WO2022198403A1 - 电化学装置和电子装置 - Google Patents

电化学装置和电子装置 Download PDF

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Publication number
WO2022198403A1
WO2022198403A1 PCT/CN2021/082146 CN2021082146W WO2022198403A1 WO 2022198403 A1 WO2022198403 A1 WO 2022198403A1 CN 2021082146 W CN2021082146 W CN 2021082146W WO 2022198403 A1 WO2022198403 A1 WO 2022198403A1
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layer
electrochemical device
current collector
pole piece
conductive agent
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PCT/CN2021/082146
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English (en)
French (fr)
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郭俊
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宁德新能源科技有限公司
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Priority to PCT/CN2021/082146 priority Critical patent/WO2022198403A1/zh
Priority to CN202180004743.4A priority patent/CN114270560A/zh
Publication of WO2022198403A1 publication Critical patent/WO2022198403A1/zh
Priority to US18/371,017 priority patent/US20240021838A1/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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/668—Composites of electroconductive material and synthetic resins
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical energy storage, in particular to electrochemical devices and electronic devices.
  • a primer layer is usually provided between the current collector and the active material layer to enhance the adhesion between the current collector and the active material layer and prevent desorption during cycling. membrane.
  • the electrical conductivity of the undercoat layer is usually slightly weaker, which affects the improvement of the rate capability of electrochemical devices.
  • the content of the conductive agent in the undercoat layer is usually increased, which will reduce the content of the binder in the undercoat layer, thereby adversely affecting the full play of the adhesion performance of the undercoat layer. . Therefore, further improvements in this regard are expected.
  • Some embodiments of the present application provide an electrochemical device including a pole piece including a current collector, a first layer and a second layer.
  • the first layer includes a conductive agent having a specific surface area (BET) of 60 m 2 /g to 1500 m 2 /g.
  • the second layer includes an active material, wherein the second layer is disposed on at least one surface of the current collector and the first layer is disposed between the current collector and the second layer.
  • the mass content of the conductive agent is 50% to 80% based on the total mass of the first layer.
  • the ratio of the orthographic projected area of the first layer on the surface of the current collector to the area of the current collector is 30% to 100%.
  • the surface roughness (Ra) of the first layer is 0.5 ⁇ m to 1.5 ⁇ m.
  • the single-sided thickness T of the first layer is 0.2 ⁇ m to 1 ⁇ m.
  • the conductive agent includes at least one of conductive carbon black, ketjen black, acetylene black, conductive graphite, graphene, carbon nanotubes, or carbon fibers.
  • the first layer further includes a binder including polyacrylic acid, polyacrylate, polymethacrylic acid, polyacrylamide, polymethacrylamide, polymethacrylate, polyvinyl alcohol or at least one of sodium alginate.
  • the average particle size D 50 of the conductive agent particles in the first layer and the thickness T of the first layer satisfy that T is in the range of 2*D 50 to 5*D 50 .
  • the first layer further includes a dispersant including one or both of lithium carboxymethylcellulose or sodium carboxymethylcellulose.
  • the areal density of the first layer is 0.03 mg/cm 2 to 0.3 mg/cm 2 .
  • the weight average molecular weight of the binder is 1W to 50W. In some embodiments, the mass content of the binder is 10% to 48% based on the total mass of the first layer. In some embodiments, the mass content of the dispersant is 1% to 10% based on the total mass of the first layer.
  • Embodiments of the present application also provide an electronic device, including the above electrochemical device.
  • a first layer is disposed between the current collector and the second layer, wherein the first layer includes a conductive agent with a large specific surface area, and the conductive agent with a large specific surface area improves the conductivity of the conductive network path constructed per unit area.
  • the first layer includes a conductive agent with a large specific surface area, and the conductive agent with a large specific surface area improves the conductivity of the conductive network path constructed per unit area.
  • FIG. 1 and 2 illustrate cross-sectional views of a pole piece of some embodiments of the present application taken along a plane defined by a thickness direction and a width direction of the pole piece.
  • the pole piece includes a current collector, a first layer disposed on at least one surface of the current collector, and a second layer disposed between the current collector and the second layer.
  • the pole piece may be a positive pole piece and/or a negative pole piece.
  • the positive pole piece is given by taking the positive pole piece as an example, and it should be understood that the negative pole piece may adopt a corresponding structure.
  • the positive electrode sheet includes a current collector 121 , a first layer 122 and a second layer 123 , wherein the first layer 122 is disposed between the current collector 121 and the second layer 123 .
  • the first layer 122 and the second layer 123 are shown as being located on one side of the current collector 121 in FIG. 1, this is merely exemplary, and the first layer 122 and the second layer 123 may both be located on the current collector 121. Both sides of fluid 121.
  • the second layer 123 includes an active material, eg, a positive active material.
  • the first layer 122 includes a conductive agent having a specific surface area (BET) of 60 m 2 /g to 1500 m 2 /g.
  • BET specific surface area
  • the conductive agent with a large specific surface area in this range increases the number of conductive network paths constructed per unit area in the first layer 122, thereby achieving better conductive connectivity, reducing the electronic resistance of the pole piece, and improving the electrochemical performance. The rate capability and cycle performance of the device.
  • the mass content of the conductive agent is 50% to 80% based on the total mass of the first layer 122 . If the mass content of the conductive agent is too small, for example, less than 50%, the conductivity of the first layer 122 will be adversely affected, and if the mass content of the conductive agent is too large, for example, more than 80%, due to the adhesion of the conductive agent itself The junction performance is slightly weaker, and an excessive amount of the conductive agent may adversely affect the adhesion between the first layer 122 and the current collector 121 .
  • the ratio of the orthographic projected area of the first layer 122 on the surface of the current collector 121 to the area of the current collector 121 is 30% to 100%. If the ratio of the orthographic projection area of the first layer 122 on the surface of the current collector 121 to the area of the current collector 121 is too small, the first layer 122 can improve the adhesion between the current collector 121 and the second layer 123 relatively limited. Preferably, the ratio of the orthographic projection area of the first layer 122 on the surface of the current collector 121 to the area of the current collector 121 is 50% to 70%. At this time, the roughness of the first layer 122 is improved, which can play a better bond. effect, while minimizing the adverse effect on the energy density of the electrochemical device.
  • the first layer 122 may be linear along the length and/or width of the positive pole piece. At this time, a part of the second layer 123 may be in direct contact with the current collector 121 . Compared with the first layer 122 as a continuous coating, the discontinuous first layer 122 can increase the contact area and the riveting effect between the first layer 122 and the second layer 123, and improve the adhesion of the positive electrode sheet .
