WO2024061011A1 - 锂离子电池和用电设备 - Google Patents

锂离子电池和用电设备 Download PDF

Info

Publication number
WO2024061011A1
WO2024061011A1 PCT/CN2023/117492 CN2023117492W WO2024061011A1 WO 2024061011 A1 WO2024061011 A1 WO 2024061011A1 CN 2023117492 W CN2023117492 W CN 2023117492W WO 2024061011 A1 WO2024061011 A1 WO 2024061011A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
sub
negative electrode
material layer
lithium
Prior art date
Application number
PCT/CN2023/117492
Other languages
English (en)
French (fr)
Inventor
李枝贤
刘帅
田雷雷
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Publication of WO2024061011A1 publication Critical patent/WO2024061011A1/zh

Links

Classifications

    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or 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
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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

  • This application relates to the field of new energy batteries, specifically a lithium-ion battery and electrical equipment.
  • Lithium-ion batteries are widely used in consumer electronics (such as mobile phones, laptops and other electronic products) and electric vehicles due to their high energy density and long cycle life.
  • the safety issues of lithium-ion batteries have become increasingly prominent. If used improperly, problems such as burning or even explosion may occur.
  • Research has found that the above safety problems in lithium-ion batteries are mainly related to the following four short-circuit methods: 1) the positive electrode material layer contacts the negative electrode material layer; 2) the positive electrode material layer contacts the copper foil; 3) the aluminum foil contacts the negative electrode material layer; 4) the aluminum foil Contact copper foil.
  • method 3) is more likely to cause thermal runaway, resulting in battery combustion and explosion.
  • lithium titanate As the negative electrode active material, lithium titanate itself can inhibit the formation of lithium dendrites, using lithium titanate as the negative electrode active material can improve the separation between aluminum foil and Safety between layers of negative material.
  • lithium titanate due to the low specific capacity of lithium titanate, when lithium titanate is used as the negative active material, the energy density of lithium-ion batteries is low and cannot meet the energy density requirements of existing products, making commercial applications impossible.
  • This application provides a lithium-ion battery and electrical equipment to obtain a lithium-ion battery with both high safety and high energy density.
  • the present application provides a lithium-ion battery.
  • the lithium-ion battery includes a positive electrode sheet and a negative electrode sheet.
  • the positive electrode sheet includes a stacked positive electrode current collector and a positive electrode material layer
  • the negative electrode sheet includes a stacked stacked positive electrode sheet.
  • Negative current collector and negative electrode material layer, the negative electrode material layer includes a first sub-layer, the negative electrode active material in the first sub-layer includes lithium titanate, the area density of the first sub-layer is ⁇ 0.1 mg/cm 2 , the negative electrode material layer and the positive electrode
  • the capacity ratio Nc/Pc of the material layer is 0 ⁇ Nc/Pc ⁇ 1.04.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer. Since the negative electrode active material in the first sub-layer of the negative electrode material layer is lithium titanate, during the recycling process of the lithium-ion battery, titanium Lithium acid acid has a high lithium insertion potential, which can inhibit the formation of lithium dendrites, thereby preventing thermal runaway caused by contact between the positive electrode current collector and the negative electrode material layer. Therefore, the lithium-ion battery has high safety.
  • the positive electrode active material and The relative dosage between negative active materials makes the dosage between positive active materials and negative active materials more consistent, avoiding unnecessary addition of positive active materials and negative active materials. Therefore, when the capacity of the positive electrode plate of the battery is certain, , the amount of negative electrode material can be reduced to reduce the volume of the negative electrode piece, thereby improving the energy density of the lithium-ion battery while ensuring the safety between the first sub-layer and the positive electrode current collector.
  • the capacity ratio Nc/Pc of the negative electrode material layer and the positive electrode material layer is 0.2 ⁇ Nc/Pc ⁇ 1.04; preferably, Nc/Pc ⁇ 0.3, Nc/Pc ⁇ 1.02, and further preferably, Nc/Pc ⁇ 0.4, Nc/Pc ⁇ 1.
  • the through hole preferably has a ratio of Nc/Pc, which can effectively avoid the cycle attenuation of the lithium-ion battery caused by the relative low content of the negative active material, thereby maintaining good cycle performance of the lithium-ion battery.
  • the negative electrode material layer includes a second sub-layer, the second sub-layer is provided between the negative electrode current collector and the first sub-layer, and the negative electrode active material in the second sub-layer includes carbon material or silicon base Material. Since carbon materials and silicon-based materials have high specific capacities, the energy density of lithium-ion batteries can be further improved by providing a negative active material containing carbon materials and/or silicon-based materials as the second sub-layer.
  • the mass ratio of the second sub-layer to the first sub-layer is greater than or equal to 1, preferably 7:1 to 12:1, preferably greater than or equal to 7.5:1, less than or equal to 11.5:1, further Preferably it is greater than or equal to 8:1 and less than or equal to 11:1.
  • a lithium-containing metal layer is provided between the first sub-layer and the second sub-layer.
  • the lithium-containing metal layer has a higher specific capacity.
  • the negative electrode material layer includes a lithium-containing metal layer, and the lithium-containing metal layer is provided between the negative electrode current collector and the first sub-layer.
  • the length dimension of the first sublayer is greater than or equal to the length dimension of the second sublayer
  • the width dimension of the first sublayer is greater than or equal to the width dimension of the second sublayer
  • the length of the first sublayer is greater than or equal to the length of the second sublayer, and the width of the second sublayer is greater than or equal to the width of the second sublayer.
  • the first sublayer can block the lithium dendrites on the surface of the second sublayer from penetrating the separator, thus preventing A short circuit between the positive and negative pole pieces.
  • the orthographic projection area of the positive electrode material layer on the plane where the first sublayer is located is less than or equal to the area of the first sublayer, and along the width direction of the positive electrode material layer, the size difference between the first sublayer and the positive electrode material layer is less than 1.5 mm; along the length direction of the positive electrode material layer, the size difference between the first sublayer and the positive electrode material layer is less than 3 mm.
  • a single-side margin between the cathode material layer and the first sub-layer is 0 to 0.1 mm. In a possible implementation, along the length direction of the cathode material layer, a single-side margin between the cathode material layer and the first sub-layer is 0 to 1 mm.
  • the lithium-ion battery implemented in this application uses lithium titanate as the active material of the first sub-layer, so that the total margin in the width direction between the first sub-layer and the cathode material layer can be controlled to 0 to 1.5 mm.
  • the side margin is controlled at 0-0.1 mm
  • the total margin in the length direction between the first sub-layer and the cathode material layer is controlled at 0-3.0 mm
  • the single-side margin is controlled at 0-1 mm.
  • the size difference between the first sub-layer and the cathode material layer is small, and further, they can be set to the same size. Therefore, the waste of size space of the first sub-layer or the cathode material layer can be avoided, and thus can Further improve the energy density of lithium-ion batteries.
  • the cathode material layer is doped with nanometer metal oxide particles. Adding nanometer metal oxides to the cathode material layer can reduce the activity of the cathode material layer, prevent lithium ions in the cathode material layer from being embedded into the anode material layer too quickly, and alleviate the inability of the anode material layer to accommodate lithium ions from the cathode material layer in time. The problem of lithium ions precipitating on the surface. By adding an appropriate amount of nanometal oxides to the cathode material layer, it can help reduce the amount of negative active material and further reduce the Nc/Pc ratio, thereby further increasing the energy density of the battery.
  • At least one of the first sub-layer and the second sub-layer is doped with nanometer metal oxide particles. Adding nano-metal oxide to at least one of the first sub-layer and the second sub-layer of the negative electrode material layer can further improve the safety of the negative electrode material layer. Adding nano-metal oxide to the negative electrode material layer helps to reduce the weight of the negative electrode plate. When the aluminum foil contacts the negative electrode piece, the addition of nanometal oxide can increase the polarization of the negative electrode piece during short circuit, thus improving the safety of the battery.
  • the cathode active material in the cathode material layer is LiCo 1-x M x O 2 , where 0 ⁇ x ⁇ 1, M is selected from Ni, Mn, Al, Ca, Mg, Sr, At least one of Ti, V, Cr, Fe, Cu, Zn, Mo, W, Y, La, Zr, Sn, Se, Te and Bi.
  • the positive current collector includes an aluminum foil current collector, an aluminum alloy current collector, or an aluminum composite current collector; and the negative electrode current collector includes a copper foil current collector, a copper alloy current collector, or a copper composite current collector.
  • the present application provides a lithium-ion battery, which includes a positive electrode plate and a negative electrode plate, the positive electrode plate includes a positive electrode collector and a positive electrode material layer arranged in a stacked manner, the negative electrode plate includes a negative electrode collector and a negative electrode material layer arranged in a stacked manner, the negative electrode material layer includes a first sublayer, and the negative electrode active material in the first sublayer includes lithium titanate; the orthographic projection area of the positive electrode material layer on the plane where the first sublayer is located is less than or equal to the area of the first sublayer, and along the width direction of the positive electrode material layer, the size difference between the first sublayer and the positive electrode material layer is less than 1.5 mm; along the length direction of the positive electrode material layer, the size difference between the first sublayer and the positive electrode material layer is less than 3 mm.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer. Since the negative electrode active material in the first sub-layer of the negative electrode material layer is lithium titanate, during the recycling process of the lithium-ion battery, titanium Lithium acid acid has a high lithium insertion potential, which can inhibit the formation of lithium dendrites, thereby preventing thermal runaway caused by contact between the positive electrode current collector and the negative electrode material layer. Therefore, the lithium-ion battery has high safety.
  • the size of the first sub-layer containing lithium titanate in the negative electrode material layer is larger than the size of the positive electrode material layer, and by limiting the size difference between the first sub-layer and the positive electrode material layer within the above range, on the one hand, when When the size of the first sub-layer is constant, the size of the cathode material layer can be maximized to increase the area of the cathode material layer, thereby increasing the capacity of the cathode material layer, thereby ensuring that the space between the first sub-layer and the cathode current collector can be maintained While improving safety, it also improves the energy density of lithium-ion batteries.
  • the size of the positive electrode material layer is constant, the size of the first sub-layer can be reduced to the greatest extent, which can effectively reduce the area of the negative electrode piece, thereby reducing the volume of the negative electrode piece, thus ensuring the first While ensuring safety between the sub-layer and the cathode current collector, it also improves the energy density of the lithium-ion battery.
  • a single-side margin between the cathode material layer and the first sub-layer is 0 to 0.1 mm. In a possible implementation, along the length direction of the cathode material layer, a single-side margin between the cathode material layer and the first sub-layer is 0 to 1 mm. In a possible implementation, the size of the cathode material layer and the first sub-layer are the same. In this implementation, the size difference between the first sub-layer and the cathode material layer is small, and further, they can be set to the same size. Therefore, the waste of size space of the first sub-layer or the cathode material layer can be avoided, and thus can Further improve the energy density of lithium-ion batteries.
  • the negative electrode material layer includes a second sub-layer, the second sub-layer is provided between the negative electrode current collector and the first sub-layer, and the second sub-layer
  • the negative active materials include carbon materials or silicon-based materials.
  • a lithium-containing metal negative electrode layer is provided between the first sub-layer and the second sub-layer.
  • the negative electrode material layer includes a lithium-containing metal layer, and the lithium-containing metal layer is provided between the negative electrode current collector and the first sub-layer.
  • the present application provides an electrical device, including a power module and the lithium-ion battery of the first aspect or the lithium-ion battery of the second aspect of the application, wherein the lithium-ion battery is electrically connected to the power module, as The power module provides power.
