WO2022266800A1 - 负极、电化学装置和电子装置 - Google Patents

负极、电化学装置和电子装置 Download PDF

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WO2022266800A1
WO2022266800A1 PCT/CN2021/101237 CN2021101237W WO2022266800A1 WO 2022266800 A1 WO2022266800 A1 WO 2022266800A1 CN 2021101237 W CN2021101237 W CN 2021101237W WO 2022266800 A1 WO2022266800 A1 WO 2022266800A1
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Prior art keywords
negative electrode
active material
electrode active
carbon
lithium
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PCT/CN2021/101237
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English (en)
French (fr)
Inventor
郑子桂
杜鹏
谢远森
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宁德新能源科技有限公司
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Priority to CN202180005821.2A priority Critical patent/CN114631204A/zh
Priority to PCT/CN2021/101237 priority patent/WO2022266800A1/zh
Publication of WO2022266800A1 publication Critical patent/WO2022266800A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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 application relates to the field of electrochemical energy storage, in particular to negative electrodes, electrochemical devices and electronic devices.
  • the negative electrode made of graphite has high sheet resistance and poor fast charging performance.
  • some high-gram capacity such as: silicon-based negative electrode materials, tin-based negative electrode materials, hard carbon materials, etc.
  • anode materials to replace the commonly used graphite however, these high gram-capacity anode materials also bring some new problems, and further improvements are expected.
  • Some embodiments of the present application provide a negative electrode, including a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, and the bonding between the negative electrode active material layer and the negative electrode current collector The force is greater than or equal to 7N/m.
  • the binding force between the negative electrode active material layer and the negative electrode current collector is greater than or equal to 10 N/m.
  • the negative active material includes hard carbon.
  • At least one of the conditions (a) to (d) is satisfied: (a) carbon materials are grown in situ on the surface of the negative electrode active material; (b) the Dv50 of the negative electrode active material is 6 ⁇ m to 20 ⁇ m; (c) the negative electrode active material also includes nitrogen and transition metal elements; (d) the cohesion of the negative electrode active material is 5N/m to 100N/m.
  • the carbon material includes at least one of a fibrous carbon material, a flake carbon material, or a granular carbon material;
  • the mass of the transition metal element in the negative electrode active material is 0.1% to 10%, and the mass of the nitrogen element in the negative electrode active material is 0.1% to 5%;
  • the transition metal The element includes at least one of Co, Fe, Cr, Pt, Cu, Mn, Ag, Ni or Zn;
  • the mass percentage of the nitrogen element or the transition metal element in the negative electrode active material particle The content gradually decreases from the surface of the negative electrode active material particle to the center of the negative electrode active material particle.
  • At least one of the conditions (i) to (k) is satisfied: (i) the fibrous carbon material has a diameter of 50 nm to 500 nm and a length > 1 ⁇ m; (j) the sheet carbon material The length of >1 ⁇ m; (k) the average particle diameter of the granular carbon material is 50nm to 500nm.
  • Some embodiments of the present application provide an electrochemical device, which includes an electrolyte, a separator, a positive electrode, and any one of the above-mentioned negative electrodes, and the separator is disposed between the positive electrode and the negative electrode.
  • the electrolyte includes at least one of fluoroether, fluoroethylene carbonate, or ether nitrile.
  • the electrolyte solution includes a lithium salt, the lithium salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, the concentration of the lithium salt is 1mol/L to 2mol/L, and the bis(fluorosulfonyl)imide The molar ratio of lithium and lithium hexafluorophosphate is 0.05 to 4.
  • An embodiment of the present application also provides an electronic device, including the above-mentioned electrochemical device.
  • the embodiments of the present application improve the bonding force between the negative electrode active material layer and the negative electrode current collector, making the structure of the negative electrode more stable, which is beneficial to reducing the sheet resistance of the negative electrode and improving the performance of the electrochemical device.
  • Some embodiments of the present application provide a negative electrode including a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector.
  • the negative active material layer may be located on one side or both sides of the negative current collector.
  • the negative active material layer includes a negative active material.
  • the negative active material includes hard carbon.
  • hard carbon on the one hand, the gram capacity of hard carbon is greater than that of commonly used graphite, which can reach about twice the gram capacity of graphite, so that the energy density of the electrochemical device can be improved.
  • the negative electrode active material containing hard carbon it helps to improve the bonding force between the negative electrode active material layer and the negative electrode current collector, thereby improving the structural stability of the negative electrode, which is conducive to improving the electrochemical device prepared by the negative electrode. cycle performance.
  • the binding force between the negative electrode active material layer and the negative electrode current collector is greater than or equal to 7 N/m.
  • the embodiments of the present application improve the bonding force between the negative electrode active material layer and the negative electrode current collector, making the structure of the negative electrode more stable, which is conducive to improving the cycle performance of the electrochemical device prepared by the negative electrode.
  • the binding force between the negative electrode active material layer and the negative electrode current collector is greater than or equal to 10 N/m.
  • the bonding force between the negative active material layer and the negative current collector can be increased to greater than or equal to 10N/m, far greater than 2N/m when graphite is used as the negative active material to 6N/m.
  • carbon materials are grown in situ on the surface of the hard carbon in the negative electrode active material.
  • pure hard carbon is used as the negative electrode active material, in addition to the above-mentioned advantages, there will also be some disadvantages.
  • the edges and corners of hard carbon particles are usually sharp, which will cause damage to the negative electrode current collector during the cold pressing process. In this case, it is not conducive to the full play of the electrochemical performance of the electrochemical device; on the other hand, the sharp edges and corners of the hard carbon particles are not conducive to the slippage between the particles, resulting in brittle fracture during processing and strip breakage during cold pressing.
  • One of the strategies to solve the above unfavorable factors is to coat a layer of material on the surface of hard carbon particles to cover the edges and corners of hard carbon particles, but the coating layer is easy to fall off from the surface of hard carbon particles; it is also possible to combine hard carbon with graphite. Mixing, using the good slip characteristics of graphite, but this will sacrifice the high gram capacity of hard carbon and affect the energy density of electrochemical devices; in addition, one-dimensional carbon tubes or two-dimensional graphene can also be added, which can be very large Cover the sharp edges and corners of hard carbon to a certain extent, and improve the situation of hard carbon stabbing the isolation film and copper foil during processing.
  • the lubricating effect of carbon tubes or graphene can also increase the slip between hard carbon particles , to improve the band breaking problem of hard carbon during processing, however, carbon tubes or graphene are expensive, and the second addition is unevenly dispersed, resulting in its actual effect not as expected.
  • This application grows a carbon material that can increase slip on the surface of hard carbon in situ to solve the sharp edges and corners of hard carbon particles, increase the slip between hard carbon particles, and solve the problem of hard carbon in the process of processing. Difficult slippage and damage to the negative electrode current collector.
  • the hard carbon has a Dv50 of 6 ⁇ m to 20 ⁇ m.
  • the particle size test method refers to GB/T 19077-2016.
  • the testing equipment used is Mastersizer 3000 produced by Malvern Company. Particle size measurement is accomplished by measuring the intensity of scattered light as a laser beam passes through a dispersed particle sample during testing.
  • the refractive index of the particles used in the test is 1.8, one sample is tested three times, and the particle size is finally measured by taking the average value of the three tests to measure Dv50. If the Dv50 of the hard carbon is too small, the specific surface area of the hard carbon is large, and side reactions with the electrolyte are easy to occur. If the Dv50 of hard carbon is too large, it is not conducive to the improvement of rate performance.
