WO2025035587A1 - Feuille d'électrode négative et son procédé de fabrication, et batterie lithium-ion - Google Patents

Feuille d'électrode négative et son procédé de fabrication, et batterie lithium-ion Download PDF

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Publication number
WO2025035587A1
WO2025035587A1 PCT/CN2023/127290 CN2023127290W WO2025035587A1 WO 2025035587 A1 WO2025035587 A1 WO 2025035587A1 CN 2023127290 W CN2023127290 W CN 2023127290W WO 2025035587 A1 WO2025035587 A1 WO 2025035587A1
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Prior art keywords
active material
material layer
electrode sheet
silicon
negative electrode
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English (en)
Chinese (zh)
Inventor
彭成龙
朱伯礼
高云雷
袁学强
于子龙
项海标
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Zhejiang Liwinon Energy Technology Co Ltd
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Zhejiang Liwinon Energy Technology Co Ltd
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Publication of WO2025035587A1 publication Critical patent/WO2025035587A1/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
    • 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
    • H01M4/13—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
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of 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
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative electrode sheet and a preparation method thereof, and a lithium ion battery.
  • Another direction is to solve the volume expansion problem of silicon-based electrodes by optimizing the battery cell production process.
  • Selecting silicon-based materials with excellent performance and combining them with optimized battery cell production processes can better solve the adverse effects of electrode structure destruction caused by silicon volume expansion, which leads to a decrease in battery cell performance.
  • placing graphite in the first layer plays a role in fast charging
  • placing silicon particles in the second layer plays a role in improving energy density
  • these methods cannot solve the problem of increased battery cell thickness caused by the volume expansion of silicon.
  • there are currently technologies designed for graphite orientation which accelerate the ion transfer rate and thus improve the charging capacity by designing vertically oriented graphite.
  • the purpose of the present invention is: in order to reduce the risk of demolding and increase the energy density of the battery cell, the present invention designs a double-layer coating process, the first active material layer serves as the bottom layer, including silicon-based granular material, the second active material layer serves as the surface layer, including vertically oriented graphite, and the gaps between the vertical graphite on the surface layer provide expansion buffer space for the expansion of the silicon particles in the bottom layer.
  • a negative electrode sheet comprises a current collector, a first active material layer coated on at least one surface of the current collector and a second active material layer coated on the surface of the first active material layer, wherein the first active material layer comprises a silicon-based material and the second active material layer comprises vertically oriented graphite.
  • the viscosity ⁇ 1 of the first active material layer and the viscosity ⁇ 2 of the second active material layer satisfy the relationship: 0.5 ⁇ 1/ ⁇ 2 ⁇ 2.5.
  • the viscosity ⁇ 1 of the first active material layer is 3000-7000 mPa ⁇ s; and the viscosity ⁇ 2 of the second active material layer is 3000-5000 mPa ⁇ s.
  • the mass ratio of the silicon-based material to the vertically oriented graphite is (2-6):(4-8); and the silicon content in the silicon-based material is 2-15%.
  • the current collector includes at least one of copper foil, carbon paper and nickel foil; and the thickness of the current collector is 3 ⁇ m to 20 ⁇ m.
  • the silicon-based material includes at least one of silicon particles, silicon nanowires, and silicon-carbon skeleton composite materials; more preferably, silicon particles.
  • the vertically oriented graphite includes at least one of magnetic graphite and ordinary graphite magnetized by a magnetic fluid; wherein the magnetic fluid includes at least one of ferrosoferric oxide, ferrous oxide and ferric oxide.
  • the present invention also provides a method for preparing the above-mentioned negative electrode sheet, comprising the following steps:
  • the first active material layer slurry and the second active material layer slurry are coated on the current collector and dried to obtain a negative electrode sheet.
  • the mass ratio of the silicon-based material, the binder, the thickener and the conductive agent is (92-97%): (2.0-3.5%): (0.1-0.5%): (0.05-0.2%).
  • the mass ratio of the magnetic graphite, the binder and the thickener is (95% to 98%): (0.6 to 1.5%): (1.0 to 1.5%).
  • the binder includes at least one of PPA and SBR; the thickener includes at least one of CMC, PAA, PAN and polyacrylate; the conductive agent includes at least one of carbon nanotubes and graphene; the solvent is an aqueous solvent or an oil solvent, and the oil solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide and dimethyl sulfoxide.
  • the drying wind box is provided with a magnetic field emission device for converting part or all of the magnetic graphite material in the second active material layer slurry into vertically oriented graphite and vertically distributing it on the current collector.
  • the drying temperature is 60°C to 80°C.
  • the present invention also provides a lithium ion battery, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator spaced between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet is the negative electrode sheet mentioned above.
