WO2024055730A1 - 正极片、电芯和电池 - Google Patents

正极片、电芯和电池 Download PDF

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WO2024055730A1
WO2024055730A1 PCT/CN2023/106145 CN2023106145W WO2024055730A1 WO 2024055730 A1 WO2024055730 A1 WO 2024055730A1 CN 2023106145 W CN2023106145 W CN 2023106145W WO 2024055730 A1 WO2024055730 A1 WO 2024055730A1
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Prior art keywords
positive electrode
electrode sheet
semiconductor material
resistance value
sheet according
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PCT/CN2023/106145
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English (en)
French (fr)
Inventor
张保海
彭冲
李俊义
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珠海冠宇电池股份有限公司
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Publication of WO2024055730A1 publication Critical patent/WO2024055730A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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
    • H01M2004/028—Positive 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

  • This application relates to the technical field of lithium-ion batteries, specifically to positive electrode sheets, cells and batteries.
  • lithium-ion batteries must have high performance. If you need to take into account both fast charging and energy density, low-temperature discharge and high-temperature storage, high and low temperature cycles, etc., the most important one and the one with the largest usage scenario must be a lithium-ion battery that takes into account both high and low temperature cycles; but the two are often one and the same.
  • the present invention provides a positive electrode sheet, an electric core and a battery.
  • the positive electrode sheet fully solves the problem that existing lithium-ion batteries cannot achieve both high and low temperature cycles, solves the problem of lithium precipitation at the edge of the negative electrode, and improves the overall performance of lithium-ion batteries.
  • the invention provides a positive electrode sheet.
  • the positive active material layer of the positive electrode sheet includes a positive active material, a conductive agent, a binder and a semiconductor material.
  • the lithium-embedding ability of the negative electrode is related to the material itself. Once the material is fixed, its lithium-intercalating ability cannot be changed by external changes. Therefore, it is necessary to choose one that avoids side reactions as much as possible, but ensures a certain lithium-intercalating ability. negative electrode; therefore, it is necessary to invent a positive electrode sheet whose conductivity can change according to changes in temperature. In order to achieve both high and low temperatures, according to the above analysis, the conductivity of the positive electrode side becomes weaker at room temperature, reducing the release of lithium ions. Improving the conductivity of the positive electrode at high temperatures reduces the polarization of the positive electrode side, reduces side reactions and improves the stability of the positive electrode side.
  • the positive electrode formula of the positive electrode sheet provided by the invention not only contains conventional materials, such as positive electrode materials, conductive agents, and binders, but also adds a semiconductor material, which has high impedance and non-conductivity at normal temperatures and low impedance at high temperatures.
  • the conductive characteristics can achieve the above requirements, making the positive electrode have poor conductivity at normal temperature, less lithium removal, and the negative electrode is not prone to lithium precipitation. It has high conductivity at high temperatures, small polarization, and good high-temperature life, achieving both high and low temperatures.
  • the semiconductor material is selected from one or two types of inorganic compound semiconductor binary systems and oxides of transition metal elements.
  • the inorganic compound semiconductor binary system is selected from one or two of group IV-IV compound semiconductor materials and group V-VI compound semiconductor materials;
  • the Group IV-IV compound semiconductor material is selected from one or both of SiC and GeSi;
  • the Group V-VI compound semiconductor material is selected from one or more of Bi 2 Te 3 , Bi 2 Se 3 , Bi 2 S 3 , and As 2 Te 3 .
  • the oxide of the transition metal element is selected from one or more oxides of Zr, Cu, Zn, Sc, Ti, V, Cr, Mn, Fe, Co, and Ni;
  • the oxide of the transition metal element is one or both of ZrO 2 and Cr 2 O 3 .
  • the particle size D 50 of the semiconductor material is 1 to 1000 nm.
  • Exemplary values are any one of 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 or any of the above. Any value between a range of two values.
  • the particle size of the semiconductor material of the present invention is smaller in order to achieve large-area distribution, without the problem of local aggregation and local non-conductivity, and to ensure that a large area inside the pole piece is still conductive.
  • the particle size D 50 of the semiconductor material is 1 to 100 nm.
  • the particle size D 50 of the semiconductor material is 10 nm.
  • the amount of semiconductor material is 10wt% to 30wt% of the amount of conductive agent.
  • Exemplary ones are any one of 10wt%, 12wt%, 14wt%, 15wt%, 16wt%, 18wt%, 20wt%, 22wt%, 24wt%, 25wt%, 26wt%, 28wt%, 30wt% or any two of the above. Any value between the range of two values.