  • the surface roughness (Ra) of the first layer 122 is 0.5 ⁇ m to 1.5 ⁇ m.
  • the contact area and the contact area between the first layer 122 and the second layer 123 and between the current collector 121 and the first layer 122 are increased.
  • the riveting effect improves the bonding force between them, thereby improving the stability of the conductive network during the cycle of the electrochemical device, and improving the cycle performance of the electrochemical device.
  • the single-sided thickness T of the first layer 122 is 0.2 ⁇ m to 1 ⁇ m. If the thickness of the first layer 122 is too thin, the effect of improving the adhesion between the current collector 121 and the second layer 123 is relatively limited, and if the thickness of the first layer 122 is too thick, it will adversely affect the performance of the electrochemical device Energy Density. By setting the single-sided thickness T of the first layer 122 to be 0.2 ⁇ m to 1 ⁇ m, while improving the rate performance and cycle performance of the electrochemical device, a higher energy density of the electrochemical device is ensured.
  • the average particle size D 50 of the conductive agent particles in the first layer 122 and the thickness T of the first layer 122 satisfy that T is in the range of 2*D 50 to 5*D 50 . In this way, it can be ensured that the first layer 122 has 2 to 5 conductive agent particles in the same thickness direction, so as to ensure effective stacking of the conductive agent particles in the first layer 122 and facilitate the construction of the conductive network in the first layer 122 . If T is less than 2*D 50 , it is unfavorable for the construction of the conductive network of the first layer 122 in the thickness direction. If T is greater than 5*D 50 , the first layer 122 is too thick, which is unfavorable for the energy density of the electrochemical device. promote.
  • the conductive agent may include at least one of conductive carbon black, ketjen black, acetylene black, conductive graphite, graphene, carbon nanotubes, or carbon fibers.
  • the first layer 122 may further include a binder, and the binder may include polyacrylic acid, polyacrylate (sodium polyacrylate, calcium polyacrylate, etc.), polymethacrylic acid, polyacrylamide, polymethacrylate at least one of acrylamide, polymethacrylate, polyvinyl alcohol or sodium alginate.
  • the weight average molecular weight of the binder is 1W to 50W.
  • the weight average molecular weight of the binder By making the weight average molecular weight of the binder from 1W to 50W, it can be ensured that the binder is anchored to the residual functional groups (for example, carboxyl group/hydroxyl group/phenol group, etc.) on the particle surface of the conductive agent with an anionic dispersant, thereby realizing the conductive agent effective dispersion. If the weight average molecular weight of the binder is too large, for example, greater than 50W, it is not conducive to the effective dispersion of the conductive agent. In some embodiments, the mass content of the binder is 10% to 48% based on the total mass of the first layer 122 .
  • the mass content of the binder is too small, it is unfavorable to fully exert the adhesion performance of the first layer 122 , and if the mass content of the binder is too large, the electrical conductivity of the first layer 122 will be adversely affected.
  • the first layer 122 further includes a dispersant, and the dispersant may include one or both of lithium carboxymethylcellulose or sodium carboxymethylcellulose.
  • the mass content of the dispersant is 1% to 10% based on the total mass of the first layer 122 . If the mass content of the dispersant is too small, it is unfavorable to exert the dispersing effect of the dispersant; if the mass content of the dispersant is too large, it is unfavorable to improve the electrical conductivity of the first layer 122 .
  • the areal density of the first layer 122 is set to 0.03 mg/cm 2 to 0.3 mg/cm 2 .
  • the second layer 123 is a positive electrode active material layer and includes a positive electrode active material.
  • the positive active material includes lithium cobalt oxide, lithium iron phosphate, lithium iron manganese phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadyl phosphate, sodium vanadyl phosphate, lithium vanadate, manganese At least one of lithium oxide, lithium nickelate, lithium nickel cobalt manganese oxide, lithium rich manganese based material or lithium nickel cobalt aluminate.
  • the positive electrode active material layer may further include a conductive agent.
  • the conductive agent in the positive active material layer may include at least one of conductive carbon black, Ketjen black, lamellar graphite, graphene, carbon nanotubes, or carbon fibers.
  • the positive electrode active material layer may further include a binder, and the binder in the positive electrode active material layer may include carboxymethyl cellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyamide At least one of imine, polyamideimide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin or polyfluorene.
  • CMC carboxymethyl cellulose
  • the mass ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode active material layer may be (80 ⁇ 99):(0.1 ⁇ 10):(0.1 ⁇ 10).
  • the thickness of the cathode active material layer may be 10 ⁇ m to 500 ⁇ m.
  • the current collector of the positive electrode sheet can be made of Al foil, of course, other current collectors commonly used in the art can also be used.
  • the thickness of the current collector of the positive electrode sheet may be 1 ⁇ m to 200 ⁇ m.
  • the positive active material layer may be coated only on a partial area of the current collector of the positive electrode sheet.
  • the second layer 123 is a negative electrode active material layer.
  • the anode active material layer includes an anode active material, and the anode active material may include at least one of graphite, hard carbon, silicon, silicon oxide, or organic silicon.
  • a conductive agent and a binder may also be included in the anode active material layer.
  • the conductive agent in the negative active material layer may include at least one of conductive carbon black, Ketjen black, lamellar graphite, graphene, carbon nanotubes, or carbon fibers.
  • the binder in the negative active material layer may include carboxymethyl cellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyimide, polyamideimide, polysilicon At least one of oxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin or polyfluorene.
  • the mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode active material layer may be (80 ⁇ 98):(0.1 ⁇ 10):(0.1 ⁇ 10).
  • the current collector of the negative electrode sheet can be at least one of copper foil, nickel foil or carbon-based current collector.
  • the electrode assembly of the electrochemical device may further include a separator disposed between the positive electrode and the negative electrode.
  • the release membrane includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid.
  • the polyethylene includes at least one selected from high density polyethylene, low density polyethylene or ultra-high molecular weight polyethylene. Especially polyethylene and polypropylene, they have a good effect on preventing short circuits and can improve the stability of the battery through the shutdown effect.
  • the thickness of the isolation film is in the range of about 5 ⁇ m to 500 ⁇ m.
  • the surface of the separator may further include a porous layer, the porous layer is disposed on at least one surface of the substrate of the separator, the porous layer includes inorganic particles and a binder, and the inorganic particles are selected from alumina (Al 2 O 3 ), silicon oxide (SiO 2 ), magnesium oxide (MgO), titanium oxide (TiO 2 ), hafnium dioxide (HfO 2 ), tin oxide (SnO 2 ), ceria (CeO 2 ), nickel oxide (NiO) ), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, hydroxide At least one of calcium or barium sulfate.
