WO2022241642A1 - Élément d'électrode négative, appareil électrochimique et appareil électronique - Google Patents

Élément d'électrode négative, appareil électrochimique et appareil électronique Download PDF

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WO2022241642A1
WO2022241642A1 PCT/CN2021/094381 CN2021094381W WO2022241642A1 WO 2022241642 A1 WO2022241642 A1 WO 2022241642A1 CN 2021094381 W CN2021094381 W CN 2021094381W WO 2022241642 A1 WO2022241642 A1 WO 2022241642A1
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silicon
negative electrode
based material
carbon
active material
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PCT/CN2021/094381
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English (en)
Chinese (zh)
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贾彦龙
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宁德新能源科技有限公司
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Priority to CN202180005479.6A priority Critical patent/CN114503301A/zh
Priority to PCT/CN2021/094381 priority patent/WO2022241642A1/fr
Publication of WO2022241642A1 publication Critical patent/WO2022241642A1/fr

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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical energy storage, and in particular to negative electrode sheets, electrochemical devices and electronic devices.
  • Some embodiments of the present application provide a negative electrode sheet, which includes a negative electrode current collector and a negative electrode active material layer on at least part of the surface of the negative electrode current collector.
  • the negative active material layer includes a negative active material
  • the negative active material includes a silicon-based material.
  • the surface of the silicon-based material has carbon nanotubes grown in situ.
  • the negative active material further includes a carbon material layer present on the surface of the silicon-based material.
  • the thickness of the carbon material layer is 0.5 ⁇ m to 1 ⁇ m.
  • the mass ratio of the carbon material layer to the silicon-based material is 0.01 to 0.1.
  • the silicon-based material includes at least one of silicon, silicon-oxygen material, or silicon-carbon material.
  • the carbon nanotubes have a length of 300 nm to 500 nm. In some embodiments, the mass ratio of carbon nanotubes to silicon-based material is 0.001 to 0.05.
  • the negative electrode active material in a Raman test, includes a peak ID of the D peak at 1300 cm ⁇ 1 and a peak I G of the G peak at 1580 cm ⁇ 1 , the ratio ID of ID to I G /I G is 0.2 to 2.
  • the silicon-based material includes nano-Si crystal grains, the half-maximum width of the diffraction peak 28.3 ⁇ 0.1° of the Si(111) crystal plane obtained by X-ray diffraction of the nano-Si crystal grains is greater than 0.81°, and the nano-Si crystal grains The grain size of the grains is less than 10nm.
  • Some embodiments of the present application provide an electrochemical device, which includes a positive pole piece, a negative pole piece, and a separator between the positive pole piece and the negative pole piece, wherein the negative pole piece is any one of the above-mentioned Negative pole piece.
  • An embodiment of the present application also provides an electronic device, including the above-mentioned electrochemical device.
  • the bonding force between the silicon-based material and the carbon nanotubes is greatly enhanced by using the silicon-based material with carbon nanotubes grown on the surface in situ, avoiding the carbon material coating on the surface of the silicon-based material. Insufficient conductivity caused by inhomogeneity and shedding of the cladding due to volume expansion of the silicon-based material during cycling.
  • the introduction of carbon nanotubes creates a gap between the negative electrode active materials, which reserves a certain space for the volume expansion of the silicon-based material, alleviates the adverse effects caused by the volume expansion of the silicon-based material, and improves the performance of the negative electrode. Cycling performance of electrochemical devices formed from active materials.
  • a negative electrode sheet which includes 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, and the negative active material includes a silicon-based material.
  • carbon nanotubes are grown in situ on the surface of the silicon-based material.
  • some elements such as Cu and Ni can be introduced on the surface of the silicon-based material as active sites, and then carbon nanotubes can be formed in situ at the active sites by, for example, chemical vapor deposition (CVD).
  • CVD chemical vapor deposition
  • toluene or hydrocarbons can be used as the carbon source, and the carbon source can be brought into the silicon-based material surface by the carrier gas H 2 , Ar, etc. to deposit near the active sites .
  • the cross-sectional lattice of the carbon nanotubes left by the in-situ growth can be seen through a transmission electron microscope.
  • the bonding force between the silicon-based material and the carbon nanotubes is greatly enhanced by using the silicon-based material with carbon nanotubes grown on the surface in situ, avoiding the carbon material coating on the surface of the silicon-based material. Insufficient conductivity caused by inhomogeneity and shedding of the cladding due to volume expansion of the silicon-based material during cycling.
