写为CNT)、第二粘结剂(质量百分比1.6％的聚偏氟乙烯(简写为PVDF))分散于N-甲基吡咯烷酮溶剂体系中充分搅拌混合均匀，得到正极活性物质的浆料(在后称作“第二浆料”)；Step (4) Combine the second active material (lithium cobalt oxide, 97.3% by mass), the second conductive agent (0.6% by mass of conductive carbon (trade name: Super P)) and 0.5% by mass of carbon nanotubes (abbreviated as CNT) and the second binder (polyvinylidene fluoride (abbreviated as PVDF) with a mass percentage of 1.6%) are dispersed in the N-methylpyrrolidone solvent system and stirred thoroughly to obtain a slurry of the positive electrode active material (hereinafter referred to as as "second slurry");
步骤(5)将第二浆料涂覆在步骤(3)中得到的涂有保护层的正极集流体的目标区域；Step (5) applying the second slurry to the target area of the positive electrode current collector coated with the protective layer obtained in step (3);
步骤(6)将步骤(5)中的含有第二浆料的正极集流体进行烘干以去除溶剂，从而得到所要正极。Step (6) Drying the positive electrode current collector containing the second slurry in step (5) to remove the solvent, thereby obtaining the desired positive electrode.
下表1具体示出了实施例1至33和对比例1至2中的正极中的保护层差异。Table 1 below specifically shows the differences in protective layers in the positive electrodes in Examples 1 to 33 and Comparative Examples 1 to 2.
表1Table 1
Figure PCTCN2022084041-appb-000001
Figure PCTCN2022084041-appb-000001
Figure PCTCN2022084041-appb-000002
Figure PCTCN2022084041-appb-000002
除上述差异外，实施例1至33和对比例1至2中正极的正极活性材料层、正极集流体等并没有差异，均采用前述工艺制备。Except for the above differences, there are no differences in the positive active material layer, positive current collector, etc. of the positive electrodes in Examples 1 to 33 and Comparative Examples 1 to 2, and they are all prepared using the aforementioned process.
电化学装置的制作Fabrication of electrochemical devices
电化学装置的正极的制作如前述。The positive electrode of the electrochemical device was fabricated as described above.
负极：将活性物质人造石墨、导电剂乙炔黑、粘结剂丁苯橡胶(简写为SBR)、增稠剂羧甲基纤维素钠(简写为CMC)按照质量比为95∶2∶2∶1在水中充分搅拌混合均匀后，涂覆于Cu箔上烘干、冷压，得到负极。Negative electrode: Combine the active material artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (abbreviated as SBR), and thickener sodium carboxymethylcellulose (abbreviated as CMC) in a mass ratio of 95:2:2:1 After thoroughly stirring and mixing in water, it is coated on Cu foil, dried, and cold pressed to obtain a negative electrode.
电解液：在含水量<10ppm的氩气气氛手套箱中，将碳酸乙烯酯(简写为 EC)、碳酸二乙酯(简写为DEC)、碳酸丙烯酯(简写为PC)，按照2∶6∶2的质量比混合均匀，再将充分干燥的锂盐LiPF 6溶解于上述溶剂，之后加入1，3-丙烷磺内酯、氟代碳酸乙烯酯和己二腈。混合后，LiPF 6的含量为12.5％、1，3-丙烷磺内酯的含量为1.5％、氟代碳酸乙烯酯的含量为3％、己二腈的含量为2％，其余为EC、DEC和PC，其中，各物质含量是以电解液的总重量计。 Electrolyte: In an argon atmosphere glove box with a water content of <10ppm, mix ethylene carbonate (abbreviated as EC), diethyl carbonate (abbreviated as DEC), and propylene carbonate (abbreviated as PC) according to 2:6: Mix evenly at a mass ratio of 2, then dissolve the fully dried lithium salt LiPF 6 in the above solvent, and then add 1,3-propane sultone, fluoroethylene carbonate and adiponitrile. After mixing, the content of LiPF 6 is 12.5%, the content of 1,3-propane sultone is 1.5%, the content of fluoroethylene carbonate is 3%, the content of adiponitrile is 2%, and the rest are EC and DEC and PC, where the content of each substance is based on the total weight of the electrolyte.
隔离膜：以聚乙烯(简写为PE)多孔聚合薄膜作为隔离膜。Isolation film: Polyethylene (abbreviated as PE) porous polymer film is used as the isolation film.