  • the hard carbon-containing negative electrode active material further includes nitrogen and transition metal elements.
  • XPS analysis can be used to determine whether the negative electrode active material containing hard carbon includes nitrogen and transition metal elements.
  • the carbon material of this application is obtained by the cracking of small molecules, and under normal circumstances, small molecules will directly volatilize without carbon residues during the pyrolysis process.
  • Carbon materials can introduce transition metal salts and nitrogen-containing small molecule materials. Utilizing the combination of nitrogen in small molecules and d orbitals of transition metal elements, carbon materials with specific structures/morphologies can be pyrolyzed in situ under the action of transition metals. According to different small molecules, they can be heated on the surface of hard carbon particles Solve the fibrous, flake or granular carbon materials to improve the poor processability of hard carbon particles and the problems of stabbing separators and negative electrode collectors.
  • the cohesion between the negative active materials is 5 N/m to 100 N/m. If the cohesion between the negative electrode active materials is too small, it is not conducive to the stability of the structure of the negative electrode active materials; if the cohesion between the negative electrode active materials is too large, it is not conducive to the improvement of the rate performance of the electrochemical device.
  • the carbon material grown in situ on the surface of the hard carbon includes at least one of a fibrous carbon material, a flake carbon material, or a granular carbon material.
  • the fibrous carbon material has a diameter of 50 nm to 500 nm and a length > 1 ⁇ m. If the diameter of the fibrous carbon material is too small, the stability of the fibrous carbon material is relatively weak; if the diameter of the fibrous carbon material is too large, the encapsulation flexibility of the fibrous carbon material is relatively weak. In addition, if the length of the fibrous carbon material is too small, the effect of the carbon material on improving slip between hard carbon particles is relatively limited.
  • Diameter and length test of fibrous carbon material The material powder is photographed and observed with a SEM scanning electron microscope, and then, using image analysis software, 50 fibrous carbon materials are randomly selected from 10 SEM photos for each SEM photo, and measured out The respective diameters and lengths of these fibrous carbon materials, then calculate the average value of 10*50 carbon nanotube diameters and lengths, which is the diameter and length of fibrous carbon materials (this length and diameter are similar to the length and length of carbon nanotubes diameter measurement).
  • the length of the flake carbon material is >1 ⁇ m. If the length of the flaky carbon material is too small, the effect of the carbon material on improving the slip between hard carbon particles is relatively limited.
  • the length of the sheet-like carbon material was photographed and observed by the SEM scanning electron microscope, and then, using image analysis software, 50 sheet-like carbon materials were randomly selected from 10 SEM photos, and the maximum length of these sheet-like carbon materials was measured. The longest length, and then calculate the average of the longest lengths of 10 ⁇ 50 sheet-like carbon materials, which is the length of the sheet-like carbon materials.
  • the granular carbon material has an average particle size of 50 nm to 500 nm. If the average particle size of the granular carbon material is too small, it is not conducive to the full coating of hard carbon particles; if the average particle size of the granular carbon material is too large, it will affect the granular carbon material to improve the sliding between hard carbon particles. shifting effect.
  • the average particle size test of granular carbon materials is to observe the material powder by SEM scanning electron microscope, and then use image analysis software to randomly select 10 granular carbon materials from the SEM photos, and calculate the respective particle size of these material particles.
  • the mass of the transition metal element in the negative electrode active material is 0.1% to 10%, and the mass of nitrogen element in the negative electrode active material is 0.1% to 5%. If the mass percentage content of transition metal element or nitrogen element is too small, then be unfavorable for the in-situ growth of the carbon material on hard carbon particle surface; The improvement effect of the carbon residue in the process is no longer significantly increased, and it is not conducive to the improvement of the energy density of the electrochemical device.
  • the transition metal element includes at least one of Co, Fe, Cr, Pt, Cu, Mn, Ag, Ni or Zn.
  • the mass percentages of nitrogen and transition metal elements in the negative active material gradually decrease from the surface of the negative active material to the center of the negative active material.
  • the mass percent content of nitrogen element and transition metal element is tested by linear scanning electron microscope energy spectrum. During the test, first use ion polishing or liquid nitrogen brittle fracture to cut the pole piece of the negative electrode active material along the cross section, find the centered negative electrode active material particle in the scanning electron microscope, draw a straight line from the inside of the particle to the surface and move it along the cross section. Carry out linear scanning energy spectrum test along the straight line, and select N element and transition metal element as the test element.
  • the average length from the center of the volume of the negative active material to the surface is set to be L
  • the quality of the nitrogen element and the transition metal element on the surface of the negative active material is n
  • the distance between the interior of the negative active material and the surface length is l Any point
  • the mass percent content m of nitrogen element or transition metal element, m (n ⁇ l)/L, and satisfy: 0 ⁇ m ⁇ 1. In this way, the gradient distribution of the in-situ grown carbon material can be realized, which is beneficial to the effect of increasing the slippage of the hard carbon particles.
  • the preparation method of the negative electrode active material containing hard carbon comprises the steps of: dispersing the hard carbon material in the first solvent to prepare the first solution; adding the nitrogen-containing raw material of the carbon material and the transition metal nitrate to the A uniform second solution is obtained from the first solution; the second solution is stirred, evaporated to dryness, and heat-treated under an inert gas to obtain a negative electrode active material.
  • the first solvent includes at least one of distilled water, ethanol, dimethylformamide, or tetrahydrofuran.
  • the nitrogen-containing raw material of the carbon material includes melamine, dicyandiamine, methylimidazole, bispyridylamine, o-phenylenediamine, bipyridine, dibromobipyridine, pyrimidine, orthophenanthroline, At least one of dibromophenanthroline or imidazolylpyridine.
  • transition metal nitrates include Co(NO 3 ) 2 , Fe(NO 3 ) 3 , Cr(NO 3 ) 3 , H 2 PtCl 6 , Mn(NO 3 ) 2 , AgNO 3 , Ni(NO 3 ) 3 , 3 ) 2 or at least one of Zn(NO 3 ) 2 . It should be understood that this preparation method is only exemplary, and other suitable preparation methods can also be used.
  • carbon materials with different shapes can be obtained by adding different small molecular carbon sources.
  • fibrous carbon materials can be grown in situ on the surface of hard carbon particles, and the fibrous carbon materials are located on the surface of hard carbon particles, which can not only effectively improve the The contact problem between hard carbon blocks the separator and the negative electrode current collector, and can effectively increase the slip between hard carbon particles and improve the brittle fracture problem.
  • sheet-like carbon materials can be grown in situ on the surface of hard carbon particles, and the sheet-like carbon materials located on the surface of hard carbon particles can also effectively improve the performance of hard carbon particles.
  • the problem of contact between particles prevents hard carbon from stabbing the separator and negative electrode collector, and effectively increases the slip between hard carbon particles.
  • different contents of transition metal salts also make the carbon residue rate of the carbon material cracked by the small molecule carbon source different.
  • a conductive agent and a binder may also be included in the negative electrode active material layer.
  • the conductive agent in the negative electrode active material layer may include at least one of conductive carbon black, Ketjen black, flake graphite, graphene, carbon nanotubes, or carbon fibers.
  • the binder in the negative active material layer may include carboxymethylcellulose (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 active material, the conductive agent and the binder in the negative active material layer may be (78 to 98.5):(0.1 to 10):(0.1 to 10).
  • the negative active material may be a hard carbon-containing negative active material. It should be understood that the foregoing are examples only, and any other suitable materials and mass ratios may be used.
