WO2023098646A1 - Séparateur et batterie le comprenant - Google Patents

Séparateur et batterie le comprenant Download PDF

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Publication number
WO2023098646A1
WO2023098646A1 PCT/CN2022/134907 CN2022134907W WO2023098646A1 WO 2023098646 A1 WO2023098646 A1 WO 2023098646A1 CN 2022134907 W CN2022134907 W CN 2022134907W WO 2023098646 A1 WO2023098646 A1 WO 2023098646A1
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WO
WIPO (PCT)
Prior art keywords
polymer
battery
separator
layer
heat
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Application number
PCT/CN2022/134907
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English (en)
Chinese (zh)
Inventor
张祖来
李素丽
艾新平
李俊义
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珠海冠宇电池股份有限公司
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Application filed by 珠海冠宇电池股份有限公司 filed Critical 珠海冠宇电池股份有限公司
Publication of WO2023098646A1 publication Critical patent/WO2023098646A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the disclosure belongs to the technical field of batteries, and relates to a diaphragm and a battery containing the diaphragm, in particular to a high-safety diaphragm and a battery containing the diaphragm.
  • batteries have been widely used in smartphones, tablet computers, smart wearables, power tools, and electric vehicles.
  • consumers' demands on battery life and application environment continue to increase, which requires batteries to have a long cycle life while taking into account high safety performance.
  • the purpose of this disclosure is to solve the problems of potential safety hazards in the use of existing batteries, and the inability to balance battery energy density and safety performance, and provide a separator and a battery containing the separator, and the battery can take into account high energy density. and high security.
  • a diaphragm the diaphragm includes a substrate, a heat-resistant layer and a polymer layer, the heat-resistant layer is arranged on the first surface of the substrate, the polymer layer is arranged on the substrate and the polymer layer on the second surface opposite to the first surface and/or on the surface of the heat-resistant layer;
  • the polymer layer includes a first polymer and a second polymer
  • the melting point of the first polymer is 100°C to 130°C;
  • the second polymer is selected from polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer (such as polyvinylidene fluoride-hexafluoropropylene copolymer), polyimide, polyacrylonitrile , polymethyl methacrylate, at least one of aramid resin and polyacrylic acid.
  • polyvinylidene fluoride-hexafluoropropylene copolymer refers to hexafluoropropylene-modified polyvinylidene fluoride.
  • the particle size of the first polymer is 0.1 ⁇ m ⁇ 10 ⁇ m.
  • the first polymer is at least one selected from polyethylene, polymethacrylic acid, polymethacrylate and polypropylene.
  • the polymethacrylate in the first polymer can be selected from polyalkylmethacrylate, such as polymethacrylate C 1-10 alkylester, exemplarily polymethylmethacrylate At least one of methyl acrylate, polyethyl methacrylate, poly-n-propyl methacrylate and polyisopropyl methacrylate.
  • polyalkylmethacrylate such as polymethacrylate C 1-10 alkylester
  • polymethylmethacrylate At least one of methyl acrylate, polyethyl methacrylate, poly-n-propyl methacrylate and polyisopropyl methacrylate.
  • the first polymer is selected from polyethylene, and the second polymer is selected from polyvinylidene fluoride-hexafluoropropylene copolymer; or, the first polymer is selected from polyethylene, and the The second polymer is selected from polymethyl methacrylate; or, the first polymer is selected from polypropylene, and the second polymer is selected from polyvinylidene fluoride-hexafluoropropylene copolymer; or, the first polymer is selected from polyvinylidene fluoride-hexafluoropropylene copolymer; A polymer is selected from polypropylene, and the second polymer is selected from polymethyl methacrylate; or, the first polymer is selected from polymethacrylic acid, and the second polymer is selected from polymethacrylic acid methyl ester; or, the first polymer is selected from polyethyl methacrylate, and the second polymer is selected from polyvinylidene fluoride-hexaflu
  • the number average molecular weight of the first polymer is 50,000 Da to 500,000 Da.
  • the number average molecular weight of the second polymer is 100,000 Da to 1,500,000 Da.
  • the mass percentage of the first polymer in the entire polymer layer is 10%-90%, such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% % or 90%.
  • the mass percentage of the second polymer in the entire polymer layer is 10%-90%, such as 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% % or 90%.
  • both the first polymer and the second polymer can be prepared by methods known in the art, or purchased from commercial channels.
  • the thickness of the polymer layer is 0.5 ⁇ m ⁇ 10 ⁇ m, such as 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m or 10 ⁇ m.
  • the heat-resistant layer includes ceramic and adhesive.