  • the introduction of carbon nanotubes creates a gap between the negative electrode active materials, which reserves a certain space for the volume expansion of the silicon-based material, alleviates the adverse effects caused by the volume expansion of the silicon-based material, and improves the performance of the negative electrode. Cycling performance of electrochemical devices formed from active materials.
  • the negative active material further includes a carbon material layer present on the surface of the silicon-based material.
  • the silicon-based material with a carbon material layer on the surface and carbon nanotubes grown in situ is collectively referred to as a silicon-based composite material, that is, a silicon-based composite material includes a silicon-based material, in-situ grown carbon nanotubes, and A layer of carbon material on the surface of a silicon-based material.
  • the carbon nanotubes grown in situ are combined with the carbon material layer existing on the surface of the silicon-based material, so that the conductivity of the negative electrode active material based on the silicon-based material is greatly enhanced.
  • the carbon nanotubes also act as rivets between the silicon-based material and the carbon material layer, which enhances the structural stability of the negative electrode active material and avoids the carbon material due to the volume expansion and contraction of the silicon-based material during the cycle. layer shedding problem.
  • the thickness of the carbon material layer is 0.5 ⁇ m to 1 ⁇ m. If the thickness of the carbon material layer is too small, the effect of the carbon material layer on inhibiting the volume expansion of the silicon-based material is relatively limited; if the thickness of the carbon material layer is too large, the effect of the carbon material layer on inhibiting the volume expansion of the silicon-based material is no longer significant increase, and is not conducive to the improvement of the energy density of the electrochemical device.
  • the thickness of the carbon material layer can be characterized by a scanning electron microscope, specifically, the detection is carried out under the conditions of 10kV and 10mA, and the thickness of the carbon material layer can be determined by a cross-sectional SEM test. It should be understood that this is only exemplary, and other suitable methods may also be used to characterize the thickness of the carbon material layer.
  • the mass ratio of the carbon material layer to the silicon-based material is 0.01 to 0.1. If the mass ratio of the carbon material layer to the silicon-based material is too small, the effect of the carbon material layer on inhibiting the volume expansion of the silicon-based material is relatively limited; if the mass ratio of the carbon material layer to the silicon-based material is too large, the carbon material layer inhibits the silicon The effect of the volume expansion of the base material is no longer significantly increased, and it is not conducive to the improvement of the energy density of the electrochemical device.
  • the silicon-based material includes at least one of silicon, silicon-oxygen material, or silicon-carbon material. These silicon-based materials are high-gram-capacity materials, which are beneficial to increase the energy density of electrochemical devices.
  • the silicon-based material includes SiM x , and M is an element such as O, C, etc., 0.5 ⁇ x ⁇ 1.6.
  • the carbon nanotubes have a length of 300 nm to 500 nm. If the length of the carbon nanotubes is too small, the effect of the carbon nanotubes on improving the structural stability of the negative electrode active material is relatively limited. If the length of the carbon nanotubes is too large, the suppressing effect of the carbon nanotubes on volume expansion during cycling of the silicon-based material is weakened. In some embodiments, the length of the carbon nanotubes can be measured under a scanning microscope. In some embodiments, the length of the carbon nanotubes can be characterized by a scanning electron microscope, specifically, the detection is carried out under the conditions of 10kV and 10mA, and the length of the carbon nanotubes can be determined by a cross-sectional SEM test. It should be understood that this is only exemplary, and other suitable methods can also be used for characterization.
  • the mass ratio of carbon nanotubes to silicon-based material is 0.001 to 0.05. If the mass ratio of carbon nanotubes to silicon-based materials is too small, the role of carbon nanotubes in improving the conductivity of silicon-based materials is relatively limited; if the mass ratio of carbon nanotubes to silicon-based materials is greater than 0.05, carbon nanotubes can improve the conductivity of silicon-based materials. The effect of the conductivity of the base material is no longer significantly increased, and it is not conducive to the improvement of the energy density of the electrochemical device.
  • the negative electrode active material in a Raman test, includes a peak ID of the D peak at 1300 cm ⁇ 1 and a peak I G of the G peak at 1580 cm ⁇ 1 , the ratio ID of ID to I G /I G is 0.2 to 2.
  • the negative active material includes silicon carbon material.
  • the ratio ID/ IG can reflect the defect degree of the negative electrode active material, and the larger the ratio ID/ IG is, the larger the defect of the negative electrode active material is.
  • the negative electrode active material has defects to a certain extent, which is beneficial to the improvement of the conductivity of the negative electrode active material. If the ratio I D / IG is too small, it is not conducive to the improvement of the conductivity of the negative electrode active material.
