WO2023124913A1 - Matériau actif d'électrode négative, son procédé de préparation, et batterie secondaire et appareil associés - Google Patents

Matériau actif d'électrode négative, son procédé de préparation, et batterie secondaire et appareil associés Download PDF

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WO2023124913A1
WO2023124913A1 PCT/CN2022/138071 CN2022138071W WO2023124913A1 WO 2023124913 A1 WO2023124913 A1 WO 2023124913A1 CN 2022138071 W CN2022138071 W CN 2022138071W WO 2023124913 A1 WO2023124913 A1 WO 2023124913A1
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negative electrode
active material
electrode active
deposition
optionally
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PCT/CN2022/138071
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English (en)
Chinese (zh)
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吕子建
王家政
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宁德时代新能源科技股份有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, in particular to a negative electrode active material, a preparation method thereof, and related secondary batteries and devices.
  • SiO x materials With the continuous improvement of people's requirements for the specific energy of lithium-ion batteries, the application of silicon negative electrode materials has become an irresistible trend.
  • the research hotspots of major material manufacturers are mainly concentrated in the SiO x material.
  • silicon oxide materials will generate Li 2 O and Li 4 SiO 4 inactive products during the lithium intercalation process, resulting in partial Li deactivation, the first-time efficiency of SiO x materials is generally only about 70%, and the first-time efficiency is low. It is one of the important factors restricting the practical application of SiO x .
  • the purpose of this application is to provide a negative electrode active material, its preparation method and its related secondary battery and device, aiming to make the battery have both higher initial Coulombic efficiency and better fast charging performance.
  • the first aspect of the present application provides a negative electrode active material, including silicon oxide particles, and the bulk phase of the silicon oxide particles contains conductive components.
  • Silicon oxide (SiO) has become one of the most promising anode materials for lithium-ion batteries due to its high theoretical specific capacity, suitable potential for intercalating lithium, long cycle charge and discharge life, abundant reserves, and environmental friendliness.
  • SiO materials have become the most promising anode materials for lithium-ion batteries due to its high theoretical specific capacity, suitable potential for intercalating lithium, long cycle charge and discharge life, abundant reserves, and environmental friendliness.
  • the inherent low intrinsic conductivity of SiO materials and the volume change effect encountered during cycling are still the main technical obstacles restricting their practical commercialization. Therefore, this application improves the conductivity of the silicon oxide bulk phase by distributing conductive components inside the silicon oxide bulk phase, and improves the lithium intercalation and delithiation capabilities of the material, which helps to achieve higher first-time Coulombic efficiency and better fast charging performance.
  • the conductive component is selected from carbon-based materials; optionally, the carbon-based material is selected from one or more of conductive carbon black, carbon nanotubes, graphene, and carbon fibers. Porous carbon with a high specific surface area is used as a conductive component to further improve the conductivity of the negative electrode active material.
  • the conductive component includes carbon nanotubes, and optionally, the diameter of the carbon nanotubes is 1.6 ⁇ 0.4 nm, and the length of the carbon nanotubes is 5-20 ⁇ m.
  • the use of carbon nanotubes is conducive to further improving the conductivity and volume expansion adaptability of the negative electrode active material. Its fibrous structure can form a continuous conductive network in the negative electrode active material, and further promote the penetration of the electrolyte in the electrode material. Carbon nanotubes have better fillability and compressibility when the tube diameter is 1.6 ⁇ 0.4nm and the tube length is 5-20 ⁇ m, which can improve the binding efficiency of the conductive component and the silicon oxide bulk phase, and further Improved conductivity and first Coulombic efficiency.
  • the mass percentage of the conductive component and the silicon oxide is 1%-5%, optionally 2%-4%.
  • the addition amount of the conductive component should not be too high or too low, too little can not significantly improve the conductivity, adding too much will easily lead to an increase in specific surface area, affecting the first coulombic efficiency and gram capacity of the material. When the proportion of the conductive component is in an appropriate range, the capacity can be further improved.