  • the amount of the semiconductor can be used as much as possible not to affect its conductivity at room temperature while taking into account its high-temperature conductivity.
  • the amount of semiconductor material is 12wt%-30wt% of the amount of conductive agent.
  • the amount of semiconductor material is 18wt%-30wt% of the amount of conductive agent.
  • the mass ratio of the positive electrode active material, conductive agent, and binder is (75 to 100): (0.5 to 15): (0.5 to 15).
  • the mass ratio of the positive active material, conductive agent, and binder is (90 ⁇ 100):(0.5 ⁇ 3):(0.5 ⁇ 3).
  • the positive active material is selected from one or more of lithium cobalt oxide, nickel cobalt manganese, lithium iron phosphate, nickel cobalt aluminum, and lithium manganate;
  • the conductive agent is selected from one or more of acetylene black, conductive carbon black, Ketjen black, conductive fibers, conductive polymers, carbon nanotubes, graphene, flake graphite, conductive oxides, and metal particles;
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinylpyrrolidone, One or more of vinyl ether, polymethylmethacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber.
  • the positive electrode sheet further includes a positive electrode current collector.
  • the resistance value of the positive electrode sheet including semiconductor material is tested at 25°C in an unassembled state.
  • the resistance value of the positive electrode sheet including semiconductor material is recorded as X 0 , and X 0 is 390 to 1600 ⁇ ;
  • the resistance value of the positive electrode sheet including semiconductor material is recorded as X 1 , and X 1 is 550 to 1750 ⁇ ;
  • the resistance value of the positive electrode sheet including semiconductor material is recorded as X 2 , and X 2 is 616 to 2188 ⁇ ;
  • the resistance value of the positive electrode sheet including semiconductor material is recorded as X 3 , and X 3 is 733 to 2844 ⁇ ;
  • X 0 , X 1 , X 2 , and X 3 satisfy the following relationships:
  • the resistance value of the positive electrode sheet excluding semiconductor material is tested at 25°C and in an unassembled state.
  • the resistance value of the positive electrode sheet excluding semiconductor material is recorded as Y 0 , and Y 0 is 300 to 1000 ⁇ ;
  • the resistance value of the positive electrode sheet excluding semiconductor materials is recorded as Y 1 , and Y 1 is 350 to 1100 ⁇ ;
  • X 0 , Y 0 , X 1 , Y 1 satisfy the following relationships:
  • the distribution area of the conductive agent on the surface of the positive electrode active material particles is larger than the distribution area of the semiconductor material on the surface of the positive electrode active material particles.
  • the invention also provides an electric core, which includes the above-mentioned positive electrode sheet.
  • the resistance value of the battery core is tested at 25°C;
  • the resistance value of the battery core is recorded as A 1 , and A 1 is 18 to 65 m ⁇ ;
  • the resistance value of the battery core is recorded as A 2 , and A 2 is 19 to 76 m ⁇ ;
  • the resistance value of the battery core is recorded as A 3 , and A 3 is 21 to 84 m ⁇ ;
  • a 1 , A 2 , and A 3 satisfy the following relationships:
  • Batteries have a variety of structures, including multi-pole batteries, STP-structured batteries, conventional-structured batteries, etc. Batteries with different structures have different corresponding resistance values, so the above-mentioned battery core resistance values are not limited to Therefore, the above cell resistance value is only an exemplary description.
  • the battery core further includes one or more of a negative electrode sheet, a separator, and an electrolyte.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer includes a negative electrode Active substances, conductive agents, binders and thickeners.
  • the mass ratio of the negative active material, conductive agent, binder, and thickener in the negative active material layer is (75 to 100): (0.5 to 15): (0.5 to 15): (0.1 to 15).
  • the mass ratio of the negative active material, conductive agent, binder, and thickener is (90 ⁇ 100):(0.5 ⁇ 3):(0.5 ⁇ 3):(0.5 ⁇ 2.5).
  • the negative active material is selected from one or more of artificial graphite, natural graphite, mesocarbon microspheres, soft carbon, hard carbon, organic polymer carbon, and lithium titanate;
  • the conductive agent is selected from one or more of conductive carbon black, carbon fiber, Ketjen black, acetylene black, carbon nanotubes, and graphene;
  • the binder is selected from one or more of styrene-butadiene rubber, polyvinylidene fluoride, polyacrylic acid, polytetrafluoroethylene, and polyethylene oxide;
  • the thickening agent is selected from one of sodium carboxymethylcellulose, lithium carboxymethylcellulose, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose. or more.