  • the mass of ceramics in the heat-resistant layer accounts for 20-99wt.% of the total mass of the heat-resistant layer, for example 20wt.%, 30wt.%, 40wt.%, 60wt.%, 80wt.%, 90wt.%, 95wt.%, 99wt.%, or any value within the range of the aforementioned pairwise values.
  • the mass of the binder in the heat-resistant layer accounts for 1 to 80wt.% of the total mass of the heat-resistant layer, exemplarily 1wt.%, 5wt.%, 10wt.%, 20wt.%, 30wt.%. %, 50wt.%, 60wt.%, 80wt.%, or any value within the range of the aforementioned pairwise values.
  • the ceramic in the heat-resistant layer is selected from one, two or more of alumina, boehmite, magnesium oxide, boron nitride and magnesium hydroxide.
  • the binder in the heat-resistant layer is selected from polytetrafluoroethylene, polyvinylidene fluoride, hexafluoropropylene-vinylidene fluoride copolymer (such as polyvinylidene fluoride-hexafluoropropylene copolymer) , polyimide, polyacrylonitrile and polymethyl methacrylate, two or more.
  • the solvent used to prepare the heat-resistant layer and the polymer layer is selected from acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone, cyclohexane , methanol, ethanol, isopropanol and water.
  • the air permeability value of the membrane after baking in an oven at 130°C for 10 minutes is more than 10 times higher than that before baking;
  • the air permeability increase value of the separator covered with the polymer layer of the first polymer baked in an oven at 130° C. for 10 minutes is more than 100 times higher.
  • the heat-resistant layer has a thickness of 0.5 ⁇ m ⁇ 5 ⁇ m, such as 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m or 5 ⁇ m.
  • the substrate has a thickness of 3 ⁇ m ⁇ 20 ⁇ m, such as 3 ⁇ m, 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 15 ⁇ m, 18 ⁇ m or 20 ⁇ m.
  • the substrate is selected from polyethylene, polypropylene, polyethylene and polypropylene composites, polyamide, polyethylene terephthalate, polybutylene terephthalate, polystyrene, at least one of polyparaphenylene.
  • the present disclosure also provides a battery including the above separator.
  • the battery further includes a positive electrode sheet, a negative electrode sheet, and the separator is placed between the positive electrode sheet and the negative electrode sheet.
  • the first surface of the substrate is close to the negative electrode sheet, and the second surface of the substrate opposite to the first surface is close to the positive electrode sheet.
  • the polymer layer of the separator is adjacent to the negative electrode sheet.
  • the inventors of the present invention have found that when the polymer layer of the separator is close to the negative electrode sheet, the cycle performance of the battery is further improved, which may be due to the fact that the polymer layer of the separator is easily separated from the The electrolyte solution swells, and the adhesion between the swollen polymer layer and the surface of the negative electrode is significantly enhanced, and the adhesion may come from van der Waals force, hydrogen bond and anchor effect.
  • the adhesive force between the polymer layer on the surface of the separator and the surface of the negative electrode can be 0.5N/m-20N/m, such as 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 , 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20N/m.
  • the adhesive force between the polymer layer on the surface of the separator and the surface of the negative electrode is 1N/m ⁇ 10N/m.
  • the adhesive force between the polymer layer on the surface of the separator and the surface of the negative electrode is 1.2N/m ⁇ 8N/m.
  • the battery further includes a non-aqueous electrolyte, and the non-aqueous electrolyte includes a non-aqueous organic solvent.
  • the battery is, for example, a Li-ion battery.
  • the non-aqueous electrolytic solution further includes a lithium salt.
  • the lithium salt is selected from at least one of lithium bistrifluoromethylsulfonylimide, lithium bisfluorosulfonylimide and lithium hexafluorophosphate, and the lithium salt accounts for the total mass of the non-aqueous electrolyte 13 ⁇ 20wt.% of.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material, a conductive agent and a binder. agent;
  • the positive electrode active material is selected from lithium cobalt oxide or lithium cobalt oxide that has been doped and coated with two or more elements in Al, Mg, Mn, Cr, Ti, and Zr. , Ti, Zr with two or more elements doped and coated with lithium cobalt oxide, the chemical formula is Li x Co 1-y1-y2-y3-y4 A y1 B y2 C y3 D y4 O 2 ; 0.95 ⁇ x ⁇ 1.05, 0.01 ⁇ y1 ⁇ 0.1, 0.01 ⁇ y2 ⁇ 0.1, 0 ⁇ y3 ⁇ 0.1, 0 ⁇ y4 ⁇ 0.1, A, B, C, D are selected from two or more of Al, Mg, Mn, Cr, Ti, Zr Various elements.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material, a conductive agent and a binding agent. agent;
  • the negative electrode active material is selected from graphite or graphite composite material containing 1-15wt% SiOx /C or Si/C.
  • the present disclosure provides a separator and a battery including the separator, and the battery can have both high energy density and high safety.