  • Figure 1 is a schematic structural diagram of a lithium-ion battery
  • Figure 2 is a schematic structural diagram of a negative electrode piece of the present application.
  • Figure 3 is a schematic structural diagram of another negative electrode piece of the present application.
  • Figure 4 is a schematic structural diagram of another negative electrode piece of the present application.
  • Figure 5 is a schematic structural diagram of another negative electrode piece of the present application.
  • lithium titanate as the negative electrode active material
  • lithium titanate As the negative electrode active material
  • lithium titanate because lithium titanate itself that it does not emit lithium to improve the safety between the positive and negative electrodes.
  • lithium-ion batteries using lithium titanate as the negative active material have low energy density and cannot meet the commercial application of existing electronic products.
  • FIG 1 is a schematic structural diagram of a lithium-ion battery.
  • the lithium-ion battery includes a positive electrode plate 10 and a negative electrode plate 20.
  • a separator 30 and a filling layer can be disposed between the positive electrode plate 10 and the negative electrode plate 20.
  • the electrolyte 40 is between the positive electrode piece 10 and the negative electrode piece 20 and infiltrates the separator 30 .
  • lithium ions are extracted from the positive active material of the positive electrode sheet 10 and are embedded in the negative active material of the negative electrode sheet 20 after passing through the electrolyte 40 ; during discharge, lithium ions are released from the negative active material and pass through the electrolyte 40 and then inserted into the positive active material.
  • the positive electrode sheet 10 includes a positive electrode current collector 11 and a positive electrode material layer 12 .
  • the material of the positive electrode current collector 11 may be, for example, aluminum foil, aluminum alloy, aluminum composite, etc., or may be gold foil.
  • the selection of specific materials for the positive electrode current collector 11 can be determined based on the chemical potential of the negative electrode current collector, and is not specifically limited here.
  • the cathode material layer 12 may include components such as cathode active materials, conductive agents, and binders.
  • the cathode active material in the cathode material layer 12 can be LiCo 1-x M x O 2 , where 0 ⁇ x ⁇ 1, M can be selected from Ni, Mn, Al, Ca, Mg, Sr, Ti, V, Cr, Fe, Cu, At least one of Zn, Mo, W, Y, La, Zr, Sn, Se, Te and Bi.
  • the conductive agent in the positive electrode material layer 12 may be conductive carbon black, acetylene black, carbon nanotubes, or a mixture of the above materials.
  • Binders may include polyvinylidene difluoride (PVDF), polymerized styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylamide Acrylonitrile (polyacrylonitrile, PAN), polyethylene oxide (polyethylene oxidized, PEO), vinylidene fluoride-hexafluoropropylene copolymer (poly(vinylidene fluoride-co-hexafluoropropene), PVDF-HFP), polymethyl methacrylate ( One or a combination of at least two of polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE).
  • PVDF polyvinylidene difluoride
  • SBR polymerized styrene butadiene rubber
  • nanometal oxides that can be added to the cathode material layer 12 include silicon oxide (SiO 2 ), boehmite (AlOOH), aluminum oxide (Al 2 O 3 ), magnesium oxide (MgO), zirconium oxide (ZrO), oxide One or more of zinc (ZnO), titanium oxide (TiO 2 ), etc.
  • FIG. 2 is a schematic structural diagram of a negative electrode piece.
  • the negative electrode piece 20 includes a stacked negative electrode current collector 21 and a negative electrode material layer 22.
  • the material of the negative electrode current collector 21 includes but is not limited to copper foil, copper alloys or copper composite materials.
  • the negative electrode material layer 22 at least includes a first sub-layer 221, and the first sub-layer 221 may include lithium titanate, a conductive agent and a binder.
  • lithium titanate can be elemental lithium titanate (Li 4 Ti 5 O 12 ), carbon-coated lithium titanate (C-Li 4 Ti 5 O 12 ), or a combination of the two.
  • the conductive agent and binder in the first sub-layer 221 may refer to the optional materials of the conductive agent and binder in the positive electrode material layer, which will not be repeated here.
  • the first sublayer 221 may contain nano-metal oxides, which may be one or more of silicon oxide (SiO 2 ), boehmite (AlOOH), aluminum oxide (Al 2 O 3 ), magnesium oxide (MgO), zirconium oxide (ZrO), zinc oxide (ZnO), titanium oxide (TiO 2 ), and the like.
  • nano-metal oxides may be one or more of silicon oxide (SiO 2 ), boehmite (AlOOH), aluminum oxide (Al 2 O 3 ), magnesium oxide (MgO), zirconium oxide (ZrO), zinc oxide (ZnO), titanium oxide (TiO 2 ), and the like.
  • Figure 3 is a schematic structural diagram of a negative electrode piece according to another embodiment.
  • the negative electrode material layer 22 of the negative electrode piece also includes a second sub-layer 222, wherein the The second sub-layer 222 is located between the negative electrode current collector 21 and the first sub-layer 221 .
  • the second sub-layer 222 includes a negative active material, a conductive agent and a binder.
  • the negative active material in the second sub-layer 222 may include carbon material or silicon-based material.
  • the silicon-based material may include, for example, silicon material, silicon composite. Materials, silicon carbon materials, etc.
  • the negative active material may be selected from one or more of graphite, Si, SiOx, Si-C and Si halides, where 0 ⁇ x ⁇ 2.
  • the first sub-layer 221 may be a negative electrode material layer including carbon material or silicon-based material, and may also be a negative electrode material layer formed of lithium metal or lithium alloy.
  • the mass ratio of the second sub-layer 222 to the first sub-layer 221 may be, for example, 7:1 ⁇ 12:1, and the ratio between the two may be, for example, 7:1, 8:1, 9:1, 10:1, or 11: 1 or 12:1.
  • the first sub-layer 221 is located at the outermost layer of the negative electrode plate, and the second sub-layer 222 is located at the middle layer.
  • the specific capacity of the negative active material in the second sub-layer 222 that is, the carbon material and the silicon-based material is higher than It is much higher than that of lithium titanate. Therefore, by providing the second sub-layer 222, the energy density of the lithium-ion battery can be further improved.
  • the negative active material in the second sub-layer 222 is a negative active material that is easy to precipitate lithium. By disposing it in the middle layer, the lithium precipitated on the surface of the second sub-layer 222 can be limited to the first sub-layer 221 and the second sub-layer 222 . between layers 222. In addition, contact between the negative active material in the second sub-layer 222 and the positive current collector can be avoided, further improving the safety of the lithium-ion battery.
  • FIG. 4 is a schematic structural diagram of a negative electrode plate according to another embodiment of the present application.
  • the negative electrode material layer 22 may include a first sub-layer 221 and a second sub-layer 221 .
  • a lithium metal layer 223 may also be included.
  • the lithium metal layer 223 is located between the first sub-layer 221 and the second sub-layer 222.
  • the lithium metal layer 223 between the first sub-layer 221 and the second sub-layer 222 can be a lithium metal layer 223 added separately during the preparation process of the negative electrode sheet, or it can be a self-made lithium metal layer 223 added during the cycle of the lithium ion battery.
  • the lithium metal layer 223 formed by the lithium deposited in the second sub-layer 222 is formed.
  • the energy density and safety of the lithium-ion battery can be further improved.
  • the negative active material in the second sub-layer 222 is a silicon-based material
  • the formed lithium metal layer 223 can supplement the silicon-based material with lithium to improve the cycle stability of the silicon-based material and thereby increase the lithium ion content. Battery cycle performance.
  • the length dimension of the first sub-layer 221 is greater than or equal to the length dimension of the second sub-layer 222
  • the width dimension of the first sub-layer 221 is greater than or equal to It is equal to the width dimension of the second sub-layer 222 to avoid contact between the second sub-layer 222 and the positive electrode piece.
  • the structure of the negative electrode piece has been exemplified above.
  • the relationship between the positive electrode material layer and the negative electrode material layer will be explained below.
  • the capacity ratio Nc/Pc of the negative electrode material layer and the positive electrode material layer satisfies 0 ⁇ Nc/Pc ⁇ 1.04, where the area density of the first sub-layer 221 is ⁇ 0.1 mg/cm 2 .
  • the positive electrode active material and the negative electrode active material can be effectively controlled.
  • the relative dosage between the positive electrode active material and the negative electrode active material makes the dosage between the positive electrode active material and the negative electrode active material more consistent and avoids unnecessary addition of the positive electrode active material and the negative electrode active material.
  • the negative electrode material layer reduces the amount of negative electrode material as much as possible to reduce the volume of the negative electrode piece and thereby increase the energy density of the lithium-ion battery.
  • the area density of the first sub-layer may be, for example, 0.1 mg/cm 2 , 0.2 mg/cm 2 , 0.3 mg/cm 2 , 0.4 mg/cm 2 , 0.5 mg/cm 2 , or 0.6 mg/cm 2 , 0.7mg/cm 2 , 0.8mg/cm 2 , 0.9mg/cm 2 or 1.0mg/cm 2 or greater.
  • the maximum density of the first sub-layer is not specifically limited here.
  • the capacity ratio of the negative electrode material layer to the positive electrode material layer is Nc/Pc ⁇ 0.2, further, Nc/Pc ⁇ 0.3, and further, Nc/Pc ⁇ 0.5; for example, the capacity ratio of the negative electrode material layer to the positive electrode material
  • the capacity ratio of the layer is Nc/Pc ⁇ 1.04, further Nc/Pc ⁇ 1.00, further Nc/Pc ⁇ 0.95.
  • the risk of lithium precipitation can be reduced as much as possible while ensuring the increase in energy density of the lithium-ion battery, and improve the safety and cycle of the lithium-ion battery. performance.
  • the upper limit of the capacity ratio Nc/Pc between the negative electrode material layer and the positive electrode material layer the amount of negative electrode material can be further reduced, thereby further increasing the energy density of the lithium-ion battery.
  • Figure 5 shows the size relationship between the first sub-layer and the cathode material layer in an embodiment of the present application.
  • the size of the first sub-layer 221 is greater than or equal to the size of the cathode material layer 12, and the size of the first sub-layer 221 is greater than or equal to the size of the cathode material layer 12.
  • the single-sided margin W1 or W2 in the width direction between 221 and the cathode material layer 12 is greater than or equal to 0 mm, preferably 0 to 0.1 mm, and the total bilateral margin W1 + W2 is 0 to 1.5 mm.
  • the single-sided margin L1 or L2 between the first sub-layer 221 and the cathode material layer 12 is greater than or equal to 0 mm, preferably 0 to 1 mm, and the total bilateral margin L1+L2 is 0 ⁇ 3mm.
  • the size of the positive electrode material layer 12 is constant, the size of the first sub-layer 221 can be reduced to the greatest extent, thereby effectively reducing the area of the negative electrode piece, thereby reducing the volume of the negative electrode piece.
  • the size difference between the first sub-layer and the positive electrode material layer is in the range of 0 to 0.1 mm
  • a lithium metal layer can be precipitated between the negative electrode current collector and the first sub-layer, and the precipitated Since the lithium metal layer is between the first sub-layer and the negative electrode current collector, due to the high safety of the first sub-layer, the lithium metal layer will not penetrate the first sub-layer.
  • the lithium metal layer can also be used as a Negative active material effectively increases the energy density of the negative electrode piece.
  • a second sub-layer containing silicon-based material can be provided between the first sub-layer and the negative electrode current collector.
  • lithium will precipitate on the surface of the second sub-layer to form a lithium metal layer (specific capacity up to 3860mAh/g).
  • the precipitated lithium can replenish lithium for the silicon-based material, thereby reducing the silicon-based material.
  • the lithium replenishment cost of the material can be reduced and the utilization rate of the battery can be further improved.
  • the embodiment of the present application is a lithium-ion battery, which mainly consists of a positive electrode piece 10 and a negative electrode piece 20 (the negative electrode current collector is copper foil, and the negative electrode material layer includes a first sub-layer 221 and a second sub-layer 222.
  • the structure can be referred to the figure. 3.
  • the single-side margins L1, L2, W1 and W2 are 0.1mm respectively.
  • the structure can be seen in Figure 5), LiFP 6 electrolyte, PE isolation film, etc.
  • the preparation process of the lithium-ion battery includes the following steps:
  • Preparation of the positive electrode sheet Mix lithium cobalt oxide (specific capacity: 180mAh/g), conductive carbon black, and polyvinylidene fluoride binder PVDF in mass proportions of: 96%, 2%, and 2%, respectively. And use N-methylpyrrolidone (NMP) as the solvent and stir evenly to obtain the positive electrode slurry, which is coated on the surface of the aluminum foil current collector by extrusion or transfer coating, and dried to obtain the positive electrode sheet, wherein, The weight of the positive electrode material layer is 0.216g.
  • NMP N-methylpyrrolidone
  • Preparation of the first negative electrode slurry Mix lithium titanate (specific capacity: 170mAh/g), conductive carbon black and polyvinylidene fluoride binder PVDF in mass proportions of 96%, 2% and 2% respectively. , and stir evenly using NMP as the solvent to obtain the first negative electrode slurry.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, it is then gravure printed, extruded or transfer coated on the surface of the negative second sub-layer.