  • the negative electrode current collector may use at least one of copper foil, nickel foil, or carbon-based current collector.
  • the embodiment of the present application also provides an electrochemical device, the electrochemical device includes an electrode assembly, and the electrode assembly includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.
  • the negative electrode is any one of the above-mentioned negative electrodes.
  • the electrochemical device includes a lithium-ion battery, although the present application is not limited thereto.
  • the electrochemical device may also include an electrolyte.
  • the electrolyte may be one or more of gel electrolyte, solid electrolyte and electrolyte.
  • the electrolyte includes at least one of fluoroether, fluoroethylene carbonate, or ether nitrile.
  • the electrolyte solution also includes a lithium salt, the lithium salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, the concentration of the lithium salt is 1mol/L to 2mol/L, and the bis(fluorosulfonyl)imide The molar ratio of lithium amide and lithium hexafluorophosphate is 0.05 to 4.
  • the electrolyte solution may also include a non-aqueous solvent.
  • the non-aqueous solvent can be carbonate compound, carboxylate compound, ether compound, other organic solvent or their combination.
  • the carbonate compound can 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 Ester (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 Ester (MEC) and combinations thereof.
  • Examples of the cyclic carbonate compound are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), or combinations thereof.
  • fluorocarbonate compound examples include fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, Fluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-carbonic acid - 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 carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-carbonic acid - Difluoro-1-methylethylene carbonate, 1,1,2-trifluor
  • carboxylate compounds are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decanolactone, Valerolactone, mevalonolactone, caprolactone, methyl formate, or combinations thereof.
  • ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxy ethyl ethane, 2-methyltetrahydrofuran, tetrahydrofuran or a combination thereof.
  • organic solvents examples include dimethylsulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, methyl Amides, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters or combinations thereof.
  • the positive electrode includes a current collector and a positive active material layer disposed on the current collector, and the positive active material layer may include a positive active material.
  • the positive electrode active material includes lithium cobaltate, lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadyl phosphate, sodium vanadyl phosphate, lithium vanadate, manganese Lithium oxide, lithium nickelate, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials or lithium nickel cobalt aluminate.
  • the positive 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, flake graphite, graphene, carbon nanotubes, or carbon fibers.
  • the positive electrode active material layer can also include a binder, and the binder in the positive electrode active material layer can include carboxymethylcellulose (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 carboxymethylcellulose
  • the mass ratio of the positive active material, the conductive agent and the binder in the positive active material layer may be (80 to 99):(0.1 to 10):(0.1 to 10).
  • the positive active material layer may have a thickness of 10 ⁇ m to 500 ⁇ m. It should be understood that the above description is only an example, and any other suitable material, thickness and mass ratio may be used for the positive electrode active material layer.
  • Al foil can be used as the current collector of the positive electrode, and of course, other current collectors commonly used in the field can also be used.
  • the current collector of the positive electrode may have a thickness of 1 ⁇ m to 50 ⁇ m.
  • the positive active material layer may be coated only on a partial area of the current collector of the positive electrode.
  • the isolation film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid.
  • polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene.
  • the thickness of the isolation film is in the range of about 5 ⁇ m to 50 ⁇ m.
  • the surface of the isolation membrane may also include a porous layer, the porous layer is arranged on at least one surface of the isolation membrane, 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 oxide (HfO 2 ), tin oxide (SnO 2 ), cerium oxide (CeO 2 ), nickel oxide (NiO), Zinc oxide (ZnO), calcium oxide (CaO), zirconia (ZrO 2 ), yttrium oxide (Y 2 O 3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or at least one of barium sulfate.
  • alumina Al 2 O 3
  • SiO 2 silicon oxide
  • MgO magnesium oxide
  • TiO 2 titanium oxide
  • HfO 2 hafnium
  • the pores of the isolation membrane have a diameter in the range of about 0.01 ⁇ m to 1 ⁇ m.
  • the binder of the porous layer is selected from polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, poly At least one of vinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, 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 electrode and/or negative electrode of the electrochemical device may be a wound or stacked multi-layer structure, or a single-layer structure in which a single-layer positive electrode, a separator, and a single-layer negative electrode are stacked.
  • the positive electrode, separator, and negative electrode are sequentially wound or stacked into an electrode part, and then packed into an aluminum-plastic film for packaging, injected with an electrolyte, formed, Encapsulation, that is, made of lithium-ion batteries. Then, performance tests were performed on the prepared lithium-ion batteries.
  • Embodiments of the present application also provide an electronic device including the above electrochemical device.
  • 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-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Unmanned aerial vehicles, lighting equipment, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • Preparation of the positive electrode mix the positive active material lithium cobaltate, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) in a weight ratio of 97:1.4:1.6, and add N-methylpyrrolidone (NMP) as a solvent , stir well.
  • the slurry (solid content is 72wt%) is uniformly coated on the aluminum foil of the positive electrode current collector with a coating thickness of 80 ⁇ m, dried at 85°C, and then cold-pressed, cut into pieces, and slit, and vacuum-coated at 85°C Dry under the same conditions for 4 hours to obtain a positive electrode.
  • negative electrode Dissolve commercial artificial hard carbon, binder styrene-butadiene rubber and sodium carboxymethylcellulose (CMC) in deionized water at a weight ratio of 97:2:1 to form negative electrode slurry (solid content is 40wt%). Copper foil with a thickness of 10 ⁇ m was used as the negative electrode current collector, and the negative electrode slurry was coated on the negative electrode current collector with a coating thickness of 50 ⁇ m, dried at 85 ° C, and then cold-pressed, cut into pieces, and cut at 120 °C under vacuum conditions for 12 hours to obtain a negative electrode.
  • CMC carboxymethylcellulose
  • the isolation membrane is polyethylene (PE) with a thickness of 7 ⁇ m.
  • Preparation of lithium-ion battery stack the positive electrode, separator, and negative electrode in order, so that the separator is in the middle of the positive electrode and the negative electrode to play the role of isolation, and wind up to obtain the electrode assembly.
  • the electrode assembly is placed in the outer packaging aluminum-plastic film, after dehydration at 80°C, the above electrolyte is injected and packaged, and the lithium-ion battery is obtained through chemical formation, degassing, trimming and other processes.
  • embodiment 2 The difference between embodiment 2 and embodiment 1 is that the negative electrode active material adopts the negative electrode active material containing hard carbon, and others are the same as embodiment 1, and the preparation method of the negative electrode active material containing hard carbon is as follows:
  • Embodiments 3 to 7 are basically the same as Embodiment 2, except that the mass ratio of the transition metal to the small molecular material in the nitrate is different.
  • the mass ratios of the transition metal in the nitrates of Examples 3 to 7 and the small molecule material are 10%, 5%, 2%, 1%, 0% respectively, and Comparative Example 1 replaces the hard carbon in Example 1 with Graphite, others are identical with embodiment 1.
  • Examples 8 to 13 are different from Example 2 in terms of the mass ratio of the small molecule material and the transition metal in the nitrate to the small molecule material, and the other aspects are the same as Example 2.
  • the small molecule materials in Examples 8 to 13 were replaced with phthalenediammonium.
  • the mass ratios of transition metals and small molecule materials in the nitrates of Examples 8 to 13 were 20%, 10%, 5%, 2%, 1%, and 0%, respectively.
  • Examples 14 to 33 are different from Example 2 in terms of the small molecule material, nitrate species and/or the mass ratio of the transition metal in the nitrate to the small molecule material, and the other aspects are the same as Example 2, see the table below for details.