  • alumina Al 2 O 3
  • silicon oxide SiO 2
  • magnesium oxide MgO
  • titanium oxide TiO 2
  • hafnium dioxide
  • the pores of the isolation membrane have diameters in the range of about 0.01 ⁇ m to 1 ⁇ m.
  • the binder of the porous layer is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyamide At least one of vinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the porous layer on the surface of the separator can improve the heat resistance, oxidation resistance and electrolyte wettability of the separator, and enhance the adhesion between the separator and the pole piece.
  • the electrode assembly of the electrochemical device is a wound electrode assembly, a stacked electrode assembly, or a folded electrode assembly.
  • the positive pole piece and/or the negative pole piece of the electrochemical device may be a multi-layer structure formed by winding or stacking, or may be a single-layer positive pole piece, a separator, and a single-layer negative pole piece superimposed single-layer structure.
  • the electrochemical device includes a lithium-ion battery, although the present application is not so limited.
  • the electrochemical device may also include an electrolyte.
  • the electrolyte may be one or more of a gel electrolyte, a solid electrolyte, and an electrolytic solution, and the electrolytic solution includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from LiPF6, LiBF4 , LiAsF6, LiClO4 , LiB ( C6H5 ) 4 , LiCH3SO3 , LiCF3SO3 , LiN ( SO2CF3 ) 2 , LiC ( SO2CF3 ) 3 , LiSiF 6 , LiBOB or one or more of lithium difluoroborate.
  • LiPF 6 is chosen as the lithium salt because it has high ionic conductivity and can improve cycle characteristics.
  • the non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or a combination thereof.
  • the carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound, or a combination thereof.
  • chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl carbonate Ethyl esters (MEC) and combinations thereof.
  • chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl carbonate Ethyl esters (MEC) and combinations thereof.
  • Examples of the cyclic carbonate compound are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), or a combination thereof.
  • fluorocarbonate compound examples include fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Fluoroethylene, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-carbonate -Difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, or a combination thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Fluoroethylene, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-carbonate -Difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene
  • carboxylate compounds are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decolactone, Valerolactone, mevalonolactone, caprolactone, methyl formate, or a combination thereof.
  • ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxy Ethane, 2-methyltetrahydrofuran, tetrahydrofuran, or a combination thereof.
  • organic solvents examples include dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, methyl amide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters or combinations thereof.
  • the positive electrode, separator, and negative electrode are sequentially wound or stacked to form electrode parts, which are then packaged in, for example, an aluminum-plastic film, and then injected into an electrolytic film. Liquid, chemical formation, packaging, that is, into a lithium-ion battery. Then, the performance test of the prepared lithium-ion battery was carried out.
  • electrochemical devices eg, lithium ion batteries
  • electrochemical devices eg, lithium ion batteries
  • Other methods commonly used in the art may be employed without departing from the disclosure of the present application.
  • Embodiments of the present application also provide electronic devices including the above electrochemical devices.
  • the electronic device in the embodiment of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, Video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power, motors, automobiles, motorcycles, power-assisted bicycles, bicycles, Lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large-scale household storage batteries and lithium-ion capacitors, etc.
  • SP conductive carbon black
  • CMC 2.4 wt % sodium carboxymethyl cellulose
  • PAA-Na 32.6 wt % sodium polyacrylate
  • the positive electrode active material lithium iron phosphate, the conductive agent conductive carbon black, and the binder polyacrylic acid are dissolved in a weight ratio of 98.2:0.5:1.3.
  • NMP N-methylpyrrolidone
  • negative pole piece graphite, sodium carboxymethyl cellulose (CMC) and binder styrene-butadiene rubber are dissolved in deionized water in a weight ratio of 97.8:1.3:0.9 to form a negative electrode slurry.
  • a 10 ⁇ m-thick copper foil was used as the current collector of the negative electrode, and the negative electrode slurry was coated on the current collector of the negative electrode, dried, and cut to obtain a negative electrode.
  • the isolation film substrate is polyethylene (PE) with a thickness of 8 ⁇ m, and 2 ⁇ m alumina ceramic layers are coated on both sides of the isolation film substrate, and finally, 2.5 ⁇ m alumina ceramic layers are coated on both sides of the coated ceramic layer. mg of binder polyvinylidene fluoride (PVDF), dried.
  • PE polyethylene
  • PVDF binder polyvinylidene fluoride
  • EC ethylene carbonate
  • PC propylene carbonate
  • Preparation of lithium ion battery stack the positive pole piece, the separator and the negative pole piece in order, so that the separator is in the middle of the positive pole piece and the negative pole piece to play a role of isolation, and coil to obtain the electrode assembly.
  • the electrode assembly is placed in the outer packaging aluminum-plastic film, and after dehydration at 80°C, the above electrolyte is injected and packaged, and the lithium ion battery is obtained through the process of forming, degassing, and trimming.
  • Example 2 the specific surface area of the conductive agent of the first layer was different from that in Example 1.
  • Example 4 the mass content of each component in the first layer was different from that in Example 2.
  • Example 20 to 23 the thickness and areal density of the first layer were different from those of Example 2.
  • Example 24 the thickness of the first layer and the D50 of the conductive agent were different from those of Example 2.
  • Example 27 the weight average molecular weight of the binder in the first layer was different from Example 2.
  • Disassemble the battery to obtain the positive pole piece (including the current collector, the first layer and the second layer), use the dimethyl carbonate (DMC) solvent to soak the pole piece for 30min, wash off the electrolyte, and repeat the soaking and cleaning 3 times. Then, the positive pole piece is naturally air-dried. For the air-dried pole piece, use tape to peel off the second layer (or use N-methylpyrrolidone (NMP) to soak the pole piece for 30min, clean the second layer, and dry it) to obtain a pole piece containing the current collector and the first layer. piece. Then use Deheng DHTW-15 sampling cutting table to cut the length*width 40mm*20mm sample of the pole piece including the first layer.
  • DMC dimethyl carbonate
  • NMP N-methylpyrrolidone
  • the coverage of the first layer (the ratio of the orthographic projection area of the first layer on the surface of the current collector to the area of the current collector) was analyzed, and 5 parallel samples were tested and the average value was obtained.
  • the positive pole piece including the current collector, the first layer and the second layer
  • DMC dimethyl carbonate
  • NMP N-methylpyrrolidone
  • DMC dimethyl carbonate
  • NMP N-methylpyrrolidone
  • Use Deheng DHTW-15 sampling cutting table to cut the pole piece including the first layer to length*width 40mm*20mm samples, a total of 20 pieces.