  • the first negative electrode slurry is applied and dried to obtain the negative electrode sheet 20 containing the first sub-layer 221 and the second sub-layer 222, where the mass ratio of the second sub-layer 222 to the first sub-layer 221 is 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 3. Among them, the weight of the negative electrode material layer is 0.11g.
  • the specific capacity of the negative electrode material layer in Embodiment 1 is the specific capacity of the second sub-layer.
  • the embodiment of the present application is a lithium-ion battery.
  • the preparation process of the lithium-ion battery can be referred to the preparation process of the lithium-ion battery of Embodiment 1.
  • the difference from Embodiment 1 is that the second negative electrode material is a graphite-silicon-oxygen composite material.
  • the capacity ratio of the negative electrode material layer to the positive electrode material layer is reduced to 0.8, so that the second negative electrode material self-replenishes lithium.
  • the specific process includes the following steps:
  • preparation of positive electrode sheet refer to the preparation of positive electrode sheet in Example 1.
  • the weight of the positive electrode material layer is 0.31 g.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, it is then coated on the surface of the second sub-layer by gravure printing, extrusion or transfer coating.
  • the first negative electrode slurry is applied and dried to obtain a negative electrode sheet containing a first sub-layer 221 and a second sub-layer 222, where the mass ratio of the second sub-layer 222 to the first sub-layer 221 is 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 3. Among them, the weight of the negative electrode material layer is 0.093g.
  • the embodiment of the present application is a lithium-ion battery.
  • the preparation process of the lithium-ion battery can refer to the preparation process of the lithium-ion battery in Example 2.
  • the difference from Example 2 is that a lithium metal layer is added to supplement the second negative electrode material layer. lithium.
  • the specific process includes the following steps:
  • Preparation of the positive electrode piece refer to the preparation of the positive electrode piece in Example 1. Among them, the weight of the positive electrode material layer is 0.31g.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, a lithium metal layer is first set on the surface of the second sub-layer.
  • the thickness of the lithium metal layer is 10 ⁇ m ⁇ 0.5 ⁇ m, and then apply the first negative electrode slurry on the surface of the lithium metal layer by gravure printing, extrusion or transfer coating, and dry it to obtain the first sub-layer 221, the lithium metal layer 223 and the second
  • the negative electrode piece 20 of the sub-layer 222 has a mass ratio of the second sub-layer 222 to the first sub-layer 221 of 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 4. Among them, the weight of the negative electrode material layer is 0.093g.
  • the embodiment of the present application is a lithium-ion battery.
  • the preparation process of the lithium-ion battery can be referred to the preparation process of the lithium-ion battery in Embodiment 1.
  • the difference from Embodiment 1 is that there is no second negative electrode material layer.
  • the specific process includes the following steps:
  • Preparation of the positive electrode piece refer to the preparation of the positive electrode piece in Example 1. Among them, the weight of the positive electrode material layer is 0.11g.
  • the first negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating, and after drying, the negative electrode piece 20 containing the first sub-layer 221 is obtained.
  • the structure of the obtained negative electrode piece can be referred to FIG. 2.
  • the weight of the negative electrode material layer is 0.093g.
  • the relative size relationship between the first sub-layer and the cathode material layer can be referred to Figure 5, where the size differences L1 and L2 between the two in the length direction are both 0.1 mm, and the size difference in the width direction W1 and W2 are both 0.1mm.
  • the preparation process of the lithium-ion battery in this embodiment is the same as that in Embodiment 1.
  • the difference compared with Embodiment 1 is that the first sub-layer and the cathode material layer have the same size, that is, both are on one side in the length direction.
  • the margins L1 and L2 are 0mm respectively, and the single-sided margins W1 and W2 in the width direction are 0mm respectively.
  • the embodiment of the present application is a lithium-ion battery.
  • the preparation process of the lithium-ion battery can be referred to the preparation process of the lithium-ion battery in Embodiment 2.
  • the difference is that the capacity ratio of the negative electrode material layer and the positive electrode material layer is reduced to 0.2.
  • the specific process includes the following steps:
  • Preparation of the positive electrode piece refer to the preparation of the positive electrode piece in Example 2. Among them, the weight of the positive electrode material layer is: 0.31g.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, it is then coated on the surface of the second sub-layer by gravure printing, extrusion or transfer coating.
  • the first negative electrode slurry is applied and dried to obtain a negative electrode sheet containing a first sub-layer 221 and a second sub-layer 222, where the mass ratio of the second sub-layer 222 to the first sub-layer 221 is 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 3. Among them, the weight of the negative electrode material layer is 0.023g.
  • Example 7 The preparation process of the lithium ion battery in Example 7 is the same as that in Example 2.
  • the difference compared with Example 2 is that the capacity ratio of the negative electrode material layer and the positive electrode material layer is reduced to 0.4.
  • the specific values are listed in Table 1.
  • Preparation of the positive electrode piece refer to the preparation of the positive electrode piece in Example 2. Among them, the weight of the positive electrode material layer is 0.31g.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, it is then coated on the surface of the second sub-layer by gravure printing, extrusion or transfer coating.
  • the first negative electrode slurry is applied and dried to obtain a negative electrode sheet containing a first sub-layer 221 and a second sub-layer 222, where the mass ratio of the second sub-layer 222 to the first sub-layer 221 is 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 3. Among them, the weight of the negative electrode material layer is 0.047g.
  • Example 8 The preparation process of the lithium ion battery of Example 8 is the same as that of Example 2.
  • the difference from Example 2 is that the capacity ratio of the negative electrode material layer and the positive electrode material layer is 0.6 and the single-side margins L1, L2, W1 and W2 is 0.05mm respectively, and the specific values are listed in Table 1.
  • Preparation of the positive electrode piece refer to the preparation of the positive electrode piece in Example 2. Among them, the weight of the positive electrode material layer is 0.31g.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, it is then coated on the surface of the second sub-layer by gravure printing, extrusion or transfer coating.
  • the first negative electrode slurry is applied and dried to obtain a negative electrode sheet containing a first sub-layer 221 and a second sub-layer 222, where the mass ratio of the second sub-layer 222 to the first sub-layer 221 is 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 3. Among them, the weight of the negative electrode material layer is 0.065g.
  • the embodiment of the present application is a lithium-ion battery, which is mainly composed of a positive electrode plate, a negative electrode plate, LiFP 6 electrolyte, PE isolation film, etc.
  • the battery provided in Comparative Example 1 only includes one negative electrode layer, and the negative electrode layer is made of graphite, and each single side margin is 0.1 mm.
  • the preparation process of the lithium-ion battery includes the following steps:
  • positive electrode sheet lithium cobalt oxide, conductive carbon black and polyvinylidene fluoride binder PVDF are mixed in a mass ratio of 96%, 2% and 2% respectively, and N-methylpyrrolidone (NMP) is used as a solvent and stirred to obtain positive electrode slurry.
  • NMP N-methylpyrrolidone
  • the positive electrode sheet is obtained by coating the surface of the aluminum foil current collector by extrusion or transfer coating and drying.
  • the weight of the positive electrode material layer is 0.216 g.
  • the negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating, and the negative electrode sheet is obtained after drying. Among them, the weight of the negative electrode material layer is 0.117g.
  • the present application embodiment is a lithium-ion battery, which is mainly composed of a positive electrode sheet, a negative electrode sheet, a LiFP 6 electrolyte, a PE isolation film, etc.
  • the battery provided in Comparative Example 2 includes two negative electrode layers, the first negative electrode layer is made of lithium titanate, and the second negative electrode layer is made of graphite, and the margins of each layer are 0.1 mm.
  • the preparation process of the lithium-ion battery includes the following steps:
  • Preparation of the first negative electrode slurry Mix lithium titanate, conductive carbon black and polyvinylidene fluoride binder PVDF in mass proportions of 96%, 2% and 2% respectively, and stir evenly using NMP as the solvent. The first negative electrode slurry is obtained.
  • the second negative electrode slurry is coated on the surface of the copper foil current collector by extrusion or transfer coating. After drying, it is then gravure printed, extruded or transfer coated on the surface of the negative second sub-layer.
  • the first negative electrode slurry is applied and dried to obtain a negative electrode sheet containing a first sub-layer 221 and a second sub-layer 222, where the mass ratio of the second sub-layer 222 to the first sub-layer 221 is 9:1.
  • the structure of the obtained negative electrode piece can be referred to Figure 3. Among them, the weight of the negative electrode material layer is 0.117g.
  • the embodiment of the present application is a lithium-ion battery, which is mainly composed of a positive electrode plate, a negative electrode plate, LiFP 6 electrolyte, PE isolation film, etc.
  • the preparation process is the same as Comparative Example 2, except that the single-side margins of the first sub-layer and the cathode material layer are 1 mm respectively.
  • the capacity ratio of the negative electrode material layer to the positive electrode material layer is Nc/Pc.
  • the capacity of the negative electrode material layer (Nc) the specific capacity of the negative electrode active material * the mass of the negative electrode material * the mass of the negative electrode active material.
  • Ratio; capacity of the positive electrode material layer (Pc) specific capacity of the positive electrode active material * mass of the positive electrode material * mass proportion of the positive electrode active material.
  • the mass of the negative electrode active material is the total mass of the negative electrode active material in the negative electrode material layer, and the mass ratio of the negative electrode active material is the ratio of the mass of the negative electrode active material in the negative electrode material layer to the mass of the negative electrode material.
  • the mass proportion of the positive electrode active material is the ratio of the mass of the positive electrode active material to the mass of the positive electrode material in the positive electrode material layer.
  • the negative electrode sheet is provided with a first sub-layer containing lithium titanate.
  • the energy density of the battery composed of lithium titanate is relatively low. Therefore, in order to reduce the lithium titanate band In order to avoid the loss of energy density without affecting the safety of the negative electrode piece, in each embodiment of the present application, the ratio of Nc/Pc is adjusted to achieve the purpose of increasing the energy density of the lithium-ion battery.
  • Example 2 during continuous charging, excess lithium will be stored at the interface between the first sublayer and the second sublayer. Since the second sublayer contains silicon-based materials, the precipitated lithium can be used to replenish lithium for the silicon-based materials, simplifying the lithium replenishment process of traditional silicon-based materials and reducing the lithium replenishment cost of silicon-based materials. At the same time, the first sublayer containing lithium titanate can serve as a protective layer to prevent the precipitated lithium from forming lithium dendrites that pierce the diaphragm.
  • lithium replenishment effect of the silicon-based material can be improved, so the performance of the negative electrode plate can be improved. energy density, thereby increasing the energy density of the battery.
  • the lithium ion battery of Example 4 only contains the first sub-layer.
  • the lithium metal layer of the lithium ion battery of this example can be directly formed on the surface of the negative electrode current collector. Therefore, the lithium ion efficiency can be further improved. Battery energy density.
  • the lithium metal layer can be formed by low-temperature charging or overcharge charging, thereby reducing the cost and difficulty of forming the lithium metal layer.
  • the first sub-layer and the cathode material layer are arranged opposite each other, and the sizes of the two are basically the same.
  • the size and space of the first sub-layer or the cathode material layer can be avoided. Waste to make full use of the space along the length and width of the lithium-ion battery, thereby increasing the energy density of the battery.
  • Example 1 It can be seen from the relevant data of Example 1 and Example 5 that the energy density of the lithium-ion battery can be increased by reducing the single-side margin between the first sub-layer and the cathode material layer.
  • this application provides an electrical device, which includes an electrical module and a lithium-ion battery of the present application, wherein the lithium-ion battery is electrically connected to the electrical module to provide power for the electrical module.
  • the electrical equipment of the present application includes, for example, but is not limited to, mobile phones, computers, telephone watches, flat-panel display devices, energy storage devices, vehicles and other power devices.