  • the electrolyte is a non-aqueous electrolyte
  • the non-aqueous electrolyte includes a non-aqueous organic solvent, a lithium salt and additives.
  • the non-aqueous organic solvent is selected from ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), fluoroethylene carbonate (FEC), dimethyl carbonate (DMC) ), one or more of ethyl methyl carbonate (EMC), ethylene carbonate, ⁇ -butyrolactone, methyl propyl carbonate, and ethyl propionate.
  • the lithium salt is selected from one of LiPF 6 , LiBF 4 , LiSbF 6 , LiClO 4 , LiCF 3 SO 3 , LiAlO 4 , LiAlCl 4 , Li(CF 3 SO 2 ) 2 N, LiBOB, and LiDFOB or more.
  • the additive is selected from one or more of 1,3-propane sultone, fluoroethylene carbonate, vinylene carbonate, ethylene ethylene carbonate, vinyl sulfate, and lithium difluorophosphate. .
  • the present invention also provides a battery, which includes the above-mentioned positive electrode sheet and/or the above-mentioned battery core.
  • the battery further includes a casing.
  • the positive electrode material is doped with a semiconductor material that can change according to the change of temperature. Its conductivity is high in internal resistance and low in conductivity at normal temperature. As the temperature rises, it shows a trend of low internal resistance and high conductivity; realizing the positive electrode side on the Its conductivity becomes weaker at room temperature, reducing the release of lithium ions. At high temperatures, it improves the conductivity of the cathode, reduces polarization on the cathode side, reduces side reactions, and improves the stability of the cathode side. This can not only prevent lithium precipitation at room temperature, but also achieve prolonged high temperature cycle life and achieve the purpose of taking into account both high and low temperatures.
  • FIG. 1 is a schematic diagram of the cathode sheet of the present invention, which includes: 1 cathode active material layer; 2 semiconductor material; 3 cathode current collector.
  • the present invention discloses a positive electrode sheet, a cell and a battery. Persons skilled in the art can learn from the contents of this article and appropriately improve the process parameters for implementation. It should be noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are deemed to be included in the present invention.
  • the methods and applications of the present invention have been described through preferred embodiments. Relevant persons can obviously make modifications or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to achieve and Apply the technology of this invention.
  • lithium cobalt oxide as the positive active material, then add the conductive agent acetylene black and the binder polyvinylidene fluoride into the stirring tank at a mass ratio of 97.2:1.5:1.3, and then add semiconductor zirconium dioxide (D 50 is 10nm ), with a mass ratio of 12% to the conductive agent. Then add NMP solvent, stir thoroughly according to the well-known batching process, pass through a 200-mesh screen, and prepare a positive electrode slurry. The solid content of the positive electrode slurry is 70% to 75%. .
  • the positive electrode slurry is coated on the aluminum foil current collector using a coating machine; it is dried at 120°C to prepare an initial positive electrode piece; the above initial electrode piece is cut according to actual needs to prepare a positive electrode piece.
  • the positive electrode sheet, the negative electrode sheet, and the separator are sandwiched in the middle and rolled to prepare a lithium-ion battery core, which is packaged with aluminum plastic film, baked to remove moisture, and then injected with electrolyte.
  • the lithium-ion battery core is obtained by using a hot-pressing process.
  • Example 1 The difference from Example 1 is that the mass ratio of zirconium dioxide and conductive agent used is 18%.
  • Example 2 The difference from Example 1 is that the mass ratio of zirconium dioxide and conductive agent used is 22%.
  • Example 1 The difference from Example 1 is that the mass ratio of zirconium dioxide and conductive agent used is 10%.
  • Example 2 The difference from Example 1 is that the mass ratio of zirconium dioxide and conductive agent used is 30%.
  • Example 2 The difference from Example 1 is that the D 50 of the semiconductor zirconium dioxide is 1 nm.
  • Example 2 The difference from Example 1 is that the D 50 of the semiconductor zirconium dioxide is 1 ⁇ m.
  • Example 2 The difference from Example 1 is that the D 50 of the semiconductor zirconium dioxide is 0.5 ⁇ m.
  • Embodiment 1 The difference from Embodiment 1 is that the semiconductor used is SiC.