  • Test principle AC four-terminal test method, load AC current Is to the test object, the sensor collects the voltage drop V IS caused by the test object, and derives the corresponding resistance R according to Ohm 's law.
  • DMC dimethyl carbonate
  • the lithium-ion battery Place the lithium-ion battery in an incubator at 25°C ⁇ 2°C or 45°C ⁇ 2°C for 2 hours, charge it to 3.65V at a rate of 1C, and then charge it to 0.05C at a constant voltage at 3.65V. Then, the cycle performance was tested by discharging at 1C rate to 2.5V. When the lithium-ion battery was cycled 500 times, the ratio of the capacity to the initial capacity was the cycle capacity retention rate.
  • Tables 1 and 2 show the respective parameters and evaluation results of Examples 1 to 3 and Comparative Example 1, respectively.
  • Tables 3 and 4 show the respective parameters and evaluation results of Examples 4 to 31, respectively.

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Abstract

本申请提供了电化学装置和电子装置。电化学装置包括极片，极片包括集流体、第一层和第二层。第一层包括导电剂，导电剂的比表面积(BET)为60m2/g至1500m2/g。第二层包括活性材料，其中，第一层设置在集流体和第二层之间。本申请的实施例通过在集流体和第二层之间设置第一层，其中第一层包括大的比表面积的导电剂，大的比表面积的导电剂提高了单位面积构建的网络通路的数量，从而达到更好的导电连通作用，降低了极片的电子电阻，提升电化学装置的倍率性能和循环性能。

Description

电化学装置和电子装置 技术领域
本申请涉及电化学储能领域，尤其涉及电化学装置和电子装置。
背景技术
随着电化学装置(例如，锂离子电池)的发展和进步，对其倍率性能、循环性能和能量密度提出了越来越高的要求。目前，为了提升电化学装置的安全性能和循环性能，通常在集流体和活性材料层之间提供底涂层，以增强集流体和活性材料层之间的粘结力，防止循环过程中的脱膜。
然而，底涂层的导电性能通常稍弱，影响了电化学装置的倍率性能的提升。而为了增强底涂层的导电性，通常增加底涂层中的导电剂的含量，这会降低底涂层中的粘结剂的含量，从而不利地影响底涂层的粘结性能的充分发挥。因此，期待这方面的进一步改进。
发明内容
本申请的一些实施例提供了一种电化学装置，电化学装置包括极片，极片包括集流体、第一层和第二层。第一层包括导电剂，导电剂的比表面积(BET)为60m 2/g至1500m 2/g。第二层包括活性材料，其中，第二层设置在集流体的至少一个表面上，第一层设置在集流体和第二层之间。
在一些实施例中，基于第一层的总质量，导电剂的质量含量为50％至80％。在一些实施例中，第一层在集流体的表面的正投影面积与集流体的面积比为30％至100％。在一些实施例中，第一层的表面粗糙度(Ra)为0.5μm至1.5μm。在一些实施例中，第一层的单面厚度T为0.2μm至1μm。
在一些实施例中，导电剂包括导电炭黑、科琴黑、乙炔黑、导电石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，第一层还包括粘结剂，粘结剂包括聚丙烯酸、聚丙烯酸盐、聚甲基丙烯酸、聚丙烯酰胺、聚甲基丙烯酰胺、聚甲基丙烯酸盐、聚乙烯醇或海藻酸钠中的至少一种。在 一些实施例中，第一层中的导电剂颗粒的平均粒径D 50与第一层的厚度T满足：T在2*D 50至5*D 50的范围内。在一些实施例中，第一层还包括分散剂，分散剂包括羧甲基纤维素锂或羧甲基纤维素钠中的一种或两种。在一些实施例中，第一层的面密度为0.03mg/cm 2至0.3mg/cm 2。
在一些实施例中，粘结剂的重均分子量为1W至50W。在一些实施例中，基于第一层的总质量，粘结剂的质量含量为10％至48％。在一些实施例中，基于第一层的总质量，分散剂的质量含量为1％至10％。
本申请的实施例还提供了一种电子装置，包括上述电化学装置。
本申请的实施例通过在集流体和第二层之间设置第一层，其中第一层包括大的比表面积的导电剂，大的比表面积的导电剂提高了单位面积构建的导电网络通路的数量，从而达到更好的导电连通作用，降低了极片的电子电阻，提升电化学装置的倍率性能和循环性能。
附图说明
图1和图2示出了本申请的一些实施例的极片沿着极片的厚度方向和宽度方向限定的平面获得的截面图。
具体实施方式
下面的实施例可以使本领域技术人员更全面地理解本申请，但不以任何方式限制本申请。
本申请的一些实施例提供了一种电化学装置，电化学装置包括极片。在一些实施例中，极片包括集流体、第一层和第二层，第二层设置在集流体至少一个表面上，第一层设置在集流体和第二层之间。在一些实施例中，该极片可以为正极极片和/或负极极片。为了简单的目的，下面以正极极片为例进行说明，应该理解，负极极片可以采用相应的结构。
如图1所示，正极极片包括集流体121、第一层122和第二层123，其中，第一层122设置在集流体121和第二层123之间。应该理解，虽然图1中将第一层122和第二层123示出为位于集流体121的一侧，然而，这仅是示例性的，第一层122和第二层123可以均位于集流体121的两侧。在一些实施例中，第二层123包括活性材料，例如，正极活性材料。在一些实施例 中，第一层122包括导电剂，导电剂的比表面积(BET)为60m 2/g至1500m 2/g。具有处于该范围的大的比表面积的导电剂提高了第一层122中单位面积构建的导电网络通路的数量，从而达到更好的导电连通作用，降低了极片的电子电阻，提升了电化学装置的倍率性能和循环性能。
在一些实施例中，基于第一层122的总质量，导电剂的质量含量为50％至80％。如果导电剂的质量含量太少，例如，小于50％，则会不利地影响第一层122的导电性，如果导电剂的质量含量太大，例如，大于80％，则由于导电剂自身的粘结性能稍弱，过量的导电剂会不利地影响第一层122与集流体121之间的粘结。