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕、置于外包装中，注入配好的电解液并封装，经过化成，脱气，切边等工艺得到锂离子电池。Stack the positive electrode, isolation film, and negative electrode in order, so that the isolation film is between the positive and negative electrodes for isolation, roll it up, place it in the outer package, inject the prepared electrolyte and package it, and then form and degas , trimming and other processes to obtain lithium-ion batteries.
性能测试方法Performance testing methods
锂离子电池内阻Lithium-ion battery internal resistance
使用电阻仪，采用正弦、1000Hz频率波测试锂离子电池的交流内阻。Use a resistance meter to test the AC internal resistance of the lithium-ion battery using sinusoidal and 1000Hz frequency waves.
锂离子电池内阻增长率Lithium-ion battery internal resistance growth rate
存储条件1(85℃放置6h)：Storage condition 1 (placed at 85°C for 6 hours):
在25±3℃的环境中，将锂离子电池以0.5C恒流充电至4.45V，再以4.45V恒压充电至0.025C，测试锂离子电池初始内阻记为IMP0。将锂离子电池放入85±3℃的高温炉中6h(小时)后取出，待锂离子电池温度降至25±3℃后，测试其内阻记为“IMP6h”，记锂离子电池85℃放置6h IMP增长率为(IMP6h-IMP0)/IMP0×100％。In an environment of 25±3°C, charge the lithium-ion battery to 4.45V at a constant current of 0.5C, and then charge to 0.025C at a constant voltage of 4.45V. The initial internal resistance of the tested lithium-ion battery is recorded as IMP0. Put the lithium-ion battery into a high-temperature furnace at 85±3℃ for 6h (hours) and then take it out. After the temperature of the lithium-ion battery drops to 25±3℃, test its internal resistance and record it as "IMP6h". Record the lithium-ion battery as 85℃ After leaving it for 6h, the IMP growth rate is (IMP6h-IMP0)/IMP0×100%.
存储条件2(60℃放置30天)：Storage condition 2 (placed at 60℃ for 30 days):
在25±3℃的环境中，将锂离子电池以0.5C恒流充电至4.45V，再以4.45V恒压充电至0.025C，测试锂离子电池初始内阻记为IMP1。将锂离子电池放入60±3℃的高温炉中30d，将锂离子电池从高温炉中取出，待锂离子电池温度降至25±3℃后，测试锂离子电池内阻为IMP30d，记锂离子电池60℃放置30天IMP增长率为(IMP30d-IMP1)/IMP1×100％。In an environment of 25±3°C, charge the lithium-ion battery to 4.45V at a constant current of 0.5C, and then charge to 0.025C at a constant voltage of 4.45V. The initial internal resistance of the tested lithium-ion battery is recorded as IMP1. Put the lithium-ion battery into a high-temperature furnace at 60±3°C for 30 days. Take the lithium-ion battery out of the high-temperature furnace. After the temperature of the lithium-ion battery drops to 25±3°C, test the internal resistance of the lithium-ion battery to be IMP30d, and record it as lithium The IMP growth rate of an ion battery placed at 60°C for 30 days is (IMP30d-IMP1)/IMP1×100%.
中心穿钉通过率Center nail pass rate
将待测的锂离子电池以0.05C的倍率恒流充电至4.45V，随后以4.45V恒压充电至电流为0.025C(截止电流)，使锂离子电池达到满充状态，记录测试前锂离子电池外观。在25±3℃环境中对电池进行穿钉测试，钢钉直径4mm，穿刺速度30mm/s，穿钉位置位于锂离子电池几何中心，测试进行3.5min(分)或电池表面温度降到50℃以后停止测试，以10个锂离子电池为一组，观察测试过程中锂离子电池状态，以锂离子电池不燃烧、不***为通过标准，确认锂离子电池通过的个数。Charge the lithium-ion battery to be tested to a constant current of 0.05C to 4.45V, and then charge it to a constant voltage of 4.45V until the current is 0.025C (cut-off current), so that the lithium-ion battery reaches a fully charged state. Record the lithium-ion battery before testing. Battery appearance. Perform a nail penetration test on the battery in an environment of 25±3°C. The diameter of the steel nail is 4mm, the penetration speed is 30mm/s, and the nail penetration position is located at the geometric center of the lithium-ion battery. The test lasts for 3.5 minutes (minutes) or the battery surface temperature drops to 50°C. After that, the test is stopped, and 10 lithium-ion batteries are used as a group. The status of the lithium-ion batteries during the test is observed. The passing criteria of the lithium-ion batteries not burning or exploding are used to confirm the number of passing lithium-ion batteries.