  • Embodiment 1 The difference from Embodiment 1 is that the semiconductor used is Bi 2 Te 3 .
  • Embodiment 1 The difference from Embodiment 1 is that the semiconductor used is Cr 2 O 3 .
  • Example 1 The difference from Example 1 is that no semiconductor material is added.
  • Resistance test method Take the pole piece and directly use a four-probe tester (model ST-2258C) to test the resistance. Take the battery core and directly use the load meter (model IT8551+) to test the resistance.
  • the initial state is the state after cycling 0 to 10T; the positive electrode piece in the initial state, cycle 50T, and cycle 100T is the pole piece after assembly, that is, the pole piece removed from the battery core.
  • the initial state is the state after cycling 0 to 10T; the positive electrode piece in the initial state, cycle 50T, and cycle 100T is the assembled pole piece, that is, the pole piece removed from the battery core; Y 0 is the unassembled state of Comparative Example 1 The lower resistance value, Y 1 , is the initial state resistance value of Comparative Example 1.
  • test data in the above table are the test results of the multi-pole cell structure. If it is a cell structure with other structures, the specific resistance value will be different, but the resistance ratio is approximate; the initial state is the state after cycling 0 ⁇ 10T.
  • the lithium-ion batteries prepared in each example and comparative example were charged at 3C/discharged at 0.7C at 25°C and 45°C, and the battery was disassembled at room temperature cycle of 500T ⁇ 800T to confirm the lithium deposition at the edge of the negative electrode of the battery.
  • the disassembly results and cycle data are as follows:
  • the lithium-ion batteries prepared in Examples 1-11 of the present invention can effectively solve the problem of Existing lithium-ion batteries cannot achieve the purpose of balancing high and low temperatures, and can fully solve the problem of lithium precipitation at the edge of the battery's normal temperature cycle.