  • the prepared battery can effectively improve the safety performance of the battery while taking into account the energy density of the battery.
  • the present application adds a first polymer to the polymer layer, and the melting point of the first polymer is between 100°C and 130°C.
  • the introduction of the first polymer can make the membrane close before 130°C. , to isolate the shuttle of lithium ions between the positive and negative electrodes inside the battery to achieve the purpose of improving safety, and because the melting point of the polymer is above 100°C, it will not melt during the cell preparation process and affect the normal charge and discharge performance of the battery; at the same time , adding a second polymer to the polymer layer can improve the interfacial stability between the separator and the pole piece, and ensure that the battery has good cycle performance; by using the synergistic effect of the first polymer and the second polymer, the preparation
  • the high-quality battery takes into account safety and cycle performance at the same time.
  • the particle size of the first polymer is between 0.1 ⁇ m and 10 ⁇ m, by blending with the second polymer, the thickness of the separator will not be additionally increased, which ensures the energy density of the
  • the lithium-ion batteries of Comparative Examples 1-4 and Examples 1-8 were all prepared according to the following preparation methods, the only difference being that the composition of the polymer layer on the surface of the separator (the first polymer and the second polymer) was different, the specific difference As shown in Table 1, among them, in Comparative Examples 1-4 and Examples 1-8, the swelling degree of the first polymer is ⁇ 5%.
  • the positive electrode active material LiCoO 2 LiCoO 2
  • the binder polyvinylidene fluoride (PVDF) the binder polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the positive electrode slurry is evenly coated on an aluminum foil with a thickness of 10 ⁇ m; after the above-mentioned coated aluminum foil is baked in an oven with 5 different temperature gradients, Dry in an oven at 120° C. for 8 hours, and then roll and cut to obtain the desired positive electrode sheet.
  • a 1% sodium carboxymethylcellulose (CMC) binder and a 1.8% styrene-butadiene rubber (SBR) binder are made into a slurry by a wet process and coated on the negative electrode current collector copper foil The surface was dried (temperature: 85° C., time: 5 h), rolled and die-cut to obtain the negative electrode sheet.
  • Polyethylene with a particle size of 1 ⁇ m, a melting point of 115° C., and a molecular weight of 300,000 Da was selected as the first polymer, and polyvinylidene fluoride-hexafluoropropylene copolymer was selected as the second polymer.
  • the polyethylene particles and the polyvinylidene fluoride-hexafluoropropylene copolymer particles were respectively dispersed in the aqueous solution and mixed to obtain a dispersion liquid M including the first polymer and the second polymer.
  • the surface of one side of the polyethylene substrate with a thickness of 5 ⁇ m is coated with an aluminum oxide layer with a thickness of 2 ⁇ m (the composition is 92wt% aluminum oxide, 4wt% methacrylic acid, 4wt% polymethylcellulose sodium ), the surface of the other side of the polyethylene substrate and the surface of the aluminum oxide layer are each coated with a polymer layer with a thickness of 2 ⁇ m.
  • the dispersion M is coated with a thickness of A 5 ⁇ m polyethylene substrate and a 2 ⁇ m thick aluminum oxide layer on both sides were dried to obtain a separator with a 2 ⁇ m thick polymer layer on both sides.
  • the positive electrode sheet, separator, and negative electrode sheet prepared above were wound to obtain a bare battery without liquid injection (wherein the first surface of the polyethylene base material was close to the negative electrode sheet side, and the second surface of the polyethylene base material opposite to the first surface The two surfaces are close to the side of the positive electrode sheet); the bare cell is placed in the outer packaging foil, the above-mentioned prepared electrolyte is injected into the dried bare cell, and it is subjected to vacuum packaging, standing, formation, shaping, sorting and other processes , to obtain the desired Li-ion battery.
  • Electrochemical performance test is carried out to the battery obtained in the above-mentioned comparative examples and examples, and the relevant instructions are as follows:
  • the air permeability value of the diaphragm obtained in the above examples and comparative examples which is the air permeability value G0 of the diaphragm before baking, and then place the diaphragm in an oven at a temperature of 130°C ⁇ 2°C for 10 minutes, take out the diaphragm and test the air permeability value of the diaphragm, which is After baking, the air permeability value of the diaphragm is G1.
  • the test method of the air permeability value refers to the national standard GB/T 36363-20183.2 air permeability test.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Separators (AREA)

