WO2022160382A1 - 粘结剂、负极浆料、负极及锂离子电池 - Google Patents

粘结剂、负极浆料、负极及锂离子电池 Download PDF

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WO2022160382A1
WO2022160382A1 PCT/CN2021/076032 CN2021076032W WO2022160382A1 WO 2022160382 A1 WO2022160382 A1 WO 2022160382A1 CN 2021076032 W CN2021076032 W CN 2021076032W WO 2022160382 A1 WO2022160382 A1 WO 2022160382A1
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polymer
block
negative electrode
binder
polymerized
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PCT/CN2021/076032
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English (en)
French (fr)
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魏迪锋
李�昊
李若楠
孙化雨
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远景动力技术(江苏)有限公司
远景睿泰动力技术(上海)有限公司
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Priority to EP21921981.3A priority Critical patent/EP4287322A1/en
Priority to US18/009,989 priority patent/US20230231139A1/en
Priority to JP2022578862A priority patent/JP7497468B2/ja
Publication of WO2022160382A1 publication Critical patent/WO2022160382A1/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
    • H01M4/62—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, 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
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • Embodiments of the present invention relate to lithium ion batteries, and in particular, to a binder, a negative electrode slurry, a negative electrode and a lithium ion battery.
  • the negative electrode binder is one of the important auxiliary functional materials in the lithium ion battery, and it is the main source of the internal mechanical properties of the electrode.
  • the traditional negative electrode binders are mainly materials such as styrene-butadiene rubber, acrylic polymers or acrylate polymers. Although these materials have strong cohesive force and good electrochemical stability, their Non-conductive, it is easy to increase the internal impedance of the negative electrode, which in turn makes the fast charging performance of the lithium-ion battery worse.
  • the following two methods are mainly adopted in the prior art.
  • improve the affinity of the active material with the binder For example, the patent text with the authorization announcement number of JP5373388B2 describes a method for mechanochemical treatment of graphite particles, which makes the surface of graphite particles hydrophilic, uniform in particle size, reduced in average particle size, and wetted on the surface.
  • the improved properties and the increased affinity for water-based binders are beneficial to the improvement of the charging efficiency of lithium-ion batteries.
  • this method requires the use of special graphite particle processing equipment, the cost is high, and the same effect cannot be achieved for battery systems in which the negative electrode active material is not graphite (eg, silicon).
  • the patent text with the authorization announcement number CN105489898B describes a conductive aqueous binder that can improve the overall conductivity of the battery, which includes graphene, carbon nanotubes, cross-linked polymers and multivalent metal ions water-soluble salt solution , wherein, graphene and carbon nanotubes are respectively bonded with cross-linked polymer to form a three-dimensional conductive network structure, and the cross-linked polymer is cross-linked with multivalent metal ion water-soluble salt solution to form a three-dimensional bonding network structure.
  • the conductive water-based adhesive is mainly a combination of a variety of existing materials, its composition is complex, the cost of raw materials used for preparing the conductive water-based adhesive is relatively high, and it is difficult to popularize on a large scale, and the conductive water-based adhesive is used in There is an incompatibility problem when using a silicon system as a negative electrode.
  • the patent document with publication number CN108417836A describes an ABA-type triblock polymer electrode binder with polyacrylic blocks at both ends and polyacrylate blocks in the middle; Acrylic monomers and/or acrylic monomers are polymerized, and the polyacrylate blocks are polymerized from one or more of methyl acrylate, butyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.
  • the polyacrylate block has a certain swelling ability to the electrolyte and forms an ion-conducting channel
  • the ion-conducting ability of the binder can be improved to a certain extent, but the inventors found that because the ABA type triblock polymer electrode binder The modulus is too high, and the use of it alone will cause the rigidity of the pole piece to be too strong, causing the electrode material to fall off the foil.
  • the field still needs to find a negative electrode binder with strong ion conductivity, simple composition, low cost, suitable modulus, good thickening and dispersing effect, compatible with various negative electrode systems at the same time, and easy to scale promotion.
  • the purpose of the embodiments of the present invention is to provide a binder with strong ion-conducting ability, simple components, low cost, suitable modulus, and good thickening and dispersing effect, so that the lithium ion battery using the binder has better fast speed Charging capability, lower DC internal resistance and better low temperature discharge capability.
  • an embodiment of the present invention provides a binder, the binder includes a first block polymer and a second block polymer;
  • the first block polymer is a lithiated tetra-block polymer, and the tetra-block polymer has a structure represented by B-C-B-A, wherein A represents polymer block A, B represents polymer block B, C represents the polymer block C;
  • the polymer block A is polymerized from alkenyl formic acid monomer
  • the polymer block B is polymerized from aromatic vinyl monomers
  • the polymer block C is polymerized from acrylate monomers
  • the second block polymer is a lithiated triblock polymer, and the triblock polymer has a structure represented by E-F-E, wherein E represents polymer block E, and F represents polymer block F;
  • the polymer block E is polymerized from alkenyl formic acid monomer
  • the polymer block F is polymerized from acrylate monomers.
  • the structure of the alkenyl carboxylic acid monomer in the four-block polymer is wherein, R 11 and R 12 are independently hydrogen or C 1-4 alkyl, and the C 1-4 alkyl is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; preferably, the alkenyl formic acid is acrylic acid.
  • the structure of the aromatic vinyl monomer in the four-block polymer is wherein, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 are independently hydrogen or C 1-4 alkyl group, and the C 1-4 alkyl group is selected from methyl, ethyl, n-propyl , isopropyl, n-butyl, isobutyl or tert-butyl; preferably, R 21 , R 22 , R 23 , R 24 , R 25 , R 26 are hydrogen or methyl, more preferably, the aromatic Ethylene is styrene.