  • the ratio ID/ IG can be determined by the following steps: the light source is a 532nm Raman spectrometer, the test range is selected from 0cm ⁇ 1 to 4000cm ⁇ 1 , and the ratio of ID/ IG is calculated statistically.
  • the silicon-based material includes nano-Si crystal grains, the half-maximum width of the diffraction peak 28.3 ⁇ 0.1° of the Si(111) crystal plane obtained by X-ray diffraction of the nano-Si crystal grains is greater than 0.81°, and the nano-Si crystal grains
  • the grain size of the grains is less than 10nm. If the grain size of the nano-Si grains is too large, the cycle expansion of the nano-Si grains will be severe, which is not conducive to the control of the volume expansion of the electrochemical device and the improvement of cycle performance.
  • the silicon-based material has a Dv50 of 500 nm to 5 ⁇ m. In some embodiments, the silicon-based material has a Dv50 of 700 nm to 2 ⁇ m. Dv50 represents the value of the particle size at which the cumulative volume reaches 50% from the small particle size side in the volume-based particle size distribution. If the Dv50 of the silicon-based material is too small, the specific surface area of the silicon-based material is large, and side reactions with the electrolyte are likely to occur. If the Dv50 of the silicon-based material is too large, it is not conducive to the control of the cycle expansion of the silicon-based material and the improvement of the rate performance. In some embodiments, an ultrasonic particle size analyzer is used to test the particle size distribution of the negative electrode active material, such as Dv50, Dv99.
  • the Dv50 of the silicon-based material with the carbon material layer and carbon nanotubes on its surface is 3 ⁇ m to 8 ⁇ m, and the Dv99 is 8 ⁇ m to 22 ⁇ m.
  • Dv99 represents the value of the particle size reaching 99% of the cumulative volume from the small particle size side in the volume-based particle size distribution.
  • the carbon material layer includes a porous carbon material, and the porous carbon material is filled with a polymer to cover the silicon-based material with carbon nanotubes grown in situ, or coated with pitch/resin, etc.
  • Decomposition of the formed CNT-carbon mixed layer That is, carbon nanotubes grown in situ on the surface of silicon-based materials can also be mixed in the carbon material layer, and the introduction of carbon nanotubes makes the carbon material layer provide a porous environment, which is reserved for the cyclic expansion of silicon-based materials. A certain space is beneficial to alleviate the adverse effects brought by the cyclic expansion of silicon-based materials.
  • the negative electrode active material may further include other materials such as graphite.
  • 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 electrode active material can be a mixture of silicon-based material and other materials, and the silicon-based material can be 1%-80%. It should be understood that the above description is only an example, 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, which includes an electrode assembly, and the electrode assembly includes a positive pole piece, a negative pole piece, and a separator arranged between the positive pole piece and the negative pole piece.
  • the negative electrode sheet is any one of the above-mentioned negative electrode sheets.
  • the positive electrode sheet 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 may be used as the current collector of the positive pole piece, and of course, other current collectors commonly used in the field may also be used.
  • the thickness of the current collector of the positive electrode sheet may be 1 ⁇ m to 50 ⁇ m.
  • the positive electrode active material layer may only be coated on a partial area of the current collector of the positive electrode sheet.
  • 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), oxide Zinc (ZnO), calcium oxide (CaO), zirconia (ZrO 2 ), yttrium oxide (Y 2 O 3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or sulfuric acid at least one of barium.
  • alumina Al 2 O 3
  • Silicon oxide SiO 2
  • magnesium oxide MgO
  • titanium oxide TiO 2
  • hafnium oxide HfO 2
  • 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 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 a gel electrolyte, a solid electrolyte and an electrolytic solution, and the electrolytic solution includes a lithium salt and a non-aqueous solvent.
  • the lithium salt is selected from 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 , LiC(SO 2 CF 3 ) 3 , LiSiF 6 , LiBOB or one or more of lithium difluoroborate.
  • LiPF 6 is selected as a lithium salt because it has high ion conductivity and can improve cycle characteristics.
  • 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 carbonate - difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate or a combination thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Fluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2 carbonate - difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-
  • 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, 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 sheet mix the positive active material lithium cobaltate, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) according to the weight ratio of 97.5:1.0:1.5, and add N-methylpyrrolidone (NMP) As a solvent, stir well.