满充状态下的正极电阻Positive resistance in fully charged state
1)0.05C的倍率恒流充电至4.45V，随后以4.45V恒压充电至电流为0.025C(截止电流)，使锂离子电池达到满充状态；1) Charge with a constant current of 0.05C to 4.45V, and then charge with a constant voltage of 4.45V until the current is 0.025C (cut-off current), so that the lithium-ion battery reaches a fully charged state;
2)将锂离子电池拆解，得到正极；2) Disassemble the lithium-ion battery to obtain the positive electrode;
3)将2)中所得正极在湿度为5％至15％的环境中放置30min，然后密封转移到电阻测试地点；3) Place the positive electrode obtained in 2) in an environment with a humidity of 5% to 15% for 30 minutes, and then seal and transfer it to the resistance test location;
4)使用BER1200型号膜片电阻测试仪测试3)中所得正极的电阻，相邻测试点间隔2mm至3mm，至少测试15个不同点，所有测试点的电阻均值记为满充状态下的正极电阻R，其中测试参数为：压头面积153.94mm 2，压力3.5t，保持时间50s。 4) Use the BER1200 diaphragm resistance tester to test the resistance of the positive electrode obtained in 3). The distance between adjacent test points is 2mm to 3mm. Test at least 15 different points. The average resistance of all test points is recorded as the positive electrode resistance in the fully charged state. R, where the test parameters are: pressure head area 153.94mm 2 , pressure 3.5t, holding time 50s.
保护层厚度Protective layer thickness
1)在(25±3)℃的环境下，将涂有保护层的正极从锂离子电池中拆出。用无尘纸拭去正极表面残留的电解液；1) Remove the positive electrode coated with protective layer from the lithium-ion battery in an environment of (25±3)℃. Use dust-free paper to wipe away the remaining electrolyte on the surface of the positive electrode;
2)在等离子体下切割涂有保护层的正极，得到其横截面；2) Cut the positive electrode coated with a protective layer under plasma to obtain its cross section;
3)在扫描电镜SEM下观察2)中得到的正极的横截面，并测试保护层的厚度Tμm，相邻测试点间隔2mm至3mm，至少测试15个不同点，所有测试点的均值记为保护层的厚度Tμm。3) Observe the cross section of the positive electrode obtained in 2) under a scanning electron microscope SEM, and test the thickness of the protective layer Tμm. The distance between adjacent test points is 2mm to 3mm. At least 15 different points are tested. The average value of all test points is recorded as protection. The thickness of the layer is Tμm.
下表2示出了实施例1至33和对比例1至2的各项性能。Table 2 below shows various properties of Examples 1 to 33 and Comparative Examples 1 to 2.
表2Table 2
Figure PCTCN2022084041-appb-000003
Figure PCTCN2022084041-appb-000003
Figure PCTCN2022084041-appb-000004
Figure PCTCN2022084041-appb-000004
1.探讨保护层的有无、保护层的厚度(T，μm)、满充正极电阻(R，Ω)和保护层的W/X(W：保护层溶解过滤后的剩余重量(单位g)；X：保护层溶解前的重量(单位g))对电化学装置的性能影响1. Discuss the presence or absence of the protective layer, the thickness of the protective layer (T, μm), the fully charged positive electrode resistance (R, Ω) and the W/X of the protective layer (W: the remaining weight after the protective layer is dissolved and filtered (unit g) ;
由前述表1和表2可知，保护层满足W/X≤10％的实施例1至33相比于没有保护层的对比例1以及W/X远大于10％的对比例2，锂离子电池的高温存储内阻增长率得到显著改善(在85℃下6小时或60℃下3天的条件下，高温存储内阻增长率在40％以下)，可能的原因在于，满足W/X≤10％的保护层整体倾向为亲水性而非亲油性，从而可以抑制保护层在油性电解液中由于溶胀而大面积损失粘结力，从而维持粘结作用，抑制高温存储内阻的增长。同时，由实施例15和实施例16的比较可发现，当保护层的W/X变小时(亦即粘结剂的水溶性更好时)，其在提高电化学装置的中心穿钉通过率的同时，改善高温存储内阻增长率的效果更明显。It can be seen from the aforementioned Table 1 and Table 2 that Examples 1 to 33 in which the protective layer satisfies W/X ≤ 10% are compared with Comparative Example 1 without a protective layer and Comparative Example 2 in which W/X is much greater than 10%. The high-temperature storage internal resistance growth rate has been significantly improved (under the conditions of 6 hours at 85°C or 3 days at 60°C, the high-temperature storage internal resistance growth rate is below 40%). The possible reason is that W/X≤10 % of the protective layer as a whole tends to be hydrophilic rather than lipophilic, which can prevent the protective layer from losing its adhesive force due to swelling in the oily electrolyte, thereby maintaining the bonding effect and inhibiting the growth of internal resistance in high-temperature storage. At the same time, from the comparison between Example 15 and Example 16, it can be found that when the W/X of the protective layer becomes smaller (that is, when the water solubility of the binder is better), it can improve the central nail penetration rate of the electrochemical device. At the same time, the effect of improving the growth rate of high-temperature storage internal resistance is more obvious.