  • the present invention has at least the following beneficial effects:
  • the present invention designs a double-layer coating process.
  • the first active material layer serves as the bottom layer and includes a silicon-based granular material.
  • the second active material layer serves as the surface layer and includes vertically oriented graphite. The gaps between the vertical graphite on the surface layer provide an expansion buffer space for the expansion of the silicon particles in the bottom layer.
  • the double-layer coating structure and magnetic field deflection process of the negative electrode sheet of the present invention increase the energy density of the battery and avoid the risk of demolding of the vertically oriented graphite on the surface.
  • the vertically oriented graphite layer on the surface accelerates the transmission speed of lithium ions, adapts to the large volume change during charging and discharging, shortens the transmission path of electrons in the vertical direction, improves the electrode conductivity and the electron collection efficiency of the battery, and the electrolyte and the electrode are fully in contact, increasing the active sites and providing a certain buffer space for the expansion of the bottom silicon-based material. It is beneficial to reduce the expansion rate of the battery cell, while also ensuring the structural stability, which is beneficial to improving the cycle performance and charging capacity of the battery cell.
  • FIG1 is a schematic diagram of the structure of a negative electrode sheet in one embodiment of the present invention.
  • the present invention provides a negative electrode sheet, including a current collector, a first active material layer coated on at least one surface of the current collector, and a second active material layer coated on the surface of the first active material layer, the first active material layer includes a silicon-based material, and the second active material layer includes vertically oriented graphite.
  • the viscosity ⁇ 1 of the first active material layer and the viscosity ⁇ 2 of the second active material layer satisfy the relationship: 0.5 ⁇ 1/ ⁇ 2 ⁇ 2.5; ⁇ 1/ ⁇ 2 can specifically be 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5; when the viscosity ⁇ 1 of the first active material layer and the viscosity ⁇ 2 of the second active material layer are controlled within the above range, the adhesion between the first active material layer and the second active material layer can be ensured to be better, so that the electrode is not prone to stratification, and the battery can form a complete path for electrons and ions, thereby solving the problem of battery performance deterioration due to electrode stratification, affecting the capacity retention rate of the battery during cycling.
  • the viscosity ⁇ 1 of the first active material layer is 3000-7000 mPa ⁇ s, specifically 3000 mPa ⁇ s, 3500 mPa ⁇ s, 4000 mPa ⁇ s, 4500 mPa ⁇ s, 5000 mPa ⁇ s, 5500 mPa ⁇ s, 6000 mPa ⁇ s, 6500 mPa ⁇ s, 7000 mPa ⁇ s; when the viscosity ⁇ 1 of the first active material layer is controlled within the above range, a uniform and fixed coating can be formed to ensure that the battery has good electrochemical properties; if the viscosity is too small, it will lead to excessive fluidity and fail to form a uniform and fixed coating. If the viscosity is too high, the slurry will lack fluidity and will easily become uneven, affecting the electrochemical performance of the battery cell.
  • the viscosity ⁇ 2 of the second active material layer is 3000-5000mPa ⁇ s, specifically 3000mPa ⁇ s, 3200mPa ⁇ s, 3500mPa ⁇ s, 3800mPa ⁇ s, 4000mPa ⁇ s, 4200mPa ⁇ s, 4500mPa ⁇ s, 4800mPa ⁇ s, 5000mPa ⁇ s; when the viscosity ⁇ 2 of the second active material layer is controlled within the above range, it can be well bonded with the first active material layer, so that the two coatings are not prone to stratification, so that the battery can form a complete path for electrons and ions, thereby solving the problem of battery performance deterioration due to electrode stratification, affecting the capacity retention rate of the battery during cycling.
  • the mass ratio of silicon-based material to vertically oriented graphite is (2-6):(4-8), specifically 2:8, 3:7, 4:6, 5:5, 6:4.
  • the mass ratio of silicon-based material to vertically oriented graphite is controlled within the above range, while ensuring that the battery has a high energy density, the underlying silicon-based material can be protected by the vertically oriented graphite, thereby effectively suppressing the volume expansion caused by the silicon-based material. If the content of silicon-based material is too much, the volume expansion of the battery will increase seriously, thereby deteriorating the battery and affecting the performance of the battery. If the content of silicon-based material is too little, the battery cannot be guaranteed to have a high energy density.
  • the silicon content in the silicon-based material is 2-15%, specifically 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%; when the silicon content in the silicon-based material is controlled within the above range, the second active material layer can effectively control the volume expansion of the silicon-based material, thereby ensuring that the battery has a higher energy density while also having better performance.
  • the current collector includes at least one of copper foil, carbon paper, and nickel foil; the thickness of the current collector is 3 ⁇ m to 20 ⁇ m, specifically 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, and 20 ⁇ m.