在一些实施例中，第一层122在集流体121的表面的正投影面积与集流体121的面积比为30％至100％。如果第一层122在集流体121的表面的正投影面积与集流体121的面积比太小，则第一层122能够起到的改善集流体121与第二层123之间的粘结的作用相对有限。优选地，第一层122在集流体121的表面的正投影面积与集流体121的面积比为50％至70％，此时第一层122的粗糙度提升，能够起到较好的粘结作用，同时可以最小化对电化学装置的能量密度的不利影响。如图2所示，在一些实施例中，第一层122在正极极片的长度和/或宽度方向上可以是线型的。此时，部分第二层123可以与集流体121直接接触。相对于作为连续涂层的第一层122，非连续的第一层122能够增大第一层122和第二层123之间的接触面积和铆合作用，改善了正极极片的粘结力。
在一些实施例中，第一层122的表面粗糙度(Ra)为0.5μm至1.5μm。通过选择第一层122的较大的表面粗糙度(0.5μm至1.5μm)，增大了第一层122和第二层123之间以及集流体121和第一层122之间的接触面积和铆合作用，改善了它们之间的粘结力，从而提高电化学装置循环过程中的导电网络的稳定性，改善了电化学装置的循环性能。
在一些实施例中，第一层122的单面厚度T为0.2μm至1μm。如果第一层122的厚度太薄，则改善集流体121和第二层123之间的粘结力的作用相对有限，如果第一层122的厚度太厚，则会不利地影响电化学装置的能量密度。通过使第一层122的单面厚度T为0.2μm至1μm，在改善电化学装置的倍率性能和循环性能的同时，保证了电化学装置的较高的能量密度。在一些 实施例中，第一层122中的导电剂颗粒的平均粒径D 50与第一层122的厚度T满足：T在2*D 50至5*D 50的范围内。如此，可以确保第一层122在同一厚度方向上具有2至5个导电剂颗粒，从而确保第一层122中的导电剂颗粒的有效堆叠，有利于促进第一层122中的导电网络的构建。如果T小于2*D 50，则不利于第一层122在厚度方向上的导电网络的构建，如果T大于5*D 50，则第一层122过厚，不利于电化学装置的能量密度的提升。
在一些实施例中，导电剂可以包括导电炭黑、科琴黑、乙炔黑、导电石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，第一层122还可以包括粘结剂，粘结剂可以包括聚丙烯酸、聚丙烯酸盐(聚丙烯酸钠、聚丙烯酸钙等)、聚甲基丙烯酸、聚丙烯酰胺、聚甲基丙烯酰胺、聚甲基丙烯酸盐、聚乙烯醇或海藻酸钠中的至少一种。在一些实施例中，粘结剂的重均分子量为1W至50W。通过使粘结剂的重均分子量为1W至50W，可以保证粘结剂以阴离子分散剂锚定于导电剂的颗粒表面的残余官能团(例如，羧基/羟基/酚基等)，从而实现导电剂的有效分散。如果粘结剂的重均分子量太大，例如，大于50W，则不利于导电剂的有效分散。在一些实施例中，基于第一层122的总质量，粘结剂的质量含量为10％至48％。如果粘结剂的质量含量太小，则不利于第一层122的粘结性能的充分发挥，如果粘结剂的质量含量太大，则第一层122的导电性能会受到不利的影响。
在一些实施例中，第一层122还包括分散剂，分散剂可以包括羧甲基纤维素锂或羧甲基纤维素钠中的一种或两种。在一些实施例中，基于第一层122的总质量，分散剂的质量含量为1％至10％。如果分散剂的质量含量太小，则不利于分散剂的分散效果的发挥；如果分散剂的质量含量太大，则不利于第一层122的导电性能的提高。
在一些实施例中，为了使第一层122的表面粗糙度为0.5μm至1.5μm，并且第一层122的单面厚度T为0.2μm至1μm，将第一层122的面密度设置为0.03mg/cm 2至0.3mg/cm 2。
在一些实施例中，在正极极片包括上述结构时，第二层123为正极活性材料层，并且包括正极活性材料。在一些实施例中，正极活性材料包括钴酸锂、磷酸铁锂、磷酸锰铁锂、磷酸铁钠、磷酸钒锂、磷酸钒钠、磷酸钒氧锂、磷酸钒氧钠、钒酸锂、锰酸锂、镍酸锂、镍钴锰酸锂、富锂锰基材料或镍钴铝 酸锂中的至少一种。在一些实施例中，正极活性材料层还可以包括导电剂。在一些实施例中，正极活性材料层中的导电剂可以包括导电炭黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，正极活性材料层还可以包括粘结剂，正极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。在一些实施例中，正极活性材料层中的正极活性材料、导电剂和粘结剂的质量比可以为(80～99)：(0.1～10)：(0.1～10)。在一些实施例中，正极活性材料层的厚度可以为10μm至500μm。
在一些实施例中，正极极片的集流体可以采用Al箔，当然，也可以采用本领域常用的其他集流体。在一些实施例中，正极极片的集流体的厚度可以为1μm至200μm。在一些实施例中，正极活性材料层可以仅涂覆在正极极片的集流体的部分区域上。
在一些实施例中，当负极极片包括上述结构时，第二层123为负极活性材料层。在一些实施例中，负极活性材料层包括负极活性材料，负极活性材料可以包括石墨、硬碳、硅、氧化亚硅或有机硅中的至少一种。在一些实施例中，负极活性材料层中还可以包括导电剂和粘结剂。在一些实施例中，负极活性材料层中的导电剂可以包括导电炭黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，负极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。在一些实施例中，负极活性材料层中的负极活性材料、导电剂和粘结剂的质量比可以为(80～98)：(0.1～10)：(0.1～10)。在一些实施例中，负极极片的集流体可以采用铜箔、镍箔或碳基集流体中的至少一种。
在一些实施例中，电化学装置的电极组件还可以包括设置在正极极片和负极极片之间的隔离膜。在一些实施例中，隔离膜包括聚乙烯、聚丙烯、聚偏氟乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺或芳纶中的至少一种。例如，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯或超高分子量聚乙烯中的至少一种。尤其是聚乙烯和聚丙烯，它们对防止短路具有良好的作用， 并可以通过关断效应改善电池的稳定性。在一些实施例中，隔离膜的厚度在约5μm至500μm的范围内。