  • the structure of the acrylate monomer in the four-block polymer is wherein, R 31 is a straight-chain or branched-chain C 1-10 alkyl; more preferably, R 31 is a straight-chain or branched-chain C 4-8 alkyl, further preferably, R 31 is
  • the first block polymer has the structure represented by the general formula (I);
  • R 41 is C 4-8 alkyl; preferably, R 41 is
  • R 42 and R 43 are phenyl or C 1-4 alkyl substituted phenyl, and the C 1-4 alkyl phenyl is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl , isobutyl or tert-butyl substituted phenyl; preferably, R 42 and R 43 are phenyl.
  • the first block polymer is wherein, n is 10-50; x is 200-500; y is 400-1000; z is 200-500.
  • the alkenyl formic acid in the triblock polymer is wherein, R 51 and R 52 are independently hydrogen or C 1-4 alkyl group, and the C 1-4 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; preferably, the alkenyl formic acid is acrylic acid.
  • the acrylate in the triblock polymer is wherein, R 61 is a C 1-4 alkyl group, and the C 1-4 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl; preferably , the acrylate is methyl acrylate.
  • the degree of polymerization of the polymer block E is 70-700
  • the degree of polymerization of the polymer block F is 70-700
  • the second block polymer has the structure represented by the general formula (II);
  • k is 70 ⁇ 700
  • l is 70 ⁇ 700
  • m is 70 ⁇ 700
  • the mass ratio of the first block polymer to the second block polymer is 99:1-1:99; more preferably 9:1-1:9, for example: 9:1 , 8:2, 7:3, 6:4, 5:5, 4:6, 7:3, 8:2, 1:9.
  • the mass ratio of the first block polymer and the second block polymer is 9:1.
  • a second aspect of the present invention provides a negative electrode slurry for a lithium ion battery, the negative electrode slurry comprising a negative electrode active material, a conductive agent, and the binder described in the first aspect of the present invention.
  • a third aspect of the present invention further provides a lithium ion battery negative electrode comprising the above-mentioned negative electrode slurry, the negative electrode comprises a current collector and a negative electrode active material layer covering the current collector, and the negative electrode active material layer is composed of the negative electrode slurry The material is coated on the current collector to form.
  • the negative electrode active material of the negative electrode of the present invention is a material that can intercalate and deintercalate lithium. Including but not limited to, crystalline carbon (natural graphite and artificial graphite, etc.), amorphous carbon, carbon-coated graphite and resin-coated graphite and other carbon materials, indium oxide, silicon oxide, tin oxide, lithium titanate, zinc oxide and oxide Lithium and other oxide materials.
  • the negative electrode active material may also be lithium metal or a metal material that can form an alloy with lithium. Specific examples of metals that can be alloyed with lithium include Cu, Sn, Si, Co, Mn, Fe, Sb, and Ag. A binary or ternary alloy containing these metals and lithium can also be used as the negative electrode active material.
  • negative electrode active materials may be used alone or in combination of two or more.
  • a carbon material such as graphite and a Si-based active material such as Si, Si alloy, and Si oxide can be combined.
  • graphite and a Si-based active material may be combined.
  • the ratio of the mass of the Si-based active material to the total mass of the carbon material and the Si-based active material may be 0.5% or more and 95% or less, 1% or more and 50% or less, or 2% or more and 40% or less.
  • the negative electrode active material is dispersed in the above-described dense inter-crosslinked network structure.
  • the negative electrode active material includes graphite and/or a graphite-containing compound.
  • the conductive agent of the negative electrode of the present invention is a conductive material that does not cause chemical changes, and can be selected from natural graphite, artificial graphite, carbon black, acetylene black, carbon fiber, polyphenylene derivatives, including copper, nickel, aluminum, silver At least one of metal powder and metal fiber.
  • the current collector of the negative electrode of the present invention can be at least one selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, and conductive metal-coated polymer materials.
  • a fourth aspect of the present invention provides a lithium ion battery, the lithium ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode is the negative electrode provided in the fourth aspect of the present invention.
  • the positive electrode of the lithium ion battery of the present invention includes a positive electrode active material, and the positive electrode active material may be a lithium-containing composite oxide.
  • the lithium-containing composite oxide include LiMnO 2 , LiFeO 2 , LiMn 2 O 4 , Li 2 FeSiO 4 LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiNi 5 CO 2 Mn 3 O 2 , Li z Ni (1-xy) Co x My O 2 (x, y , and z are values satisfying 0.01 ⁇ x ⁇ 0.20, 0 ⁇ y ⁇ 0.20, and 0.97 ⁇ z ⁇ 1.20, and M is selected from Mn , at least one element of V, Mg, Mo, Nb and Al), LiFePO 4 and Li z CO (1-x) M x O 2 (x and z satisfy 0 ⁇ x ⁇ 0.1 and 0.97 ⁇ z ⁇ 1.20 where M represents at least one element selected from the group consisting of Mn, Ni, V, Mg, Mo, Nb and Al).
  • the positive electrode active material may also be Li z Ni (1-xy) Co x My O 2 (x, y and z are values satisfying 0.01 ⁇ x ⁇ 0.15, 0 ⁇ y ⁇ 0.15 and 0.97 ⁇ z ⁇ 1.20, and M represents At least one element selected from Mn, Ni, V, Mg, Mo, Nb and Al) or Li z CO (1-x) M x O 2 (x and z satisfy 0 ⁇ x ⁇ 0.1 and 0.97 ⁇ z A numerical value of ⁇ 1.20, M represents at least one element selected from the group consisting of Mn, V, Mg, Mo, Nb and Al).
  • the positive electrode active material is NCM523.