另外，根据实施例1至33可发现，满足R≥1.5的实施例1至32的中心穿钉通过率(通过量/测试总量)明显优于实施例33。由此可见，通过加入的保护层控制满充正极电阻R≥1.5，可以显着提高锂离子电池的中心穿钉通过率。同时，满足R≤5的实施例1至31的高温存储内阻增长率也明显优于实施例32。由此可见，通过 控制1.5≤R≤5，可以获得同时具有较高的穿钉通过率和较低的高温存储内阻增长率的锂离子电池。In addition, according to Examples 1 to 33, it can be found that the center nail penetration rate (throughput/total test amount) of Examples 1 to 32 that satisfies R≥1.5 is significantly better than that of Example 33. It can be seen that by controlling the full-charge positive electrode resistance R≥1.5 by adding a protective layer, the center nail penetration rate of lithium-ion batteries can be significantly improved. At the same time, the high-temperature storage internal resistance growth rate of Examples 1 to 31 satisfying R≤5 is also significantly better than that of Example 32. It can be seen that by controlling 1.5≤R≤5, a lithium-ion battery with both a higher nail penetration rate and a lower high-temperature storage internal resistance growth rate can be obtained.
此外，保护层的厚度T≥0.5μm，即可在有效提高锂离子电池的中心穿钉通过率的同时，高温存储内阻增长率的改善效果也更明显。In addition, the thickness of the protective layer T ≥ 0.5 μm can effectively improve the center nail penetration rate of the lithium-ion battery, and at the same time, the improvement effect of high-temperature storage internal resistance growth rate is also more obvious.
2.探讨保护层的组成对电化学装置的性能的影响2. Explore the impact of the composition of the protective layer on the performance of the electrochemical device
2.1导电剂2.1 Conductive agent
本申请实施例1至33中保护层所用的导电剂包括碳纳米管(简写为CNT)、导电碳(简写为SP)、科琴黑、石墨烯(简写为GN)、石墨纤维中的至少一种。然而，应当理解，本申请保护层所用的导电剂不限于具体实施例所列举的种类，其可以包含其类似物。The conductive agent used in the protective layer in Examples 1 to 33 of the present application includes at least one of carbon nanotubes (abbreviated as CNT), conductive carbon (abbreviated as SP), Ketjen black, graphene (abbreviated as GN), and graphite fiber. kind. However, it should be understood that the conductive agent used in the protective layer of the present application is not limited to the types listed in the specific embodiments, and may include analogs thereof.
2.2粘结剂2.2 Binder
本申请实施例1至33中保护层所用的粘结剂可包括丙烯腈、丙烯酸盐、丙烯酰胺聚合物、聚丙烯酸、羧甲基纤维素钠、聚丙烯酸钠、聚丙烯酸酯、聚丙烯腈或丁腈橡胶中的至少一种。然而，应当理解，本申请保护层所用的粘结剂不限于具体实施例所列举的种类，其可以包含丙烯酸、丙烯酰胺、丙烯酸盐、丙烯腈或丙烯酸酯中的至少一种形成的聚合物或者包含其类似物。The binder used for the protective layer in Examples 1 to 33 of the present application may include acrylonitrile, acrylate, acrylamide polymer, polyacrylic acid, sodium carboxymethyl cellulose, sodium polyacrylate, polyacrylate, polyacrylonitrile or At least one type of nitrile rubber. However, it should be understood that the adhesive used in the protective layer of the present application is not limited to the types listed in the specific embodiments. It may include a polymer formed from at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylic ester, or Contains its analogues.