Abstract

La présente divulgation concerne un séparateur et une batterie le comprenant. La batterie peut présenter à la fois une densité d'énergie élevée et une sécurité élevée. Selon la présente divulgation, une conception raisonnée de la composition de deux polymères dans une couche de polymère dans le séparateur de batterie permet à la batterie préparée d'améliorer efficacement les performances de sécurité de la batterie tout en tenant compte de la densité d'énergie de la batterie. En particulier, selon la présente demande, un premier polymère est ajouté à la couche de polymère, le point de fusion du premier polymère étant de 100 °C à 130 °C, l'introduction du premier polymère pouvant permettre au séparateur d'obtenir une fermeture de pore avant que la température atteigne 130 °C pour isoler le transfert d'ions lithium entre des électrodes positive et négative dans la batterie, permettant ainsi d'améliorer la sécurité ; de plus, la taille de particule du premier polymère étant de 0,1 µm à 10 µm, le mélange du premier polymère avec le second polymère n'augmente pas davantage l'épaisseur du séparateur, permettant ainsi d'assurer la densité d'énergie de la batterie.
PCT/CN2022/134907 2021-11-30 2022-11-29 Séparateur et batterie le comprenant WO2023098646A1 (fr)

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CN202111442799.6 2021-11-30
CN202111442799.6A CN114156599A (zh) 2021-11-30 2021-11-30 一种隔膜及含有所述隔膜的电池

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Publication number Priority date Publication date Assignee Title
CN114156599A (zh) * 2021-11-30 2022-03-08 珠海冠宇电池股份有限公司 一种隔膜及含有所述隔膜的电池

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CN102522516A (zh) * 2011-12-22 2012-06-27 中国科学院青岛生物能源与过程研究所 锂离子二次电池用不对称复合隔膜及其制备方法
CN109841783A (zh) * 2017-11-28 2019-06-04 宁德时代新能源科技股份有限公司 锂离子电池及其隔离膜
CN110729440A (zh) * 2019-09-29 2020-01-24 深圳中兴新材技术股份有限公司 一种锂离子电池涂层隔膜、制备方法及锂离子电池
US20200185676A1 (en) * 2018-01-30 2020-06-11 Lg Chem, Ltd. Separator for electrochemical device and method for manufacturing the same
CN114156599A (zh) * 2021-11-30 2022-03-08 珠海冠宇电池股份有限公司 一种隔膜及含有所述隔膜的电池

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CN103928649B (zh) * 2014-04-10 2016-08-24 佛山市金辉高科光电材料有限公司 一种改性无纺布锂离子电池隔膜及其制备方法
CN106784539A (zh) * 2017-01-24 2017-05-31 厦门大学 一种无纺布陶瓷隔膜及其制备方法和应用

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102522516A (zh) * 2011-12-22 2012-06-27 中国科学院青岛生物能源与过程研究所 锂离子二次电池用不对称复合隔膜及其制备方法
CN109841783A (zh) * 2017-11-28 2019-06-04 宁德时代新能源科技股份有限公司 锂离子电池及其隔离膜
US20200185676A1 (en) * 2018-01-30 2020-06-11 Lg Chem, Ltd. Separator for electrochemical device and method for manufacturing the same
CN110729440A (zh) * 2019-09-29 2020-01-24 深圳中兴新材技术股份有限公司 一种锂离子电池涂层隔膜、制备方法及锂离子电池
CN114156599A (zh) * 2021-11-30 2022-03-08 珠海冠宇电池股份有限公司 一种隔膜及含有所述隔膜的电池

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