  • Example 34 the small molecular material, the mass ratio of the transition metal in the nitrate to the small molecular material, the Dv50 of the hard carbon particles, and the morphology and size of the carbon material are different from Example 5, and the other aspects are the same as Example 5.
  • the hard carbon negative electrode active material, styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) are fully stirred and mixed in an appropriate amount of deionized water according to a weight ratio of 97:2:1, so that it forms a uniform negative electrode slurry,
  • the solid content of the negative electrode slurry is 40wt%.
  • Instron (model 33652) tester to test: Take the negative electrode (30mm in width and 100mm to 160mm in length), and fix it on the On the steel plate, paste the adhesive tape on the surface of the negative electrode active material layer. One side of the adhesive tape is connected to the paper tape of equal width. The migration rate was 50mm/min, and the polymerization strength between the negative electrode active materials inside the negative electrode active material layer was tested under 180° (that is, stretched in the opposite direction).
  • the test temperature is room temperature
  • the pressure is 0.4T
  • the pressure is 26MPa. Take 10 points at different positions for each test, and take the average value.
  • the broken belt mentioned here refers to the brittle fracture of the negative electrode during the process before the negative electrode passes through the cold pressing roller and is wound up.
  • the current collector of the negative electrode is 6 ⁇ m copper foil, and the coating weight of one side of the negative electrode is between 5mg/cm 2 and 8mg/cm 2 ;
  • the negative electrode material in the negative electrode is hard carbon material, and its 5 tons of powder compaction density is between 0.9g /cm 3 to 1.2g/cm 3 ;
  • the cold-pressed compacted density of the negative electrode during the cold-pressing process is between 0.9g/cm 3 and 1.2g/cm 3 , and the tension of the winding device of the cold-pressing equipment is between 3N and 10N .
  • the broken bands are divided into serious broken bands, moderate broken bands, and mild broken bands according to the degree of broken bands; in the process of cold pressing every 10 meters of the negative electrode, brittle broken bands occur 4 times or more at the negative electrode as severe broken bands , 2 to 3 brittle fractures are moderate fault zones, and 1 brittle fractures are minor fault zones.
  • Lithium-ion battery capacity retention rate after 400 cycles
  • Cycle capacity retention rate capacity at 400 cycles/capacity at first discharge ⁇ 100%.
  • Table 1 shows the respective parameters and evaluation results of Examples 1 to 13 and Comparative Example 1.
  • the mass content of transition metal elements and the content of nitrogen element both refer to the mass ratio of transition metal elements and nitrogen elements in the calcined sample to the entire negative electrode active material.
  • the mass ratio of the transition metal element in the nitrate and the small molecular material refers to the ratio of the weight of the transition metal in the whole nitrate to the weight of the small molecular material.
  • the weight of the added nitrate is 2g, where Co
  • theoretically all diamines can be used (all carbon-containing small molecules with amino groups can be used), because small molecules contain N and can combine with transition metal elements.
  • Example 1 By comparing Example 1 and Comparative Example 1, it can be seen that by using hard carbon as the negative electrode active material, the binding force between the negative electrode active material layer and the negative electrode current collector is significantly increased. Moreover, compared with graphite materials, the sheet resistance of hard carbon materials is smaller, which is conducive to the improvement of its fast charge and discharge performance.
  • Examples 1, 2 and 3 By comparing Examples 1, 2 and 3, it can be seen that by using the negative electrode active material of the modified hard carbon composite particles, compared with the use of hard carbon, the bonding force between the negative electrode active material layer and the negative electrode current collector can be further increased.
  • Examples 2 and 3 have basically no broken bands, and the content of transition metal nitrate should not be too high. If it is too high, the content of transition metals in the composite particles will be too high, and the transition metals will agglomerate into small particles, which will affect the conversion of small molecules into carbon materials. Contact with hard carbon substrates.
  • Graphite materials do not suffer from band breakage due to their soft quality.
  • hard carbon materials suffer from severe band breakage due to their hardness and sharp edges.
  • the hard carbon in Example 1 is severely broken due to its hard quality and sharp edges and corners. This is because there is no slippage and buffer space between the particles during processing due to the hard quality, resulting in high stress between the particles and brittle fracture.
  • Examples 2 to 6 and 8 to 12 in-situ grow carbon materials on the surface of hard carbon that can assist slippage and buffer the stress between particles, wrapping the sharp edges and corners of the hard carbon substrate, thus improving the corners and corners of the hard carbon substrate
  • the sharp problem improves the cohesion between the particles and the current collector, and at the same time improves the situation of the broken belt during processing, so its processing performance is improved, and there is no broken belt during processing.
  • Example 7 and Example 13 only small molecules were added and no transition metal salt was added, so that the small molecules were completely volatilized during the calcination process, and carbon materials could not be grown on the surface of the hard carbon, so there were no broken bands during processing. has been solved.
  • Comparative example 1 is graphite that has not been modified by small molecules and nitrates. Its cohesive force is lower than that of hard carbon, but because graphite is soft and has a layered structure, it can slip during cold pressing. No belt breaks will occur. However, compared with hard carbon, especially modified hard carbon, graphite has a larger sheet resistance, which is not conducive to the output of rapid charge and discharge performance.
  • Table 2 shows the respective parameters and evaluation results of Examples 14 to 33 and Comparative Example 1.
  • Table 2 is an extension of cobalt nitrate in Table 1 to other nitrates such as iron nitrate and zinc nitrate. Extending the transition metal elements in the transition metal nitrates from Co to Fe and Zn can still achieve the purpose of improving the processing performance and reducing the sheet resistance, and the broken band of the electrode composed of the obtained negative electrode active material is improved.
  • Examples 14 to 18 it can be seen that as the content of the transition metal salt gradually increases, the adhesive force and cohesive strength of the pole piece formed in the obtained negative electrode active material are improved, and the condition of the broken band during processing is also improved. .
  • Examples 14 to 18 with 19 to 23 it can be known that the same rules as in Examples 14 to 18 can be obtained by using different types of small molecule materials. Similarly, by comparing Examples 24 to 28 and Examples 29 to 33, it can be seen that the same rules as those of Examples 14 to 18 can also be obtained by using different types of transition metal salts.
  • Table 3 shows the parameters and evaluation results of Examples 1, 3, 9, 34 and Comparative Example 1.
  • Table 4 shows the respective parameters and evaluation results of Examples 35 to 37 and Example 1.
  • Examples 35 to 37 differ only in the composition of the electrolyte as shown in Table 4.
  • the graphite material forms a LiC intercalation compound after lithium intercalation, and has a certain volume expansion, so as the number of cycles of the lithium-ion battery increases, the thickness of the lithium-ion battery Increasingly, the thickness increased by 12% after 400 cycles.
  • the large d 002 interplanar spacing (about 0.36nm to 0.4nm) of hard carbon materials as well as the existence of a large number of micropores and their isotropic properties, hard carbon materials have almost no volume change after lithium intercalation, and 400 cycles
  • the final electrode thickness change is small, less than or equal to 5%. Especially after modification by small molecule carbon materials, the buffer between the particles increases and the volume expansion changes smaller.
  • Examples 35 to 37 show that by changing the lithium salt concentration and composition of the electrolyte, the thickness expansion is suppressed, and the cycle performance and thickness expansion performance are better.