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Abstract

本申请涉及锂离子电池技术领域，具体涉及正极片、电芯和电池。该正极片的正极活性物质层包括正极活性物质、导电剂、粘结剂和半导体材料。本发明在正极材料中掺杂半导体材料，既能防止常温析锂，又能实现延长高温循环寿命、实现高低温兼顾的目的。

Description

正极片、电芯和电池 技术领域
本申请涉及锂离子电池技术领域，具体涉及正极片、电芯和电池。
背景技术
随着设备的发展，人们对便携式移动办公设备的需求越来越迫切，同时为了满足人们的办公需求其使用环境也变得越来越苛刻，那么必然锂离子电池的就必须具备高的性能，如需要同时兼顾快充与能量密度，低温放电与高温储存，高低温循环兼顾等，其中最重要的也是使用场景最大的功能必然是高低温循环兼顾的锂离子电池；但是这两者往往是一个矛盾点，提高负极动力学必然可以提高常温循环寿命；但在高温下高动力学的负极副反应增多，高温循环寿命就会下降；降低负极动力学提高正极动力学其高温循环寿命就会变好，但是其常温就会析锂，常温循环寿命就会降低；无法实现高低温循环兼顾。
发明内容
有鉴于此，本发明提供了正极片、电芯和电池。该正极片充分解决现有锂离子电池不能实现高低温循环兼顾的问题，解决负极边缘析锂问题，提高锂离子电池的综合性能。
为了实现上述发明目的，本发明提供以下技术方案：
本发明提供了一种正极片，该正极片的正极活性物质层包括正极活性物质、导电剂、粘结剂和半导体材料。
从常温循环的原理看，要想实现常温长寿命就必须提高负极动力学(提高负极的嵌锂能力)或者降低正极的导电性(降低正极脱锂速度，间接降低负极侧单位时间内的锂离子浓度，让负极有足够的时间嵌锂，避免析锂)。从高温循环的原理看，要想改善高温循环就必须降低负极侧的副反应，降低电解液消耗(降低负极动力学，这会导致常温析锂)或者提高正极侧的导电性，降低正极在高温高电压下极化，降低反应 的发生，减少电解液的消耗，稳定正极结构，提高高温循环寿命(提高正极导电性，间接提高其脱锂能力，负极侧单位时间内的锂离子浓度提升，负极侧有析锂的风险)。
基于上述，理解负极的嵌锂能力与材料自身有关，一旦固定材料，其嵌锂能力无法受外界的变化而变化，所以需要选择一款尽量避免副反应的发生，但需要保证一定嵌锂能力的负极；因此需要发明一种正极片，其导电性可以根据温度的变化而变化，要想实现高低温兼顾，根据上述分析，正极侧在常温下其导电性变弱，减少锂离子的脱出，在高温下提高正极的导电性降低正极侧极化，降低副反应提高正极侧的稳定性。
本发明提供的正极片其正极配方除了含有常规的材料，如正极材料、导电剂、粘结剂之外，还加入了一种半导体材料，该材料具有常温下高阻抗不导电，高温下低阻抗导电的特点，这样可以实现上述需求，使得正极片在常温下导电性差、脱锂少、负极不易析锂，高温下导电性高、极化小、高温寿命好，实现高低温兼顾。
作为优选，半导体材料选自无机化合物半导体二元系、过渡金属元素的氧化物中的一种或两种。
作为优选，无机化合物半导体二元系选自Ⅳ-Ⅳ族化合物半导体材料、Ⅴ-Ⅵ族化合物半导体材料中的一种或两种；
在本发明具体实施例中，Ⅳ-Ⅳ族化合物半导体材料选自SiC、GeSi中的一种或两种；
在本发明具体实施例中，Ⅴ-Ⅵ族化合物半导体材料选自Bi2Te3、Bi2Se3、Bi2S3、As2Te3中的一种或多种。
作为优选，过渡金属元素的氧化物选自Zr、Cu、Zn、Sc、Ti、V、Cr、Mn、Fe、Co、Ni中的一种或多种的氧化物；
在本发明具体实施例中，过渡金属元素的氧化物为ZrO2、Cr2O3中的一种或两种。
作为优选，半导体材料的粒径D50为1～1000nm。示例性的为1、10、20、30、40、50、60、70、80、90、100、200、300、400、500、600、700、800、900、1000中任一数值或上述任意两两数值组成的范围值之间的任一数值。
本发明半导体材料的粒径较小，是为了实现大面积分布，不出现局部聚集呈现局部不导电的问题，确保极片内部大面积还是导电状态。
优选地，半导体材料的粒径D50为1～100nm。
在本发明具体实施例中，半导体材料的粒径D50为10nm。
作为优选，半导体材料的用量为导电剂用量的10wt％～30wt％。示例性的为10wt％、12wt％、14wt％、15wt％、16wt％、18wt％、20wt％、22wt％、24wt％、25wt％、26wt％、28wt％、30wt％中任一数值或上述任意两两数值组成的范围值之间的任一数值。该半导体的用量可以尽量不影响其常温导电性，又兼顾高温导电性能。