Abstract

一种锂离子电池和用电设备。该锂离子电池包括正极极片和负极极片，正极极片包括叠层设置的正极集流体和正极材料层，负极极片包括叠层设置的负极集流体和负极材料层，负极材料层包括第一子层，第一子层中的负极活性材料包括钛酸锂，第一子层的面密度≥0.1mg/cm 2，负极材料层和正极材料层的容量比Nc/Pc为0＜Nc/Pc≤1.04。该锂离子电池在具有高安全性的前提下具有较高的能量密度。

Description

锂离子电池和用电设备
相关申请的交叉引用
本申请要求在2022年09月22日提交中国专利局、申请号为202211160158.6、申请名称为“锂离子电池和用电设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及新能源电池领域，具体涉及一种锂离子电池和用电设备。
背景技术
锂离子电池因其能量密度高、循环寿命长等优点，被广泛地应用于消费类电子产品(例如手机，笔记本等电子产品)以及电动汽车等方面。但是近年来锂离子电池的安全性问题日益突出，若使用不当，会出现燃烧甚至爆炸等问题。经研究发现，锂离子电池出现上述安全问题主要与以下4种短路方式有关：1)正极材料层接触负极材料层；2)正极材料层接触铜箔；3)铝箔接触负极材料层；4)铝箔接触铜箔。以上短路方式中，第3)种方式更容易导致热失控的发生，从而因此电池的燃烧和爆炸。为解决电池安全性的问题，现有方案之一是利用钛酸锂作为负极活性材料，由于钛酸锂自身能够抑制锂枝晶的形成，因此利用钛酸锂作为负极活性材料能够提高隔离铝箔与负极材料层之间的安全性。但由于钛酸锂的比容量较低，导致利用钛酸锂作为负极活性材料时，锂离子电池的能量密度较低，无法满足现有产品对能量密度的要求，从而无法实现商业化应用。
发明内容
本申请提供了一种锂离子电池和用电设备，以获得一种兼具高安全性和高能量密度的锂离子电池。
第一方面，本申请提供一种锂离子电池，该锂离子电池包括正极极片和负极极片，正极极片包括叠层设置的正极集流体和正极材料层，负极极片包括叠层设置的负极集流体和负极材料层，负极材料层包括第一子层，第一子层中的负极活性材料包括钛酸锂，第一子层的面密度≥0.1mg/cm2，负极材料层和正极材料层的容量比Nc/Pc为0<Nc/Pc≤1.04。
本申请的锂离子电池，负极极片包括负极集流体和负极材料层，由于负极材料层中的第一子层中的负极活性材料为钛酸锂，在锂离子电池的循环使用过程中，钛酸锂具有较高的嵌锂电位，能够抑制锂枝晶的形成，进而可防止正极集流体与负极材料层接触而发生热失控，因此，该锂离子电池具有较高的安全性。此外，通过控制第一子层的面密度≥0.1mg/cm2，且通过控制负极材料层和正极材料层的容量比Nc/Pc为0<Nc/Pc≤1.04，可有效控制正极活性材料和负极活性材料之间的相对用量，使正极活性材料和负极活性材料之间的用量更为匹配，避免正极活性材料和负极活性材料不必要的添加，因此，在电池的正极极片的容量一定时，可降低负极材料用量，以减少负极极片的体积，从而可在保证第一子层与正极集流体之间安全性的同时，提高锂离子电池的能量密度。
在一种可能的实现方式中，负极材料层和正极材料层的容量比Nc/Pc为0.2≤Nc/Pc≤1.04；优选地，Nc/Pc≥0.3，Nc/Pc≤1.02，进一步优选地，Nc/Pc≥0.4，Nc/Pc≤1。通孔优选Nc/Pc之间的比值，可有效避免因负极活性材料相对含量过低导致的锂离子电池发生循环衰减，从而使锂离子电池保持较好的循环性能。
在一种可能的实现方式中，负极材料层包括第二子层，第二子层设于负极集流体和第一子层之间，第二子层中的负极活性材料包括碳材料或硅基材料。由于碳材料和硅基材料具有较高的比容量，因此，通过设置含有碳材料和/或硅基材料的负极活性材料作为第二子层，可进一步提高锂离子电池的能量密度。
在一种可能的实现方式中，第二子层与第一子层的质量比大于或等于1，优选为7:1～12:1，优选大于等于7.5:1，小于等于11.5:1，进一步优选大于等于8:1，小于等于11:1。
在一种可能的实现方式中，第一子层与第二子层之间设有含锂金属层。含锂金属层具有更高的比容量，通过设置含锂金属层，可进一步提高锂离子电池的能量密度。
在一种可能的实现方式中，负极材料层包括含锂金属层，含锂金属层设于负极集流体和第一子层之间。
在一种可能的实现方式中，第一子层的长度尺寸大于或等于第二子层的长度尺寸，第一子层的宽度尺寸大于或等于第二子层的宽度尺寸。
负极材料层中，第一子层的长度大于或等于第二子层的长度，第二子层的宽度大于或等于第二子层的宽度，这样，当负极材料层发生析锂时，锂会沉积在第二子层的表面形成锂枝晶，由于第一子层的尺寸大于等于第二子层，因此，第一子层可以阻挡第二子层表面的锂枝晶刺穿隔膜，从而避免正极极片和负极极片之间的短路。
在一种可能的实现方式中，所述正极材料层在所述第一子层所在平面的正投影面积小于或等于所述第一子层的面积，且沿所述正极材料层的宽度方向，所述第一子层和所述正极材料层的尺寸差小于1.5mm；沿所述正极材料层的长度方向，所述第一子层和所述正极材料层的尺寸差小于3mm。
在一种可能的实现方式中，沿所述正极材料层的宽度方向，所述正极材料层与所述第一子层之间的单侧边距为0～0.1mm。在一种可能的实现方式中，沿所述正极材料层的长度方向，所述正极材料层与所述第一子层之间的单侧边距为0～1mm。
本申请实现方式的锂离子电池，采用钛酸锂作为第一子层的活性材料，从而可使第一子层与正极材料层之间在宽度方向的总边距控制在0～1.5mm，单侧边距控制在0～0.1mm，所述第一子层与所述正极材料层之间在长度方向的总边距控制在0～3.0mm，单侧边距控制在0～1mm。该实现方式中，第一子层与正极材料层的尺寸差距较小，进一步地，可设置为相同的尺寸，由此，可避免第一子层或正极材料层的尺寸空间的浪费，进而可进一步提高锂离子电池的能量密度。
在一种可能的实现方式中，正极材料层掺杂有纳米金属氧化物颗粒。在正极材料层中添加纳米金属氧化物可降低正极材料层的活性，避免正极材料层中的锂离子嵌入到负极材料层的速度过快，缓解负极材料层因无法及时容纳来自于正极材料层的锂离子而在表面析出的问题。通过在正极材料层中添加适量的纳米金属氧化物，可有助于减少负极活性材料的用量，有利于进一步降低Nc/Pc比，从而进一步提升电池的能量密度。
在一种可能的实现方式中，第一子层和第二子层中的至少一个掺杂有纳米金属氧化物颗粒。负极材料层的第一子层以及第二子层中的至少一个添加纳米金属氧化物可进一步提升负极材料层的安全性，纳米金属氧化物添加至负极材料层中，有助于降低负极极片的反应活性，当发生铝箔接触负极极片时，纳米金属氧化物的添加可使得负极极片在短路时的极化增加，从而提升电池的安全性。
在一种可能的实现方式中，正极材料层中的正极活性材料为LiCo1-xMxO2，其中，0≤x≤1，M选自Ni、Mn、Al、Ca、Mg、Sr、Ti、V、Cr、Fe、Cu、Zn、Mo、W、Y、La、Zr、Sn、Se、Te和Bi中的至少一种。
在一种可能的实现方式中，正极集流体包括铝箔集流体、铝合金集流体或铝复合集流体；负极集流体包括铜箔集流体、铜合金集流体或铜复合集流体。
其中，本申请上述各可能实现方式中的数据，例如第一子层的面密度、Nc/Pc、第一子层与正极材料层之间的边距等数据，在测量时，工程测量误差范围内的数值均应理解为在本申请所限定的范围内。
第二方面，本申请提供一种锂离子电池，该锂离子电池包括正极极片和负极极片，所述正极极片包括叠层设置的正极集流体和正极材料层，所述负极极片包括叠层设置的负极集流体和负极材料层，所述负极材料层包括第一子层，所述第一子层中的负极活性材料包括钛酸锂；所述正极材料层在所述第一子层所在平面的正投影面积小于或等于所述第一子层的面积，且沿所述正极材料层的宽度方向，所述第一子层和所述正极材料层的尺寸差小于1.5mm；沿所述正极材料层的长度方向，所述第一子层和所述正极材料层的尺寸差小于3mm。
本申请的锂离子电池，负极极片包括负极集流体和负极材料层，由于负极材料层中的第一子层中的负极活性材料为钛酸锂，在锂离子电池的循环使用过程中，钛酸锂具有较高的嵌锂电位，能够抑制锂枝晶的形成，进而可防止正极集流体与负极材料层接触而发生热失控，因此，该锂离子电池具有较高的安全性。此外，负极材料层含有钛酸锂的第一子层的尺寸大于正极材料层的尺寸，且通过将第一子层与正极材料层之间的尺寸差限定在如上范围内时，一方面，当第一子层的尺寸一定时，可最大限度地提高正极材料层的尺寸，以提升正极材料层的面积，进而提高正极材料层的容量，从而可在保证第一子层与正极集流体之间安全性的同时，提升锂离子电池的能量密度。另一方面，当正极材料层的尺寸一定时，可最大程度地减少第一子层的尺寸，进而可有效减小负极极片的面积，进而降低负极极片的体积，从而可在保证第一子层与正极集流体之间安全性的同时，提高锂离子电池的能量密度。
在一种可能的实现方式中，沿所述正极材料层的宽度方向，所述正极材料层与所述第一子层之间的单侧边距为0～0.1mm。在一种可能的实现方式中，沿所述正极材料层的长度方向，所述正极材料层与所述第一子层之间的单侧边距为0～1mm。在一种可能的实现方式中，所述正极材料层与所述第一子层的尺寸相同。该实现方式中，第一子层与正极材料层的尺寸差距较小，进一步地，可设置为相同的尺寸，由此，可避免第一子层或正极材料层的尺寸空间的浪费，进而可进一步提高锂离子电池的能量密度。
在一种可能的实现方式中，所述负极材料层包括第二子层，所述第二子层设于所述负极集流体和所述第一子层之间，所述第二子层中的负极活性材料包括碳材料或硅基材料。
在一种可能的实现方式中，所述第一子层与所述第二子层之间设有含锂金属负极层。
在一种可能的实现方式中，所述负极材料层包括含锂金属层，所述含锂金属层设于所述负极集流体和所述第一子层之间。
第三方面，本申请提供了一种用电设备，包括用电模块和本申请第一方面的锂离子电池或第二方面的锂离子电池，其中，锂离子电池与用电模块电连接，为用电模块提供电力。
上述第三方面可以达到的技术效果，可以参照上述第一方面中的相应效果描述，这里不再重复赘述。
附图说明
图1为一种锂离子电池的结构示意图；
图2为本申请一种负极极片的结构示意图；
图3为本申请另一种负极极片的结构示意图；
图4为本申请另一种负极极片的结构示意图；
图5为本申请另一种负极极片的结构示意图。
附图标记：
10-正极极片；11-正极集流体；12-正极材料层；20-负极极片；21-负极集流体；
22-负极材料层；221-第一子层；222-第二子层；223-锂金属层；30-隔膜；40-电解液。
具体实施方式
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
以下实施例中所使用的术语只是为了描述特定实施例的目的，而并非旨在作为对本申请的限制。如在本申请的说明书和所附权利要求书中所使用的那样，单数表达形式“一个”、“一种”、“所述”、“上述”、“该”和“这一”旨在也包括例如“一个或多个”这种表达形式，除非其上下文中明确地有相反指示。
在本说明书中描述的参考“一个实施例”或“一些实施例”等意味着在本申请的一个或多个实施例中包括结合该实施例描述的特定特征、结构或特点。由此，在本说明书中的不同之处出现的语句“在一个实施例中”、“在一些实施例中”、“在其他一些实施例中”、“在另外一些实施例中”等不是必然都参考相同的实施例，而是意味着“一个或多个但不是所有的实施例”，除非是以其他方式另外特别强调。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。
目前，锂离子电池的安全性已成为关注的热点问题。为了解决锂离子电池的安全性问题，现有方法之一是利用钛酸锂作为负极活性材料，利用钛酸锂自身不析锂的特性，提高正负极之间的安全性。但是，由于钛酸锂的比容量较低，利用钛酸锂作为负极活性材料的锂离子电池，其能量密度较低，已无法满足现有电子产品商业化应用。
为解决上述问题，本申请提供一种锂离子电池。图1为一种锂离子电池的结构示意图，如图1所示，该锂离子电池包括正极极片10和负极极片20，正极极片10和负极极片20之间可设置隔膜30以及填充于正极极片10和负极极片20之间并浸润隔膜30的电解液40。充电时，锂离子从正极极片10的正极活性材料中脱出，经过电解液40后嵌入到负极极片20的负极活性材料中；放电时，锂离子从负极活性材料中脱出，经过电解液40后插入到正极活性材料中。
如图1所示，正极极片10包括正极集流体11和正极材料层12。正极集流体11的材料例如可为铝箔、铝合金、铝复合体等，也可为金箔。其中，正极集流体11的具体材料的选择可根据负极集流体的化学电位进行确定，在此不做具体的限定。
