WO2022267013A1 - 电化学装置及电子装置 - Google Patents

电化学装置及电子装置 Download PDF

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Publication number
WO2022267013A1
WO2022267013A1 PCT/CN2021/102399 CN2021102399W WO2022267013A1 WO 2022267013 A1 WO2022267013 A1 WO 2022267013A1 CN 2021102399 W CN2021102399 W CN 2021102399W WO 2022267013 A1 WO2022267013 A1 WO 2022267013A1
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Prior art keywords
nanowires
inorganic salt
active material
lithium
pole piece
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PCT/CN2021/102399
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English (en)
French (fr)
Inventor
李巍巍
张艳如
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to CN202180030655.1A priority Critical patent/CN117378054A/zh
Priority to PCT/CN2021/102399 priority patent/WO2022267013A1/zh
Publication of WO2022267013A1 publication Critical patent/WO2022267013A1/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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

  • the present application relates to the field of energy storage, in particular to an electrochemical device and an electronic device.
  • lithium-ion batteries As a new type of energy storage device, lithium-ion batteries have been widely used in 3C digital, electric tools, energy storage grid, aerospace and other fields. With the development of science and technology, people have higher and higher requirements on the performance of lithium-ion batteries. As the battery capacity increases, the charging current increases, and the polarization of the battery continues to increase. Especially for cells with high volumetric energy density, the density of the pole piece is high, and the internal pores are small. The impedance of long-distance transmission in the liquid increases, which further deteriorates the ion polarization and causes an irreversible decrease in battery capacity.
  • the present application provides an electrochemical device, in which the ion polarization of the electrode sheet is low, so that it has higher discharge rate performance and cycle performance.
  • the present application also provides an electronic device including the electrochemical device.
  • the present application provides an electrochemical device, which includes an electrode pole piece, the electrode pole piece includes a current collector and an active material layer, and the active material layer includes active material particles and inorganic salt nanowires, so The inorganic salt nanowire is located on the surface of the active material particle and/or the first end and the second end of the inorganic salt nanowire are located on different surfaces of the active material particle.
  • the inorganic salt nanowires can be adsorbed on the surface of active material particles or bridged between active material particles.
  • the inorganic salt nanowires can act as a "bridge", so that the non-contact active material surface and the electrolyte can still transmit lithium ions through the inorganic salt nanowires, which greatly improves the battery life. Cycling performance of chemical devices.
  • the inorganic salt nanowires include at least one of ionic inorganic salt nanowires.
  • the inorganic salt nanowires include phosphate nanowires, tungstate nanowires, carbonate nanowires, sulfate nanowires, silicate nanowires, aluminosilicate nanowires, At least one of borate nanowires, nitrate nanowires, zirconate nanowires, titanate nanowires or LLZTO nanowires.
  • the length of the inorganic salt nanowires is 0.04 ⁇ m to 20 ⁇ m, and the aspect ratio of the inorganic salt nanowires is 10 to 2000.
  • the length of the inorganic salt nanowires is 0.1 ⁇ m to 10 ⁇ m, and the aspect ratio of the inorganic salt nanowires is 20 to 1000. If the length of the inorganic salt nanowire is too small, the transmission path of lithium ions in the inorganic salt nanowire is too short, making little contribution to the conduction of lithium ions; It also cannot effectively enhance the conduction of lithium ions. If the aspect ratio of inorganic salt nanowires is too small, its specific surface area will decrease, and the ability to accept and release lithium ions will be weakened; good.
  • the specific surface area (BET) of the inorganic salt nanowire is 10m 2 /g to 500m 2 /g.
  • the specific surface area is too large, the inorganic salt nanowires are easy to agglomerate, resulting in poor dispersion, which makes the conduction effect of lithium ions poor; Also biased.
  • the mass content of the inorganic salt nanowires is 0.1% to 5%. If the content of inorganic salt nanowires is too high, the transmission distance of lithium ions in the electrolyte and between particles will increase instead, and the electronic conductance will also be blocked to a certain extent, resulting in increased polarization and poor performance of electrochemical devices.
  • the electrode pole piece satisfies at least one of the following conditions (a) to (c): (a) the contact angle between the electrode pole piece and the electrolyte solution is ⁇ 45°, wherein the The electrolyte solution is dimethyl carbonate containing 1mol/L lithium hexafluorophosphate; (b) the sheet resistance of the electrode sheet is ⁇ 10 ⁇ ; (c) the bonding force between the active material layer and the current collector is 1N/m to 100N/m; (d) the ionic impedance of the electrode pole piece is ⁇ 40m ⁇ .
  • the contact angle between the electrode sheet and the electrolyte solution is ⁇ 45°, wherein the electrolyte solution is dimethyl carbonate containing 1 mol/L lithium hexafluorophosphate. If the contact angle is too large, the wettability between the pole piece and the electrolyte is poor, which is not conducive to the improvement of the rate performance and cycle performance of the electrochemical device.
  • the sheet resistance of the electrode pole piece is ⁇ 10 ⁇ .
  • the ionic impedance of the electrode pole piece is ⁇ 40m ⁇ . Excessively high electrode sheet resistance and ionic impedance will increase the polarization of the cell, thereby deteriorating the rate performance and cycle performance of the electrochemical device.
  • the bonding force between the active material layer and the current collector is 1N/m to 100N/m. If the adhesion force is too low, the particle bonding becomes weaker, which leads to an increase in the polarization of the cell, thereby deteriorating the rate performance and cycle performance of the electrochemical device.
  • the active material includes a positive electrode active material or a negative electrode active material
  • the positive electrode active material includes lithium iron phosphate, lithium manganese iron phosphate, lithium cobaltate, lithium nickel cobalt manganate, nickel cobalt aluminum acid
  • the negative electrode active material includes at least one of carbon material or silicon material.
  • the active material layer further includes a binder and/or a conductive agent
  • the binder includes polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethyl cellulose , lithium carboxymethyl cellulose, modified polyvinylidene fluoride, modified SBR rubber or polyurethane
  • the conductive agent includes conductive carbon black, conductive graphite, carbon fiber, multi-walled carbon nanotubes, single-walled carbon At least one of nanotubes, hard carbon, soft carbon, Ketjen black or graphene.
  • the present application provides an electronic device, which includes the electrochemical device described in the first aspect.
  • This application greatly reduces the ionic polarization of the electrochemical device during charging and discharging by adding inorganic salt nanowires with low conductivity and high ion-conducting ability to the electrode pole piece, thereby significantly improving the performance of the electrochemical device. Discharge rate performance and cycle performance enhance product competitiveness.
  • the term "about” is used to describe and account for small variations.
  • the terms can refer to instances in which the event or circumstance occurred exactly as well as instances in which the event or circumstance occurred with close approximation.
  • the term may refer to a range of variation of less than or equal to ⁇ 10% of the stated value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, less than or equal to ⁇ 10%, Less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%.
  • a list of items linked by the term "at least one of” can mean any combination of the listed items. For example, if the items A and B are listed, the phrase "at least one of A and B" means A only; only B; or A and B. In another example, if the items A, B, and C are listed, 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.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • references to “embodiment”, “partial embodiment”, “an embodiment”, “another example”, “example”, “specific example” or “partial example” in the entire specification mean that At least one embodiment or example in the present application includes a specific feature, structure, material or characteristic described in the embodiment or example.
  • descriptions that appear throughout the specification such as: “in some embodiments”, “in an embodiment”, “in one embodiment”, “in another example”, “in an example In”, “in a particular example” or “example”, they are not necessarily referring to the same embodiment or example in this application.
  • the particular features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.
  • the present application provides an electrochemical device, which includes an electrode pole piece, the electrode pole piece includes a current collector and an active material layer, and the active material layer includes active material particles and inorganic salt nanowires, so The inorganic salt nanowire is located on the surface of the active material particle and/or the first end and the second end of the inorganic salt nanowire are located on different surfaces of the active material particle.
  • the electrode sheet is a positive electrode sheet and/or a negative electrode sheet.
  • the present application adds low-conductivity, high ion-conducting inorganic salt nanowires to the electrode pole piece, the inorganic salt nanowires can be adsorbed on the surface of active material particles or bridged between active material particles, between active materials and A lithium ion transmission path for directional transmission is established between the active material and the electrolyte, and the conduction of lithium ions in the active material layer is enhanced, thereby reducing the ion polarization during charge and discharge, so that the electrochemical device and electrons containing the electrode pole piece The device has better discharge rate performance ring and cycle performance.
  • the inorganic salt nanowires can act as a "bridge", so that the non-contact active material surface and the electrolyte can still transmit lithium ions through the inorganic salt nanowires, which greatly improves the battery life. Cycling performance of chemical devices.
  • the inorganic salt nanowires include at least one of ionic inorganic salt nanowires.
  • the inorganic salt nanowires include phosphate nanowires, tungstate nanowires, carbonate nanowires, sulfate nanowires, silicate nanowires, aluminosilicate nanowires, At least one of borate nanowires, nitrate nanowires, zirconate nanowires, titanate nanowires or LLZTO nanowires.