在一些实施例中，隔离膜表面还可以包括多孔层，多孔层设置在隔离膜的基材的至少一个表面上，多孔层包括无机颗粒和粘结剂，无机颗粒选自氧化铝(Al 2O 3)、氧化硅(SiO 2)、氧化镁(MgO)、氧化钛(TiO 2)、二氧化铪(HfO 2)、氧化锡(SnO 2)、二氧化铈(CeO 2)、氧化镍(NiO)、氧化锌(ZnO)、氧化钙(CaO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、碳化硅(SiC)、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。在一些实施例中，隔离膜的孔具有在约0.01μm至1μm的范围的直径。多孔层的粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、羧甲基纤维素钠、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。隔离膜表面的多孔层可以提升隔离膜的耐热性能、抗氧化性能和电解质浸润性能，增强隔离膜与极片之间的粘结性。
在本申请的一些实施例中，电化学装置的电极组件为卷绕式电极组件、堆叠式电极组件或折叠式电极组件。在一些实施例中，电化学装置的正极极片和/或负极极片可以是卷绕或堆叠式形成的多层结构，也可以是单层正极极片、隔离膜、单层负极极片叠加的单层结构。
在一些实施例中，电化学装置包括锂离子电池，但是本申请不限于此。在一些实施例中，电化学装置还可以包括电解质。电解质可以是凝胶电解质、固态电解质和电解液中的一种或多种，电解液包括锂盐和非水溶剂。锂盐选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB或者二氟硼酸锂中的一种或多种。例如，锂盐选用LiPF 6，因为它具有高的离子导电率并可以改善循环特性。
非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。
碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。
链状碳酸酯化合物的实例为碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、 碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)及其组合。所述环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)或者其组合。所述氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯、碳酸三氟甲基亚乙酯或者其组合。
羧酸酯化合物的实例为乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯、己内酯、甲酸甲酯或者其组合。
醚化合物的实例为二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃、四氢呋喃或者其组合。
其它有机溶剂的实例为二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯、和磷酸酯或者其组合。
在本申请的一些实施例中，以锂离子电池为例，将正极极片、隔离膜、负极极片按顺序卷绕或堆叠成电极件，之后装入例如铝塑膜中进行封装，注入电解液，化成、封装，即制成锂离子电池。然后，对制备的锂离子电池进行性能测试。
本领域的技术人员将理解，以上描述的电化学装置(例如，锂离子电池)的制备方法仅是实施例。在不背离本申请公开的内容的基础上，可以采用本领域常用的其他方法。
本申请的实施例还提供了包括上述电化学装置的电子装置。本申请实施例的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、 手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
下面列举了一些具体实施例和对比例以更好地对本申请进行说明，其中，采用锂离子电池作为示例。为了简单的目的，下面仅以正极极片包括第一层作为示例。
实施例1
正极极片的制备：采用铝箔作为正极极片的集流体，在铝箔表面均匀的涂布第一层的浆料，浆料的组成为65wt％导电碳黑(SP，BET＝60m 2/g)、2.4wt％羧甲基纤维素钠(CMC)和32.6wt％聚丙烯酸钠(PAA-Na，分子量30W)，干燥后得到单面厚度约200nm的涂层(万分尺测试)。随后在第一层上涂布第二层即正极活性材料层，具体地，将正极活性材料磷酸铁锂、导电剂导电炭黑、粘结剂聚丙烯酸按重量比98.2：0.5：1.3的比例溶于N-甲基吡咯烷酮(NMP)溶液中，形成正极活性材料层的浆料，将该浆料涂覆于第一层上，得到正极活性材料层，经过干燥、冷压、裁切后得到正极极片。
负极极片的制备：将石墨，羧甲基纤维素钠(CMC)和粘结剂丁苯橡胶按重量比97.8：1.3：0.9的比例溶于去离子水中，形成负极浆料。采用10μm厚度铜箔作为负极极片的集流体，将负极浆料涂覆于负极极片的集流体上，干燥，裁切后得到负极极片。
隔离膜的制备：隔离膜基材为8μm厚的聚乙烯(PE)，在隔离膜基材的两侧各涂覆2μm氧化铝陶瓷层，最后在涂布了陶瓷层的两侧各涂覆2.5mg的粘结剂聚偏氟乙烯(PVDF)，烘干。
电解液的制备：在含水量小于10ppm的环境下，将LiPF 6加入非水有机溶剂(碳酸乙烯酯(EC)：碳酸丙烯酯(PC)＝50：50，重量比)，LiPF 6的浓度为1.15mol/L，混合均匀，得到电解液。
锂离子电池的制备：将正极极片、隔离膜、负极极片按顺序依次叠好，使隔离膜处于正极极片和负极极片中间起到隔离的作用，并卷绕得到电极组件。 将电极组件置于外包装铝塑膜中，在80℃下脱去水分后，注入上述电解液并封装，经过化成，脱气，切边等工艺流程得到锂离子电池。
实施例和对比例是在实施例1或2的步骤的基础上进行参数变更，具体变更的参数如下面的表格所示。
在实施例2至3以及对比例1中，第一层的导电剂的比表面积与实施例1不同。
在实施例4至8中，第一层中的各个成分的质量含量与实施例2不同。
在实施例9至14中，第一层在集流体的表面的正投影面积与集流体的面积比与实施例2不同。
在实施例15至19中，第一层的表面粗糙度与实施例2不同。
在实施例20至23中，第一层的厚度和面密度与实施例2不同。
在实施例24至26中，第一层的厚度和导电剂的D50与实施例2不同。
在实施例27至31中，第一层中的粘结剂的重均分子量与实施例2不同。
下面描述本申请的各个参数的测试方法。
覆盖度测试方法
将电池拆解得到正极极片(含集流体、第一层和第二层)，使用碳酸二甲酯(DMC)溶剂将极片浸泡30min后清洗掉电解液，重复浸泡与清洗3次。然后将正极极片自然风干。风干后的极片，使用胶带将第二层剥离(或使用N-甲基吡咯烷酮(NMP)浸泡极片30min，将第二层清洗掉，烘干)，得到含集流体和第一层的极片。然后使用德亨DHTW-15取样切台将包括第一层的极片裁切成长*宽＝40mm*20mm样品。将样品平整放置于两个玻璃板(长*宽＝60mm*40m，玻璃板洁净，无划痕)之间，轻轻按压整平，然后使用光学显微镜50X倍率拍照，运用VHX-5000分析软件自动分析第一层的覆盖度(第一层在集流体的表面的正投影面积与集流体的面积比)，测试5个平行样品取平均值。