  • the separator of the lithium ion battery of the present invention is not particularly limited, and a single-layer or laminated microporous film, woven fabric, or non-woven fabric of polyolefin such as polypropylene and polyethylene can be used.
  • non-aqueous electrolyte of the lithium ion battery of the present invention there is no particular limitation, and electrolyte formulations commonly used in the art can be used, which will not be described in detail here.
  • the reagents and raw materials used in the present invention are all commercially available.
  • the embodiments of the present invention have at least the following advantages:
  • the binder provided by the first aspect of the present invention has better ion-conducting ability, which helps to reduce the internal resistance of the electrode.
  • the adhesive provided by the first aspect of the present invention has better cohesiveness and better dispersion and thickening effect, and has a suitable modulus.
  • the prepared lithium ion battery has better fast charging capability, lower DC internal resistance and better low temperature discharge capability.
  • Step 3 Preparation of Polyacrylic Acid-Styrene-Isooctyl Acrylate (PAA-PSt-PEHA)
  • Step 4 Preparation of Polyacrylic Acid-Styrene-Isooctyl Acrylate-Styrene (PAA-PSt-PEHA-PSt)
  • Step 5 Preparation of lithiated polyacrylic acid-styrene-isooctyl acrylate-styrene (PAA-PSt-PEHA-PSt)
  • PAA-PSt-PEHA-PSt polyacrylic acid-styrene-iso-octyl acrylate-styrene
  • step 4 15-25g mass fraction of lithium hydroxide solution (containing hydroxide Lithium 0.75-3.75 g), stirring and reacting at a rotational speed of 300 rpm/h for 60 minutes to obtain the lithiated polyacrylic acid-styrene-isooctyl acrylate-styrene (PAA-PSt-PEHA-PSt).
  • RAFT reagent 0.6 parts of RAFT reagent, 0.2 parts of initiator and 20 parts of acrylic monomers were in 150 parts of deionized water solvent, and stirred and reacted at 70° C. for 18 hours to obtain a reaction mixture containing the compound of formula (1′); wherein, RAFT The reagent is Wherein, R is acetate group; Z is benzyl; Initiator is potassium persulfate;
  • step 1 To the reaction mixture obtained in step 1, add 60 parts of methyl acrylate monomers, and then continue to stir for 6 hours at 70°C to obtain a reaction mixture containing the compound of formula (2');
  • Step 3 Preparation of polyacrylic acid-methyl acrylate-acrylic acid (PAA-PMA-PAA)
  • step 2 To the reaction mixture obtained in step 2, add 20 parts of acrylic monomers, and then continue stirring at 70 ° C for 18 hours to obtain a reaction mixture containing the compound of formula (3');
  • Step 4 Preparation of lithiated polyacrylic acid-methyl acrylate-acrylic acid (PAALi-PMA-PAALi)
  • step 3 Adjust the pH of the reaction mixture obtained in step 3 to 5, then add a 10% mass fraction of lithium hydroxide aqueous solution, and carry out lithiation at 25° C. for 4 hours;
  • PAALi-PSt-PEHA-PSt lithiated polyacrylic acid-styrene-acrylic isooctanoate-styrene
  • PAALi-PSt lithiated polyacrylic acid-methyl acrylate-acrylic acid
  • PMA-PAALi was stirred and mixed at a mass ratio of 9:1, the stirring speed was 200 rpm, the temperature was 30° C., and the time was 2 hours.
  • the cathode active material NCM523, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 96:2:2, and then dispersed in N-methyl-2-pyrrolidone (NMP)
  • NMP N-methyl-2-pyrrolidone
  • the positive electrode slurry was obtained, and the obtained positive electrode slurry was obtained.
  • the slurry is uniformly coated on both sides of the aluminum foil, dried, calendered and dried in a vacuum at 80°, and then welded with an aluminum lead wire with an ultrasonic welder to obtain a positive plate with a thickness of 120-150 ⁇ m.
  • Example 3 Mix the composite negative electrode active material graphite, conductive carbon black Super-P, and the binder prepared in Example 3 in a mass ratio of 95:2:3, and then disperse them in deionized water to obtain a negative electrode slurry. Coating the slurry on both sides of the copper foil, drying, calendering and vacuum drying, and welding nickel lead wires with an ultrasonic welder to obtain a negative electrode plate with a thickness of 80-100 ⁇ m.
  • a separator with a thickness of 20 ⁇ m is placed between the positive plate and the negative plate, and then the sandwich structure composed of the positive plate, the negative plate and the separator is wound, and the rolled body is flattened and placed in an aluminum foil packaging bag. Vacuum bake for 48h to obtain the cell to be injected.
  • the electrolyte was injected into the cells in the glove box, sealed in vacuum, and kept at rest for 24 h. Then, the routine formation of the first charging is carried out according to the following steps: 0.02C constant current charging to 3.05V, 0.05C constant current charging to 3.75V, 0.2C constant current charging to 4.05V, and vacuum sealing. Then, it was further charged to 4.2V with a constant current of 0.33C, and after being left at room temperature for 24 hours, it was discharged to 3.0V with a constant current of 0.2C.
  • lithium ion batteries were prepared according to the same method as Example 12, except that in the preparation of the negative pole pieces, the binders used were the binders prepared in Examples 3 to 11, respectively. .
  • the cathode active material NCM523, conductive carbon black Super-P, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 96:2:2, and then dispersed in N-methyl-2-pyrrolidone (NMP)
  • NMP N-methyl-2-pyrrolidone
  • the positive electrode slurry was obtained, and the obtained positive electrode slurry was obtained.
  • the slurry is uniformly coated on both sides of the aluminum foil, dried, calendered and dried in a vacuum at 80°, and then welded with an aluminum lead wire with an ultrasonic welder to obtain a positive plate with a thickness of 120-150 ⁇ m.