  • the phosphate nanowires include hydroxyapatite nanowires, fluoroapatite nanowires, chloroapatite nanowires, oxysilicoapatite nanowires, strontium apatite nanowires or at least one of lithium apatite nanowires.
  • the tungstate nanowires include barium tungstate nanowires and/or lead tungstate nanowires.
  • the carbonate nanowires include strontium carbonate nanowires and/or barium carbonate nanowires.
  • the sulfate wires include calcium sulfate nanowires and/or barium sulfate nanowires.
  • the length of the inorganic salt nanowires is 0.04 ⁇ m to 20 ⁇ m. If the length of the inorganic salt nanowire is too small, the transmission path of lithium ions in the inorganic salt nanowire is too short, making little contribution to the conduction of lithium ions; It also cannot effectively enhance the conduction of lithium ions.
  • the length of the inorganic salt nanowire is 0.2 ⁇ m, 0.3 ⁇ m, 0.5 ⁇ m, 0.7 ⁇ m, 0.9 ⁇ m, 1.0 ⁇ m, 1.5 ⁇ m, 2.0 ⁇ m, 2.5 ⁇ m, 3.0 ⁇ m, 3.5 ⁇ m, 4.0 ⁇ m, 4.5 ⁇ m ⁇ m, 5.0 ⁇ m, 5.5 ⁇ m, 6.0 ⁇ m, 7.0 ⁇ m, 7.5m, 8.0 ⁇ m, 9.0 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 17 ⁇ m, 19 ⁇ m or any combination of these values.
  • the inorganic salt nanowires have a length of 0.1 ⁇ m to 10 ⁇ m. In some embodiments, the inorganic salt nanowires have a length of 1 ⁇ m to 5 ⁇ m.
  • the aspect ratio of the inorganic salt nanowires is 10 to 2000. If the aspect ratio of inorganic salt nanowires is too small, its specific surface area will decrease, and the ability to accept and release lithium ions will be weakened; good.
  • the aspect ratio of the inorganic salt nanowire is 20, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 800, 900, 1000 , 1200, 1400, 1500, 1700, 1900, or a range of any two of these values.
  • the inorganic salt nanowires have an aspect ratio of 20 to 1000.
  • the inorganic salt nanowires have an aspect ratio of 100 to 700.
  • the specific surface area of the inorganic salt nanowire is 10m 2 /g to 500m 2 /g.
  • the BET test method can use the national standard GB/T 19587-2004 gas adsorption BET method.
  • the specific surface area is too large, the inorganic salt nanowires are easy to agglomerate, resulting in poor dispersion, which makes the conduction effect of lithium ions poor; Also biased.
  • the specific surface area of the inorganic salt nanowire is 20m 2 /g, 50m 2 /g, 100m 2 /g, 150m 2 /g, 200m 2 /g, 250m 2 /g, 300m 2 /g, 350m 2 /g 2 /g, 400m 2 /g, 450m 2 /g or a range consisting of any two of these values. In some embodiments, the specific surface area of the inorganic salt nanowire is 50m 2 /g to 400m 2 /g.
  • the mass content of the inorganic salt nanowires is 0.1% to 5%. If the content of inorganic salt nanowires is too high, the transmission distance of lithium ions in the electrolyte and between particles will increase instead, and the electronic conductance will also be blocked to a certain extent, resulting in increased polarization and poor performance of electrochemical devices.
  • the mass content of inorganic salt nanowires is 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.5%, 2.7%, 2.9%, %, 3.0%, 3.2%, 3.5%, 3.8%, 4.0%, 4.2%, 4.5%, 4.7%, or a range consisting of any two of these values.
  • the contact angle between the electrode sheet and the electrolyte solution is ⁇ 45°, wherein the electrolyte solution is dimethyl carbonate containing 1 mol/L lithium hexafluorophosphate. If the contact angle is too large, the wettability between the pole piece and the electrolyte is poor, which is not conducive to the improvement of the rate performance and cycle performance of the electrochemical device.
  • the contact angle between the electrode pole piece and the electrolyte solution is 10°, 15°, 20°, 23°, 25°, 27°, 30°, 32°, 34°, 35°, 37° , 39°, 40°, 43°, or any two of these values.
  • the sheet resistance of the electrode pole piece is ⁇ 10 ⁇ , such as 0.5 ⁇ , 1.0 ⁇ , 2.0 ⁇ , 3.0 ⁇ , 4.0 ⁇ , 5.0 ⁇ , 6.0 ⁇ , 7.0 ⁇ , 8.0 ⁇ , 9.0 ⁇ or a range of any two of these values.
  • the ionic impedance of the electrode pole piece is ⁇ 40m ⁇ , such as 3m ⁇ , 5m ⁇ , 7m ⁇ , 10m ⁇ , 15m ⁇ , 20m ⁇ , 23m ⁇ , 25m ⁇ , 27m ⁇ , 30m ⁇ , 32m ⁇ , 34m ⁇ , 36m ⁇ , 38m ⁇ or these A range of any two of the values. Excessively high electrode sheet resistance and ionic impedance will increase the polarization of the cell, thereby deteriorating the rate performance and cycle performance of the electrochemical device.
  • the bonding force between the active material layer and the current collector is 1 N/m to 100 N/m. If the adhesion force is too low, the particle bonding becomes weaker, which leads to an increase in the polarization of the cell, thereby deteriorating the rate performance and cycle performance of the electrochemical device.
  • the bonding force between the active material layer and the current collector is 2N/m, 3N/m, 4N/m, 5N/m, 6N/m, 7N/m, 8N/m, 9N/m , 10N/m, 15N/m, 20N/m, 30N/m, 40N/m, 50N/m, 60N/m, 70N/m, 80N/m, 90N/m or any two of these values .
  • the active material includes a positive active material or a negative active material.
  • the positive electrode active material includes at least one of a lithium transition metal phosphate compound, a phosphate compound, or a lithium transition metal composite oxide.
  • the positive electrode active material includes a lithium transition metal compound, which has a structure capable of detaching and intercalating lithium ions.
  • the positive electrode active material includes lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganate, lithium nickel manganese oxide or lithium cobalt manganese oxide at least one of the
  • the negative electrode active material includes at least one of carbon material or silicon material.
  • the carbon material can be any carbon-based negative active material commonly used in lithium-ion rechargeable electrochemical devices.
  • Examples of carbon materials include crystalline carbon, amorphous carbon, and combinations thereof.
  • the crystalline carbon may be amorphous or plate-shaped, platelet-shaped, spherical or fibrous natural or artificial graphite.
  • the amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonization product, fired coke, or the like. Both low-crystalline carbon and high-crystalline carbon can be used as the carbon material.
  • soft carbon and hard carbon may be generally included.
  • natural graphite, crystalline graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesocarbon microbeads, mesophase pitch, and high-temperature calcined carbons may generally be included.
  • the silicon material is a general term for materials including silicon as a constituent element, and a simple substance of silicon is also included in the silicon-based material.
  • the silicon material includes at least one of silicon, silicon-carbon composite, or silicon oxide SiOx (0 ⁇ x ⁇ 2).
  • the active material layer further includes a binder.
  • the binder includes polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, modified polyvinylidene fluoride, modified SBR at least one of rubber or polyurethane.
  • the polyolefin-based binder includes at least one of polyethylene, polypropylene, polyalkene, polyenol, or polyacrylic acid.
  • the active material layer further includes a conductive agent
  • the conductive agent includes conductive carbon black, conductive graphite, carbon fiber, multi-walled carbon nanotubes, single-walled carbon nanotubes, hard carbon, soft carbon, At least one of Ketjen black or graphene.
  • the current collector includes a positive electrode current collector or a negative electrode current collector.
  • the negative electrode current collector may be copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with conductive metal, or a combination thereof.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil can be used.
  • the composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate.
  • the electrochemical device includes an electrolyte and a separator.
  • the electrolyte in the electrochemical device of the present application includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2.
  • LiPF 6 may be selected as a lithium salt because it can give high ion conductivity and improve cycle characteristics.
  • Non-aqueous solvent can be carbonate compound, carboxylate compound, ether compound, other organic solvents or their combination.
  • the above-mentioned carbonate compound can be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound or a combination thereof.
  • Examples of the aforementioned chain carbonate compounds are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), carbonic acid Methyl ethyl ester (MEC) and combinations thereof.
  • Examples of cyclic carbonate compounds are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), and combinations thereof.
  • fluorocarbonate compounds are fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate Ethyl carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-dicarbonate Fluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Ethyl carbonate 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • 1,2-dicarbonate Fluoro-1-methylethylene carbonate
  • Examples of the above carboxylate compounds are methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone , decanolactone, valerolactone, mevalonolactone, caprolactone, and combinations thereof.
  • ether compounds examples include dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethyl Oxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and combinations thereof.
  • Examples of the aforementioned other organic solvents are dimethylsulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, Formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters, and combinations thereof.
  • the material and shape of the separator used in the electrochemical device of the present application are not particularly limited, and it can be any technology disclosed in the prior art.
  • the separator includes a polymer or an inorganic material formed of a material stable to the electrolyte of the present application.