举例而言，实施例17至20显示粘结剂包含选自聚丙烯酸钠、聚丙烯酸酯、聚丙烯腈、丁腈橡胶中的至少一种时，皆能在提高电化学装置的中心穿钉通过率的同时，改善高温存储内阻增长率。For example, Examples 17 to 20 show that when the binder includes at least one selected from the group consisting of sodium polyacrylate, polyacrylate, polyacrylonitrile, and nitrile rubber, it is possible to improve the center penetration of the electrochemical device. At the same time, it improves the growth rate of high-temperature storage internal resistance.
2.3流平剂2.3 Leveling agent
本申请实施例1至33中保护层所用的流平剂可包括含氧烯烃聚合物、乙醇、硅氧烷类化合物、丙烯酸酯聚合物、丙烯酸盐聚合物、***或乙醇中的至少一种。然而，应当理解，本申请保护层所用的流平剂不限于具体实施例所列举的种类，其可以包含其类似物。The leveling agent used for the protective layer in Examples 1 to 33 of the present application may include at least one of oxygen-containing olefin polymers, ethanol, silicone compounds, acrylate polymers, acrylate polymers, diethyl ether or ethanol. However, it should be understood that the leveling agent used in the protective layer of the present application is not limited to the types listed in the specific embodiments, and may include analogs thereof.
综上所述，本申请的电化学装置可具有改善的高温存储内阻增长率，以及较高 的中心穿钉通过率。In summary, the electrochemical device of the present application can have improved high-temperature storage internal resistance growth rate and a higher center penetration rate.
整个说明书中对“一些实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因此，在整个说明书中的各处所出现的描述，例如：“在一些实施例中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例“，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。References throughout this specification to “some embodiments,” “partial embodiments,” “one embodiment,” “another example,” “example,” “specific example,” or “partial example” mean the following: At least one embodiment or example in this application includes a specific feature, structure, material or characteristic described in the embodiment or example. Accordingly, phrases such as "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in one example," etc. may appear in various places throughout this specification. "in", "in a particular example" or "for example" do not necessarily refer to the same embodiment or example in this application. Furthermore, the specific features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。Although illustrative embodiments have been shown and described, those skilled in the art will understand that the above-described embodiments are not to be construed as limitations of the present application, and that changes may be made in the embodiments without departing from the spirit, principles and scope of the present application. , substitutions and modifications.

Claims (10)

  1. 一种电化学装置，其包括：正极，所述正极包括正极集流体、保护层和正极活性材料层，所述保护层设置于所述正极集流体与所述正极活性材料层之间，其中，取Xg所述保护层在25℃至35℃分散于50Xg水中，并用分散盘直径为50mm至80mm的搅拌器在1200r/min的搅拌速度下搅拌，采用100目筛子的滤网过滤、干燥后，所述滤网上的所述保护层的重量为Wg，其中W/X≤10％。An electrochemical device comprising: a positive electrode, the positive electrode includes a positive electrode current collector, a protective layer and a positive electrode active material layer, the protective layer is disposed between the positive electrode current collector and the positive electrode active material layer, wherein, Take The weight of the protective layer on the filter is Wg, where W/X≤10%.
  2. 根据权利要求1所述的电化学装置，其中，所述保护层的红外光谱在1400cm -1至1700cm -1和/或2100cm -1至2300cm -1范围内具有特征峰。 The electrochemical device according to claim 1, wherein the infrared spectrum of the protective layer has characteristic peaks in the range of 1400 cm -1 to 1700 cm -1 and/or 2100 cm -1 to 2300 cm -1 .
  3. 根据权利要求1所述的电化学装置，其中，满足下列条件中的至少一者：The electrochemical device according to claim 1, wherein at least one of the following conditions is met:
    (i)在所述电化学装置处于满充状态时，所述正极的电阻为RΩ，1.5≤R≤5；(i) When the electrochemical device is in a fully charged state, the resistance of the positive electrode is RΩ, 1.5≤R≤5;
    (ii)所述保护层的厚度为Tμm，T≥0.5。(ii) The thickness of the protective layer is Tμm, T≥0.5.
  4. 根据权利要求1所述的电化学装置，其中，所述保护层包含第一活性物质、第一粘结剂和第一导电剂。The electrochemical device of claim 1, wherein the protective layer includes a first active material, a first binder, and a first conductive agent.