  • At least a part of the surface of the negative electrode active material is provided with a carbon coating layer.
  • the surface of the negative electrode active material is coated with a carbon coating layer, which can further improve the conductivity of the material, and the addition of the carbon coating layer plays a buffer role in the volume expansion and contraction of the material during charge and discharge, thereby further improving the cycle performance of the battery.
  • the volume distribution particle diameter Dv50 of the negative electrode active material is 4 ⁇ m-10 ⁇ m; optionally, it is 6 ⁇ m-8 ⁇ m. If the Dv50 of the negative electrode active material is in an appropriate range, the fast charging performance of the secondary battery can be further improved, and the energy density of the battery can also be improved.
  • the specific surface area of the negative electrode active material is 0.5m2/g-2m2/g; optionally, it is 0.8m2/g-1.6m2/g. If the specific surface area of the negative electrode active material is within the above range, lithium consumption can be reduced, and the first Coulombic efficiency of the secondary battery can be further improved.
  • the powder resistivity of the negative electrode active material at 4 MPa is ⁇ 1 ⁇ cm; optionally, it is ⁇ 0.8 ⁇ cm. If the powder resistivity of the negative electrode active material is within the above range, the first Coulombic efficiency and cycle life of the negative electrode active material can be further improved.
  • the second aspect of the present application also provides a method for preparing a negative electrode active material, comprising the steps of:
  • S1 Provide silica powder, silicon powder and conductive components
  • the silicon dioxide powder and the silicon powder are formed into silicon dioxide vapor, the valve between the heating chamber and the deposition chamber is opened, and the silicon dioxide vapor is deposited by vapor phase deposition. vapor deposition on at least a portion of the surface of the conductive component to obtain the negative active material;
  • the negative electrode active material includes silicon oxide particles, and the bulk phase of the silicon oxide particles contains conductive components.
  • the negative electrode active material obtained by the preparation method provided in this application includes a silicon oxide composition containing a conductive component in the bulk phase.
  • the gas phase deposition process is adopted, the process is simple, the consumables are less, and the combination efficiency of the conductive component and the silicon oxide is high and strong. Large, significantly improving the conductivity of the silicon oxide bulk phase, improving the lithium insertion and delithiation capabilities of the material, and improving the energy density and fast charging performance of the secondary battery.
  • step S2 silicon powder and silicon dioxide powder are mixed according to a molar ratio of (0.75-1):1.
  • the molar ratio of silicon powder to silicon dioxide powder is within the above range, the effect of forming silicon oxide is better, avoiding that too high oxygen content affects the first coulombic efficiency of the material, or too low oxygen content affects the cycle stability of the material.
  • step S2 the heating chamber and the deposition chamber of the vapor deposition method are evacuated to 100Pa-500Pa; optionally 200Pa-400Pa.
  • step S3 at a temperature of 1200°C-1500°C, the silicon dioxide powder and the silicon powder are formed into silicon oxide vapor.
  • step S3 the mass percentage of the conductive component to the total mass of silicon dioxide powder and silicon powder is 1-5%; optionally 2-4%.
  • the deposition temperature in the vapor phase deposition method is 400°C-800°C, optionally 600°C-800°C.
  • the deposition rate of silicon oxide is moderate, which helps to better realize the bulk phase combination of silicon oxide and conductive components.
  • step S3 the step of the vapor phase deposition method includes passing silicon oxide vapor into the deposition chamber containing the conductive component for natural cooling deposition, and the deposition chamber is in a moving state.
  • the deposition chamber is in a moving state, so that the conductive components are more evenly distributed into the deposited silicon oxide, and the uniformity of distribution is improved.
  • the deposition chamber is in a rotating state, and the rotational speed of the deposition chamber is 0.5r/min-3r/min; it may be 1r/min-2r/min.
  • the deposition chamber is in the above-mentioned appropriate speed range, which further improves the uniformity of deposition and the consistency of material structure.