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Abstract

本申请提供了负极、电化学装置和电子装置。该负极包括负极集流体和负极活性材料层，负极活性材料层与负极集流体之间的粘结力大于或等于7N/m。本申请的实施例改善了负极活性材料层和负极集流体之间的粘结力，使得负极的结构更加稳定，有利于提升电化学装置的快充性能。

Description

负极、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，尤其涉及负极、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，对其循环性能和能量密度提出了越来越高的要求。石墨制备的负极的膜片电阻较高，快充性能较差，目前，为了提升电化学装置的性能，通常采用一些高克容量(例如：硅基负极材料、锡基负极材料、硬碳材料等)的负极材料来代替常用的石墨，然而，这些高克容量的负极材料也带来了一些新的问题，期待进一步的改进。
发明内容
本申请的一些实施例提供了一种负极，包括负极集流体和负极活性材料层，所述负极活性材料层包括负极活性材料，所述负极活性材料层与所述负极集流体之间的粘结力大于或等于7N/m。
在一些实施例中，所述负极活性材料层与所述负极集流体之间的粘结力大于或等于10N/m。
在一些实施例中，所述负极活性材料包括硬碳。
在一些实施例中，满足条件(a)至(d)中的至少一者：(a)所述负极活性材料中的表面原位生长有碳材料；(b)所述负极活性材料的Dv50为6μm至20μm；(c)所述负极活性材料还包括氮元素和过渡金属元素；(d)所述负极活性材料的内聚力为5N/m至100N/m。
在一些实施例中，满足条件(e)至(h)中的至少一者：(e)所述碳材料包括纤维状碳材料、片状碳材料或颗粒状碳材料中的至少一种；(f)所述负极活性材料中的所述过渡金属元素的质量为0.1％至10％，所述负极活性材料中的所述氮元素的质量为0.1％至5％；(g)所述过渡金属元素包括Co、Fe、Cr、Pt、Cu、Mn、Ag、Ni或Zn中的至少一种；(h)所述负极活性材 料颗粒中的所述氮元素或所述过渡金属元素的质量百分含量从所述负极活性材料颗粒表面至所述负极活性材料颗粒的中心逐渐减小。
在一些实施例中，满足条件(i)至(k)中的至少一者：(i)所述纤维状碳材料的直径为50nm至500nm，长度＞1μm；(j)所述片状碳材料的长度＞1μm；(k)所述颗粒状碳材料的平均粒径为50nm至500nm。
本申请的一些实施例提供了一种电化学装置，该电化学装置包括电解液、隔离膜、正极和上述任一负极，隔离膜设置在所述正极和所述负极之间。
在一些实施例中，电解液包括氟醚、氟代碳酸乙烯酯或醚腈中至少一种。在一些实施例中，电解液包括锂盐，锂盐包括双(氟磺酰基)酰亚胺锂和六氟磷酸锂，锂盐的浓度为1mol/L至2mol/L，双(氟磺酰基)酰亚胺锂和六氟磷酸锂的摩尔比为0.05至4。
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。
本申请的实施例改善了负极活性材料层和负极集流体之间的粘结力，使得负极的结构更加稳定，有利于降低负极的膜片电阻，提高电化学装置的性能。
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负极，该负极包括负极集流体和位于负极集流体上的负极活性材料层。在一些实施例中，负极活性材料层可以位于负极集流体的一侧或两侧上。在一些实施例中，负极活性材料层包括负极活性材料。
在一些实施例中，负极活性材料包括硬碳。通过采用硬碳，一方面硬碳的克容量大于常用的石墨的克容量，可达到石墨的克容量的约两倍，从而能够提升电化学装置的能量密度。另外，通过采用含有硬碳的负极活性材料，有助于提升负极活性材料层和负极集流体之间的粘结力，进而提升负极的结构稳定性，有利于提升由该负极制备的电化学装置的循环性能。
在一些实施例中，负极活性材料层与负极集流体之间的粘结力大于或等于7N/m。本申请的实施例改善了负极活性材料层和负极集流体之间的粘结 力，使得负极的结构更加稳定，有利于提升由该负极制备的电化学装置的循环性能。
在一些实施例中，负极活性材料层与负极集流体之间的粘结力大于或等于10N/m。通过采用含有硬碳的负极活性材料，发现可以将负极活性材料层与负极集流体之间的粘结力提升至大于或等于10N/m，远远大于采用石墨作为负极活性材料时的2N/m至6N/m。
在一些实施例中，负极活性材料中的硬碳的表面原位生长有碳材料。在采用纯硬碳作为负极活性材料时，除了以上所述的优点之外，也会存在一些不利因素，例如，硬碳颗粒的棱角通常比较尖锐，使得在冷压过程中会存在损伤负极集流体的情况，不利于电化学装置的电化学性能的充分发挥；另一方面，硬碳颗粒尖锐的棱角不利于颗粒间的滑移，使得出现加工脆断、冷压分条断带情况。
解决上述不利因素的策略之一，可以在硬碳颗粒表面包覆一层物质，将硬碳颗粒的棱角包覆住，然而包覆层容易从硬碳颗粒表面脱落；也可以将硬碳与石墨混合，利用石墨的良好滑移特性，但是这会牺牲硬碳的高克容量，影响电化学装置的能量密度；另外，也可以添加一维的碳管或二维的石墨烯，它们可很大程度上包裹住硬碳的尖锐的棱角部分，改善硬碳在加工过程中刺伤隔离膜和铜箔的情况，同时，碳管或石墨烯的润滑作用，还可以增加硬碳颗粒间的滑移，改善硬碳在加工过程中的断带问题，然而，碳管或石墨烯价格昂贵，二次加入分散不均匀，导致其实际效果不如预期。
本申请在硬碳的表面原位生长可增加滑移的碳材料，用以解决硬碳颗粒的尖锐的棱角情况，并且增加硬碳颗粒之间的滑移，同时解决硬碳在加工过程中出现的难滑移和损伤负极集流体等问题。
在一些实施例中，硬碳的Dv50为6μm至20μm。颗粒粒度测试方法参照GB/T 19077-2016。所用测试设备为马尔文公司生产的Mastersizer 3000。测试过程中当激光束穿过分散的颗粒样品时，通过测量散射光的强度来完成粒度测量。测试所用颗粒折射率为1.8，一个样品测试三次，颗粒粒度最终取三次测试的平均值测得Dv50。如果硬碳的Dv50太小，则硬碳的比表面积较大，容易与电解液发生副反应。如果硬碳的Dv50太大，则不利于倍率性能的提升。
在一些实施例中，含有硬碳的负极活性材料还包括氮元素和过渡金属元素。在一些实施例中，可以通过XPS分析来确定含有硬碳的负极活性材料是否包括氮元素和过渡金属元素。本申请的碳材料由小分子裂解而来，而通常情况下，小分子在热解过程中会直接挥发而没有碳残余，为了使小分子碳可以在硬碳颗粒表面热解出增加滑移的碳材料，可以引入过渡金属盐及选用含氮的小分子材料。利用小分子中氮元素与过渡金属元素的d轨道的结合，在过渡金属的作用下原位热解出具有特定结构/形貌的碳材料，根据小分子的不同，可在硬碳颗粒表面热解出纤维状、片状或颗粒状的碳材料，用以改善硬碳颗粒的加工性能差、刺伤隔离膜和负极集流体的问题。
在一些实施例中，负极活性材料之间的内聚力为5N/m至100N/m。如果负极活性材料之间的内聚力太小，则不利于负极活性材料的结构的稳定；如果负极活性材料之间的内聚力太大，则不利于电化学装置的倍率性能的提升。