正极材料层12可包括正极活性材料、导电剂和粘结剂等组分。其中，正极材料层12中的正极活性材料可为LiCo1-xMxO2，其中，0≤x≤1，M可选自Ni、Mn、Al、Ca、Mg、Sr、Ti、V、Cr、Fe、Cu、 Zn、Mo、W、Y、La、Zr、Sn、Se、Te和Bi中的至少一种。
正极材料层12中的导电剂可为导电碳黑、乙炔黑、碳纳米管或以上材料混合而成。粘结剂可包括聚偏氟乙烯(polyvinylidene difluoride，PVDF)、丁苯橡胶(polymerized styrene butadiene rubber，SBR)、羧甲基纤维素(carboxymethyl cellulose，CMC)，聚丙烯酸(polyacrylic acid，PAA)，聚丙烯腈(polyacrylonitrile，PAN)，聚氧化乙烯(polyethylene oxidized，PEO)、偏氟乙烯-六氟丙烯共聚物(poly(vinylidene fluoride-co-hexafluoropropene)，PVDF-HFP)、聚甲基丙烯酸甲酯(polymethyl methacrylate，PMMA)、聚四氟乙烯(polytetrafluoroethylene，PTFE)中的一种及至少两种的组合。
其中，正极材料层12中可添加纳米金属氧化物为氧化硅(SiO2)、勃姆石(AlOOH)、氧化铝(Al2O3)、氧化镁(MgO)、氧化锆(ZrO)、氧化锌(ZnO)、氧化钛(TiO2)等其中一种或多种。
图2为一种负极极片的结构示意图，如图2所示，在一种可选实施例中，负极极片20包括叠层设置的负极集流体21和负极材料层22。负极集流体21的材料包括但不限于铜箔、铜合金类或铜复合材料等。其中，负极材料层22至少包括第一子层221，第一子层221中可包括钛酸锂、导电剂和粘结剂。其中，钛酸锂可为单质型钛酸锂(Li4Ti5O12)，也可为碳包覆型钛酸锂(C-Li4Ti5O12)，还可为两种的组合物。第一子层221中的导电剂和粘结剂可参照正极材料层中的导电剂和粘结剂的可选材料，在此不再重复赘述。
其中，第一子层221中可添加纳米金属氧化物，纳米金属氧化物可为氧化硅(SiO2)、勃姆石(AlOOH)、氧化铝(Al2O3)、氧化镁(MgO)、氧化锆(ZrO)、氧化锌(ZnO)、氧化钛(TiO2)等其中一种或多种。
图3为另一种实施例的负极极片的结构示意图，如图3所示，在一种可选实施例中，负极极片的负极材料层22还包括第二子层222，其中，第二子层222位于负极集流体21和第一子层221之间。第二子层222包括负极活性材料、导电剂和粘结剂，其中，第二子层222中的负极活性材料可包括碳材料或硅基材料等，硅基材料例如可包括硅材料、硅复合材料、硅碳材料等。示例性地，负极活性材料例如可选自石墨、Si、SiOx、Si-C及Si的卤化物中的一种或几种，其中0<x≤2。其中，第一子层221除可为包含碳材料或硅基材料的负极材料层外，还可为由锂金属或锂合金形成的负极材料层。第二子层222与第一子层221的质量比例如可为7:1～12:1，两者之比例如可为7:1、8:1、9:1、10:1、11:1或12:1。
该实施例中，第一子层221位于负极极片的最外层，第二子层222位于中间层，第二子层222中的负极活性材料，即碳材料和硅基材料的比容量要远高于钛酸锂，因此，通过设置第二子层222，可进一步提高锂离子电池的能量密度。另外，第二子层222中的负极活性物质为易于析锂的负极活性材料，将其设置在中间层，可将第二子层222表面析出的锂限制在第一子层221和第二子层222之间。另外，还可避免第二子层222中的负极活性材料与正极集流体接触，进一步提高锂离子电池的安全性。
图4为本申请另一种实施例的负极极片的结构示意图，如图4所示，在本申请另一种实施例中，负极材料层22除可包括第一子层221和第二子层222外，还可包括锂金属层223，锂金属层223位于第一子层221和第二子层222之间。其中，第一子层221与第二子层222之间的锂金属层223可为在负极极片的制备过程中单独添加的锂金属层223，也可为在锂离子电池的循环过程中自第二子层222析出的锂形成的锂金属层223。
同样，通过设置第二子层222以及锂金属层223，可进一步提高锂离子电池的能量密度以及安全性。另外，当第二子层222中的负极活性材料为硅基材料时，通过形成的锂金属层223可实现对硅基材料的补锂，以提高硅基材料的循环稳定性，进而提高锂离子电池的循环性能。
当负极极片中同时包含第一子层221和第二子层222时，第一子层221的长度尺寸大于或等于第二子层222的长度尺寸，第一子层221的宽度尺寸大于或等于第二子层222的宽度尺寸，以避免第二子层222和正极极片接触。
以上对负极极片的结构做了举例说明，以下将对正极材料层与负极材料层的关系做解释说明。
在本申请各可能实施例的锂离子电池中，负极材料层与正极材料层的容量比Nc/Pc满足0<Nc/Pc≤1.04，其中，第一子层221的面密度≥0.1mg/cm2。
通过使负极材料层与正极材料层的容量比Nc/Pc满足0<Nc/Pc≤1.04，且第一子层的面密度满足≥0.1mg/cm2，可有效控制正极活性材料和负极活性材料之间的相对用量，使正极活性材料和负极活性材料之间的用量更为匹配，避免正极活性材料和负极活性材料不必要的添加，因此，在电池的正极极片的容量一定时，可使负极材料层在满足高安全性的前提下，尽可能地降低负极材料的用量，以减少负极极片的体积，进而提高锂离子电池的能量密度。
作为示例性说明，第一子层的面密度例如可为0.1mg/cm2、0.2mg/cm2、0.3mg/cm2、0.4mg/cm2、0.5mg/cm2、0.6mg/cm2、0.7mg/cm2、0.8mg/cm2、0.9mg/cm2或1.0mg/cm2或更大值，在此不对第一子层的最大密度做具体的限定。
作为优选实施例，负极材料层与正极材料层的容量比Nc/Pc≥0.2，进一步地，Nc/Pc≥0.3，更进一步地，Nc/Pc≥0.5；示例性地，负极材料层与正极材料层的容量比Nc/Pc≤1.04，进一步地，Nc/Pc≤1.00，更进一步地，Nc/Pc≤0.95。
通过优化负极材料层与正极材料层的容量比Nc/Pc的下限值，可在保证提高锂离子电池能量密度的前提下，尽可能地降低析锂风险，提高锂离子电池的安全性和循环性能。通过优化负极材料层与正极材料层的容量比Nc/Pc的上限值，可进一步降低负极材料的用量，进而可进一步提高锂离子电池的能量密度。
图5为本申请一种实施例中第一子层和正极材料层的尺寸大小关系，如图5所示，第一子层221的尺寸大于或等于正极材料层12尺寸，且第一子层221与正极材料层12之间宽度方向上单侧边距W1或W2大于或等于0mm，优选0～0.1mm，双侧总边距W1+W2为0～1.5mm。在第一子层221的长度方向，第一子层221与正极材料层12之间的单侧边距L1或L2大于或等于0mm，优选0～1mm，双侧总边距L1+L2为0～3mm。通过优化第一子层221与正极材料层12之间的尺寸差，一方面，当第一子层221的尺寸一定时，可最大限度地提高正极材料层12的尺寸，以提升正极材料层12的面积，从而在提高正极材料层12的容量的基础上，提升锂离子电池的能量密度。另一方面，当正极材料层12的尺寸一定时，可最大程度地减少第一子层221的尺寸，从而可有效地减小负极极片的面积，进而在降低负极极片的体积的基础上提高锂离子电池的能量密度，又由于第一子层的高安全性，从而可在保证第一子层与正极集流体之间安全性的同时，提高锂离子电池的能量密度。
当第一子层和正极材料层之间的尺寸差在0～0.1mm范围内时，在电池的充放电过程中，可在负极集流体与第一子层之间析出锂金属层，析出的锂金属层由于在第一子层和负极集流体之间，由于第一子层的高安全性，因此该锂金属层不会刺穿第一子层，进一步的，该锂金属层还可作为负极活性材料，有效地提高负极极片的能量密度。
另外，当第一子层和正极材料层之间的尺寸差在0～0.1mm范围内时，可在第一子层和负极集流体之间设置含有硅基材料的第二子层，此时，在锂离子电池的充电过程中，第二子层的表面会有锂析出形成锂金属层(比容量高达3860mAh/g)，析出的锂可对硅基材料进行补锂，进而可降低硅基材料的补锂成本，并可进一步提高电池的利用率。
以上对分别对锂离子电池的结构做了解释说明，以下将结合具体实施例对本申请的锂离子电池的性能做具体说明。
实施例1
本申请实施例为一种锂离子电池，主要由正极极片10、负极极片20(负极集流体为铜箔，负极材料层含第一子层221、第二子层222，结构可参照图3，单侧边距L1，L2，W1和W2分别为0.1mm，结构可参见图5)、LiFP6电解液、PE隔离膜等组成。该锂离子电池的制备过程包括如下步骤：
S11、正极极片的制备：将钴酸锂(比容量为180mAh/g)、导电碳黑以及聚偏氟乙烯粘结剂PVDF，按质量配比分别为：96％、2％、2％，并以N-甲基吡咯烷酮(n-methylpyrrolidone，NMP)为溶剂搅拌均匀得到正极浆料，通过挤压或转移涂布的方式涂覆在铝箔集流体表面，烘干后得到正极极片，其中，正极材料层的重量为0.216g。
S12、第一负极浆料制备：将钛酸锂(比容量为170mAh/g)、导电碳黑以及聚偏氟乙烯粘结剂PVDF按质量配比分别为：96％、2％、2％混合，并以NMP为溶剂搅拌均匀得到第一负极浆料。
S13、第二负极浆料制备：将石墨(比容量为355mAh/g)、导电碳黑、丁苯橡胶与羧甲基纤维素，按质量配比分别为：96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，再在负第二子层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221与第二子层222的负极极片20，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图3。其中，负极材料层的重量为0.11g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的Nc/Pc比为1.0，其中Nc/Pc计算方式如下：355×0.11×0.96 /(180×0.96×0.216)＝1.0。
需要说明的是，第一子层的容量较少，负极材料层的容量以第二子层的容量为主，故该实施例1的负极材料层的比容量为第二子层的比容量。
实施例2
本申请实施例为一种锂离子电池，该锂离子电池的制备过程可参照实施例1的锂离子电池的制备过程，与实施例1的区别在于第二负极材料采用石墨-硅氧复合材料，降低了负极材料层与正极材料层的容量比为0.8，使得第二负极材料自补锂。具体过程包括如下步骤：
S11、正极极片的制备：参照实施例1中的正极极片的制备。其中，正极材料层的重量为0.31g。
S12、第一负极浆料制备：参照实施例1中的制备过程。
S13、第二负极浆料制备：将石墨-硅氧复合材料(石墨与硅氧的质量比为0.85:0.15，比容量为480mAh/g)、导电碳黑、丁苯橡胶与羧甲基纤维素按质量配比分别为96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到石墨-硅负的第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，再在第二子层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221与第二子层222的负极极片，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图3。其中，负极材料层的重量为0.093g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的容量比Nc/Pc＝480×0.093×0.96/(180×0.96×0.31)＝0.8。
实施例3
本申请实施例为一种锂离子电池，该锂离子电池的制备过程可参照实施例2的锂离子电池的制备过程，与实施例2的区别在于增加锂金属层，为第二负极材料层补锂。具体过程包括如下步骤：
S11、正极极片的制备：参照实施例1中的正极极片的制备。其中，正极材料层的重量为0.31g。
S12、第一负极浆料制备：参照实施例1中的制备过程。