  • the preparation method also includes step S4: performing carbon coating treatment on the surface of the negative electrode active material prepared in step S3.
  • step S4 carbon coating treatment is performed by vapor deposition method; optionally, carbon coating treatment is performed using hydrocarbon gas as a carbon source in vapor deposition method; optionally, the Hydrocarbon gases include one or more of methane, acetylene, and ethylene.
  • the deposition temperature in the vapor phase deposition method is 650-950°C, optionally 750-900°C. If the vapor deposition temperature is within the above range, the formed material will have better properties, and if the temperature is low, there will be many structural defects in the carbon layer, which will affect the first effect; if the temperature is too high, it will easily lead to the disproportionation of silicon and oxygen.
  • the third aspect of the present application provides a secondary battery, which includes the negative electrode active material of the first aspect of the present application or the negative electrode active material prepared according to the method of the second aspect of the present application.
  • a fourth aspect of the present application provides a battery module including the secondary battery according to the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack, which includes the battery module according to the fourth aspect of the present application.
  • the sixth aspect of the present application provides an electric device, which includes at least one of the secondary battery according to the third aspect of the present application, the battery module according to the fourth aspect of the present application, and the battery pack according to the fifth aspect of the present application kind.
  • FIG. 1 is a schematic diagram of an embodiment of a secondary battery of the present application.
  • FIG. 2 is a schematic diagram of an embodiment of a battery module of the present application.
  • FIG. 3 is a schematic diagram of an embodiment of the battery pack of the present application.
  • FIG. 4 is an exploded view of the battery pack according to one embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of an embodiment of a device in which a secondary battery is used as a power source of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range "a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • the present application proposes a negative electrode active material, including silicon oxide particles, and the bulk phase of the silicon oxide particles contains conductive components.
  • Silicon oxide SiO x has become one of the most promising anode materials for lithium-ion batteries due to its high theoretical specific capacity, suitable potential for lithium intercalation and deintercalation, long cycle charge and discharge life, abundant reserves, and environmental friendliness.
  • the half-cell test when using 0.05C/50 ⁇ A to intercalate lithium to 5mV sequentially, its 0.05C lithium intercalation capacity accounts for 90% to 96% of the total lithium intercalation capacity.
  • the conductive component is selected from carbon-based materials; optionally, the carbon-based material is selected from one or more of conductive carbon black, carbon nanotubes, graphene, and carbon fibers.
  • the conductive component includes carbon nanotubes, and the carbon nanotubes have a diameter of 1.6 ⁇ 0.4 nm and a length of 5-20 ⁇ m.
  • the mass proportion of the conductive component in the silicon oxide particles is 1%-5%, optionally 2%-4%.
  • the addition amount of the conductive component should not be too high or too low, too little can not significantly improve the conductivity, adding too much will easily lead to an increase in specific surface area, affecting the first coulombic efficiency and gram capacity of the material. When the proportion of the conductive component is in an appropriate range, the capacity can be further improved.
  • At least a portion of the surface of the silicon oxide particles is provided with a carbon coating.
  • the surface of the negative electrode active material is coated with a carbon coating layer, which further improves the conductivity of the negative electrode active material, and the addition of the carbon coating layer plays a buffer role in the volume expansion and contraction of the negative electrode active material during charge and discharge, thereby further improving the battery performance. cycle performance.
  • the volume distribution particle diameter Dv50 of the negative electrode active material is 4 ⁇ m-10 ⁇ m; optionally, it is 6 ⁇ m-8 ⁇ m.
  • the average particle diameter Dv50 of the negative electrode active material is a well-known meaning in the art, and can be measured with instruments and methods known in the art. For example, it can be conveniently measured by laser particle size analyzer with reference to GB/T 19077-2016 particle size distribution laser diffraction method, such as the Mastersizer2000E laser particle size analyzer of British Malvern Instruments Co., Ltd.
  • Dv50 represents the particle size corresponding to when the cumulative volume distribution percentage of the silicon oxide compound reaches 50%.