  • the silicon-based material includes at least one of silicon particles, silicon nanowires, and silicon-carbon skeleton composite materials; preferably silicon particles.
  • the vertically oriented graphite includes at least one of magnetic graphite and ordinary graphite magnetized by a magnetic fluid; wherein the magnetic fluid includes at least one of ferrosoferric oxide, ferrous oxide and ferric oxide.
  • the present invention further provides a method for preparing the above-mentioned negative electrode sheet, comprising the following steps:
  • the first active material layer slurry and the second active material layer slurry are coated on the current collector and dried to obtain a negative electrode sheet.
  • the present invention designs a double-layer coating process, in which the bottom coating is a silicon-based granular material slurry layer, and the surface coating is a vertically oriented graphite slurry layer.
  • the gaps between the vertical graphites on the surface provide expansion buffer space for the expansion of the bottom silicon particles.
  • the bottom silicon-based material layer increases the energy density of the battery and avoids the risk of demolding of the vertically oriented graphite on the surface, while the vertically oriented graphite layer on the surface accelerates the lithium ion transmission speed, adapts to the large volume change during charging and discharging, shortens the electron transmission path in the vertical direction, improves the electrode conductivity and the electron collection efficiency of the battery, the electrolyte and the electrode are in full contact, the active sites are increased, and a certain buffer space is provided for the expansion of the bottom silicon-based material, which is beneficial to reducing the expansion rate of the battery cell, while also ensuring the structural stability, which is beneficial to improving the cycle performance and charging capacity of the battery cell.
  • the mass ratio of silicon-based material, binder, thickener and conductive agent is (92-97%): (2.0-3.5%): (0.1-0.5%): (0.05-0.2%); preferably 96.9%: 2.7%: 0.3%: 0.1%;
  • the mass ratio of magnetic graphite, binder and thickener is (95% to 98%): (0.6 to 1.5%): (1.0 to 1.5%); preferably 97.7%: 1.3%: 1.0%.
  • the binder includes at least one of PPA and SBR; the thickener includes at least one of CMC, PAA, PAN and polyacrylate; the conductive agent includes at least one of carbon nanotubes and graphene; the solvent is an aqueous solvent or an oil solvent, and the oil solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide and dimethyl sulfoxide.
  • a magnetic field emission device is provided in the bellows during drying to convert part or all of the magnetic graphite material in the second active material layer slurry into vertically oriented graphite and distribute it vertically on the current collector.
  • the drying temperature is 60°C-80°C, specifically 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C.
  • the present invention further provides a lithium ion battery, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet is the negative electrode sheet mentioned above.
  • the positive electrode active material in the positive electrode sheet may include but is not limited to at least one of LiCoO2 , LiNiO2 , LiMnO2 , LiMn2O4 , LiMnPO4 , LiFePO4 , LiNi1 / 3Co1 / 3Mn1 / 3O2, LiNi0.5Co0.2Mn0.3O2 , LiNi0.6Co0.2Mn0.2O2 , LiNi0.8Co0.1Mn0.1O2 , LiNi0.6Co0.1Mn0.3O2 , and LiNi0.85Co0.15Al0.05O2 .
  • the separator may be at least one of, but not limited to, polyethylene, polypropylene, polyvinylidene fluoride, and multilayer composite films thereof;
  • the electrolyte includes an electrolyte salt and an organic solvent, wherein the specific types and compositions of the electrolyte salt and the organic solvent are not subject to specific restrictions, and include positive electrode film-forming additives, negative electrode film-forming additives, and cycle-improving and low-temperature additives, etc.;
  • This embodiment provides a negative electrode sheet, including a current collector 1, and a A first active material layer and a second active material layer coated on the surface of the first active material layer, the first active material layer includes a silicon-based material 2 , and the second active material layer includes vertically oriented graphite 3 .
  • This embodiment also provides a method for preparing the above-mentioned negative electrode sheet, comprising the following steps:
  • (1) Configuration of the first active material layer slurry: silicon-based active material: carbon nanotube: PPA: SBR: CMC 96.9%: 0.1: 2.4: 0.3: 0.3 is mixed evenly, deionized water is added, and stirred evenly to obtain the first active material layer slurry, i.e., the bottom coating slurry; wherein the doping amount of silicon in the silicon-based active material is 3%; and the viscosity ⁇ 1 of the slurry is 3000 mPa ⁇ s;
  • step (3) the mass ratio of the first active material layer slurry to the second active material layer slurry is 3:7; the rest is the same as embodiment 1 and will not be repeated here.
  • step (3) the mass ratio of the first active material layer slurry to the second active material layer slurry is 4:6; the rest is the same as embodiment 1 and will not be repeated here.