  • a release film may include a substrate layer and a surface treatment layer.
  • the substrate layer is non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer is at least one selected from polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • polypropylene porous film, polyethylene porous film, polypropylene non-woven fabric, polyethylene non-woven fabric or polypropylene-polyethylene-polypropylene porous composite film can be selected.
  • At least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic materials.
  • the inorganic layer includes inorganic particles and a binder, and the inorganic particles are selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, cerium oxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, At least one of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl alkoxy , polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene at least one.
  • Polymer is contained in the polymer layer, and the material of polymer is selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl alkoxide, polyvinylidene fluoride, At least one of poly(vinylidene fluoride-hexafluoropropylene).
  • the present application provides an electronic device, which includes the electrochemical device described in the first aspect.
  • electronic devices of the present application include, but are not limited to, notebook computers, pen-input computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets , VCR, LCD TV, Portable Cleaner, Portable CD Player, Mini Disc, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, Motorcycle, Assisted Bicycle, Bicycle , Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • the contact angle test method between the electrode pole piece and the electrolyte solution is: remove the electrode pole piece from the cell, wash it with DMC (dimethyl carbonate) for 30 minutes, dry it at 100°C for 4 hours, and dry the dried electrode Spread the pole piece horizontally on the glass plate; absorb DMC containing 1mol/L LiPF 6 with a needle tube, drop a drop on the horizontally placed electrode pole piece, and take pictures from the horizontal direction of the electrode pole piece in 10s to obtain an optical image.
  • the upper vertex of the edge of the droplet on the image, the left intersection point and the right intersection point of the droplet and the electrode pole piece are fitted to a circle, and the angle between the fitted circle and the electrode pole piece is the contact angle.
  • the test method of the membrane resistance of the electrode pole piece disassemble the fully charged battery, and keep the complete electrode pole piece; rinse the obtained electrode pole piece with dimethyl carbonate for 30 minutes, and dry it at 100°C for 4 hours ; Using a four-probe resistance instrument to test the membrane resistance of the dried electrode pole piece.
  • the resistance test terminal uses two cylindrical metal terminals with a diameter of 1.2 cm. During the test, the electrode pole piece is placed in the middle of the metal terminal plane, and 0.4 tons of pressure is applied to both ends of the terminal. The resistance value at the 5th second is taken as the electrode pole piece. membrane resistance value.
  • Cohesion test of the active material layer of the electrode pole piece and the current collector In a dry environment, the outer packaging of the battery cell is disassembled, and the separator, positive pole piece, and negative pole piece are separated. Cut the electrode sheet to be tested into a rectangular strip with a width of 1cm and a length of 5cm; glue one side of the strip of the cut electrode sheet on a flat plate with double-sided adhesive, and use a speed of 25mm/min along the vertical direction of the plate Tear off the long strip of the electrode sheet from the double-sided tape, and record the force F (unit: N) used when tearing off, then the bonding force between the active material layer of the electrode sheet and the current collector is 100F (unit: N). : N/m).
  • the test method of lithium-ion battery impedance charge the battery with a current of 0.2C (0.2 times the nominal capacity) to the full charge voltage, and then charge it with a constant voltage to a current of 0.05C; then discharge it to the full discharge voltage at 0.2C to obtain
  • the actual capacity C of the lithium-ion battery is real ; then fully charge the battery in the same way; then discharge the fully charged battery at a current of 0.1C for 5 hours, record the final voltage V 1 and the final current I 1 , and then Discharge the battery for 1 second with a current of 1C, record the final voltage V 2 and the final current I 2 , then the battery impedance is (V 1 -V 2 )/(I 2 -I 1 ).
  • the test method of the 2C discharge rate of the lithium-ion battery in the environment of 25 °C, charge the battery with a current of 0.2C to the full charge voltage, and then charge the battery with a constant voltage to the current of 0.05C; then discharge the battery to the full charge with a current of 0.2C Discharge current to obtain the discharge capacity C 0.2C ; then charge the battery with a current of 0.2C to the full charge voltage, then charge the battery to a current of 0.05C with a constant voltage, and then discharge the battery to a current of 2C to the full discharge current after standing for 30 minutes to obtain the discharge capacity C 2C ; then the discharge rate is C 2C /C 0.2C ⁇ 100%.
  • the test method of the cycle performance of the lithium-ion battery in the environment of 25 °C, charge the battery with a current of 1C to the full charge voltage, and then charge the battery with a constant voltage to a current of 0.05C; then discharge the battery with a current of 1C to the full discharge current, Obtain the discharge capacity C 1 ; then charge and discharge the battery repeatedly according to the above steps, and record the discharge capacity of the xth time as C x , then the capacity retention rate of the xth time is C x /C1 ⁇ 100%.
  • Preparation of positive electrode sheet fully stir and mix the positive active material, conductive agent, binder and optional inorganic salt nanowires in an appropriate amount of N-methylpyrrolidone (abbreviated as NMP) solvent to form a uniform
  • NMP N-methylpyrrolidone
  • the positive electrode slurry is coated on the positive electrode current collector Al foil, dried and cold pressed to obtain the positive electrode sheet.
  • the specific compositions of positive electrode active material, conductive agent, binder and inorganic salt nanowires in each embodiment and comparative example are shown in Table 1 to Table 9 below.
  • negative electrode sheet Fully stir and mix the negative electrode active material, conductive agent, optional binder and optional inorganic salt nanowires in an appropriate amount of water to form a uniform negative electrode slurry; mix the slurry The material is coated on the negative electrode current collector Cu foil, dried and cold pressed to obtain the negative electrode sheet.
  • Table 1 to Table 9 The compositions of specific negative electrode active materials, conductive agents, binders and inorganic salt nanowires in each embodiment and comparative example are shown in Table 1 to Table 9 below.
  • Lithium-ion batteries can be obtained by top-side sealing, coding, vacuum drying, electrolyte injection, high-temperature standing, and chemical formation of bare cells.
  • Table 1 shows the effect of the type of inorganic salt nanowires on the performance of the prepared electrode pole piece and the lithium ion battery comprising the electrode pole piece. in:
  • the positive electrode sheets of Examples 1-1 to 1-10 consist of: 97.4wt% lithium cobaltate (positive electrode active material), 0.8wt% polyvinylidene fluoride (viscosity binder), 1.4wt% conductive carbon black (conductive agent) and 0.4wt% inorganic salt nanowires;
  • the positive pole piece of comparative example 1-1 consists of: 97.8wt% lithium cobaltate (positive electrode active material), 0.8wt% Polyvinylidene fluoride (binder) and 1.4 wt% conductive carbon black (conductive agent).
  • the composition of the negative electrode sheet of Example 1-1 to Example 1-10 and Comparative Example 1-1 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl Base cellulose (CMC, binder) and 1.0 wt% styrene-butadiene rubber (SBR, binder).
  • Example 1-1 to Example 1-10 and Comparative Example 1-1 in Table 1 it can be seen that adding inorganic salt nanowires to the electrode sheet can reduce the ion polarization during the charging and discharging process of the battery. , improve the discharge rate performance and cycle performance of the battery. This is mainly due to the fact that the inorganic salt nanowires are adsorbed on the surface of the active material particles or overlapped between the active material particles, establishing a directional transport lithium ion transmission path, which enhances the conduction of lithium ions in the active material layer, thereby reducing the ion polarization during battery charging and discharging.
  • the ionic inorganic salt nanowires can reduce the ion polarization in the charging and discharging process of the battery to a certain extent. It is speculated that this type of inorganic salt nanowire structure has internal channels for lithium ion migration, and the transmission of lithium ions in these internal channels increases the conduction of lithium ions, thereby improving the rate performance and cycle performance of lithium-ion batteries. .
  • Table 2 shows the influence of the length, aspect ratio and specific surface area of the inorganic salt nanowires on the performance of the prepared electrode pole piece and the lithium ion battery comprising the electrode pole piece. in:
  • the composition of the positive electrode sheet of Example 2-1 to Example 2-14 is: 97.4wt% lithium cobaltate, 0.8wt% polyvinylidene fluoride, 1.4wt% conductive carbon black And 0.4wt% inorganic salt nanowires (hydroxyapatite);
  • the composition of the negative electrode sheet of embodiment 2-1 to embodiment 2-14 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl cellulose (CMC, binder) and 1.0 wt% styrene-butadiene rubber (SBR, binder).
  • Example 2-1 to Example 2-10 in Table 2 it can be seen that when the length of the inorganic salt nanowire is in the range of 0.04 ⁇ m to 20 ⁇ m and the aspect ratio is in the range of 10 to 2000, the electrode pole piece has a low The ionic impedance value of the corresponding lithium-ion battery has better rate performance and capacity retention. If the length of the inorganic salt nanowire is too small, the transmission path of lithium ions in the inorganic salt nanowire is too short, making little contribution to the conduction of lithium ions; The dispersion becomes worse, and the conduction contribution to lithium ions decreases. If the aspect ratio of inorganic salt nanowires is too small, its specific surface area will decrease, and the ability to accept and release lithium ions will be weakened; The conduction contribution drops.