  • NMP N-methylpyrrolidone
  • Preparation of the negative electrode sheet Dissolve Cu(NO 3 ) 2 in deionized water to form a 1mol/L solution; add 100g of the silicon oxide (SiO) material to be treated into the Cu(NO 3 ) 2 solution at 1000 Stir for 7 minutes at a rotating speed, then filter, and dry at a temperature of 80° for later use; add the dried silicon-oxygen material into a square porcelain boat, heat it to 580°C at a rate of 5°C/min, and use 200sccm Ar/H 2 (volume ratio: 1:1, the same below) is the atmosphere, keep it for 45min until Cu(NO 3 ) 2 is converted into Cu particles; Heating to 800°C, using Ar/H 2 as carrier gas and toluene as carbon source, carbon nanotubes were formed in situ on Cu particles, the heating time was 2h, and the heating temperature was 800°C; after that, carbon nanotubes were grown in situ The nanotube silicon-oxygen material is dispersed into an aqueous solution, coated with asphalt, and then
  • the isolation membrane is polyethylene (PE) with a thickness of 15 ⁇ m.
  • EC ethylene carbonate
  • PC propylene carbonate
  • Lithium-ion battery preparation stack the positive pole piece, the separator, and the negative pole piece in order, so that the separator is in the middle of the positive pole piece and the negative pole piece to play 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.
  • parameters are changed on the basis of the steps in Example 1, and the specific changed parameters are shown in the table below.
  • the length of the carbon nanotubes in Example 2 and the particle size of the silicon-based material with the carbon material layer and carbon nanotubes on the surface are different from those in Example 1.
  • the type of silicon-based material in Example 3 and the particle size of the silicon-based material with carbon material layers and carbon nanotubes on the surface are different from Example 1.
  • the type of silicon-based material and the mass ratio of carbon nanotubes and silicon-based material in Example 4 are different from those in Example 1.
  • the mass ratio of carbon nanotubes and silicon-based materials in Example 5 and the particle size of silicon-based materials with carbon material layers and carbon nanotubes on the surface are different from those in Example 1.
  • the type of silicon-based material, the mass ratio of carbon nanotubes and silicon-based material, and the particle size of silicon-based material with carbon material layer and carbon nanotubes on the surface in Example 6 are different from Example 1.
  • the type of silicon-based material, the mass ratio of carbon nanotubes and silicon-based material, the length of carbon nanotubes, and the thickness of the carbon material layer in Example 7 are different from those in Example 1.
  • the particle size of the silicon-based material in Example 8 and the particle size of the silicon-based material with a carbon material layer and carbon nanotubes on the surface are different from Example 1.
  • the particle size of the silicon-based material in Example 9 the length of the carbon nanotubes, and the particle size of the silicon-based material with carbon material layers and carbon nanotubes on the surface are different from those in Example 1.
  • Comparative Example 1 carbon nanotubes were not grown on the silicon-oxygen material, and other steps were the same as in Example 1.
  • the carbon nanotubes in Comparative Example 2 are formed ex-situ on the surface of the silicon-based material by coating. Except for the step of growing carbon nanotubes in situ, other steps are the same as in Example 1. In addition, the carbon nanotubes The length is different from Example 1. In Comparative Example 3, the silicon-oxygen material was not modified, and the silicon-oxygen material was directly used.
  • Cyclic expansion test The test temperature is 25°C, charge to 4.45V at a constant current of 0.5C, charge at a constant voltage to 0.025C, and discharge to 3.0V at 0.5C after standing for 5 minutes.
  • the capacity obtained in this step is taken as the initial capacity, and a 0.5C charge/0.5C discharge cycle test is performed, and a screw micrometer is used to test the thickness of the lithium-ion battery when it is initially half-charged. Every cycle up to 100 times, when the lithium-ion battery is fully charged, use a screw micrometer to test the thickness of the lithium-ion battery at this time, and compare it with the thickness of the lithium-ion battery at the initial half-charge, and you can get the lithium-ion battery at this time.
  • the expansion rate of the battery is based on the expansion rate of 600 cycles as a reference for the improvement of cycle expansion.
  • the test temperature is 45°C, charge to 4.45V with a constant current of 0.5C, charge to 0.025C with a constant voltage, and discharge to 3.0V at 0.2C after standing for 5 minutes.
  • the capacity obtained in this step is taken as the initial capacity, charged at 0.5C, discharged at 2C, and the ratio of the discharge capacity at 2C to the capacity at 0.2C is the rate performance. The larger the ratio, the better the rate performance and the better the charging capacity.
  • Table 1 shows the respective parameters and evaluation results of Examples 1 to 9 and Comparative Examples 1 to 3.
  • Example 1 By comparing Example 1 and Comparative Examples 1 to 3, it can be seen that when there are no carbon nanotubes or only ex-situ grown carbon nanotubes on the surface of the silicon-based material, the cycle expansion of the electrochemical device increases and the charging capacity decreases.