  • the fast charging performance of the secondary battery can be further improved, and the energy density of the battery can also be improved.
  • the specific surface area of the negative electrode active material is 0.5m2/g-2m2/g; optionally, it is 0.8m2/g-1.6m2/g.
  • the specific surface area of the negative electrode active material is a well-known meaning in the art, and can be measured with instruments and methods known in the art, for example, can be measured with reference to the GB/T 19587-2004 gas adsorption BET method for measuring the solid substance specific surface area standard,
  • the nitrogen adsorption specific surface area analysis test method is used for testing and calculated by the BET (Brunauer Emmett Teller) method, wherein the nitrogen adsorption specific surface area analysis test can be carried out by the Tni StarlI 3020 specific surface and pore analyzer of Micromeritics Corporation in the United States.
  • the specific surface area of the negative electrode active material is too small, the internal resistance of the battery is high, the discharge platform is low, the capacity is low, the rate performance is not good, and the cycle performance is not good; the specific surface area is too large, the electrochemical performance of the material is good, but the activity is high and easy Reunion, difficult to disperse, difficult to process pole pieces.
  • the specific surface area of the negative electrode active material is within the above range, lithium consumption can be reduced, and the first Coulombic efficiency of the secondary battery can be further improved.
  • the powder resistivity of the negative electrode active material at 4 MPa is ⁇ 1 ⁇ cm; optionally ⁇ 0.8 ⁇ cm.
  • the powder resistivity is based on the GB/T 30835-2014 test method, and the ST2722 resistivity tester is used to test the powder resistance data of the above materials under 4MPa pressure. If the powder resistivity of the negative electrode active material is within the above range, the first Coulombic efficiency and cycle life of the negative electrode active material can be further improved.
  • the second aspect of the present application also provides a method for preparing a negative electrode active material, comprising the steps of:
  • S1 Provide silica powder, silicon powder and conductive components
  • the silicon dioxide powder and the silicon powder are formed into silicon dioxide vapor, the valve between the heating chamber and the deposition chamber is opened, and the silicon dioxide vapor is deposited by vapor phase deposition. vapor deposition on at least a portion of the surface of the conductive component to obtain the negative active material;
  • the negative electrode active material includes silicon oxide particles, and the bulk phase of the silicon oxide particles contains conductive components.
  • the negative electrode active material obtained by the preparation method provided in this application includes a silicon oxide composition containing a conductive component in the bulk phase.
  • the gas phase deposition process is adopted, the process is simple, the consumables are less, and the combination efficiency of the conductive component and the silicon oxide is high and strong. Large, significantly improving the conductivity of the silicon oxide bulk phase, improving the lithium insertion and delithiation capabilities of the material, and improving the energy density and fast charging performance of the secondary battery.
  • silicon powder and silicon dioxide powder are mixed according to a molar ratio of (0.75-1):1.
  • the effect of forming silicon oxide is better, avoiding that too high oxygen content affects the first coulombic efficiency of the material, or too low oxygen content affects the cycle stability of the material.
  • the heating chamber and the deposition chamber of the vapor deposition method are evacuated to 100Pa-500Pa; optionally 200Pa-400Pa.
  • the degree of vacuum is within the above range, the reaction can be carried out more easily, and the preparation efficiency of the negative electrode active material can be further improved.
  • step S3 the silicon dioxide powder and the silicon powder are formed into silicon oxide vapor at a temperature of 1200°C-1500°C.
  • the temperature is within the above range, the production efficiency of silicon oxide is further improved.
  • the mass percentage of the conductive component to the total mass of silicon dioxide powder and silicon powder is 1-5%; optionally 2-4%.
  • An appropriate mass percentage of the conductive component to the total mass of the silicon dioxide powder and the silicon powder can avoid excessive agglomeration or low yield, and further improve the preparation efficiency of the negative electrode active material.
  • the deposition temperature in the vapor phase deposition method is 400-800°C, optionally 600-800°C.