  • Table 3 shows the effect of the content of the inorganic salt nanowires in the active material layer on the performance of the prepared electrode pole piece and the lithium ion battery comprising the electrode pole piece.
  • the composition of the negative electrode sheet of embodiment 3-1 to embodiment 3-6 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl cellulose (CMC, binder) and 1.0 wt% styrene-butadiene rubber (SBR, binder).
  • Example 3-1 to Example 3-6 in Table 3 it can be seen that when the mass content of inorganic salt nanowires is in the range of 0.1% to 5.0%, the electrode pole piece has a low ionic impedance value, corresponding Lithium-ion batteries have good rate performance and capacity retention. If the content of inorganic salt nanowires is too high, the transmission distance of lithium ions in the electrolyte and between particles will increase instead, and the electronic conductance will also be blocked to a certain extent, resulting in increased polarization and poor battery performance.
  • Table 4 shows the influence of the combination of inorganic salt nanowires and different positive electrode active materials on the performance of the prepared electrode pole piece and the lithium ion battery comprising the electrode pole piece.
  • Example 4-1 to Example 4-5 of Table 4 the same inorganic salt nanowire hydroxyapatite is added, wherein the length of hydroxyapatite is 0.1 ⁇ m, the aspect ratio is 25, and the specific surface area is 333m 2 /g.
  • the composition of the positive electrode sheet of Example 4-1 to Example 4-5 is: 97.4wt% positive electrode active material, 0.8wt% polyvinylidene fluoride, 1.4wt% conductive carbon black And 0.4wt% inorganic salt nanowire (hydroxyapatite);
  • the composition of the positive electrode sheet of comparative example 4-1 to comparative example 4-5 is: 97.8wt% positive electrode active material, 0.8wt% polyvinylidene fluoride and 1.4 wt% conductive carbon black.
  • the composition of the negative electrode sheets of Example 4-1 to Example 4-5, Comparative Example 4-1 to Comparative Example 4-5 is: 97.7wt% artificial graphite (negative electrode active material) , 1.3 wt% carboxymethyl cellulose (CMC, binder) and 1.0 wt% styrene-butadiene rubber (SBR, binder).
  • Table 5 shows the influence of the combination of inorganic salt nanowires and different negative electrode active materials on the performance of the prepared electrode pole piece and the lithium ion battery comprising the electrode pole piece.
  • the same inorganic salt nanowire hydroxyapatite is added in Example 5-1 to Example 5-5 of Table 5, wherein the length of hydroxyapatite is 0.1 ⁇ m, the aspect ratio is 25, and the specific surface area is 333m 2 /g.
  • the composition of the positive electrode sheets of Example 5-1 to Example 5-5 and Comparative Example 5-1 to Comparative Example 5-5 is: 97.8wt% lithium cobaltate, 0.8wt% Polyvinylidene fluoride and 1.4 wt% conductive carbon black.
  • the composition of the negative electrode sheet of Example 5-1 to Example 5-4 is: 97.3wt% negative electrode active material, 1.3wt% carboxymethyl cellulose, 1.0wt% styrene-butadiene rubber and 0.4 wt% hydroxyapatite.
  • the composition of the negative pole piece of embodiment 5-5 is: 96.3wt% negative electrode active material, 1.3wt% carboxymethyl cellulose, 1.0wt% styrene-butadiene rubber, 0.4wt% hydroxyapatite and 1.0wt% conductive carbon black .
  • composition of the negative electrode sheets of Comparative Example 5-1 to Comparative Example 5-4 is: 97.7wt% negative electrode active material, 1.3wt% carboxymethyl cellulose and 1.0wt% styrene-butadiene rubber.
  • the composition of the negative electrode sheet of Comparative Example 5-5 is: 96.7wt% negative electrode active material, 1.3wt% carboxymethyl cellulose, 1.0wt% styrene-butadiene rubber and 1.0wt% conductive carbon black.
  • Example 5-1 to Example 5-5 According to the comparison of Example 5-1 to Example 5-5 and Comparative Examples 5-1 to 5-5 in Table 5, it can be seen that adding inorganic salt nanowires to negative electrodes containing different types of negative electrode active materials can reduce The ionic impedance of the pole piece improves the rate performance and capacity retention of lithium-ion batteries. Inorganic salt nanowires have universal applicability in negative electrodes using different negative electrode active materials.
  • Table 6 shows the impact of the type of conductive agent and the type of binder in the negative electrode active material layer on the performance of the prepared electrode sheet and the lithium ion battery comprising the electrode sheet.
  • the composition of the positive electrode sheet of Example 6-1 to Example 6-14 is: 97.4wt% lithium cobaltate, 0.8wt% binder, 1.4wt% conductive agent and 0.4wt% % Hydroxyapatite.
  • the positive electrode slurry of Examples 6-12 to Examples 6-14 uses water as a solvent.
  • the composition of the negative electrode sheet of embodiment 6-1 to embodiment 6-14 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl cellulose and 1.0wt% % Styrene Butadiene Rubber.
  • Table 7 shows the influence of the contact angle between the electrode pole piece and the electrolyte solution on the performance of the lithium-ion battery.
  • the same inorganic salt nanowire hydroxyapatite was added to the positive pole piece of Example 7-1 to Example 7-5 in Table 7, and the thickness of the pole piece was adjusted to adjust the size of the contact angle.
  • hydroxyapatite has a length of 0.1 ⁇ m, an aspect ratio of 25, and a specific surface area of 333 m 2 /g.
  • Comparative Example 7-1 no inorganic salt nanowires were added.
  • the composition of the negative electrode sheet of Example 7-1 to Example 7-5 and Comparative Example 7-1 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl Base cellulose and 1.0 wt% styrene-butadiene rubber.
  • Table 8 shows the effect of the sheet resistance of the electrode pole piece and the ionic impedance on the performance of the lithium-ion battery.
  • hydroxyapatite has a length of 0.1 ⁇ m, an aspect ratio of 25, and a specific surface area of 333 m 2 /g.
  • Comparative Example 8-1 no inorganic salt nanowires were added.
  • the composition of the negative electrode sheet of Example 8-1 to Example 8-5 and Comparative Example 8-1 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl Base cellulose and 1.0 wt% styrene-butadiene rubber.
  • Table 9 shows the effect of the adhesion of the electrode sheet on the performance of the lithium-ion battery.
  • the same inorganic salt nanowire hydroxyapatite was added to the positive pole pieces of Example 9-1 to Example 9-5 in Table 9. Among them, hydroxyapatite has a length of 0.1 ⁇ m, an aspect ratio of 25, and a specific surface area of 333 m 2 /g. In Comparative Example 9-1, no inorganic salt nanowires were added.
  • polyacrylate is used instead of polyvinylidene fluoride, and the solvent in the positive electrode slurry is water.
  • the composition of the negative electrode sheet of Example 9-1 to Example 9-5 and Comparative Example 9-1 is: 97.7wt% artificial graphite (negative electrode active material), 1.3wt% carboxymethyl Base cellulose and 1.0 wt% styrene-butadiene rubber.