  • step (3) the mass ratio of the first active material layer slurry to the second active material layer slurry is 5:5; the rest is the same as embodiment 1 and will not be repeated here.
  • step (3) the mass ratio of the first active material layer slurry to the second active material layer slurry is 6:4; the rest is the same as embodiment 1 and will not be repeated here.
  • step (1) the doping amount of silicon in the silicon-based active material is 5%; the rest is the same as embodiment 1 and will not be repeated here.
  • step (1) the doping amount of silicon in the silicon-based active material is 5%; the rest is the same as embodiment 2 and will not be repeated here.
  • step (1) the doping amount of silicon in the silicon-based active material is 5%; the rest is the same as embodiment 3 and will not be repeated here.
  • step (1) the doping amount of silicon in the silicon-based active material is 5%; the rest is the same as embodiment 4 and will not be repeated here.
  • step (1) the doping amount of silicon in the silicon-based active material is 5%; the rest is the same as embodiment 5 and will not be repeated here.
  • step (3) the mass ratio of the first active material layer slurry to the second active material layer slurry is 7:3; the rest is the same as Example 1 and will not be repeated here.
  • step (3) the mass ratio of the first active material layer slurry to the second active material layer slurry is 1:9; the rest is the same as Example 1 and will not be repeated here.
  • the negative electrode sheets and positive electrode sheets prepared in Examples 1-10 and Comparative Examples 1-4 are processed into finished batteries through post-processing such as rolling, slitting, tab welding, winding, packaging, baking, liquid injection, formation, and degassing.
  • the reason is that when the viscosity ⁇ 1 of the first active material layer slurry and the viscosity ⁇ 2 of the second active material layer slurry differ too much, the first active material layer and the second active material layer cannot be well bonded, so that the two coatings are prone to stratification, so that the battery cannot form a complete path for electrons and ions, resulting in the deterioration of the performance of the electrode stratification battery, affecting the capacity retention rate of the battery during cycling; further, when the viscosity ⁇ 1 of the first active material layer slurry is too large or too small, the fluidity of the first active material layer slurry will be too small or too large to form a uniform and fixed coating, thereby affecting the performance of the battery.
  • the bottom silicon-based material layer increases the energy density of the battery and avoids the risk of demolding of the surface vertically oriented graphite, while the surface vertically oriented graphite layer accelerates the lithium ion transmission speed, adapts to the large volume changes during charging and discharging, shortens the electron transmission path in the vertical direction, improves the electrode conductivity and the electron collection efficiency of the battery, and the electrolyte and the electrode are fully in contact, which increases the active sites and provides a certain buffer space for the expansion of the bottom silicon-based material, which is beneficial to reducing the expansion rate of the battery cell. At the same time, it also ensures the structural stability, which is beneficial to improving the cycle performance and charging capacity of the battery cell.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
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  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

Sont divulgués dans la présente invention une feuille d'électrode négative et son procédé de fabrication, ainsi qu'une batterie lithium-ion. La feuille d'électrode négative comprend un collecteur de courant, une première couche de matériau actif appliquée pour revêtir au moins une surface du collecteur de courant, et une seconde couche de matériau actif appliquée pour revêtir la surface de la première couche de matériau actif. La première couche de matériau actif comprend un matériau à base de silicium, et la seconde couche de matériau actif comprend du graphite orienté verticalement. Selon la présente invention, la première couche de matériau actif augmente la densité d'énergie d'une batterie et évite le risque associé au démoulage de la seconde couche de matériau actif ; un second matériau actif accélère le transport des ions lithium, ce qui permet de s'adapter à une modification de volume importante dans un processus de charge et de décharge, de raccourcir le trajet de transport des électrons dans la direction verticale et d'améliorer la conductivité électrique d'une électrode, ainsi que l'efficacité de collecte des électrons de la batterie ; et un électrolyte est en contact avec l'électrode, ce qui permet d'augmenter le nombre de sites actifs, de fournir un certain espace tampon pour l'expansion du matériau à base de silicium dans la première couche de matériau actif, de réduire le taux d'expansion d'un élément de batterie, d'assurer la stabilité structurale et d'améliorer les performances de cycle et la capacité de charge de l'élément de batterie.
PCT/CN2023/127290 2023-08-15 2023-10-27 Feuille d'électrode négative et son procédé de fabrication, et batterie lithium-ion Pending WO2025035587A1 (fr)

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CN202311022956.7 2023-08-15
CN202311022956.7A CN117117080A (zh) 2023-08-15 2023-08-15 一种负极片及其制备方法和锂离子电池

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CN120809746A (zh) * 2025-09-16 2025-10-17 重庆市维都利新能源有限公司 提高卷绕结构电池电化学性能的多层结构负极极片、工艺

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