在一些实施例中，在硬碳的表面原位生长的碳材料包括纤维状碳材料、片状碳材料或颗粒状碳材料中的至少一种。在一些实施例中，纤维状碳材料的直径为50nm至500nm，长度＞1μm。如果纤维状碳材料的直径太小，则纤维状碳材料的稳定性相对较弱；如果纤维状碳材料的直径太大，则纤维状碳材料的包覆柔性会相对较弱。另外，如果纤维状碳材料的长度太小，则该碳材料改善硬碳颗粒之间的滑移的作用相对受限。纤维状碳材料的直径和长度测试通过SEM扫描电镜对材料粉体进行拍摄观察，然后，使用图像解析软件，从10张SEM照片中，每张SEM照片随机选取50个纤维状碳材料，量出这些纤维状碳材料各自的直径和长度，然后计算10×50个碳纳米管直径和长度的平均值，即为纤维状碳材料的直径和长度(该长度和直径类似于碳纳米管的长度和直径的测量方式)。
在一些实施例中，片状碳材料的长度＞1μm。如果片状碳材料的长度太小，则该碳材料改善硬碳颗粒之间的滑移的作用相对受限。片状碳材料的长度通过SEM扫描电镜对材料粉体进行拍摄观察，然后，使用图像解析软件，从10张SEM照片中随机地选出50个片状碳材料，量出这些片状碳材料最长长度，然后计算10×50个片状碳材料的最长长度的平均值，即为片状碳材料的长度。
在一些实施例中，颗粒状碳材料的平均粒径为50nm至500nm。如果颗粒状碳材料的平均粒径太小，则不利于硬碳颗粒的充分包覆；如果颗粒状碳材料的平均粒径太大，则会影响颗粒状碳材料改善硬碳颗粒之间的滑移的效果。颗粒状碳材料的平均粒径测试通过SEM扫描电镜对材料粉体进行拍摄观察，然后，使用图像解析软件，从SEM照片中随机地选出10个颗粒状碳材料，求出这些材料颗粒各自的面积，接着，假设材料颗粒是球形，通过以下公式求出各自的粒径R(直径)：R＝2×(S/π) 1/2；其中，S为材料颗粒的面积；对10张SEM图像进行求出上述材料颗粒粒径R的处理，并将所得100(10×10)个材料颗粒的粒径进行算数平均，从而求得所述基体的平均粒径。
在一些实施例中，负极活性材料中的过渡金属元素的质量为0.1％至10％，负极活性材料中的氮元素的质量为0.1％至5％。如果过渡金属元素或氮元素的质量百分含量太小，则不利于硬碳颗粒表面的碳材料的原位生长；如果过渡金属元素或氮元素的质量百分含量太大，则对原位生长过程中的残碳量的提升作用不再显著增加，并且不利于电化学装置的能量密度的提升。在一些实施例中，过渡金属元素包括Co、Fe、Cr、Pt、Cu、Mn、Ag、Ni或Zn中的至少一种。
在一些实施例中，负极活性材料中的氮元素和过渡金属元素的质量百分含量从负极活性材料表面至负极活性材料的中心逐渐减小。氮元素和过渡金属元素的质量百分含量通过扫描电镜能谱的线性扫描测试。测试时先用离子抛光或液氮脆断方式将负极活性材料的极片沿截面切开，在扫描电镜中找到被居中切开的负极活性材料颗粒，从颗粒内部中往表面画一条直线并沿着该直线进行线性扫面能谱测试，测试元素选择N元素及过渡金属元素。
在一些实施例中，若设置负极活性材料的体积中心到表面的平均长度为L，负极活性材料表面的氮元素和过渡金属元素的质量为n，负极活性材料内部距离表面长度为l的任意点的氮元素或过渡金属元素的质量百分含量m，m＝(n×l)/L，且满足：0≤m≤1。如此，可以实现原位生长的碳材料的梯度分布，有利于增加硬碳颗粒的滑移的效果。
下面简要地描述负极活性材料的制备过程以更好地理解本申请，但这仅是示例性的，而不用于限制本申请。在一些实施例中，含有硬碳的负极活性 材料的制备方法包括以下步骤：将硬碳材料分散在第一溶剂中以制备第一溶液；将碳材料的含氮原料及过渡金属硝酸盐加入到第一溶液中获得均匀第二溶液；将第二溶液通过搅拌，蒸干，在惰性气体下进行热处理，得到负极活性材料材料。在一些实施例中，第一溶剂包括蒸馏水、乙醇、二甲基甲酰胺或四氢呋喃中的至少一种。在一些实施例中，碳材料的含氮原料包括三聚氰胺、二氰二胺、甲基咪唑、二吡啶胺、邻苯二胺、联吡啶、二溴联吡啶、连嘧啶、邻二氮杂菲、二溴邻菲咯啉或咪唑基吡啶中的至少一种。在一些实施例中，过渡金属硝酸盐包括Co(NO 3) 2、Fe(NO 3) 3、Cr(NO 3) 3、H 2PtCl 6、Mn(NO 3) 2、AgNO 3、Ni(NO 3) 2或Zn(NO 3) 2中的至少一种。应该理解，该制备方法仅是示例性的，还可以采用其他合适的制备方法。
在一些实施例中，添加不同的小分子碳源，可获得不同形貌的碳材料。例如，以二氰二胺为碳源，硝酸钴为过渡金属盐，可在硬碳颗粒表面原位生长出纤维状碳材料，纤维状碳材料位于硬碳颗粒表面，不仅可以有效改善硬碳颗粒之间的接触问题，阻碍硬碳刺伤隔离膜和负极集流体，还可以有效增加硬碳颗粒之间的滑移，改善脆断问题。例如，当以邻苯二胺为碳源，硝酸钴为过渡金属盐，可在硬碳颗粒表面原位生长出片状碳材料，片状碳材料位于硬碳颗粒表面，同样可以有效改善硬碳颗粒之间的接触问题，阻碍硬碳刺伤隔离膜和负极集流体，并且有效增加硬碳颗粒之间的滑移。另外，不同含量的过渡金属盐，也使得小分子碳源所裂解的碳材料的残碳率不同。例如，以邻苯二胺为碳源，硝酸钴为过渡金属盐，当硝酸钴的含量为1％时，其残碳率为10％，而当硝酸钴的含量为10％时，其残碳率可达到50％。
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(78至98.5)：(0.1至10)：(0.1至10)。负极活性材料可以是含有硬碳的负极活性材料。应该理解，以上所述仅是示例，可以采用任何其他合适的材料 和质量比。在一些实施例中，负极集流体可以采用铜箔、镍箔或碳基集流体中的至少一种。
本申请的实施例还提供了电化学装置，该电化学装置包括电极组件，电极组件包括正极、负极、设置在正极和负极之间的隔离膜。在一些实施例中，负极为上述任一种负极。
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。
在一些实施例中，电解液包括氟醚、氟代碳酸乙烯酯或醚腈中至少一种。在一些实施例中，电解液还包括锂盐，锂盐包括双(氟磺酰基)酰亚胺锂和六氟磷酸锂，锂盐的浓度为1mol/L至2mol/L，双(氟磺酰基)酰亚胺锂和六氟磷酸锂的摩尔比为0.05至4。
在一些实施例中，电解液还可以包括非水溶剂。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。
在一些实施例中，正极包括集流体和设置在集流体上的正极活性材料层，正极活性材料层可以包括正极活性材料。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至99)：(0.1至10)：(0.1至10)。在一些实施例中，正极活性材料层的厚度可以为10μm至500μm。应该理解，以上所述仅是示例，正极活性材料层可以采用任何其他合适的材料、厚度和质量比。
在一些实施例中，正极的集流体可以采用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，正极的集流体的厚度可以为1μm至50μm。在一些实施例中，正极活性材料层可以仅涂覆在正极的集流体的部分区域上。