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Abstract

本申请涉及电化学装置和电子装置。本申请的电化学装置包括电极极片，所述电极极片包括集流体和活性物质层，所述活性物质层包括活性物质颗粒和无机盐纳米线，所述无机盐纳米线位于所述活性物质颗粒表面和/或所述无机盐纳米线的第一端和第二端位于不同的活性物质颗粒表面。本申请的电极极片中添加有低导电性、高导离子能力的无机盐纳米线，降低了电化学装置充放电过程中的离子极化，有效提升了电化学装置的放电倍率性能及循环性能。

Description

电化学装置及电子装置 技术领域
本申请涉及储能领域，具体涉及一种电化学装置及电子装置。
背景技术
作为一种新型储能装置，锂离子电池已在3C数码、电动工具、储能电网、航空航天等各领域得到广泛应用。而随着科技的发展，人们对锂离子电池性能的要求变得越来越高。随着电池容量越来越大，充电电流也越来越大，电池的极化现象不断增大，特别对于高体积能量密度的电芯，极片的密度大，内部孔隙少，锂离子在电解液中长距离传输的阻抗增大，进一步恶化了离子极化，使电池容量出现不可逆的降低。为提高电池的性能，正负极极片涂覆膜中一般需要加入导电剂增加极片的导电能力，从而降低电池的电子极化。但对于离子极化的降低，一直没有较好的办法。
发明内容
针对现有技术存在的问题，本申请提供一种电化学装置，该电化学装置中电极极片的离子极化低，使得其具有更高的放电倍率性能和循环性能。本申请还提供了包括该电化学装置的电子装置。
在第一方面，本申请提供了一种电化学装置，其包括电极极片，所述电极极片包括集流体和活性物质层，所述活性物质层包括活性物质颗粒和无机盐纳米线，所述无机盐纳米线位于所述活性物质颗粒表面和/或所述无机盐纳米线的第一端和第二端位于不同的活性物质颗粒表面。本申请通过在 电极极片中添加低导电性、高导离子能力的无机盐纳米线，该无机盐纳米线能够吸附在活性物质颗粒表面或桥接在活性物质颗粒之间，在活性物质间及活性物质与电解液间建立定向传输的锂离子传输通路，增强锂离子在活性物质层内的导通，进而降低充放电过程中的离子极化，使得包含该电极极片的电化学装置和电子装置拥有更好的放电倍率性能环和循环性能。特别是在循环后期电解液浸润不足情况下，无机盐纳米线能够充当“桥梁”作用，使不接触的活性物质表面与电解液仍能通过无机盐纳米线传输锂离子，极大的改善了电化学装置的循环性能。
根据本申请的一些实施方式，所述无机盐纳米线包括离子型无机盐纳米线中的至少一种。离子型无机盐纳米线的结构内部存在可供锂离子迁移的通道，锂离子在这些内部通道中的传输增加了锂离子的导通，进而可降低电化学装置在充放电过程中的离子极化，有效改善其倍率性能和循环性能。
根据本申请的一些实施方式，所述无机盐纳米线包括磷酸盐纳米线、钨酸盐纳米线、碳酸盐纳米线、硫酸盐纳米线、硅酸盐纳米线、硅铝酸盐纳米线、硼酸盐纳米线、硝酸盐纳米线、锆酸盐纳米线、钛酸盐纳米线或LLZTO纳米线中的至少一种。
根据本申请的一些实施方式，所述无机盐纳米线的长度为0.04μm至20μm，所述无机盐纳米线的长径比为10至2000。
根据本申请的一些实施方式，所述无机盐纳米线的长度为0.1μm至10μm，所述无机盐纳米线的长径比为20至1000。无机盐纳米线的长度过小，锂离子在无机盐纳米线中传输路径过短，对锂离子的导通贡献不大； 长度过大，无机盐纳米线难以舒展，易缠结团聚、断裂，同样无法有效增强锂离子的导通。无机盐纳米线的长径比过小，其比表面积减小，接受和释放锂离子的能力被削弱；长径比过高，则易发生自团聚，难以分散，导致锂离子的导通效果不佳。
根据本申请的一些实施方式，所述无机盐纳米线的比表面积(BET)为10m 2/g至500m 2/g。比表面积过大时，无机盐纳米线易团聚，导致分散不良，进而使得锂离子的导通效果不佳；比表面积过小时，颗粒过大，同质量下的数量减少，锂离子的导通效果也偏差。
根据本申请的一些实施方式，以活性物质层的总质量计，所述无机盐纳米线的质量含量为0.1％至5％。无机盐纳米线的含量过高，锂离子在电解液、颗粒间传输的距离反而增加，且电子电导也会受到一定的阻隔，导致极化增加，电化学装置的性能变差。
根据本申请的一些实施方式，所述电极极片满足以下条件(a)至(c)中的至少一者：(a)所述电极极片与电解质溶液的接触角≤45°，其中所述电解质溶液为含有1mol/L六氟磷酸锂的碳酸二甲酯；(b)所述电极极片的膜片电阻≤10Ω；(c)所述活性物质层与集流体之间的粘结力为1N/m至100N/m；(d)所述电极极片的离子阻抗≤40mΩ。
根据本申请的一些实施方式，所述电极极片与电解质溶液的接触角≤45°，其中所述电解质溶液为含有1mol/L六氟磷酸锂的碳酸二甲酯。接触角过大，极片与电解液的浸润性差，不利于电化学装置倍率性能和循环性能的提升。
根据本申请的一些实施方式，所述电极极片的膜片电阻≤10Ω。根据本 申请的一些实施方式，所述电极极片的离子阻抗≤40mΩ。极片膜片电阻以及离子阻抗过高均会增加电芯的极化，从而恶化电化学装置的倍率性能和循环性能。
根据本申请的一些实施方式，所述活性物质层与集流体之间的粘结力为1N/m至100N/m。粘接力过低，颗粒粘接变弱，导致电芯极化增加，从而恶化电化学装置的倍率性能和循环性能。
根据本申请的一些实施方式，所述活性物质包括正极活性物质或负极活性物质，所述正极活性物质包括磷酸铁锂、磷酸锰铁锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、锰酸锂、镍锰酸锂或钴锰酸锂中的至少一种，所述负极活性物质包括碳材料或硅材料中的至少一种。
根据本申请的一些实施方式，所述活性物质层还包括粘结剂和/或导电剂，所述粘结剂包括聚偏氟乙烯、聚四氟乙烯、聚烯烃类、羧甲基纤维素钠、羧甲基纤维素锂、改性聚偏氟乙烯、改性SBR橡胶或聚氨酯中的至少一种，所述导电剂包括导电炭黑、导电石墨、碳纤维、多壁碳纳米管、单壁碳纳米管、硬碳、软碳、科琴黑或石墨烯中的至少一种。
在第二方面，本申请提供了一种电子装置，其包括第一方面所述的电化学装置。
本申请通过在电极极片中添加低导电性、高导离子能力的无机盐纳米线，极大的降低了电化学装置在充放电过程中的离子极化，由此可显著改善电化学装置的放电倍率性能及循环性能，提升产品的竞争力。
具体实施方式
本申请的实施例将会被详细的描示在下文中。本申请的实施例不应该 被解释为对本申请的限制。
如本文中所使用，术语“约”用以描述及说明小的变化。当与事件或情形结合使用时，所述术语可指代其中事件或情形精确发生的例子以及其中事件或情形极近似地发生的例子。举例来说，当结合数值使用时，术语可指代小于或等于所述数值的±10％的变化范围，例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％。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。
由术语“中的至少一种”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中的至少一种”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中的至少一种”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可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
整个说明书中对“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。
在第一方面，本申请提供了一种电化学装置，其包括电极极片，所述电极极片包括集流体和活性物质层，所述活性物质层包括活性物质颗粒和无机盐纳米线，所述无机盐纳米线位于所述活性物质颗粒表面和/或所述无机盐纳米线的第一端和第二端位于不同的活性物质颗粒表面。
根据本申请的一些实施方式，所述电极极片为正极极片和/或负极极片。
常规电极极片的活性物质层中仅添加导电剂和粘接剂，这使得在高压实密度情况下，极片孔隙率变小，锂离子通道受阻。特别是活性物质层的颗粒接触区域内基本无孔隙，锂离子不能穿梭，致使电化学装置的离子极化增加。本申请通过在电极极片中添加低导电性，高导离子能力的无机盐纳米线，所述无机盐纳米线能够吸附在活性物质颗粒表面或桥接在活性物质颗粒之间，在活性物质间及活性物质与电解液间建立定向传输的锂离子传输通路，增强锂离子在活性物质层内的导通，进而降低充放电过程中的离子极化，使得包含该电极极片的电化学装置和电子装置拥有更好的放电倍率性能环和循环性能。特别是在循环后期电解液浸润不足情况下，无机盐纳米线能够充当“桥梁”作用，使不接触的活性物质表面与电解液仍能通过无机盐纳米线传输锂离子，极大的改善了电化学装置的循环性能。
根据本申请的一些实施方式，所述无机盐纳米线包括离子型无机盐纳米线中的至少一种。离子型无机盐纳米线的结构内部存在可供锂离子迁移的通道，锂离子在这些内部通道中的传输增加了锂离子的导通，进而可降 低电化学装置在充放电过程中的离子极化，有效改善其倍率性能和循环性能。
根据本申请的一些实施方式，所述无机盐纳米线包括磷酸盐纳米线、钨酸盐纳米线、碳酸盐纳米线、硫酸盐纳米线、硅酸盐纳米线、硅铝酸盐纳米线、硼酸盐纳米线、硝酸盐纳米线、锆酸盐纳米线、钛酸盐纳米线或LLZTO纳米线中的至少一种。
在本申请的一些实施例中，磷酸盐纳米线包括羟基磷灰石纳米线、氟磷灰石纳米线、氯磷灰石纳米线、氧硅磷灰石纳米线、锶磷灰石纳米线或锂磷灰石纳米线中的至少一种。在一些实施例中，钨酸盐纳米线包括钨酸钡纳米线和/或钨酸铅纳米线。在一些实施例中，碳酸盐纳米线包括碳酸锶纳米线和/或碳酸钡纳米线。在一些实施例中，硫酸盐线包括硫酸钙纳米线和/或硫酸钡纳米线。