S13、第二负极浆料制备：将石墨-硅氧复合材料(石墨与硅氧的质量比为0.85:0.15)、导电碳黑、丁苯橡胶与羧甲基纤维素按质量配比分别为96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到石墨-硅负的第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，先在第二子层的表面设置一层锂金属层，锂金属层的厚度为10μm±0.5μm，再在锂金属层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221、锂金属层223与第二子层222的负极极片20，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图4。其中，负极材料层的重量为0.093g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的容量比Nc/Pc＝480×0.093×0.96/(180×0.96×0.31)＝0.8。
实施例4
本申请实施例为一种锂离子电池，该锂离子电池的制备过程可参照实施例1的锂离子电池的制备过程，与实施例1的区别是无第二负极材料层。具体过程包括如下步骤：
S11、正极极片的制备：参照实施例1中的正极极片的制备。其中，正极材料层的重量为0.11g。
S12、第一负极浆料制备：参照实施例1中的制备过程。
S13、第一负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后得到含有第一子层221的负极极片20，所得负极极片的结构可参照图2。其中，负极材料层的重量为0.093g。
S14、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的容量比Nc/Pc＝170×0.093×0.96/(180×0.96×0.11)＝0.8。
其中，实施例1-4中，第一子层与正极材料层的相对尺寸关系可参照图5，其中，两者在长度方向的尺寸差L1和L2均为0.1mm，在宽度方向的尺寸差W1和W2均为0.1mm。
实施例5
该实施例的锂离子电池的制备过程与实施例1相同，与实施例1相比不同之处在于，第一子层与正极材料层具有相同的尺寸，即，两者在长度方向的单侧边距L1和L2分别为0mm，在宽度方向的单侧边距W1和W2分别为0mm。
实施例6
本申请实施例为一种锂离子电池，该锂离子电池的制备过程可参照实施例2的锂离子电池的制备过程，区别在于降低负极材料层与正极材料层的容量比为0.2。具体过程包括如下步骤：
S11、正极极片的制备：参照实施例2中的正极极片的制备。其中，正极材料层的重量为：0.31g。
S12、第一负极浆料制备：参照实施例2中的制备过程。
S13、第二负极浆料制备：将石墨-硅氧复合材料(石墨与硅氧的质量比为0.85:0.15)、导电碳黑、丁苯橡胶与羧甲基纤维素按质量配比分别为96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到石墨-硅负极第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，再在第二子层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221与第二子层222的负极极片，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图3。其中，负极材料层的重量为0.023g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的容量比Nc/Pc＝480×0.023×0.96/(180×0.96×0.31)＝0.2。
实施例7
实施例7的锂离子电池的制备过程与实施例2相同，与实施例2相比不同之处在于，区别在于降低负极材料层与正极材料层的容量比为0.4。具体数值列于表1。
S11、正极极片的制备：参照实施例2中的正极极片的制备。其中，正极材料层的重量为0.31g。
S12、第一负极浆料制备：参照实施例2中的制备过程。
S13、第二负极浆料制备：将石墨-硅氧复合材料(石墨与硅氧的质量比为0.85:0.15)、导电碳黑、丁苯橡胶与羧甲基纤维素按质量配比分别为96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到石墨-硅负的第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，再在第二子层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221与第二子层222的负极极片，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图3。其中，负极材料层的重量为0.047g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的容量比Nc/Pc＝480×0.047×0.96/(180×0.96×0.31)＝0.4。
实施例8
实施例8的锂离子电池的制备过程与实施例2相同，与实施例2相比不同之处在于，负极材料层和正极材料层的容量比为0.6以及单侧边距L1，L2，W1和W2分别为0.05mm，具体数值列于表1。
S11、正极极片的制备：参照实施例2中的正极极片的制备。其中，正极材料层的重量为0.31g。
S12、第一负极浆料制备：参照实施例2中的制备过程。
S13、第二负极浆料制备：将石墨-硅氧复合材料(石墨与硅氧的质量比为0.85:0.15)、导电碳黑、丁苯橡胶与羧甲基纤维素按质量配比分别为96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到石墨-硅负的第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，再在第二子层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221与第二子层222的负极极片，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图3。其中，负极材料层的重量为0.065g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极材料层与正极材料层的容量比Nc/Pc＝480×0.065×0.96/(180×0.96×0.31)＝0.6。
对比例1
本申请实施例为一种锂离子电池，主要由正极极片、负极极片、LiFP6电解液、PE隔离膜等组成。该对比例1提供的电池仅包含一层负极层，该负极层采用石墨，各单边距分别为0.1mm。该锂离子电池的制备过程包括如下步骤：
S11、正极极片的制备：将钴酸锂、导电碳黑以及聚偏氟乙烯粘结剂PVDF，按质量配比分别为：96％、2％、2％，并以N-甲基吡咯烷酮(n-methylpyrrolidone，NMP)为溶剂搅拌均匀得到正极浆料， 通过挤压或转移涂布的方式涂覆在铝箔集流体表面，烘干后得到正极极片。其中，正极材料层的重量为0.216g。
S12、负极浆料制备：将石墨、导电碳黑、丁苯橡胶与羧甲基纤维素，按质量配比分别为：96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到负极浆料。
S13、负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后得到负极极片。其中，负极材料层的重量为0.117g。
S14、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极极片的Nc/Pc＝355×0.117×0.96/(180×0.96×0.216)＝1.07。
对比例2
本申请实施例为一种锂离子电池，主要由正极极片、负极极片、LiFP6电解液、PE隔离膜等组成。该对比例2提供的电池包含两层负极层，第一负极层采用钛酸锂，第二负极层采用石墨，各边距分别为0.1mm。该锂离子电池的制备过程包括如下步骤：
S11、正极极片的制备：参照对比例1。其中，正极材料层的重量为0.216g。
S12、第一负极浆料制备：将钛酸锂、导电碳黑以及聚偏氟乙烯粘结剂PVDF按质量配比分别为：96％、2％、2％混合，并以NMP为溶剂搅拌均匀得到第一负极浆料。
S13、第二负极浆料制备：将石墨、导电碳黑、丁苯橡胶与羧甲基纤维素，按质量配比分别为：96％：1％：2％:1％混合，并以水做溶剂搅拌均匀得到第二负极浆料。
S14、第二负极浆料通过挤压或转移涂布的方式涂覆在铜箔集流体表面，烘干后，再在负第二子层的表面以凹版印刷、挤压或转移涂布的方式涂敷第一负极浆料，烘干后得到含有第一子层221与第二子层222的负极极片，其中第二子层222与第一子层221的质量比为9:1。所得负极极片的结构可参照图3。其中，负极材料层的重量为0.117g。
S15、利用正极极片、负极极片、隔膜和电解液组组装锂离子电池。
该实施例中，负极极片的Nc/Pc＝355×0.117×0.96/(180×0.96×0.216)＝1.07。
对比例3
本申请实施例为一种锂离子电池，主要由正极极片、负极极片、LiFP6电解液、PE隔离膜等组成。其制备过程与对比例2相同，不同之处在于第一子层与正极材料层的各单侧边距分别为1mm。
以上各实施例和对比例中，负极材料层与正极材料层的容量比Nc/Pc，负极材料层的容量(Nc)＝负极活性材料的比容量*负极材料的质量*负极活性材料的质量占比；正极材料层的容量(Pc)＝正极活性材料的比容量*正极材料的质量*正极活性材料的质量占比。
负极活性材料的质量为负极材料层中负极活性材料的总质量，负极活性材料的质量占比为负极材料层中负极活性材料的质量与负极材料的质量的比值。正极活性材料的质量占比为正极材料层中正极活性材料的质量与正极材料的质量的比值。
分别对各实施例和对比例的锂离子电池进行针刺安全测试，针刺速度为100mm/s，钉子直径为2.0mm，观察电池是否燃烧或冒烟，并记录每组样品的通过率。测试结果列于表1。
表1
从表1中的数据可以看出，本申请实施例1-8的各个锂离子电池，其能量密度均高于对比例1，且针对安全测试通过率也远远高于对比例1。由实施例1-8与对比例2的相关数据可知，当Nc/Pc的值大于1.04，如对比例2和对比例3的1.07时，所对应的锂离子电池具有较高的安全性，但是其能量密度会低于实施例1-8。
实施例1-5的各个锂离子电池，负极极片中均设有含有钛酸锂的第一子层，由钛酸锂组成的电池的能量密度相对较低，因此，为了减少钛酸锂带来的能量密度的损失，同时不影响负极极片的安全性，本申请的各实施例中均通过调整Nc/Pc的比值达到提升锂离子电池的能量密度的目的。
实施例2中，在持续充电中，过量的锂将储存在第一子层和第二子层之间的界面，由于第二子层中含有硅基材料，此时，析出的锂可用来对硅基材料进行补锂，简化了传统硅基材料的补锂工艺，并可降低硅基材料的补锂成本。同时，含有钛酸锂的第一子层，可作为保护层，避免析出的锂形成锂枝晶刺穿隔膜。
实施例3的锂离子电池，通过直接设置锂金属层，由于锂金属具有较高的比容量，比容量高达3860mAh/g，可提高对硅基材料的补锂效果，故可提高负极极片的能量密度，进而提升电池的能量密度。
实施例4的锂离子电池，只含有第一子层，该实施例的锂离子电池，在充放电循环过程中，可直接在负极集流体的表面形成锂金属层，因此，可进一步提高锂离子电池的能量密度。该实施例的锂离子电池中，锂金属层可通过低温充电或过充充电等方式形成，从而可降低锂金属层的形成成本和难度。
实施例5的锂离子电池，第一子层与正极材料层相对设置，且两者的尺寸基本相同，该尺寸结构的锂离子电池中，可避免第一子层或正极材料层的尺寸空间的浪费，以充分利用锂离子电池长度和宽度方向的空间，从而可提高电池的能量密度。
通过实施例1和实施例5的相关数据可知，降低第一子层和正极材料层之间的单侧边距后，可提高锂离子电池的能量密度。
从实施例1-2以及实施例6-8的相关数据可以看出，当Nc/Pc比值不同时，所获得锂离子电池的能量密度均有所区别。其中，当Nc/Pc比值在0.6-1.0范围内时，可以获得兼顾安全性和能量密度更高的锂离子电池。
综上，通过控制Nc/Pc比值或者控制正极材料层和负极第一子层的各单侧边距的值，可以获得兼顾安全性和能量密度更高的锂离子电池。
基于同样的技术构思，本申请提供了一种用电设备，包括用电模块和本申请的锂离子电池，其中，锂离子电池与用电模块电连接，为用电模块提供电力。
其中，本申请的用电设备例如包括但不限于手机、电脑、电话手表、平面显示器件、储能设备以及车辆等动力装置。
以上，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (15)