  • a separator with a thickness of 20 ⁇ m is placed between the positive plate and the negative plate, and then the sandwich structure composed of the positive plate, the negative plate and the separator is wound, and the rolled body is flattened and placed in an aluminum foil packaging bag. Vacuum bake for 48h to obtain the cell to be injected.
  • the electrolyte was injected into the cells in the glove box, sealed in vacuum, and kept at rest for 24 h. Then, the routine formation of the first charging is carried out according to the following steps: 0.02C constant current charging to 3.05V, 0.05C constant current charging to 3.75V, 0.2C constant current charging to 4.05V, and vacuum sealing. Then, it was further charged to 4.2V with a constant current of 0.33C, and after being left at room temperature for 24 hours, it was discharged to 3.0V with a constant current of 0.2C.
  • Comparative Example 2 A lithium ion battery was prepared in the same manner as in Comparative Example 1, except that in the preparation of the negative pole piece, the binder used was SBR binder.
  • Comparative Example 3 The lithium ion battery was prepared in the same way as in Comparative Example 1, except that in the preparation of the negative pole piece, the binder used was only lithiated polyacrylic acid-styrene-acrylic isooctanoate-styrene (PAALi- -PSt-PEHA-PSt).
  • PAALi- -PSt-PEHA-PSt lithiated polyacrylic acid-styrene-acrylic isooctanoate-styrene
  • Comparative Example 4 A lithium ion battery was prepared in the same manner as in Comparative Example 1, except that in the preparation of the negative electrode, the binder used was only lithiated polyacrylic acid-methyl acrylate-acrylic acid (PAALi-PMA-PAALi).
  • the preparation process of the adhesive film prepared in Example 3 is as follows: pour 1.2 g of the adhesive into a 10cm diameter polytetrafluoroethylene watch glass, cover with a layer of filter paper, press the filter paper, put In a fume hood, the samples were air-dried in convection at room temperature for a week, and then placed in a vacuum oven at 60 °C for 12 h to complete the sample preparation.
  • the quantity of each polymer spline is 5.
  • the tensile test was carried out using a universal material testing machine. Test conditions: a force sensor with a range of 50 N was used, and the tensile rate was 1 mm/min. Each polymer sample was subjected to 5 parallel tests and the average value was obtained. The results are shown in Table 2.
  • Binders PAA binders, SBR binders, lithiated polyacrylic acid-styrene-acrylic isooctanoate-styrene (PAALi--PSt-PEHA-PSt) and lithiated prepared in Examples 4-11