  • the deposition rate of silicon oxide is moderate, which helps to better realize the bulk phase combination of silicon oxide and conductive components.
  • the step of the vapor phase deposition method includes passing the silicon oxide vapor into the deposition chamber containing the conductive component for natural cooling deposition, and the deposition chamber is in motion.
  • the deposition chamber is in a moving state, so that the conductive components are more evenly distributed into the deposited silicon oxide, and the uniformity of distribution is improved.
  • the deposition chamber is in a rotating state, and the rotational speed of the deposition chamber is 0.5r/min-3r/min; it may be 1r/min-2r/min.
  • the deposition chamber is in the above-mentioned appropriate speed range, which further improves the uniformity of deposition and the consistency of material structure.
  • it includes using crushing and classifying equipment to carry out particle size classification on the obtained negative electrode active material block.
  • the average particle size of the intermediate silica obtained by classification should not be too large. A larger Dv50 corresponds to a worse kinetics of the material, and a smaller particle size will result in an excessively high ratio, which is not good for the first effect of the material; a suitable particle size distribution is also conducive to the kinetics of the material. If the particle size distribution is too small, the yield will be low, which is unfavorable to the cost.
  • the particle size can meet the production needs, and the particle size distribution range can be optimized through grading to improve the quality stability of the product.
  • the preparation method further includes S4: performing carbon coating treatment on the surface of the negative electrode active material prepared in step S3.
  • the carbon coating can be performed by vapor deposition.
  • hydrocarbon gas is used as a carbon source to perform carbon coating treatment.
  • the hydrocarbon gas includes one or more of methane, acetylene, and ethylene.
  • the third aspect of the present application provides a secondary battery, which includes the negative electrode active material of the first aspect of the present application or the negative electrode active material prepared according to the method of the second aspect of the present application.
  • a fourth aspect of the present application provides a battery module including the secondary battery according to the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack, which includes the battery module according to the fourth aspect of the present application.
  • the sixth aspect of the present application provides an electric device, which includes at least one of the secondary battery according to the third aspect of the present application, the battery module according to the fourth aspect of the present application, and the battery pack according to the fifth aspect of the present application kind.
  • a secondary battery is provided.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • the positive pole piece includes a positive current collector and a positive film layer arranged on at least one surface of the positive current collector.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid Ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) and other substrates).
  • PP polypropylene
  • PET polyethylene terephthalic acid Ethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may be a positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon At least one of a composite material, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also may be abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may further optionally include a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive electrode film layer may also optionally include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector.
  • the negative electrode film layer includes a negative electrode active material. Silica.
  • the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode active material may be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further optionally include a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may also optionally include a conductive agent.
  • the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • CMC-Na sodium carboxymethylcellulose
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the present application has no specific limitation on the type of electrolyte, which can be selected according to requirements.
  • the electrolyte is an electrolytic solution.
  • the electrolytic solution includes an electrolytic salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the solvent may be selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may optionally include additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.
  • a separator is further included in the secondary battery.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG. 1 shows a square-shaped secondary battery 5 as an example.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 2 is a battery module 4 as an example, wherein a plurality of secondary batteries 5 may be arranged sequentially along the length direction of the battery module 4 . Of course, it can also be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules 4 can also be assembled into a battery pack 1, and the number of battery modules 4 contained in the battery pack 1 can be one or more, and those skilled in the art can determine the specific number according to the application and capacity of the battery pack 1 Make a selection.
  • FIG. 3 shows the battery pack 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the secondary battery 5 , the battery module 4 , and the battery pack 1 provided in the present application.