根据本申请的一些实施方式，所述无机盐纳米线的长度为0.04μm至20μm。无机盐纳米线的长度过小，锂离子在无机盐纳米线中传输路径过短，对锂离子的导通贡献不大；长度过大，无机盐纳米线难以舒展，易缠结团聚、断裂，同样无法有效增强锂离子的导通。
在一些实施例中，无机盐纳米线的长度为0.2μm、0.3μm、0.5μm、0.7μm、0.9μm、1.0μm、1.5μm、2.0μm、2.5μm、3.0μm、3.5μm、4.0μm、4.5μm、5.0μm、5.5μm、6.0μm、7.0μm、7.5m、8.0μm、9.0μm、10μm、11μm、12μm、13μm、14μm、15μm、17μm、19μm或这些值中任意两者组成的范围。在一些实施例中，无机盐纳米线的长度为0.1μm至10μm。在一些实施例中，无机盐纳米线的长度为1μm至5μm。
根据本申请的一些实施方式，所述无机盐纳米线的长径比为10至2000。无机盐纳米线的长径比过小，其比表面积减小，接受和释放锂离子的能力被削弱；长径比过高，则易发生自团聚，难以分散，导致锂离子的导通效果不佳。
在一些实施例中，无机盐纳米线的长径比为20、50、100、150、200、250、300、350、400、450、500、550、600、650、700、800、900、1000、1200、1400、1500、1700、1900或这些值中任意两者组成的范围。在一些实施例中，无机盐纳米线的长径比20至1000。在一些实施例中，无机盐纳米线的长径比100至700。
根据本申请的一些实施方式，所述无机盐纳米线的比表面积为10m 2/g至500m 2/g。BET测试方法可使用国标GB/T 19587-2004气体吸附BET法。比表面积过大时，无机盐纳米线易团聚，导致分散不良，进而使得锂离子的导通效果不佳；比表面积过小时，颗粒过大，同质量下的数量减少，锂离子的导通效果也偏差。
在一些实施例中，无机盐纳米线的比表面积为20m 2/g、50m 2/g、100m 2/g、150m 2/g、200m 2/g、250m 2/g、300m 2/g、350m 2/g、400m 2/g、450m 2/g或这些值中任意两者组成的范围。在一些实施例中，无机盐纳米线的比表面积为50m 2/g至400m 2/g。
根据本申请的一些实施方式，以活性物质层的总质量计，所述无机盐纳米线的质量含量为0.1％至5％。无机盐纳米线的含量过高，锂离子在电解液、颗粒间传输的距离反而增加，且电子电导也会受到一定的阻隔，导致极化增加，电化学装置的性能变差。在一些实施例中，无机盐纳米线的 质量含量为0.2％、0.4％、0.6％、0.8％、1.0％、1.2％、1.4％、1.6％、1.8％、2.0％、2.2％、2.5％、2.7％、2.9％、％、3.0％、3.2％、3.5％、3.8％、4.0％、4.2％、4.5％、4.7％或这些值中任意两者组成的范围。
根据本申请的一些实施方式，所述电极极片与电解质溶液的接触角≤45°，其中所述电解质溶液为含有1mol/L六氟磷酸锂的碳酸二甲酯。接触角过大，极片与电解液的浸润性差，不利于电化学装置倍率性能和循环性能的提升。在一些实施例中，所述电极极片与电解质溶液的接触角为10°、15°、20°、23°、25°、27°、30°、32°、34°、35°、37°、39°、40°、43°或这些值中任意两者组成的范围。
根据本申请的一些实施方式，所述电极极片的膜片电阻≤10Ω，例如0.5Ω、1.0Ω、2.0Ω、3.0Ω、4.0Ω、5.0Ω、6.0Ω、7.0Ω、8.0Ω、9.0Ω或这些值中任意两者组成的范围。根据本申请的一些实施方式，所述电极极片的离子阻抗≤40mΩ，例如为3mΩ、5mΩ、7mΩ、10mΩ、15mΩ、20mΩ、23mΩ、25mΩ、27mΩ、30mΩ、32mΩ、34mΩ、36mΩ、38mΩ或这些值中任意两者组成的范围。极片膜片电阻以及离子阻抗过高均会增加电芯的极化，从而恶化电化学装置的倍率性能和循环性能。
根据本申请的一些实施方式，所述电极极片中，活性物质层与集流体之间的粘结力为1N/m至100N/m。粘接力过低，颗粒粘接变弱，导致电芯极化增加，从而恶化电化学装置的倍率性能和循环性能。在一些实施例中，活性物质层与集流体之间的粘结力为2N/m、3N/m、4N/m、5N/m、6N/m、7N/m、8N/m、9N/m、10N/m、15N/m、20N/m、30N/m、40N/m、50N/m、60N/m、70N/m、80N/m、90N/m或这些值中任意两者组成的范 围。
根据本申请的一些实施方式，所述活性物质包括正极活性物质或负极活性物质。
根据本申请的一些实施方式，所述正极活性物质包括锂过渡金属磷酸化合物、磷酸盐化合物或锂过渡金属复合氧化物中的至少一种。在一些实施例中，正极活性物质包括锂过渡金属系化合物，其具有能够脱离、插入锂离子的结构。在一些实施例中，所述正极活性物质包括磷酸铁锂、磷酸锰铁锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、锰酸锂、镍锰酸锂或钴锰酸锂中的至少一种。
根据本申请的一些实施方式，所述负极活性物质包括碳材料或硅材料中的至少一种。在一些实施例中，碳材料可以是在锂离子可再充电电化学装置中通常使用的任何碳基负极活性物质。碳材料的示例包括结晶碳、非晶碳和它们的组合。结晶碳可以是无定形的或板形的、小片形的、球形的或纤维形的天然石墨或人造石墨。非晶碳可以是软碳、硬碳、中间相沥青碳化产物、烧制焦炭等。低结晶碳和高结晶碳均可以用作碳材料。作为低结晶碳材料，可通常包括软碳和硬碳。作为高结晶碳材料，可通常包括天然石墨、结晶石墨、热解碳、中间相沥青基碳纤维、中间相碳微珠、中间相沥青和高温锻烧炭(如石油或衍生自煤焦油沥青的焦炭)。
根据本申请的一些实施方式，所述硅材料包含硅作为构成元素的材料的总称，在该硅系材料中也包含硅的单质。在一些实施例中，硅材料包括硅、硅碳复合物或硅氧化物SiOx(0<x<2)中的至少一种。
根据本申请的一些实施方式，所述活性物质层还包括粘结剂。在一些实施例中，所述粘结剂包括聚偏氟乙烯、聚四氟乙烯、聚烯烃类、羧甲基纤维素钠、羧甲基纤维素锂、改性聚偏氟乙烯、改性SBR橡胶或聚氨酯中的至少一种。在一些实施例中，聚烯烃类粘结剂包括聚乙烯、聚丙烯、聚烯酯、聚烯醇或聚丙烯酸中的至少一种。
根据本申请的一些实施方式，所述活性物质层还包括导电剂，所述导电剂包括导电炭黑、导电石墨、碳纤维、多壁碳纳米管、单壁碳纳米管、硬碳、软碳、科琴黑或石墨烯中的至少一种。
根据本申请的一些实施方式，所述集流体包括正极集流体或负极集流体。在一些实施例中，所述负极集流体可以为铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、包覆有导电金属的聚合物基板或它们的组合。在一些实施例中，所述正极极集流体可以采用金属箔片或复合集流体。例如，可以使用铝箔。复合集流体可以通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子基材上而形成。
根据本申请的一些实施方式，所述电化学装置包括电解液和隔离膜。
在一些实施方式中，本申请的电化学装置中电解液包括锂盐和非水溶剂。
在本申请一些实施方案中，锂盐选自LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiSiF 6、LiBOB和二氟硼酸锂中的一种或多种。举例来说，锂盐可以选用LiPF 6，因为它可以给出高的离子导电率并改善循环特性。
非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂 或它们的组合。
上述碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸酯化合物或其组合。
上述链状碳酸酯化合物的实例为碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)及其组合。环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)及其组合。氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯、碳酸三氟甲基亚乙酯及其组合。
上述羧酸酯化合物的实例为甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯、己内酯及其组合。
上述醚化合物的实例为二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃、四氢呋喃及其组合。
上述其它有机溶剂的实例为二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯、和磷酸酯及其组合。
本申请的电化学装置中使用的隔离膜的材料和形状没有特别限制，其 可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的至少一种。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、聚乙烯呲咯烷酮、聚乙烯烷氧、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的至少一种。
聚合物层中包含聚合物，聚合物的材料选自聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯烷氧、聚偏氟乙烯、聚(偏氟乙烯-六氟丙烯)中的至少一种。