粗糙度测试方法
将电池拆解得到正极极片(含集流体、第一层和第二层)，使用碳酸二甲酯(DMC)溶剂将极片浸泡30min后清洗掉电解液，重复浸泡与清洗3次。然后将正极极片自然风干。风干后的极片，使用胶带将第二层剥离(或使用 N-甲基吡咯烷酮(NMP)浸泡极片30min，将第二层清洗掉，烘干)，得到含集流体和第一层的极片。使用德亨DHTW-15取样切台将包括第一层的极片裁切成长*宽＝40mm*20mm样品。用中间带圆孔(直径20mm)的两块玻璃圆板，将样品夹在两块玻璃板之间，样品中心处于圆孔中心，避免样品褶皱。运用VK-X100/200Series激光显微镜100X自动模式拍照，然后使用VK软件分析1m 2平面的粗糙度Ra，参考国家标准GB/T1031-1995《表面粗糙度参数及其数值》定义。
导电剂BET的测试方法
将电池拆解得到正极极片(含集流体、第一层和第二层)，使用碳酸二甲酯(DMC)溶剂将极片浸泡30min后清洗掉电解液，重复浸泡与清洗3次。然后将正极极片自然风干。风干后的极片，使用胶带将第二层剥离(或使用N-甲基吡咯烷酮(NMP)浸泡极片30min，将第二层清洗掉，烘干)，得到含集流体和第一层的极片。使用德亨DHTW-15取样切台将包括第一层的极片裁切成长*宽＝40mm*20mm样品，共20份。然后将10份样品放入洁净的500mL烧杯中，加入去离子水200g，浸泡1h，然后用镊子夹取样品清洗后，依次将铝箔捞出，得到浆料。将烧杯浆料使用超声清洗机(频率10Hz)分散1h，然后将浆料倒入离心管，使用离心机离心(转速4000rpm，时间30min)后，取上层液体超声分散后用0.5μm的滤纸过滤，并用NMP反复冲洗5次，将滤纸表面所得固态样品放入烤箱100℃烘烤30min，得到的粉末使用Micromeritics TriStarⅡ3020设备测试其BET。
第一层或极片的电阻测试：
将电池拆解得到正极极片(含集流体、第一层和第二层)，使用碳酸二甲酯(DMC)溶剂将极片浸泡30min后清洗掉电解液，重复浸泡与清洗3次。然后将正极极片自然风干。风干后的极片(测试第一层之间的电阻需使用胶带将第二层剥离，得到含集流体和第一层的极片)，使用德亨DHTW-15取样切台将极片裁切成长*宽＝100mm*50mm样品。使用日置BT3562电阻仪进行数据采集，接触铜柱直径14mm，测试压力25MPa(0.4t)，采点时间15s。将样品放置于两个铜柱之间，按下开关测试极片之间或第一层之间的电阻。 测试原理：交流四端子测试法，向测试物加载交流电流I s，传感器采集测试物引起的电压降V IS，根据欧姆定律推导相应电阻R。
直流电阻DCR测试流程：
1)在25℃低温箱中静置4h；
2)0.7C(即2h内完全放掉理论容量的电流值)恒流充电至3.65V，3.65V恒压充电至0.02C,休眠10min；
3)0.1C放电至2.5V，休眠5min(此步得到实际容量)；
25℃DCR的测试
4)休眠5min,0.7C恒流充电至3.65V,3.65V恒压充电至0.02C(用第3步得到的实际容量计算)；
5)休眠10min；
6)0.1C放电3h(用第3步得到的实际容量计算，得70％荷电状态(SOC)(电池剩余容量)DCR)。
粘结力测试：
将电池拆解得到正极极片(含集流体、第一层和第二层)，使用碳酸二甲酯(DMC)溶剂将极片浸泡30min后清洗掉电解液，重复浸泡与清洗3次。然后将正极极片自然风干。风干后的极片，使用德亨DHTW-15取样切台将极片裁切成长*宽＝70mm*20mm样品。然后将长*宽＝50mm*30mm的双面胶带贴于不锈钢板(长*宽＝100mm*40mm，表面光滑洁净)表面，紧密贴合粘结牢固。然后将样品贴在双面胶上，样品预留20mm长度。使用皱纹胶带将裁切好的长*宽＝100mm*20mm的长条硬纸与预留的20mm样品缠接在一起。然后使用2Kg辊辊压样品与双面胶带贴合的50mm长度位置2次，完成测试样品制作。将制作好的样品利用型号Instron 3365万能拉伸试验机和夹具进行90°拉伸测试，拉伸曲线平稳段判定为第一层与第二层间的极片粘结力，粘结力F＝拉力f(N)/样品宽度(m)。测试方法参考国标《GB/T 2791-1995胶粘剂T剥离强度试验方法》。
2C放电倍率下容量保持率测试：
将锂离子电池置于25℃±2℃的恒温箱中静置2小时，以0.5C倍率进行充电至3.65V，然后在3.65V下恒压充电至0.02C。然后搁置1.5小时，再以 0.2C倍率放电至2.5V进行循环性能测试，得到参考放电容量；以2C倍率放电至2.5V进行循环性能测试，得到实际放电容量，2C放电倍率下容量保持率＝实际放电容量/参考放电容量*100％。
循环性能测试：
将锂离子电池置于25℃±2℃或45℃±2℃的恒温箱中静置2小时，以1C倍率进行充电至3.65V，然后在3.65V下恒压充电至0.05C。随后以1C倍率放电至2.5V进行循环性能测试，当锂离子电池循环500次之后的容量与初始容量的比值为循环容量保持率。
表1和表2分别示出了实施例1至3和对比例1的各个参数和评估结果。
表1
Figure PCTCN2021082146-appb-000001
表2
Figure PCTCN2021082146-appb-000002
通过比较实施例1至3和对比例1可知，通过采用比表面积为60m 2/g至1500m 2/g的导电剂，相对于比表面积小于60m 2/g的情况，第一层和极片的电阻均降低，极片的粘结力增大，电化学装置的直流电阻降低，电化学装置的倍率性能和循环容量保持率改善；另外，在导电剂的比表面积太大时，例如大于1500m 2/g，导电剂颗粒的缺陷较多，构建导电网络的能力较差，不利于电化学装置的整体性能发挥。极片的电阻
通过比较实施例1至3可知，随着第一层中的导电剂的比表面积的增大，第一层的电阻降低，极片的电阻降低，正极极片的粘结力先增大后保持稳定，电化学装置的直流电阻降低，倍率性能改善并且循环容量保持率提升。这是因为增加第一层的导电剂的比表面积，有助于第一层的导电剂构建导电网络，第一层的导电性升高，从而降低极片的膜片电阻，提高电化学装置的动力学和循环性能。
表3和表4分别示出了实施例4至31的各个参数和评估结果。
表3
Figure PCTCN2021082146-appb-000003
Figure PCTCN2021082146-appb-000004
表4
Figure PCTCN2021082146-appb-000005
Figure PCTCN2021082146-appb-000006
其中，“/”表示不能测得数据。
通过比较实施例4至8可知，在第一层中的导电剂的质量含量为50％至80％时，随着第一层中的导电剂的质量含量的增大，第一层的电阻和极片的电阻有降低的趋势，正极极片的粘结力和电化学装置的直流电阻变化不大，电化学装置的倍率性能和循环容量保持率有增大的趋势。当第一层中的导电剂的质量含量太小时(实施例5)，第一层的电阻和极片的电阻增大，并且电化学装置的倍率性能和循环容量保持率降低。当第一层中的导电剂的质量含量太大时(实施例6)，极片的粘结力会降低。