优选地，半导体材料的用量为导电剂用量的12wt％～30wt％。
优选地，半导体材料的用量为导电剂用量的18wt％～30wt％。
作为优选，正极活性物质、导电剂、粘结剂的质量比为(75～100):(0.5～15):(0.5～15)。
在本发明具体实施例中，正极活性物质、导电剂、粘结剂的质量比为(90～100):(0.5～3):(0.5～3)。
作为优选，正极活性物质选自钴酸锂、镍钴锰、磷酸铁锂、镍钴铝、锰酸锂中的一种或多种；
作为优选，导电剂选自乙炔黑、导电炭黑、科琴黑、导电纤维、导电聚合物、碳纳米管、石墨烯、鳞片石墨、导电氧化物、金属颗粒中的一种或多种；
作为优选，粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯、聚六氟丙烯、丁苯橡胶中的一种或多种。
在本发明提供的具体实施例中，正极片还包括正极集流体。
在本发明实施方式中，在25℃、未组装状态下，测试包括半导体材料的正极片的电阻值，包括半导体材料的正极片在的电阻值记为X0，X0为390～1600Ω；
将包括半导体材料的正极片组装电芯，经过或未经过充放电循环后，在25℃条件下测试正极片的电阻值；
充放电循环0～10T后，包括半导体材料的正极片的电阻值记为X1，X1为550～1750Ω；
充放电循环50T后，包括半导体材料的正极片的电阻值记为X2，X2为616～2188Ω；
充放电循环100T后，包括半导体材料的正极片的电阻值记为X3，X3为733～2844Ω；
X0、X1、X2、X3满足如下关系：
1.09≤X1/X0≤1.41
1.12≤X2/X1≤1.25
1.33≤X3/X1≤1.65。
在本发明实施方式中，在25℃、未组装状态下，测试不包括半导体材料的正极片的电阻值，不包括半导体材料的正极片的电阻值记为Y0，Y0为300～1000Ω；
将不包括半导体材料的正极片组装电芯，经过或未经过充放电循环后，在25℃条件下测试正极片的电阻值；
充放电循环0～10T后，不包括半导体材料的正极片的电阻值记为Y1，Y1为350～1100Ω；
X0、Y0、X1、Y1满足如下关系：
1.0≤X0/Y0≤5.4
1.1≤X1/Y1≤5.0
作为优选，导电剂在正极活性物质颗粒表面的分布面积大于半导体材料在正极活性物质颗粒表面的分布面积。
本发明还提供了一种电芯，该电芯包括上述正极片。
在本发明实施方式中，经过或未经过充放电循环后，在25℃条件下测试电芯的电阻值；
充放电循环0～10T后，电芯的电阻值记为A1，A1为18～65mΩ；
充放电循环50T后，电芯的电阻值记为A2，A2为19～76mΩ；
充放电循环100T后，电芯的电阻值记为A3，A3为21～84mΩ；
A1、A2、A3满足如下关系：
1.08≤A2/A1≤1.17
1.16≤A3/A1≤1.29。
电芯具有多种结构，包括多极耳电芯、STP结构的电芯、常规结构的电芯等，不同结构的电芯，相应的电阻值也不同，所以上述的电芯电阻值并非限定于此，上述电芯电阻值仅为示例性的说明。
在本发明提供的具体实施例中，电芯还包括负极片、隔膜、电解液中的一种或多种。
作为优选，负极片包括负极集流体和负极活性物质层，负极活性物质层包括负极 活性物质、导电剂、粘结剂和增稠剂。
作为优选，负极活性物质层中负极活性物质、导电剂、粘结剂、增稠剂的质量比为(75～100):(0.5～15):(0.5～15):(0.1～15)。
在本发明具体实施例中，负极活性物质、导电剂、粘结剂、增稠剂的质量比为(90～100):(0.5～3):(0.5～3):(0.5～2.5)。
作为优选，负极活性物质选自人造石墨、天然石墨、中间相碳微球、软碳、硬碳、有机聚合物碳、钛酸锂中的一种或多种；
作为优选，导电剂选自导电炭黑、碳纤维、科琴黑、乙炔黑、碳纳米管、石墨烯中的一种或多种；
作为优选，粘结剂选自丁苯橡胶、聚偏氟乙烯、聚丙烯酸、聚四氟乙烯、聚氧化乙烯中的一种或多种；
作为优选，增稠剂选自羧甲基纤维素钠、羟甲基纤维素锂、甲基纤维素、羧甲基纤维素、羟乙基纤维素、羟丙基甲基纤维素中的一种或多种。
在本发明具体实施例中，电解液为非水电解液，非水电解液包括非水有机溶剂、锂盐和添加剂。
在一些实施例中，非水有机溶剂选自碳酸亚乙酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、氟代碳酸乙烯酯(FEC)、碳酸二甲酯(DMC)、碳酸甲乙酯(EMC)、碳酸乙烯酯、γ-丁内酯、碳酸甲丙酯、丙酸乙酯中的一种或多种。
在一些实施例中，锂盐选自LiPF6、LiBF4、LiSbF6、LiClO4、LiCF3SO3、LiAlO4、LiAlCl4、Li(CF3SO2)2N、LiBOB和LiDFOB中的一种或多种。