  • PAALi-PMA-PAALi Polyacrylic acid-methyl acrylate-acrylic acid
  • the lithium-ion batteries prepared in the examples and comparative examples were subjected to a constant current charge test at a rate of 2C, and the rate charge capacity retention rate was calculated. Discharged capacity/battery discharge capacity after charging at a rate of 1/3C). The results obtained are shown in Table 3.
  • SOC charge level

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Abstract

本申请公开了一种粘结剂、负极浆料、负极及锂离子电池。本申请中，粘结剂包括第一嵌段聚合物和第二嵌段聚合物；第一嵌段聚合物为锂化的四嵌段聚合物，其具有B-C-B-A所示的结构，其中，A表示聚合物嵌段A，B表示聚合物嵌段B，C表示聚合物嵌段C；聚合物嵌段A由烯基甲酸单体聚合而成；聚合物嵌段B由芳香基乙烯单体聚合而成；聚合物嵌段C由丙烯酸酯单体聚合而成；且第二嵌段聚合物为锂化的三嵌段聚合物，其具有E-F-E所示的结构，其中，E表示聚合物嵌段E，F表示聚合物嵌段F；聚合物嵌段E由烯基甲酸单体聚合而成；聚合物嵌段F由丙烯酸酯单体聚合而成。本申请提供的粘结剂，导离子能力强，成分简单，成本低廉，具有合适的模量，增稠分散效果。

Description

粘结剂、负极浆料、负极及锂离子电池
相关申请交叉引用
本专利申请要求于2021年01月28日提交的、申请号为2021101172950、发明名称为“粘结剂、负极浆料、负极及锂离子电池”的中国专利申请的优先权，上述申请的全文以引用的方式并入本文中。
技术领域
本发明实施例涉及锂离子电池，特别涉及粘结剂、负极浆料、负极及锂离子电池。
背景技术
负极粘结剂是锂离子电池中重要的辅助功能材料之一，是电极内部力学性能主要的来源，其主要作用是将活性物质与活性物质，集流体与活性物质粘结在一起。传统的负极粘结剂主要是苯乙烯-丁二烯橡胶、丙烯酸聚合物或丙烯酸酯类聚合物等材料，这些材料具有虽具有较强的粘结力、较好的电化学稳定性，但是其不导电，容易造成负极内部阻抗增加，进而使得锂离子电池的快速充电性能变差。
为解决上述问题，现有技术中主要采用以下两种方法。第一，提高活性材料与粘结剂的亲和性。例如：授权公告号为JP5373388B2的专利文本中记载了一种对石墨粒子进行机械化学处理的方法，该方法使得石墨粒子表面具有亲水性，且粒径均匀，平均粒径缩小，表面的润湿性得到改善，对水性粘结剂的亲和性增加，有利于锂离子电池充电效率的提升。但该方法需要使用特殊的石墨粒子处理设备，成本较高，并且对于负极活性材料非石墨(例如硅)的电池体系无法起到相同的效果。
第二，使用导离子能力更好的粘结剂替代传统的粘结剂。例如：授权公告号为CN105489898B的专利文本中记载了一种能提高电池整体导电率的导电水性粘结剂，其包括石墨烯、碳纳米管、交联聚合物以及多价金属离子水溶性盐溶液，其中，石墨烯与碳纳米管分别与交联聚合物通过化学键键合形成三维导电网络结构，交联聚合物与多价金属离子水溶性盐溶液交联形成三维粘结网络结构。但由于该导电水性粘结剂主要为多种现有材料的组合，其组成复杂，制备该导电水性粘结剂所用的原材料成本较高，难以大规模推广，且该导电水性粘结剂应用于硅体系负极时存在不兼容的问题。
公开号为CN108417836A的专利文本中记载了一种ABA型三嵌段聚合物电极粘结剂，两端为聚丙烯酸类嵌段，中间为聚丙烯酸酯类嵌段；聚丙烯酸类嵌段由甲基丙烯酸单体和/ 或丙烯酸单体聚合而成，聚丙烯酸酯类嵌段由丙烯酸甲酯、丙烯酸丁酯、丙烯酸羟乙酯、丙烯酸羟丙酯中的一种或几种聚合而成。由于聚丙烯酸酯嵌段对电解液有一定的溶胀能力，形成导离子通道，故可以一定程度提高粘结剂的导离子能力，但发明人发现由于该ABA型三嵌段聚合物电极粘结剂模量偏高，单独使用会造成极片刚性过强，导致电极物质从箔材上脱落。
因此，本领域尚需寻找一种导离子能力强，成分简单，成本低廉，具有合适的模量，增稠分散效果好，且同时兼容多种负极体系，易于规模推广的负极粘结剂。
发明内容
本发明实施方式的目的在于提供一种导离子能力强，成分简单，成本低廉，具有合适的模量，增稠分散效果好的粘结剂，使得使用了其的锂离子电池具有更优的快速充电能力，更低的直流内阻和更优的低温放电能力。
为解决上述技术问题，本发明的实施方式提供了一种粘结剂，所述粘结剂包括第一嵌段聚合物和第二嵌段聚合物；
所述第一嵌段聚合物为锂化的四嵌段聚合物，所述四嵌段聚合物具有B-C-B-A所示的结构，其中，A表示聚合物嵌段A，B表示聚合物嵌段B，C表示聚合物嵌段C；
所述聚合物嵌段A由烯基甲酸单体聚合而成；
所述聚合物嵌段B由芳香基乙烯单体聚合而成；
所述聚合物嵌段C由丙烯酸酯单体聚合而成；且
所述第二嵌段聚合物为锂化的三嵌段聚合物，所述三嵌段聚合物具有E-F-E所示的结构，其中，E表示聚合物嵌段E，F表示聚合物嵌段F；
所述聚合物嵌段E由烯基甲酸单体聚合而成；
所述聚合物嵌段F由丙烯酸酯单体聚合而成。
在一些优选的方案中，所述四嵌段聚合物中所述烯基甲酸单体的结构为
Figure PCTCN2021076032-appb-000001
其中，R 11、R 12独立地为氢或C 1～4烷基，所述C 1～4烷基选自甲基、乙基、正丙基、异丙基、正丁基、异丁基或叔丁基；优选地，所述烯基甲酸为丙烯酸。
在一些优选的方案中，所述四嵌段聚合物中所述芳香基乙烯单体结构为
Figure PCTCN2021076032-appb-000002
其中，R 21、R 22、R 23、R 24、R 25、R 26独立地为氢或C 1～4烷基，所述C 1～4烷基选自甲基、乙基、正丙基、异丙基、正丁基、异丁基或叔丁基；优选地，R 21、R 22、R 23、R 24、R 25、R 26为氢或甲基，更优选地，所述芳香基乙烯为苯乙烯。