通过比较实施例9至14可知，随着第一层在集流体的表面的正投影面积与集流体的面积比的增大，第一层的电阻降低，极片的电阻降低，正极极片的粘结力增大，电化学装置的直流电阻降低，倍率性能改善并且循环容量保持率提升。在第一层在集流体的表面的正投影面积与集流体的面积比小于30％时(实施例11)，不利于第一层和第二层的粘结和导电，导致电化学装置的倍率性能和循环性能无法充分发挥。
通过比较实施例15至19可知，在表面粗糙度为0.5μm至1.5μm时，随着第一层的表面粗糙度的提升，第一层的电阻和极片的电阻变化不大，正极极片的粘结力增大，电化学装置的直流电阻变化不大，电化学装置的倍率性能和循环容量保持率有所提升。当第一层的表面粗糙度太大时(实施例17)，第一层有超厚风险，不利于能量密度的提升；当第一层的表面粗糙度太小时(实施例17)，第一层与第二层的粘结力降低。
通过比较实施例20至23可知，随着第一层的厚度的增大，第一层的电阻和极片的电阻有下降的趋势，正极极片的粘结力变化不大，电化学装置的直流电阻有减小的趋势，电化学装置的倍率性能和循环容量保持率有所提升。然而，如果第一层的厚度太大，则不利于电化学装置的能量密度的提升。
通过比较实施例24至26可知，在第一层的厚度与导电剂的D50的比值在2至5的范围内时，随着第一层的厚度与导电剂的D50的比值的减小，第 一层的电阻减小，极片的电阻先增大后下降，极片的粘结力、电化学装置的直流电阻、倍率性能和循环容量保持率变化不大。
通过比较实施例27至31可知，在粘结剂的重均分子量为1W至50W时，随着粘结剂的重均分子量的增大，第一层的电阻和极片的电阻有增大的趋势，极片的粘结力、电化学装置的直流电阻、倍率性能和循环容量保持率变化不大。当粘结剂的重均分子量太小时(实施例27)，极片的粘结力太差；当粘结剂的重均分子量太大时(实施例31)，第一层的电阻和极片的电阻增大，电化学装置的直流电阻增大，电化学装置的倍率性能和循环容量保持率降低。
以上描述仅为本申请的较佳实施例以及对所运用技术原理的说明。本领域技术人员应当理解，本申请中所涉及的公开范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖由上述技术特征或其等同特征进行任意组合而形成的其它技术方案。例如上述特征与本申请中公开的具有类似功能的技术特征进行互相替换而形成的技术方案。

Claims (10)

  1. 一种电化学装置，其包括极片，所述极片包括：
    集流体；
    第一层，包括导电剂，所述导电剂的比表面积(BET)为60m 2/g至1500m 2/g；
    第二层，包括活性材料，其中，所述第二层设置在所述集流体的至少一个表面上，所述第一层设置在所述集流体和所述第二层之间。
  2. 根据权利要求1所述的电化学装置，其中，基于所述第一层的总质量，所述导电剂的质量含量为50％至80％。
  3. 根据权利要求1所述的电化学装置，其中，所述第一层在所述集流体的表面的正投影面积与所述集流体的面积比为30％至100％。
  4. 根据权利要求1所述的电化学装置，其中，所述第一层的表面粗糙度(Ra)为0.5μm至1.5μm。
  5. 根据权利要求1所述的电化学装置，其中，所述第一层的单面厚度T为0.2μm至1μm。
  6. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一个：
    所述导电剂包括导电炭黑、科琴黑、乙炔黑、导电石墨、石墨烯、碳纳米管或碳纤维中的至少一种；
    所述第一层还包括粘结剂，所述粘结剂包括聚丙烯酸、聚丙烯酸盐、聚甲基丙烯酸、聚丙烯酰胺、聚甲基丙烯酰胺、聚甲基丙烯酸盐、聚乙烯醇或海藻酸钠中的至少一种；
    所述第一层中的导电剂颗粒的平均粒径D 50与所述第一层的厚度T满足：T在2*D 50至5*D 50的范围内；
    所述第一层还包括分散剂，所述分散剂包括羧甲基纤维素锂或羧甲基纤维素钠中的一种或两种；
    所述第一层的面密度为0.03mg/cm 2至0.3mg/cm 2。
  7. 根据权利要求6所述的电化学装置，其中，所述粘结剂的重均分子量为1W至50W。
  8. 根据权利要求6所述的电化学装置，其中，基于所述第一层的总质量，所述粘结剂的质量含量为10％至48％。
  9. 根据权利要求6所述的电化学装置，其中，基于所述第一层的总质量，所述分散剂的质量含量为1％至10％。
  10. 一种电子装置，包括根据权利要求1至9中任一项所述的电化学装置。
PCT/CN2021/082146 2021-03-22 2021-03-22 电化学装置和电子装置 WO2022198403A1 (zh)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103907227A (zh) * 2011-10-27 2014-07-02 株式会社神户制钢所 电极材料、电极和二次电池
CN106876716A (zh) * 2017-03-14 2017-06-20 中国人民解放军63971部队 一种金属/碳复合集流体材料及其制备方法
CN107681159A (zh) * 2017-08-17 2018-02-09 清华大学 一种电池用的金属箔集流体
CN108511689A (zh) * 2017-04-05 2018-09-07 万向二三股份公司 一种含有导电涂层的锂离子电池正极片及其制备方法
CN109964348A (zh) * 2018-09-10 2019-07-02 昭和电工株式会社 蓄电装置用集电体、其制造方法和其制造中使用的涂布液

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110828826A (zh) * 2018-08-08 2020-02-21 宁德时代新能源科技股份有限公司 一种电极极片及二次电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103907227A (zh) * 2011-10-27 2014-07-02 株式会社神户制钢所 电极材料、电极和二次电池
CN106876716A (zh) * 2017-03-14 2017-06-20 中国人民解放军63971部队 一种金属/碳复合集流体材料及其制备方法
CN108511689A (zh) * 2017-04-05 2018-09-07 万向二三股份公司 一种含有导电涂层的锂离子电池正极片及其制备方法
CN107681159A (zh) * 2017-08-17 2018-02-09 清华大学 一种电池用的金属箔集流体
CN109964348A (zh) * 2018-09-10 2019-07-02 昭和电工株式会社 蓄电装置用集电体、其制造方法和其制造中使用的涂布液

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