  1. 一种锂离子电池，其特征在于，包括正极极片和负极极片，所述正极极片包括叠层设置的正极集流体和正极材料层，所述负极极片包括叠层设置的负极集流体和负极材料层，所述负极材料层包括第一子层，所述第一子层中的负极活性材料包括钛酸锂，所述第一子层的面密度≥0.1mg/cm2，所述负极材料层和所述正极材料层的容量比Nc/Pc为0<Nc/Pc≤1.04。
  2. 根据权利要求1所述的锂离子电池，其特征在于，所述负极材料层和所述正极材料层的容量比Nc/Pc为0.2≤Nc/Pc≤1.04。
  3. 根据权利要求1或2所述的锂离子电池，其特征在于，所述负极材料层包括第二子层，所述第二子层设于所述负极集流体和所述第一子层之间，所述第二子层中的负极活性材料包括碳材料或硅基材料。
  4. 根据权利要求3所述的锂离子电池，其特征在于，所述第一子层与所述第二子层之间设有含锂金属层。
  5. 根据权利要求3或4所述的锂离子电池，其特征在于，所述第一子层的长度尺寸大于或者等于所述第二子层的长度尺寸，所述第一子层的宽度尺寸大于或者等于所述第二子层的宽度尺寸。
  6. 根据权利要求3-5任一项所述的锂离子电池，其特征在于，所述第二子层与所述第一子层的质量比大于或等于1。
  7. 根据权利要求1或2所述的锂离子电池，其特征在于，所述负极材料层包括含锂金属层，所述含锂金属层设于所述负极集流体和所述第一子层之间。
  8. 根据权利要求1-7任一项所述的锂离子电池，其特征在于，所述正极材料层在所述第一子层所在平面的正投影面积小于或等于所述第一子层的面积，且沿所述正极材料层的宽度方向，所述第一子层和所述正极材料层的尺寸差小于1.5mm；沿所述正极材料层的长度方向，所述第一子层和所述正极材料层的尺寸差小于3mm。
  9. 根据权利要求8所述的锂离子电池，其特征在于，沿所述正极材料层的宽度方向，所述正极材料层与所述第一子层之间的单侧边距为0～0.1mm。
  10. 根据权利要求8或9所述的锂离子电池，其特征在于，沿所述正极材料层的长度方向，所述正极材料层与所述第一子层之间的单侧边距为0～1mm。
  11. 一种锂离子电池，其特征在于，包括正极极片和负极极片，所述正极极片包括叠层设置的正极集流体和正极材料层，所述负极极片包括叠层设置的负极集流体和负极材料层，所述负极材料层包括第一子层，所述第一子层中的负极活性材料包括钛酸锂；
    所述正极材料层在所述第一子层所在平面的正投影面积小于或等于所述第一子层的面积，且沿所述正极材料层的宽度方向，所述第一子层和所述正极材料层的尺寸差小于1.5mm；沿所述正极材料层的长度方向，所述第一子层和所述正极材料层的尺寸差小于3mm。
  12. 根据权利要求11所述的锂离子电池，其特征在于，沿所述正极材料层的宽度方向，所述正极材料层与所述第一子层之间的单侧边距为0～0.1mm。
  13. 根据权利要求11或12所述的锂离子电池，其特征在于，沿所述正极材料层的长度方向，所述正极材料层与所述第一子层之间的单侧边距为0～1mm。
  14. 根据权利要求11-13任一项所述的锂离子电池，其特征在于，所述正极材料层与所述第一子层的尺寸相同。
  15. 一种用电设备，其特征在于，包括用电模块和与所述用电模块连接的如权利要求1-14任一项所述的锂离子电池。
PCT/CN2023/117492 2022-09-22 2023-09-07 锂离子电池和用电设备 WO2024061011A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202211160158.6A CN117747909A (zh) 2022-09-22 2022-09-22 锂离子电池和用电设备
CN202211160158.6 2022-09-22