在一些优选的方案中，所述四嵌段聚合物中所述丙烯酸酯单体的结构为
Figure PCTCN2021076032-appb-000003
其中，R 31为直链或含支链的C 1～10烷基；更优选地，R 31为直链或含支链的C 4～8烷基，进一步优选地，R 31为
Figure PCTCN2021076032-appb-000004
在一些优选的方案中，所述第一嵌段聚合物具有通式(Ⅰ)所示的结构；
Figure PCTCN2021076032-appb-000005
其中，n为10～50；x为200～500；y为400～1000；z为200～500；
R 41为C 4～8烷基；优选地，R 41为
Figure PCTCN2021076032-appb-000006
R 42和R 43为苯基或C 1～4烷基取代的苯基，所述C 1～4烷基的苯基选自甲基、乙基、正丙基、异丙基、正丁基、异丁基或叔丁基取代的苯基；优选地，R 42和R 43为苯基。
在一些优选的方案中，所述第一嵌段聚合物为
Figure PCTCN2021076032-appb-000007
其中，n为10～50；x为200～500；y为400～1000；z为200～500。
在一些优选的方案中，所述三嵌段聚合物中所述烯基甲酸为
Figure PCTCN2021076032-appb-000008
其中， R 51、R 52独立地为氢或C 1～4烷基，所述C 1～4烷基选自甲基、乙基、正丙基、异丙基、正丁基、异丁基或叔丁基；优选地，所述烯基甲酸为丙烯酸。
在一些优选的方案中，所述三嵌段聚合物中所述丙烯酸酯为
Figure PCTCN2021076032-appb-000009
其中，R 61为C 1～4烷基，所述C 1～4烷基选自甲基、乙基、正丙基、异丙基、正丁基、异丁基或叔丁基；优选地，所述丙烯酸酯为丙烯酸甲酯。
在一些优选的方案中，所述聚合物嵌段E的聚合度为70～700，所述聚合物嵌F的聚合度为70～700。
在一些优选的方案中，所述第二嵌段聚合物具有通式(Ⅱ)所示的结构；
Figure PCTCN2021076032-appb-000010
其中，k为70～700；l为70～700；m为70～700；
在一些优选的方案中，所述第一嵌段聚合物和第二嵌段聚合物的质量比为99:1～1:99；更优选为9:1～1:9，例如：9:1、8:2、7:3、6:4、5:5、4:6、7:3、8:2、1:9。
在一些更优选的方案中，所述第一嵌段聚合物和第二嵌段聚合物的质量比为9:1。
本发明第二方面提供了一种锂离子电池用负极浆料，所述负极浆料包括负极活性材料、导电剂以及本发明第一方面所述的粘结剂。
在一些优选的方案中，所述负极活性材料、导电剂以及粘结剂的质量比为a:b:c，其中，a为93～97；b为3～5；c为3～5，且a+b+c＝100。例如：95:2:3。
本发明第三方面还提供了一种包括上述负极浆料的锂离子电池负极，所述负极包括集流体以及覆于所述集流体上的负极活性材料层，所述负极活性材料层由负极浆料涂覆于所述集流体上形成。
作为本发明的负极的负极活性材料，为可嵌入、脱嵌锂的材料。包括但不限于，结晶碳(天然石墨及人造石墨等)、无定形碳、碳涂层石墨及树脂涂层石墨等碳材料、氧化铟、氧化硅、氧化锡、钛酸锂、氧化锌及氧化锂等氧化物材料。负极活性材料也可以为锂金属或者可与锂形成合金的金属材料。可与锂形成合金的金属的具体例包含Cu、Sn、Si、Co、Mn、Fe、Sb及Ag。也可以使用含有这些金属与锂的二元或三元的合金作为负极活性材料。这些负极活性材料可以单独使用，也可以组合使用两种以上。从高能量密度化的角度出发，作为所述负极活性材料，可组合石墨等碳材料与Si、Si合金、Si氧化物等Si系的活性材料。从兼顾 循环特性与高能量密度化的角度出发，作为所述负极活性材料，可组合石墨与Si系的活性材料。关于所述组合，Si系的活性材料的质量相对于碳材料与Si系的活性材料的合计质量的比可以为0.5％以上95％以下，1％以上50％以下，或2％以上40％以下。各个实施方式中，负极活性材料在上述致密的互相交联的网络结构中分散。
优选地，所述负极活性材料包括石墨和/或含石墨的化合物。
作为本发明的负极的导电剂，为不引起化学变化的导电材料，可选自天然石墨、人造石墨、炭黑、乙炔黑、碳纤维、聚亚苯基衍生物、包含铜、镍、铝、银的金属粉末及金属纤维中的至少一种。
作为本发明的负极的集流体，可选自铜箔、镍箔、不锈钢箔、钛箔、镍泡沫体、铜泡沫体及涂布有导电金属的聚合物材料中的至少一种。
本发明第四方面提供了一种锂离子电池，所述锂离子电池包括正极、负极、隔膜以及电解液，其中，所述负极为本发明第四方面提供的负极。
作为本发明的锂离子电池的正极，包括正极活性材料，正极活性材料可以为含锂的复合氧化物。作为含锂的复合氧化物的具体例子，可列举如LiMnO 2、LiFeO 2、LiMn 2O 4、Li 2FeSiO 4LiNi 1/3Co 1/3Mn 1/3O 2、LiNi 5CO 2Mn 3O 2、Li zNi (1-x-y)Co xM yO 2(x、y及z为满足0.01≤x≤0.20、0≤y≤0.20及0.97≤z≤1.20的数值，M表示选自Mn、V、Mg、Mo、Nb及Al中的至少一种元素)、LiFePO 4及Li zCO (1-x)M xO 2(x及z为满足0≤x≤0.1及0.97≤z≤1.20的数值，M表示选自由Mn、Ni、V、Mg、Mo、Nb及Al组成的组中的至少一种元素)。正极活性材料也可以为Li zNi (1-x-y)Co xM yO 2(x、y及z为满足0.01≤x≤0.15、0≤y≤0.15及0.97≤z≤1.20的数值，M表示选自Mn、Ni、V、Mg、Mo、Nb及Al中的至少一种元素)或Li zCO (1-x)M xO 2(x及z为满足0≤x≤0.1及0.97≤z≤1.20的数值，M表示选自Mn、V、Mg、Mo、Nb及Al中的至少一种元素)。
优选地，所述正极活性材料为NCM523。
作为本发明的锂离子电池的隔膜，没有特别限制，可以使用聚丙烯、聚乙烯等聚烯烃的单层或层叠的微多孔性薄膜、织布或无纺布等。
作为本发明的锂离子电池的非水电解液，没有特别限制，可以使用本领域常用的电解液配方，在此不作详述。
在不违背本领域常识的基础上，上述各优选条件，可任意组合，即得本发明各较佳实例。