在一些实施例中，添加剂选自1,3-丙烷磺内酯、氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、硫酸乙烯酯、二氟磷酸锂中的一种或多种。
本发明还提供了一种电池，该电池包括上述正极片和/或上述电芯。
在本发明提供的具体实施例中，电池还包括外壳。
与现有技术相比，本发明具有的有益效果为：
本发明在正极材料中掺杂可以根据温度的变化而变化的半导体材料，其导电能力在常温下高内阻低导电，随着温度升高呈现出低内阻高导电的趋势；实现正极侧在常温下其导电性变弱、减少锂离子的脱出，在高温下提高正极的导电性、降低正极侧极化、降低副反应、提高正极侧的稳定性。这样既能防止常温析锂，又能实现延长高温 循环寿命、实现高低温兼顾的目的。
附图说明
图1为本发明正极片示意图，其中，1正极活性物质层；2半导体材料；3正极集流体。
具体实施方式
本发明公开了正极片、电芯和电池，本领域技术人员可以借鉴本文内容，适当改进工艺参数实现。特别需要指出的是，所有类似的替换和改动对本领域技术人员来说是显而易见的，它们都被视为包括在本发明。本发明的方法及应用已经通过较佳实施例进行了描述，相关人员明显能在不脱离本发明内容、精神和范围内对本文所述的方法和应用进行改动或适当变更与组合，来实现和应用本发明技术。
本发明中所用材料均可通过商业渠道获得。
下面结合实施例，进一步阐述本发明：
实施例1
本实施例锂离子电芯制备方法包括如下步骤：
1、正极浆料的制备：
以钴酸锂为正极活性材料，然后加入导电剂乙炔黑和粘结剂聚偏氟乙烯按照97.2:1.5:1.3的质量比加入到搅拌罐中，随后在加入半导体二氧化锆(D50为10nm)，其与导电剂质量比为12％，随后为加入NMP溶剂，按照公知的配料工艺进行充分搅拌，过200目的筛网，配成正极浆料，正极浆料固含量为70％～75％。
2、正极涂布、制片：
将正极浆料采用涂布机涂敷在铝箔集流体上；在120℃温度下烘干，制备得到初始正极极片；按照实际需求对上述初始极片进行裁切，制备得到正极片。
3、负极浆料的制备：
以人造石墨作为负极活性材料、导电碳炭黑作为导电剂、丁苯橡胶作为粘结剂以及羧甲基纤维素钠作为增稠剂，按照96.9:1.5:1.3:1.3的质量比加入到搅拌罐中，加入 去离子水溶剂，按照现有技术的配料工艺进行充分搅拌，通过150目的筛网进行过滤，制备得到负极涂层浆料，负极浆料固含量为40％～45％。
4、负极涂布、制片：
利用涂布机将上述负极浆料涂覆铜箔集流体，在100℃温度下烘干，制备得到初始负极极片；按照实际需求对上述初始极片进行裁切，制备得到负极片。
5、锂离子电芯的制备
将正极片、负极片，中间夹隔膜进行卷绕制备得到锂离子电池卷芯，用铝塑膜包装，烘烤去除水分后注入电解液，采用热压化成工艺化成即可得到锂离子电芯；
其中，电解液的制备方法为：在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照质量比为EC：PC：EMC：DEC＝10:30:30:30进行混合均匀，接着加入2％的氟代碳酸乙烯酯和2％的1,3-丙烷磺内酯，溶解并充分搅拌后加入锂盐LiPF6，混合均匀后得到电解液。其中LiPF6的浓度为1mol/L。
实施例2
其与实施例1的不同之处在于：所采用的二氧化锆与导电剂的质量比为18％。
实施例3
其与实施例1的不同之处在于：所采用的二氧化锆与导电剂的质量比为22％。
实施例4
其与实施例1的不同之处在于：所采用的二氧化锆与导电剂的质量比为10％。
实施例5
其与实施例1的不同之处在于：所采用的二氧化锆与导电剂的质量比为30％。
实施例6
其与实施例1的不同之处在于：半导体二氧化锆的D50为1nm。
实施例7
其与实施例1的不同之处在于：半导体二氧化锆的D50为1μm。
实施例8
其与实施例1的不同之处在于：半导体二氧化锆的D50为0.5μm。
实施例9
其与实施例1的不同之处在于：所采用的半导体为SiC。
实施例10
其与实施例1的不同之处在于：所采用的半导体为Bi2Te3。
实施例11
其与实施例1的不同之处在于：所采用的半导体为Cr2O3。
对比例1
与实施例1的不同之处在于：不添加任何半导体材料。
正极片电阻测试
对各实施例和对比例制备的正极片和电芯进行电阻测试。
电阻测试方法：取极片，直接利用四探针测试仪(型号ST-2258C)进行电阻的测试。取电芯，直接利用负载仪(型号IT8551+)进行电阻的测试。
测试结果为如下：
表1-1.包含半导体材料的正极片电阻数据

注：初始状态为循环0～10T后的状态；初始状态、循环50T、循环100T的正极片为组装后的极片，即从电芯拆出的极片。
表1-2.包含半导体材料的正极片电阻数据
注：初始状态为循环0～10T后的状态；初始状态、循环50T、循环100T的正极片为组装后的极片，即从电芯拆出的极片；Y0即对比例1未组装状态下电阻值，Y1即对比例1初始状态电阻值。