Publications (1)

Publication Number Publication Date
WO2024061011A1 true WO2024061011A1 (zh) 2024-03-28

Family

ID=90281884

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/117492 WO2024061011A1 (zh) 2022-09-22 2023-09-07 锂离子电池和用电设备

Country Status (2)

Country Link
CN (1) CN117747909A (zh)
WO (1) WO2024061011A1 (zh)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013084420A (ja) * 2011-10-07 2013-05-09 Nissan Motor Co Ltd 積層型リチウムイオン電池
CN103401016A (zh) * 2013-08-05 2013-11-20 宁德时代新能源科技有限公司 高能量密度锂离子电池
CN204793029U (zh) * 2015-07-03 2015-11-18 深圳市电科电源股份有限公司 混合负极极片及锂离子动力电池
CN105226325A (zh) * 2015-10-22 2016-01-06 郑州宇通客车股份有限公司 一种钛酸锂电池用电解液及钛酸锂电池
CN105406131A (zh) * 2015-11-30 2016-03-16 李朝 一种电容型混合负极极片锂离子动力电池
CN205429091U (zh) * 2015-11-30 2016-08-03 李朝 一种电容型混合负极极片锂离子动力电池
CN106159236A (zh) * 2016-08-26 2016-11-23 深圳博磊达新能源科技有限公司 一种快速充电钛酸锂复合负极极片及锂离子电池
US20190115621A1 (en) * 2016-06-08 2019-04-18 Kaneka Corporation Lithium-ion secondary battery and assembled battery
CN114497468A (zh) * 2020-11-11 2022-05-13 比亚迪股份有限公司 锂离子电池
CN114883575A (zh) * 2022-05-09 2022-08-09 清华大学 锂离子电池及其制备方法

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013084420A (ja) * 2011-10-07 2013-05-09 Nissan Motor Co Ltd 積層型リチウムイオン電池
CN103401016A (zh) * 2013-08-05 2013-11-20 宁德时代新能源科技有限公司 高能量密度锂离子电池
CN204793029U (zh) * 2015-07-03 2015-11-18 深圳市电科电源股份有限公司 混合负极极片及锂离子动力电池
CN105226325A (zh) * 2015-10-22 2016-01-06 郑州宇通客车股份有限公司 一种钛酸锂电池用电解液及钛酸锂电池
CN105406131A (zh) * 2015-11-30 2016-03-16 李朝 一种电容型混合负极极片锂离子动力电池
CN205429091U (zh) * 2015-11-30 2016-08-03 李朝 一种电容型混合负极极片锂离子动力电池
US20190115621A1 (en) * 2016-06-08 2019-04-18 Kaneka Corporation Lithium-ion secondary battery and assembled battery
CN106159236A (zh) * 2016-08-26 2016-11-23 深圳博磊达新能源科技有限公司 一种快速充电钛酸锂复合负极极片及锂离子电池
CN114497468A (zh) * 2020-11-11 2022-05-13 比亚迪股份有限公司 锂离子电池
CN114883575A (zh) * 2022-05-09 2022-08-09 清华大学 锂离子电池及其制备方法

Also Published As

Publication number Publication date
CN117747909A (zh) 2024-03-22

Similar Documents

Publication Publication Date Title
WO2020177623A1 (zh) 负极片、二次电池及其装置
WO2021223655A1 (zh) 一种正极片、制备方法及包含其的锂离子电池
WO2019228003A1 (zh) 一种预锂化膜及其制备方法和应用
WO2023174335A1 (zh) 一种负极浆料组合物和应用
WO2022206877A1 (zh) 电化学装置及电子装置
WO2020134780A1 (zh) 一种正极材料及其制备方法和用途
WO2022037092A1 (zh) 一种集流体、极片和电池
US10840548B2 (en) Solid electrolyte laminate and all-solid-state battery using the same
WO2022100661A1 (zh) 一种负极片及其应用
WO2022033065A1 (zh) 负极片及二次电池
WO2021223654A1 (zh) 一种正极片、制备方法及包含其的锂离子电池
WO2023155604A1 (zh) 复合隔膜及电化学装置
WO2023093576A1 (zh) 一种极片和锂离子电池
CN112467075B (zh) 一种极片、电芯及二次电池
WO2022236951A1 (zh) 一种负极及其制备方法和用途
WO2022057189A1 (zh) 一种固态电池、电池模组、电池包及其相关的装置
CN114725623A (zh) 电池、电子设备、移动装置
WO2023138577A1 (zh) 正极补锂添加剂及其制备方法和应用
WO2023108963A1 (zh) 一种锂离子电池
CN113451586A (zh) 一种二次电池的电极片、二次电池及其制备方法
CN112713266A (zh) 负极浆料及其应用
CN112786832A (zh) 一种负极片及锂离子电池
WO2022156459A1 (zh) 锂离子电池的负极片、锂离子电池和电子设备
CN114497447A (zh) 一种正极片和锂离子电池
WO2024016891A1 (zh) 预锂化极片及其制备方法、二次电池和用电装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23867302

Country of ref document: EP

Kind code of ref document: A1