本发明所用试剂和原料均市售可得。
本发明实施方式相对于现有技术而言，至少具有下述优点：
(1)本发明第一方面提供的粘结剂导离子能力更好，有助于降低电极内部阻抗。
(2)本发明第一方面提供的粘结剂粘结性较好的同时具有较好的分散增稠作用，且具 有合适的模量。
(3)使用本发明的锂化嵌段聚合物作为粘结剂，制备的锂离子电池具有更优的快速充电能力，更低的直流内阻和更优的低温放电能力。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合具体实施例对本发明的各实施方式进行详细的阐述。应理解，然而，本领域的普通技术人员可以理解，在本发明各实施方式中，为了使读者更好地理解本申请而提出了许多技术细节。但是，即使没有这些技术细节和基于以下各实施方式的种种变化和修改，也可以实现本申请所要求保护的技术方案。下列实施例中未注明具体条件的实验方法，通常按照常规条件，或按照制造厂商所建议的条件。除非另外说明，否则百分比和份数按重量计算。
实施例1 锂化聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAALi--PSt-PEHA-PSt)的制备
步骤一：聚丙烯酸(PAA)的制备
Figure PCTCN2021076032-appb-000011
称取1.0g 2-巯基-S-硫代苯甲酰乙酸(分子量为212.3g/mol)、3.0～17.0g精制丙烯酸单体混合，倒入500mL的三口烧瓶中，另外称取0.2～0.5g过硫酸钾，溶于5-10g去离子水中于低温保存备用，置于水浴锅上加入磁子于常温下搅拌溶解，随后通氮气30min以除去其中的氧气，升温至60～80℃，加入前述的过硫酸钾水溶液反应12～20小时，即得所述的聚丙烯酸(PAA)的制备。
步骤二：聚丙烯酸-苯乙烯(PAA-PSt)的制备
Figure PCTCN2021076032-appb-000012
称取98.0～245.0g苯乙烯单体，通过注射器缓慢加入到步骤一反应后的烧瓶中，在60～80℃下继续反应2～8小时，即得所述的聚丙烯酸-苯乙烯(PAA-PSt)。
步骤三：聚丙烯酸-苯乙烯-丙烯酸异辛酯(PAA-PSt-PEHA)的制备
Figure PCTCN2021076032-appb-000013
称取347.0～866.0g丙烯酸异辛酯单体，通过注射器缓慢加入到步骤二反应后的烧瓶中，在60～80℃下继续反应2～6h，即得所述的聚丙烯酸-苯乙烯-丙烯酸异辛酯(PAA-PSt-PEHA)。
步骤四：聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)的制备
Figure PCTCN2021076032-appb-000014
称取98.0～245.0g苯乙烯单体，通过注射器缓慢加入到步骤三反应后的烧瓶中，在60～80℃下继续反应2～8小时，去离子水洗涤反应后的产物至pH为3～6，即得所述的聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)。
步骤五：锂化聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)的制备
Figure PCTCN2021076032-appb-000015
取500g的步骤四所得的聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)，15～25g质量分数为5％-15％的氢氧化锂溶液(含氢氧化锂0.75～3.75g)，300rpm/h的转速搅拌反应60分钟，即得所述的锂化聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)。
实施例2 锂化聚丙烯酸-丙烯酸甲酯-丙烯酸(PAALi-PMA-PAALi)的制备
步骤一：聚丙烯酸(PAA)的制备
Figure PCTCN2021076032-appb-000016
Figure PCTCN2021076032-appb-000017
将0.6份RAFT试剂、0.2份引发剂和20份丙烯酸单体在150份的去离子水溶剂中，在70℃下搅拌反应18小时，得到含有式(1’)化合物的反应混合物；其中，RAFT试剂为
Figure PCTCN2021076032-appb-000018
其中，R为乙酸基；Z为苄基；引发剂为过硫酸钾；
步骤二：聚丙烯酸-丙烯酸甲酯(PAA-PMA)的制备
Figure PCTCN2021076032-appb-000019
往步骤一得到的反应混合物中加入60份丙烯酸甲酯单体，然后在70℃下继续搅拌6小时，得到含有式(2’)化合物的反应混合物；
步骤三：聚丙烯酸-丙烯酸甲酯-丙烯酸(PAA-PMA-PAA)的制备
Figure PCTCN2021076032-appb-000020
往步骤二得到的反应混合物中加入20份丙烯酸单体，然后在70℃下继续搅拌18小时，得到含有式(3’)化合物的反应混合物；
步骤四：锂化聚丙烯酸-丙烯酸甲酯-丙烯酸(PAALi-PMA-PAALi)的制备
Figure PCTCN2021076032-appb-000021
将步骤三得到的反应混合物的pH调至5，然后加入10％质量分数的氢氧化锂水溶液，在25℃下进行锂化4小时；
锂化反应结束后，将反应混合物沉淀、洗涤、干燥，即得到式(I’)所示的锂化聚丙烯酸-丙烯酸甲酯-丙烯酸(PAALi-PMA-PAALi)。最终得到的聚合物的分子量约为20000。
实施例3 粘结剂的制备
取实施例1制备的锂化聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAALi-PSt-PEHA-PSt)和实施例2制备的锂化聚丙烯酸-丙烯酸甲酯-丙烯酸(PAALi-PMA-PAALi)按照9:1的质量比搅拌混合，搅拌速度为200rpm，温度为30℃，时间为2小时。
表1
组别 PAALi-St-PEHA-St和PAALi-PMA-PAALi质量比
实施例4 8:2
实施例5 7:3
实施例6 6:4
实施例7 5:5
实施例8 4:6
实施例9 3:7
实施例10 2:8
实施例11 1:9
实施例12 锂离子电池的制备