在第二方面，本申请提供了一种电子装置，其包括第一方面所述的电化学装置。
本申请的电子设备或装置没有特别限定。在一些实施例中，本申请的电子设备包括但不限于，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。
下面结合实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。
测试方法
1、电极极片与电解质溶液的接触角测试方法为：将电极极片从电芯中拆除，用DMC(碳酸二甲酯)洗涤30min，在100℃下烘干4h，将烘干后的电极极片水平铺于玻璃板上；用针管吸取含有1mol/L LiPF 6的DMC后，滴一滴在水平放置的电极极片上，10s时从电极极片的水平方向拍照，得到光学图像。以图像上的液滴边缘的上顶点，液滴与电极极片的左交点、右交点拟合圆形，拟合圆形与电极极片的夹角即为接触角。
2、电极极片的膜片电阻的测试方法：将满放的电池进行拆解，保留完整的电极极片；将得到的电极极片用碳酸二甲酯漂洗30min，在100℃下烘干4h；采用四探针电阻仪器测试烘干后的电极极片的膜片电阻。具体地，电阻测试端子使用两个直径1.2cm的圆柱金属端子，测试时将电极极片置于金属端子平面中间，端子两端施加0.4吨压力，取第5秒的电阻值作为电 极极片的膜片电阻值。
3、电极极片的活性物质层与集流体的粘结力测试：在干燥环境中，将电芯外包装拆开，将隔离膜、正极极片、负极极片拆分开。将待测电极极片裁剪成宽1cm、长5cm的长方形长条；将裁剪后的电极极片的长条的一面用双面胶粘在一个平板上，沿平板垂直方向用25mm/min的速度将电极极片的长条从双面胶上撕下，并记录撕下时所使用的力F(单位：N)，则电极极片的活性物质层与集流体的粘结力为100F(单位：N/m)。
4、电极极片的离子阻抗(Rct)的测试：在干燥环境下，在电芯的尾部小心将外包装剪出一道小口，其中，正极极片为待测极片。将包裹着PE隔离膜的参比电极(一般为铜丝)伸入到极片折叠区域，置于隔离膜与负极极片间，随后用环氧树脂密封胶密封，制备成三电极电芯。
25℃下，将上述三电极电芯放电到50％SOC(充电电荷状态为满充电荷状态的一半)，以电芯正极为正极，参比电极为负极，10μA充电30min；再以电芯负极为正极，参比电极为负极，10μA充电30min完成参比电极镀锂；再将三电极电芯中的正极极片与参比电极连接，以5mV为扰动电压，测试扰动频率30mHz至100kHz间的虚部和实部的阻抗；以虚部阻抗为Y轴，实部阻抗为X轴做直角坐标系并作图，则与X轴相交处到图像最右边的拐点的X轴坐标差就是待测极片的Rct(极片的离子阻抗)。
5、锂离子电池阻抗的测试方法：将电池以0.2C(0.2倍标称容量的电流)电流充到满充电压，再恒定电压充电到0.05C电流；再0.2C放电到满放电压，得到锂离子电池的实际容量C 实；再以相同的方式将电池充满电；再将满充的电池以0.1C 实的电流放电5小时，记录结束的电压V 1，结束的 电流I 1，再将电池以1C 实的电流放电1s，记录结束的电压V 2，结束的电流I 2，则电池阻抗为(V 1-V 2)/(I 2-I 1)。
6、锂离子电池的2C放电倍率的测试方法：在25℃环境下，将电池以0.2C电流充到满充电压，再恒定电压充电到0.05C电流；再将电池以0.2C电流放电到满放电流，得到放电容量C 0.2C；再将电池0.2C电流充到满充电压，再恒定电压充电到0.05C电流，静置30min后再将电池以2C电流放电到满放电流，得到放电容量C 2C；则放电倍率为C 2C/C 0.2C×100％。
7、锂离子电池的循环性能的测试方法：在25℃环境下，将电池以1C电流充到满充电压，再恒定电压充电到0.05C电流；再将电池以1C电流放电到满放电流，得到放电容量C 1；再将电池按上述步骤重复充放电，第x次的放电容量记作C x，则第x次的容量保持率为C x/C1×100％。
实施例及对比例
1、正极极片的制备：将正极活性物质、导电剂、粘结剂以及可选的无机盐纳米线在适量的N-甲基吡咯烷酮(简写为NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料；将此浆料涂覆于正极集流体Al箔上，烘干、冷压，得到正极极片。各实施例与对比例中具体的正极活性物质、导电剂、粘结剂及无机盐纳米线的组成详见下表1至表9。
2、负极极片的制备：将负极活性物质、导电剂、可选的粘结剂以及可选的无机盐纳米线在适量的水中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于负极集流体Cu箔上，烘干、冷压，得到负极极片。各实施例与对比例中具体的负极活性物质、导电剂、粘结剂及无机盐纳米线的组 成详见下表1至表9。
3、电解液的制备：在干燥氩气气氛中，将有机溶剂碳酸乙烯酯、碳酸甲乙酯和碳酸二乙酯以质量比EC︰EMC︰DEC＝30︰50︰20混合得到有机溶液，然后向有机溶剂中加入锂盐六氟磷酸锂溶解并混合均匀，得到锂盐的浓度为1.15Mol/L的电解液。
4、锂离子电池的制备：正极极片和负极极片经激光模切、分条后进行卷绕，正极极片和负极极片之间以PE隔离膜进行分隔，从而制备得到卷绕裸电芯。裸电芯经顶侧封、喷码、真空干燥、注入电解液、高温静置后进行化成等工序，即可得到锂离子电池。
表1示出了无机盐纳米线种类对所制备得到的电极极片以及包含所述电极极片的锂离子电池的性能影响。其中：
以正极活性物质层的质量计，实施例1-1至实施例1-10的正极极片的组成为：97.4wt％钴酸锂(正极活性物质)、0.8wt％聚偏二氟乙烯(粘结剂)、1.4wt％导电炭黑(导电剂)以及0.4wt％无机盐纳米线；对比例1-1的正极极片组成为：97.8wt％钴酸锂(正极活性物质)、0.8wt％聚偏二氟乙烯(粘结剂)以及1.4wt％导电炭黑(导电剂)。
以负极活性物质层的质量计，实施例1-1至实施例1-10、对比例1-1的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素(CMC、粘结剂)以及1.0wt％丁苯橡胶(SBR、粘结剂)。
表1
Figure PCTCN2021102399-appb-000001
根据表1中的实施例1-1至实施例1-10与对比例1-1的对比可以看出，在电极极片中添加无机盐纳米线，可以降低电池充放电过程中的离子极化，提升电池的放电倍率性能及循环性能。这主要是由于无机盐纳米线吸附在活性物质颗粒表面或搭接在活性物质颗粒之间，建立了的定向传输的锂离子传输通路，增强了锂离子在活性物质层内的导通，进而降低了电池充放电过程中的离子极化。
根据表1中的实施例1-1与实施例1-10可以看出，离子型的无机盐纳米线均可以在一定程度上降低电池充放电过程中的离子极化。推测是因为此类型的无机盐纳米线结构内部存在可供锂离子迁移的通道，锂离子在这些内部通道中的传输增加了锂离子的导通，进而改善了锂离子电池的倍率性能和循环性能。
表2示出了无机盐纳米线的长度、长径比以及比表面积对所制备得到的电极极片以及包含所述电极极片的锂离子电池的性能影响。其中：
以正极活性物质层的质量计，实施例2-1至实施例2-14的正极极片的组成为：97.4wt％钴酸锂、0.8wt％聚偏二氟乙烯、1.4wt％导电炭黑以及0.4wt％无机盐纳米线(羟基磷灰石)；
以负极活性物质层的质量计，实施例2-1至实施例2-14的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素(CMC、粘结剂)以及1.0wt％丁苯橡胶(SBR、粘结剂)。
表2
Figure PCTCN2021102399-appb-000002
根据表2中的实施例2-1至实施例2-10的数据可以看出，无机盐纳米 线的长度在0.04μm至20μm、长径比在10至2000范围内时，电极极片具有低的离子阻抗值，相应的锂离子电池具有较好的倍率性能和容量保持率。无机盐纳米线的长度过小，锂离子在无机盐纳米线中传输路径过短，对锂离子的导通贡献不大；长度过大，无机盐纳米线容易缠绕、断裂，使其在极片中的分散变差，对锂离子的导通贡献降低。无机盐纳米线的长径比过小，其比表面积减小，接受和释放锂离子的能力被削弱；长径比过高，无机盐纳米线容易团聚，分散困难，难以均匀分散，对锂离子的导通贡献下降。
根据表2中的实施2-11至实施例2-14的数据可以看出，无机盐纳米线的比表面积在10m 2/g至500m 2/g范围内时，锂离子电池的倍率性能和容量保持率较优。比表面积过大时，无机盐纳米线易团聚，导致分散不良，进而使得锂离子的导通效果不佳；比表面积过小时，颗粒过大，同质量下的数量减少，锂离子的导通效果也偏差。
表3示出了无机盐纳米线在活性物质层内的含量对所制备得到的电极极片以及包含所述电极极片的锂离子电池的性能影响。在表3的实施例3-1至实施例3-6的正极极片中添加相同的无机盐纳米线羟基磷灰石，其中，羟基磷灰石的长度为0.1μm，长径比为25，比表面积为333m 2/g。
以负极活性物质层的质量计，实施例3-1至实施例3-6的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素(CMC、粘结剂)以及1.0wt％丁苯橡胶(SBR、粘结剂)。
表3
Figure PCTCN2021102399-appb-000003
根据表3中的实施例3-1至实施例3-6的数据可以看出，无机盐纳米线的质量含量在0.1％至5.0％范围内时，电极极片具有低的离子阻抗值，相应的锂离子电池具有较好的倍率性能和容量保持率。无机盐纳米线的含量过高，锂离子在电解液、颗粒间传输的距离反而增加，且电子电导也会受到一定的阻隔，导致极化增加，电池性能变差。