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50μm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至少一者表面上，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，电化学装置的正极和/或负极可以是卷绕或堆叠式形成的多层结构，也可以是单层正极、隔离膜、单层负极叠加的单层结构。
在本申请的一些实施例中，以锂离子电池为例，将正极、隔离膜、负极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、无人机、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。
实施例1
正极的制备：将正极活性材料钴酸锂、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97：1.4：1.6进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，搅拌均匀。将浆料(固含量为72wt％)均匀涂覆在正极集流体铝箔上，涂覆厚度为80μm，在85℃下烘干，然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4小时，得到正极。
负极的制备：将商业人造硬碳、粘结剂丁苯橡胶和羧甲基纤维素钠(CMC)按重量比97：2：1的比例溶于去离子水中，形成负极浆料(固含量为40wt％)。采用10μm厚度铜箔作为负极集流体，将负极浆料涂覆于负极的集流体上，涂覆厚度为50μm，在85℃下烘干，然后经过冷压、裁片、分切后，在120℃的真空条件下干燥12小时，得到负极。
隔离膜的制备：隔离膜为7μm厚的聚乙烯(PE)。
电解液的制备：在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照质量比为EC:EMC:DEC＝30:50:20进行混合，接着加入1.5wt％的1,3-丙烷磺内酯、2wt％的氟代碳酸乙烯酯，溶解并充分搅拌后加入锂盐LiPF 6，混合均匀后获得电解液，其中LiPF 6的浓度为1mol/L。
锂离子电池的制备：将正极、隔离膜、负极按顺序依次叠好，使隔离膜处于正极和负极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。
其他实施例和对比例是在实施例1的步骤的基础上进行参数变更，具体变更的参数如下所述。
实施例2与实施例1的差异在于负极活性材料，采用含有硬碳的负极活性材料，其他与实施例1相同，含有硬碳的负极活性材料的制备方法如下：
将20g硬碳材料分散在100mL溶剂中以制备A溶液，其中溶剂为蒸馏水；然后，2g小分子材料(小分子材料为二氢二胺)与一定比例的过渡金属盐(Co(NO 3) 2·6H 2O)加入到A溶液中获得均匀B溶液，硝酸盐中的过渡金属与小分子材料的质量比为20％；将B溶液在25°条件搅拌2h，然后升温蒸发掉溶剂，获得的样品在N 2气氛下900度煅烧2h。降温后，粉末过300标准筛，得到含硬碳的负极活性材料材料。
实施例3至7与实施例2基本相同，除了硝酸盐中的过渡金属与小分子材料的质量比不同之外。实施例3至7的硝酸盐中的过渡金属与小分子材料的质量比分别为10％、5％、2％、1％、0％，对比例1是将实施例1中的硬碳替换为石墨，其他与实施例1相同。
实施例8至13的小分子材料、硝酸盐中的过渡金属与小分子材料的质量比与实施例2不同，其他方面与实施例2相同。实施例8至13的小分子材料更换为邻苯二铵。实施例8至13的硝酸盐中的过渡金属与小分子材料的质量比分别为20％、10％、5％、2％、1％、0％。
实施例14至33中的小分子材料、硝酸盐种类和/或硝酸盐中的过渡金属与小分子材料的质量比与实施例2不同，其他方面与实施例2相同，具体参见下表。
实施例34中的小分子材料、硝酸盐中的过渡金属与小分子材料的质量比、硬碳颗粒的Dv50和碳材料的形貌和尺寸与实施例5不同，其他方面与实施例5相同。
下面描述本申请的各个参数的测试方法。
粘结力测试：
将硬碳负极活性材料与丁苯橡胶(SBR)和羧甲基纤维素钠(CMC)按照重量比97:2:1在适量的去离子水中充分搅拌混合，使其形成均匀的负极浆料，其中负极浆料的固含量为40wt％。将此浆料涂覆于负极集流体(6μm铜箔)上，双面涂布，涂布重量为5mg/cm 2至8mg/cm 2，涂布后在85℃下烘干，然后经过冷压、裁片、分切后，在120℃的真空条件下干燥12小时，得到负极。
用以上得到的负极片(宽度为30mm、长度为100mm至160mm)，用双面胶纸(型号：3M9448A，宽度为20mm、长度为90mm至150mm)将其固定于钢板上，将胶纸贴在负极活性材料层表面，该胶纸一侧与其等宽的纸带相连接，调整拉力机限位块至合适位置，将纸带向上翻折及滑移40mm，滑移速率为50mm/min，测试180°下(即，反方向拉伸)负极活性材料层与负极集流体之间的粘结力。
负极活性材料的内聚力的测试：
使用Instron(型号为33652)测试仪进行测试：取负极(宽度为30mm、长度为100mm至160mm)，用双面胶纸(型号：3M9448A，宽度为20mm、长度为90mm至150mm)将其固定于钢板上，将胶纸贴在负极活性材料层表面，该胶纸一侧与其等宽的纸带相连接，调整拉力机限位块至合适位置，将纸带向上翻折及滑移40mm，滑移速率为50mm/min，测试180°下(即，反方向拉伸)负极活性材料层内部负极活性材料之间的聚合强度。
膜片电阻测试：
取面积为154mm 2的负极小圆片，测试温度为室温，压力为0.4T，压强为26MPa，每次测试取10个不同位置的点，取平均值。
断带测试：
这里所述断带，是指负极通过冷压辊并收卷前的过程中，负极发生脆断的情况。负极的集流体为6μm的铜箔，负极的单面涂布重量介于5mg/cm 2至8mg/cm 2；负极中的负极材料为硬碳材料，其5吨粉末压实密度介于0.9g/cm 3至1.2g/cm 3；负极在冷压过程中的冷压压实密度介于0.9g/cm 3至1.2g/cm 3，冷压设备的收卷装置的张力介于3N至10N。
所述断带，根据断带程度分为严重断带，中度断带，和轻度断带情况；在冷压每10米负极过程中，负极发生4次及以上脆断情况为严重断带，发生2次至3次脆断为中度断带，发生1次脆断的为轻微断带。
循环400圈锂离子电池容量保持率：
将锂离子电池置于45℃恒温箱中，静置30分钟，使锂离子电池达到恒温后测试电池初始厚度。将达到恒温的锂离子电池以0.5C恒流充电至电压为4.2V，然后以4.2V恒压充电至电流为0.05C，接着以1C恒流放电至电压为 3.0V，此为一个充放电循环。以首次放电的容量为100％，反复进行充放电循环400圈，停止测试，记录循环容量保持率，同时测量电池厚度，以容量保持率及厚度膨胀率作为评价锂离子电池循环性能的指标。
循环容量保持率＝循环至400圈时的容量/首次放电时的容量×100％。
按下式计算锂离子电池的厚度膨胀率：
循环400圈锂离子电池厚度变化＝(循环400圈后的电池厚度-电池初始厚度)/电池初始厚度×100％。
文中所述压实密度的计算公式为：压实密度＝负极材料质量/负极材料受力面积/样品的厚度；冷压压实密度计算公式为：冷压压实密度＝负极材料质量/负极材料受力面积/样品的厚度。
表1示出了实施例1至13和对比例1的各个参数和评估结果。