  • the secondary battery 5 , the battery module 4 , or the battery pack 1 can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 4 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • the silicon powder and the silicon dioxide powder are physically mixed according to the molar ratio of 0.85:1, they are placed in the heating chamber of the vapor deposition furnace, and the conductive components with 5% of the total mass of the silicon dioxide and the silicon powder are placed in the deposition chamber of the vapor deposition furnace , the heating chamber communicates with the deposition chamber through a valve;
  • the heating chamber and the deposition chamber are heated to 1400°C and 700°C respectively;
  • the intermediate was coated with gas-phase carbon at a methane:nitrogen flow ratio of 1:5 at a coating temperature of 900°C for 3 hours to obtain the final negative electrode active material.
  • Example 1 The difference from Example 1 is that the relevant parameters in the preparation process were regulated to obtain the corresponding negative electrode active material, see Table 1 for details.
  • the carbon coating agent used is pitch, and the addition amount is 10% of the precursor B to obtain the precursor C;
  • the carbon nanotubes are dispersed between the silicon-oxygen inner core and the carbon layer, and do not enter into the silicon oxide bulk phase.
  • precursor A The slurry is subjected to spray granulation and heat treatment at 600° C. to obtain precursor A.
  • the precursor A was subjected to vapor phase coating treatment, acetylene was used as the carbon source, and the finished product was obtained by coating at 900°C for 2 hours.
  • the carbon nanotubes are dispersed between the silicon-oxygen inner core and the carbon layer, and do not enter the silicon-oxygen phase.
  • the precursor C 4 Sieve the precursor C and treat it with 0.5mol/L HCL for 4h.
  • the product was obtained after filtration, washing with deionized water and drying.
  • the carbon nanotubes are dispersed between the silicon-oxygen particles and the carbon layer, and do not enter into the silicon oxide bulk phase.
  • the negative electrode active material After mixing the negative electrode active material, conductive carbon black, and binder polyacrylic acid prepared in the above-mentioned examples and comparative examples in a mass ratio of 8:1:1, add deionized water as a solvent, and stir until the system is uniform under the action of a stirrer , to obtain the negative electrode slurry; the negative electrode slurry is evenly coated on the copper foil of the negative electrode current collector and dried, and the electrode pole piece is obtained after cold pressing, and the electrode pole piece is cut into small discs with a diameter of 14mm.
  • the electrolyte is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), wherein the volume ratio of EC, EMC and DEC is 20:20:60.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • LiPF6 was dissolved in the above organic solvent, and the additive fluoroethylene carbonate (FEC) was added, wherein the concentration of LiPF6 was 1mol/L, and the mass proportion of FEC in the electrolyte was 5%.
  • Discharge at a constant current rate of 0.05C to 5mV is the lithium intercalation capacity of the first cycle; then charge at a constant current rate of 0.1C to 2V, and then stand for 10min. This is a cyclic charge-discharge process, record the current value
  • the charging capacity is the delithiation capacity of the first cycle.
  • the first Coulombic efficiency (%) delithiation capacity of the first cycle / lithium insertion capacity of the first cycle x 100%
  • Table 1 Table of process parameters for the preparation of negative electrode active materials
  • the negative electrode active material of the present application effectively improves the initial Coulombic efficiency and fast charging performance of the negative electrode active material by distributing the conductive component in the silicon oxide bulk phase.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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  • Electrochemistry (AREA)
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Abstract

L'invention concerne un matériau actif d'électrode négative, son procédé de préparation, et une batterie secondaire et un appareil électrique associés à celle-ci. Le matériau actif d'électrode négative comprend des particules de monoxyde de silicium, la phase massive des particules de monoxyde de silicium contenant des composants conducteurs à l'intérieur de celles-ci. Au moyen de la distribution de composants conducteurs dans la phase massive de monoxyde de silicium, la conductivité du matériau est améliorée, et les capacités d'intercalation de lithium et de désintercalation de lithium du matériau sont améliorées, ce qui permet d'obtenir une efficacité coulombique initiale relativement élevée et une performance de charge rapide relativement bonne.
PCT/CN2022/138071 2021-12-28 2022-12-09 Matériau actif d'électrode négative, son procédé de préparation, et batterie secondaire et appareil associés WO2023124913A1 (fr)

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