表1-3.电芯电阻数据
注：上表测试数据是多极耳电芯结构的测试结果，如果是其它结构的电芯结构，具体的电阻值会不同，但电阻的比值近似；初始状态为循环0～10T后的状态。
锂离子电芯的性能测试
各实施例和对比例制备的锂离子电芯，在25℃、45℃下进行3C充电/0.7C放电，并在常温循环500T\800T下拆解电池，确认电池负极边缘析锂情况。拆解结果和循环数据如下：
表2.负极边缘析锂情况、容量保持率和膨胀数据

表3.负极边缘析锂情况、容量保持率和膨胀数据
从其实验结果可以看出采用本发明实施例1-11制备的锂离子电池可以有效解决 现有锂离子电池无法实现高低温兼顾的目的，并且可以充分解决其电池常温循环边缘析锂的问题。
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。

Claims (13)

  1. 一种正极片，其特征在于，所述正极片的正极活性物质层包括正极活性物质、导电剂、粘结剂和半导体材料。
  2. 根据权利要求1所述的正极片，其特征在于，所述半导体材料选自无机化合物半导体二元系、过渡金属元素的氧化物中的一种或两种。
  3. 根据权利要求2所述的正极片，其特征在于，所述无机化合物半导体二元系选自Ⅳ-Ⅳ族化合物半导体材料、Ⅴ-Ⅵ族化合物半导体材料中的一种或两种；
    作为优选，所述Ⅳ-Ⅳ族化合物半导体材料选自SiC、GeSi中的一种或两种；
    作为优选，所述Ⅴ-Ⅵ族化合物半导体材料选自Bi2Te3、Bi2Se3、Bi2S3、As2Te3中的一种或多种。
  4. 根据权利要求2所述的正极片，其特征在于，所述过渡金属元素的氧化物选自Zr、Cu、Zn、Sc、Ti、V、Cr、Mn、Fe、Co、Ni中的一种或多种的氧化物；
    作为优选，所述过渡金属元素的氧化物为ZrO2、Cr2O3中的一种或两种。
  5. 根据权利要求1-4中任一项所述的正极片，其特征在于，所述半导体材料的粒径D50为1～1000nm。
  6. 根据权利要求1-5中任一项所述的正极片，其特征在于，所述半导体材料的用量为导电剂用量的10wt％～30wt％。
  7. 根据权利要求1-6中任一项所述的正极片，其特征在于，所述正极活性物质、所述导电剂、所述粘结剂的质量比为(75～100):(0.5～15):(0.5～15)。
  8. 根据权利要求1-7中任一项所述的正极片，其特征在于，所述正极活性物质选自钴酸锂、镍钴锰、磷酸铁锂、镍钴铝、锰酸锂中的一种或多种；
    所述导电剂选自乙炔黑、导电炭黑、科琴黑、导电纤维、导电聚合物、碳纳米管、石墨烯、鳞片石墨、导电氧化物、金属颗粒中的一种或多种；
    所述粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯、聚六氟丙烯、丁苯橡胶中的一种或多种。
  9. 根据权利要求1-8中任一项所述的正极片，其特征在于，
    将包括半导体材料的正极片组装电芯，经过或未经过充放电循环后，在25℃条件 下测试正极片的电阻值；
    充放电循环0～10T后，包括半导体材料的正极片的电阻值记为X1；
    充放电循环50T后，包括半导体材料的正极片的电阻值记为X2；
    充放电循环100T后，包括半导体材料的正极片的电阻值记为X3；
    X1、X2、X3满足如下关系：
    1.12≤X2/X1≤1.25
    1.33≤X3/X1≤1.65。
  10. 根据权利要求1-9中任一项所述的正极片，其特征在于，所述导电剂在正极活性物质颗粒表面的分布面积大于半导体材料在正极活性物质颗粒表面的分布面积。
  11. 一种电芯，其特征在于，所述电芯包括权利要求1-10中任一项所述的正极片。
  12. 根据权利要求11所述的电芯，其特征在于，经过或未经过充放电循环后，在25℃条件下测试电芯的电阻值；
    充放电循环0～10T后，电芯的电阻值记为A1；
    充放电循环50T后，电芯的电阻值记为A2；
    充放电循环100T后，电芯的电阻值记为A3；
    A1、A2、A3满足如下关系：
    1.08≤A2/A1≤1.17
    1.16≤A3/A1≤1.29。
  13. 一种电池，其特征在于，所述电池包括权利要求1-10中任一项所述的正极片和/或权利要求11-12中任一项所述的电芯。
PCT/CN2023/106145 2022-09-13 2023-07-06 正极片、电芯和电池 WO2024055730A1 (zh)

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