表1
Figure PCTCN2021101237-appb-000001
Figure PCTCN2021101237-appb-000002
表注：过渡金属元素质量含量及氮元素含量均指煅烧后的样品中过渡金属元素与氮元素占整个负极活性材料的质量比。硝酸盐中的过渡金属元素与小分子材料的质量比是指整个硝酸盐中过渡金属的重量与小分子材料的重量的比例，如实施例3中，所加硝酸盐的重量为2g，其中Co元素所占重量为(2g×59)/291＝0.4g，所加小分子材料的重量为2g，故硝酸盐中的过渡金属与小分子的比例为0.4g/2g＝20％(其他实施例计算方式相同)。在本申请中，理论上所有的二胺都可以(所有带氨基的含碳小分子都可以)，因为小分子含N，可与过渡金属元素结合。
通过比较实施例1和对比例1可知，通过采用硬碳作为负极活性材料，负极活性材料层与负极集流体之间的粘结力显著增大。并且，相比于石墨材料，硬碳材料的膜片电阻越小，利于其快速充放电性能的提升。
通过比较实施例1、2和3可知，通过采用改性后的硬碳复合颗粒的负极活性材料，相对于采用硬碳，能够进一步增大负极活性材料层与负极集流体之间的粘结力，实施例2和3基本没有出现断带，过渡金属硝酸盐的含量不能过高，过高则使得复合颗粒中过渡金属的含量过高，过渡金属团聚成小颗粒，影响小分子转换的碳材料与硬碳基材的接触。
石墨材料因为质软而不不会出现加工断带情况，相比来说，硬碳材料因质硬且棱角尖锐而出现严重断带情况。实施例1的硬碳因质硬且棱角尖锐而出现严重断带情况，是因为因质硬导致加工过程中颗粒间没有滑移和缓冲空间，导致颗粒间的应力大而发生脆断。实施例2至6与8至12在硬碳的表面原位生长出可辅助滑移并缓冲颗粒间应力的碳材料，包裹了硬碳基材的尖锐的棱角，因而可以改善硬碳基材棱角尖锐的问题，提升了颗粒与集流体之间的粘结力，并同时改善了加工断带的情况，所以其加工性能得到改善，没有出现加工断带的情况。而实施例7和实施例13因仅加入小分子而没有加入过渡金属盐，使得小分子在煅烧过程中完全挥发，未能在硬碳的表面生长出碳材料，因而其加工断带的情况没有得到解决。
对比例1为未经过小分子与硝酸盐改性的石墨，其粘结力相比于硬碳较低，但由于石墨质软，且为层状结构，在冷压加工过程中可滑移所以不会发生断带情况。然而，相比于硬碳，特别是改性后的硬碳，石墨的膜片电阻较大，不利于快速充放电性能的输出。
表2示出了实施例14至33和对比例1的各个参数和评估结果。
表2
Figure PCTCN2021101237-appb-000003
表2是将表1中的硝酸钴扩展至其他硝酸盐如硝酸铁和硝酸锌。将过渡金属硝酸盐中的过渡金属元素由Co扩展至Fe和Zn，仍可达到改善加工性能和降低膜片电阻的目的，所获得的负极活性材料所组成的电极的断带情况得到改善。通过比较实施例14至18可知，随着过渡金属盐的含量逐渐升高，所获得的负极活性材料中所组成的极片的粘结力和内聚强度得到提升，加工 断带情况也得到改善。通过比较实施例14至18与19至23可知，采用不同的小分子材料种类，可以得到与实施例14至18相同的规律。同样地，通过比较实施例24至28和比较实施例29至33可知，采用不同的过渡金属盐种类，也能得到与实施例14至18相同的规律。
表3示出了实施例1、3、9、34和对比例1的各个参数和评估结果。
表3
Figure PCTCN2021101237-appb-000004
从表3可以看出，通过固定过渡金属硝酸盐不变，改变小分子材料的种类，可以在硬碳颗粒表面生长出不同的形貌，并且均可达到改善加工性能的目的，所获得的负极活性材料所组成的电极的断带情况得到改善，并且降低了其膜片电阻，电池综合性能更好。
表4示出了实施例35至37和实施例1的各个参数和评估结果。
Figure PCTCN2021101237-appb-000005
Figure PCTCN2021101237-appb-000006
表注：实施例35至37与实施例3相比，不同的仅仅是电解液成分有如表4中的不同。
由表4可知，通过对比实施例1和对比例1，石墨材料因嵌锂后形成LiC 6插层化合物，有一定的体积膨胀，所以随着锂离子电池的循环次数增加，锂离子电池的厚度越来增加，400次循环后厚度增加12％。而硬碳材料因其d 002面间距较大(约0.36nm至0.4nm)，以及存在大量微孔及其各向同性的属性，使得硬碳材料在嵌锂后几乎没有体积变化，400圈循环后的电极厚度变化较小，小于等于5％。特别是经过小分子碳材料改性后，其颗粒间的缓冲增加，体积膨胀变化更小。
另一方面，实施例35至37表明经过改变电解液锂盐浓度和组成，厚度膨胀被抑制，循环性能和厚度膨胀性能更佳。
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. 一种负极，包括负极集流体和负极活性材料层，所述负极活性材料层包括负极活性材料，所述负极活性材料层与所述负极集流体之间的粘结力大于或等于7N/m。
  2. 根据权利要求1所述的负极，其中，所述负极活性材料层与所述负极集流体之间的粘结力大于或等于10N/m。
  3. 根据权利要求1所述的负极，其中，所述负极活性材料包括硬碳。
  4. 根据权利要求1所述的负极，其中，满足条件(a)至(d)中的至少一者：
    (a)所述负极活性材料中的表面原位生长有碳材料；
    (b)所述负极活性材料的Dv50为6μm至20μm；
    (c)所述负极活性材料还包括氮元素和过渡金属元素；
    (d)所述负极活性材料的内聚力为5N/m至100N/m。
  5. 根据权利要求4所述的负极，其中，满足条件(e)至(h)中的至少一者：
    (e)所述表面原位生长碳材料包括纤维状碳材料、片状碳材料或颗粒状碳材料中的至少一种；
    (f)所述负极活性材料中的所述过渡金属元素的质量为0.1％至10％，所述负极活性材料中的所述氮元素的质量为0.1％至5％；
    (g)所述过渡金属元素包括Co、Fe、Cr、Pt、Cu、Mn、Ag、Ni或Zn中的至少一种；
    (h)所述负极活性材料颗粒中的所述氮元素或所述过渡金属元素的质量百分含量从所述负极活性材料颗粒表面至所述负极活性材料颗粒的中心逐渐减小。
  6. 根据权利要求5所述的负极，其中，满足条件(i)至(k)中的至少一者：
    (i)所述纤维状碳材料的直径为50nm至500nm，长度＞1μm；
    (j)所述片状碳材料的长度＞1μm；
    (k)所述颗粒状碳材料的平均粒径为50nm至500nm。
  7. 一种电化学装置，包括电解液、隔离膜、正极和根据权利要求1至6中任一项所述的负极，所述隔离膜设置在所述正极和所述负极之间。
  8. 根据权利要求7所述的电化学装置，其中，所述电解液包括氟醚、氟代碳酸乙烯酯或醚腈中的至少一种。
  9. 根据权利要求7所述的电化学装置，其中，所述电解液包括锂盐，所述锂盐包括双(氟磺酰基)酰亚胺锂和六氟磷酸锂，所述锂盐的浓度为1mol/L至2mol/L，所述双(氟磺酰基)酰亚胺锂和所述六氟磷酸锂的摩尔比为0.05至4。
  10. 一种电子装置，包括根据权利要求7至9中任一项所述的电化学装置。
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