表4示出了采用无机盐纳米线与不同的正极活性物质的配合时对所制备得到的电极极片以及包含所述电极极片的锂离子电池的性能影响。在表4的实施例4-1至实施例4-5中添加相同的无机盐纳米线羟基磷灰石，其中，羟基磷灰石的长度为0.1μm，长径比为25，比表面积为333m 2/g。
以正极活性物质层的质量计，实施例4-1至实施例4-5的正极极片的组成为：97.4wt％正极活性物质、0.8wt％聚偏二氟乙烯、1.4wt％导电炭黑以及0.4wt％无机盐纳米线(羟基磷灰石)；对比例4-1至对比例4-5的正极 极片的组成为：97.8wt％正极活性物质、0.8wt％聚偏二氟乙烯以及1.4wt％导电炭黑。
以负极活性物质层的质量计，实施例4-1至实施例4-5、对比例4-1至对比例4-5的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素(CMC、粘结剂)以及1.0wt％丁苯橡胶(SBR、粘结剂)。
表4
Figure PCTCN2021102399-appb-000004
根据表4中的实施例4-1至实施例4-5与对比例4-1至4-5的对比可以看出，在含有不同类型正极活性材料的正极中添加无机盐纳米线均可以降低极片的离子阻抗，提高锂离子电池的倍率性能和容量保持率。无机盐纳米线在采用不同正极活性物质的正极中具有普适性。
表5示出了采用无机盐纳米线与不同的负极活性物质的配合时对所制 备得到的电极极片以及包含所述电极极片的锂离子电池的性能影响。在表5的实施例5-1至实施例5-5中添加相同的无机盐纳米线羟基磷灰石，其中，羟基磷灰石的长度为0.1μm，长径比为25，比表面积为333m 2/g。
以正极活性物质层的质量计，实施例5-1至实施例5-5、对比例5-1至对比例5-5的正极极片的组成为：97.8wt％钴酸锂、0.8wt％聚偏二氟乙烯以及1.4wt％导电炭黑。
以负极活性物质层的质量计，实施例5-1至实施例5-4的负极极片的组成为：97.3wt％负极活性物质、1.3wt％羧甲基纤维素、1.0wt％丁苯橡胶以及0.4wt％羟基磷灰石。实施例5-5的负极极片的组成为：96.3wt％负极活性物质、1.3wt％羧甲基纤维素、1.0wt％丁苯橡胶、0.4wt％羟基磷灰石以及1.0wt％导电炭黑。
对比例5-1至对比例5-4的负极极片的组成为：97.7wt％负极活性物质、1.3wt％羧甲基纤维素以及1.0wt％丁苯橡胶。对比例5-5的负极极片的组成为：96.7wt％负极活性物质、1.3wt％羧甲基纤维素、1.0wt％丁苯橡胶以及1.0wt％导电炭黑。
表5
Figure PCTCN2021102399-appb-000005
Figure PCTCN2021102399-appb-000006
根据表5中的实施例5-1至实施例5-5与对比例5-1至5-5的对比可以看出，在含有不同类型负极活性材料的负极中添加无机盐纳米线均可以降低极片的离子阻抗，提高锂离子电池的倍率性能和容量保持率。无机盐纳米线在采用不同负极活性物质的负极中具有普适性。
表6示出了负极活性物层中导电剂种类和粘结剂种类对所制备得到的电极极片以及包含所述电极极片的锂离子电池的性能影响。在表6的实施例6-1至实施例6-14的正极极片中添加相同的无机盐纳米线羟基磷灰石，其中，羟基磷灰石的长度为0.1μm，长径比为25，比表面积为333m 2/g。
以正极活性物质层的质量计，实施例6-1至实施例6-14的正极极片的组成为：97.4wt％钴酸锂、0.8wt％粘接剂、1.4wt％导电剂以及0.4wt％羟基磷灰石。其中实施例6-12至实施例6-14的正极浆料采用水作为溶剂。
以负极活性物质层的质量计，实施例6-1至实施例6-14的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素以及1.0wt％丁苯橡胶。
表6
Figure PCTCN2021102399-appb-000007
表7示出了电极极片与电解质溶液的接触角对锂离子电池的性能影响。在表7的实施例7-1至实施例7-5的正极极片中添加相同的无机盐纳米线羟基磷灰石，并调整极片的厚度来调整接触角的大小。其中，羟基磷灰石 的长度为0.1μm，长径比为25，比表面积为333m 2/g。对比例7-1中不添加无机盐纳米线。
以负极活性物质层的质量计，实施例7-1至实施例7-5、对比例7-1的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素以及1.0wt％丁苯橡胶。
表7
Figure PCTCN2021102399-appb-000008
根据表7中的数据可以看出，接触角过大，极片与电解液的浸润性差，不利于锂离子电池的倍率和循环性能。
表8示出了电极极片的膜片电阻以及离子阻抗对锂离子电池的性能影响。在表8的实施例8-1至实施例8-5的正极极片中添加相同的无机盐纳米线羟基磷灰石，并调整极片的厚度来调整接触角的大小，调整无机盐纳米线和导电剂的含量调控膜片电阻。其中，羟基磷灰石的长度为0.1μm，长径比为25，比表面积为333m 2/g。对比例8-1中不添加无机盐纳米线。
以负极活性物质层的质量计，实施例8-1至实施例8-5、对比例8-1的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤维素以及1.0wt％丁苯橡胶。
表8
Figure PCTCN2021102399-appb-000009
根据表8中的数据可以看出，膜片电阻以及离子阻抗过高均会增加电芯的极化，从而恶化锂离子电池的倍率和循环性能。
表9示出了电极极片的粘结力对锂离子电池的性能影响。在表9的实施例9-1至实施例9-5的正极极片中添加相同的无机盐纳米线羟基磷灰石。其中，羟基磷灰石的长度为0.1μm，长径比为25，比表面积为333m 2/g。对比例9-1中不添加无机盐纳米线。其中实施例9-4中采用聚丙烯酸酯代替聚偏氟乙烯，正极浆料中的溶剂为水。
以负极活性物质层的质量计，实施例9-1至实施例9-5、对比例9-1的负极极片的组成为：97.7wt％人造石墨(负极活性物质)、1.3wt％羧甲基纤 维素以及1.0wt％丁苯橡胶。
表9
Figure PCTCN2021102399-appb-000010
根据表9中的数据可以看出，粘接力过低，颗粒粘接变弱，导致电芯极化增加，从而恶化锂离子电池的倍率和循环性能。
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。

Claims (10)

  1. 一种电化学装置，包括电极极片，所述电极极片包括集流体和活性物质层，所述活性物质层包括活性物质颗粒和无机盐纳米线，所述无机盐纳米线位于所述活性物质颗粒表面和/或所述无机盐纳米线的第一端和第二端位于不同的活性物质颗粒表面。
  2. 根据权利要求1所述的电化学装置，其中，所述无机盐纳米线包括离子型无机盐纳米线中的至少一种。
  3. 根据权利要求1所述的电化学装置，其中，所述无机盐纳米线包括磷酸盐纳米线、钨酸盐纳米线、碳酸盐纳米线、硫酸盐纳米线、硅酸盐纳米线、硅铝酸盐纳米线、硼酸盐纳米线、硝酸盐纳米线、锆酸盐纳米线、钛酸盐纳米线或LLZTO纳米线中的至少一种。
  4. 根据权利要求1所述的电化学装置，其中，所述无机盐纳米线的长度为0.04μm至20μm，所述无机盐纳米线的长径比为10至2000。
  5. 根据权利要求1所述的电化学装置，其中，所述无机盐纳米线的长度为0.1μm至10μm，所述无机盐纳米线的长径比为20至1000。
  6. 根据权利要求1所述的电化学装置，其中，所述无机盐纳米线的比表面积为10m 2/g至500m 2/g。
  7. 根据权利要求1所述的电化学装置，其中，以活性物质层的总质量计，所述无机盐纳米线的质量含量为0.1％至5％。
  8. 根据权利要求1所述的电化学装置，其中，所述电极极片满足以下条件(a)至(d)中的至少一者：
    (a)所述电极极片与电解质溶液的接触角≤45°，其中所述电解质溶 液为含有1mol/L六氟磷酸锂的碳酸二甲酯；
    (b)所述电极极片的膜片电阻≤10Ω；
    (c)所述活性物质层与集流体之间粘结力为1N/m至100N/m；
    (d)所述电极极片的离子阻抗≤40mΩ。
  9. 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(e)至(f)的至少一者：
    (e)所述活性物质包括正极活性物质或负极活性物质，所述正极活性物质包括磷酸铁锂、磷酸锰铁锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、锰酸锂、镍锰酸锂或钴锰酸锂中的至少一种，
    所述负极活性物质包括碳材料或硅材料中的至少一种；
    (f)所述活性物质层还包括粘结剂和/或导电剂，
    所述粘结剂包括聚偏氟乙烯、聚四氟乙烯、聚烯烃类、羧甲基纤维素钠、羧甲基纤维素锂、改性聚偏氟乙烯、改性SBR橡胶或聚氨酯中的至少一种，
    所述导电剂包括导电炭黑、导电石墨、碳纤维、多壁碳纳米管、单壁碳纳米管、硬碳、软碳、科琴黑或石墨烯中的至少一种。
  10. 一种电子装置，其包括权利要求1至9中任一项所述的电化学装置。
PCT/CN2021/102399 2021-06-25 2021-06-25 电化学装置及电子装置 Ceased WO2022267013A1 (zh)

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