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  • Battery Electrode And Active Subsutance (AREA)

Abstract

La présente demande concerne un élément d'électrode négative, un appareil électrochimique et un appareil électronique. L'élément d'électrode négative comprend un collecteur de courant négatif et une couche de matériau actif négatif située sur au moins une partie d'une surface du collecteur de courant négatif. La couche de matériau actif négatif comprend un matériau actif négatif, et le matériau actif négatif comprend un matériau à base de silicium. Des nanotubes de carbone sont mis à croître in situ sur une surface du matériau à base de silicium. Un mode de réalisation de la présente demande entraîne une augmentation importante de la force d'adhérence entre le matériau à base de silicium et les nanotubes de carbone, le problème lié à une conductivité électrique insuffisante du fait d'un revêtement irrégulier lors du simple recouvrement d'une surface du matériau à base de silicium avec un matériau carboné est empêché, et le problème lié à la chute de la couche de recouvrement due à l'expansion de volume du matériau à base de silicium au cours du cyclage est empêché.
PCT/CN2021/094381 2021-05-18 2021-05-18 Élément d'électrode négative, appareil électrochimique et appareil électronique WO2022241642A1 (fr)

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CN202180005479.6A CN114503301A (zh) 2021-05-18 2021-05-18 负极极片、电化学装置和电子装置
PCT/CN2021/094381 WO2022241642A1 (fr) 2021-05-18 2021-05-18 Élément d'électrode négative, appareil électrochimique et appareil électronique

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CN116960280B (zh) * 2023-09-18 2024-04-30 宁德新能源科技有限公司 负极极片、其制备方法、以及包含其的电化学装置及电子装置

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