  5. 根据权利要求4所述的电化学装置，其中，满足下列条件中的至少一者：The electrochemical device according to claim 4, wherein at least one of the following conditions is met:
    (iii)所述保护层还包含流平剂；(iii) the protective layer also contains a leveling agent;
    (iv)所述第一粘结剂为水性粘结剂；(iv) the first adhesive is a water-based adhesive;
    (v)基于所述保护层的质量，所述第一导电剂的质量百分比为0.5％至15％，所述第一活性物质的质量百分比为60％至98.5％，所述第一粘结剂的质量百分比为1％至20％。(v) Based on the quality of the protective layer, the mass percentage of the first conductive agent is 0.5% to 15%, the mass percentage of the first active material is 60% to 98.5%, and the first binder The mass percentage is 1% to 20%.
  6. 根据权利要求5所述的电化学装置，所述流平剂包括硅氧烷类化合物、硅氧烷类衍生物、含氧烯烃聚合物、丙烯酸酯类聚合物、丙烯酸盐类聚合物、醇类化合物、醚类化合物或氟碳化合物中的至少一种，基于所述保护层的质量，所述流平剂的质量百分比为0.01％至5％。The electrochemical device according to claim 5, the leveling agent includes silicone compounds, silicone derivatives, oxygen-containing olefin polymers, acrylate polymers, acrylate polymers, alcohols At least one of chemical compounds, ether compounds or fluorocarbons, the mass percentage of the leveling agent is 0.01% to 5% based on the mass of the protective layer.
  7. 根据权利要求4所述的电化学装置，其中，所述第一粘结剂满足如下特征 中的至少一者：The electrochemical device according to claim 4, wherein the first binder satisfies at least one of the following characteristics:
    (a)包含丙烯酸、丙烯酰胺、丙烯酸盐、丙烯腈或丙烯酸酯中的至少一种形成的聚合物；(a) A polymer comprising at least one of acrylic acid, acrylamide, acrylate, acrylonitrile or acrylate;
    (b)包含羧甲基纤维素盐或丁腈橡胶中的至少一者；(b) Contains at least one of carboxymethyl cellulose salt or nitrile rubber;
    (c)所述第一粘结剂的重量平均分子量为20万至200万。(c) The first binder has a weight average molecular weight of 200,000 to 2,000,000.
  8. 根据权利要求4所述的电化学装置，其中，所述第一活性物质包含磷酸铁锂、磷酸锰铁锂、锰酸锂或镍钴锰酸锂中的至少一种；所述第一导电剂包含石墨烯、石墨纤维、碳纳米管、科琴黑或导电碳中的至少一种。The electrochemical device according to claim 4, wherein the first active material includes at least one of lithium iron phosphate, lithium iron manganese phosphate, lithium manganate or lithium nickel cobalt manganate; the first conductive agent Containing at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
  9. 根据权利要求1所述的电化学装置，其中，所述正极活性材料层包含第二活性物质、第二粘结剂和第二导电剂，满足如下特征中的至少一者：The electrochemical device according to claim 1, wherein the positive active material layer includes a second active material, a second binder and a second conductive agent, satisfying at least one of the following characteristics:
    (d)基于所述正极活性材料层的质量，所述第二活性物质的质量百分比为91.5％至99％，所述第二粘结剂的质量百分比为0.5％至5％，所述第二导电剂的质量百分比为0.5％至3.5％；(d) Based on the mass of the positive active material layer, the mass percentage of the second active material is 91.5% to 99%, the mass percentage of the second binder is 0.5% to 5%, and the second The mass percentage of conductive agent is 0.5% to 3.5%;
    (e)所述第二活性物质包含钴酸锂、锰酸锂或镍钴锰酸锂中的至少一种；(e) The second active material includes at least one of lithium cobalt oxide, lithium manganate or lithium nickel cobalt manganate;
    (f)所述第二粘结剂包含聚丙烯酸、聚偏氟乙烯、聚四氟乙烯-六氟丙烯、聚丙烯酸钠、丁腈橡胶或聚丙烯酸酯中的至少一种；(f) The second binder includes at least one of polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene-hexafluoropropylene, sodium polyacrylate, nitrile rubber or polyacrylate;
    (g)所述第二导电剂包含石墨烯、石墨纤维、碳纳米管、科琴黑或导电碳中的至少一种。(g) The second conductive agent includes at least one of graphene, graphite fiber, carbon nanotube, Ketjen black or conductive carbon.
  10. 一种电子装置，其包括根据权利要求1-9中任一项所述的电化学装置。An electronic device comprising the electrochemical device according to any one of claims 1-9.
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