正极极片的制备
按96:2:2的质量比混合正极活性材料NCM523、导电碳黑Super-P和粘结剂聚偏二氟乙烯(PVDF)，然后将它们分散在N-甲基-2-吡咯烷酮(NMP)中，得到正极浆料，所得正极浆料。将浆料均匀涂布在铝箔的两面上，经过烘干、压延和真空80°干燥，并用超声波焊机焊上铝制引出线后得到正极板，极板的厚度在120～150μm。
负极极片的制备
按95:2:3的质量比混合复合负极活性材料石墨、导电碳黑Super-P、实施例3制备的粘结剂，然后将它们分散在去离子水中，得到负极浆料。将浆料涂布在铜箔的两面上，经过烘干、压延和真空干燥，并用超声波焊机焊上镍制引出线后得到负极板，极板的厚度在80～100μm。
电芯的制备
在正极板和负极板之间放置厚度为20μm的隔膜，然后将正极板、负极板和隔膜组成的三明治结构进行卷绕，再将卷绕体压扁后放入铝箔包装袋，在85℃下真空烘烤48h，得到待注液的电芯。
电芯注液化成
在手套箱中将电解液注入电芯中，经真空封装，静止24h。然后按以下步骤进行首次充电的常规化成：0.02C恒流充电到3.05V，0.05C恒流充电至3.75V，0.2C恒流充电至4.05V，真空封口。然后进一步以0.33C的电流恒流充电至4.2V，常温搁置24小时后，以0.2C的电流恒流放电至3.0V。
其他的实施例13～实施例20，按照与实施例12相同的方法制备锂离子电池，差别在于负极极片制备中，所用的粘结剂分别为实施例3～实施例11制备的粘结剂。
对比例1 锂离子电池的制备
正极极片的制备
按96:2:2的质量比混合正极活性材料NCM523、导电碳黑Super-P和粘结剂聚偏二氟乙烯(PVDF)，然后将它们分散在N-甲基-2-吡咯烷酮(NMP)中，得到正极浆料，所得正极浆料。将浆料均匀涂布在铝箔的两面上，经过烘干、压延和真空80°干燥，并用超声波焊机焊上铝制引出线后得到正极板，极板的厚度在120～150μm。
负极极片的制备
按95:2:3的质量比混合复合负极活性材料石墨、导电碳黑Super-P、PAA粘结剂，然后将它们分散在去离子水中，得到负极浆料。将浆料涂布在铜箔的两面上，经过烘干、压延和真空干燥，并用超声波焊机焊上镍制引出线后得到负极板，极板的厚度在80～100μm。
电芯的制备
在正极板和负极板之间放置厚度为20μm的隔膜，然后将正极板、负极板和隔膜组成的三明治结构进行卷绕，再将卷绕体压扁后放入铝箔包装袋，在85℃下真空烘烤48h，得到待注液的电芯。
电芯注液化成
在手套箱中将电解液注入电芯中，经真空封装，静止24h。然后按以下步骤进行首次充电的常规化成：0.02C恒流充电到3.05V，0.05C恒流充电至3.75V，0.2C恒流充电至4.05V，真空封口。然后进一步以0.33C的电流恒流充电至4.2V，常温搁置24小时后，以0.2C的电流恒流放电至3.0V。
对比例2按照与对比例1相同的方法制备锂离子电池，差别在于负极极片制备中，所用的粘结剂为SBR粘结剂。
对比例3按照与对比例1相同的方法制备锂离子电池，差别在于负极极片制备中， 所用的粘结剂仅为锂化聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAALi--PSt-PEHA-PSt)。
对比例4按照与对比例1相同的方法制备锂离子电池，差别在于负极极片制备中，所用的粘结剂仅为锂化聚丙烯酸-丙烯酸甲酯-丙烯酸(PAALi-PMA-PAALi)。
测试例1
(1)粘结剂拉伸性能测试
将实施例3制备的粘结剂制程胶膜，制备过程如下：将含有1.2g粘结剂倒在直径为10cm的聚四氟乙烯表面皿中，盖上一层滤纸，并压住滤纸，放入通风橱中常温下对流风干一周时间，然后放入真空烘箱中60℃真空干燥12h完成制样。
按照ISO 37-1994中的2型和4型试样所示尺寸，在切割机上切割成哑铃型样条并按照GB 16421-1996标准实施，每种聚合物样条数量为5个。使用万能材料试验机进行拉伸测试，测试条件：使用量程为50N的力传感器，拉伸速率为1mm/min，每种聚合物样品进行5次平行试验取平均值，所得结果见表2。
实施例4～11制备的粘结剂、PAA粘结剂、SBR粘结剂、锂化聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAALi--PSt-PEHA-PSt)以及锂化聚丙烯酸-丙烯酸甲酯-丙烯酸(PAALi-PMA-PAALi)按照相同的方法进拉伸性能测试，所得结果见表2。
表2
Figure PCTCN2021076032-appb-000022
Figure PCTCN2021076032-appb-000023
(2)快速充电能力测试
25℃下，采用2C的倍率对实施例和对比例制备的锂离子电池进行恒流充电测试，计算其倍率充电容量保持率，电池在2C的倍率充电保持率＝电池在2C的倍率下充电后放出的容量/电池在1/3C的倍率下充电后放出的容量)。所得结果见表3。
(3)直流内阻(DCR)测试
25℃下，取实施例和对比例中制备的电池分别在带电量(SOC)为50％下4C放电30s，直流内阻R＝-(V1-V2)/I，其中V1为放电前电压，V2为放电后的电压，I为放电电流，计算直流内阻。所得结果见表3。
(4)低温放电能力测试
取实施例和对比例制备的电池，测定其-20℃下的放电容量保持率：25℃下，将分容后满电态的电池以1C放电到3.0V，初次放电容量记为DC(25℃)。后25℃下以1C恒流恒压充到4.2V，截止电流0.05C。后降温到-20℃搁置4h，再以1C放电到3.0V，记录放电容量DC(-20℃)。-20℃下放电容量保持率＝100％*DC(-20℃)/DC(25℃)。所得结果见表3。
表3
Figure PCTCN2021076032-appb-000024
Figure PCTCN2021076032-appb-000025
本领域的普通技术人员可以理解，上述各实施方式是实现本发明的具体实施例，而在实际应用中，可以在形式上和细节上对其作各种改变，而不偏离本发明的精神和范围。

Claims (13)

  1. 一种粘结剂，其特征在于，所述粘结剂包括第一嵌段聚合物和第二嵌段聚合物；
    所述第一嵌段聚合物为锂化的四嵌段聚合物，所述四嵌段聚合物具有B-C-B-A所示的结构，其中，A表示聚合物嵌段A，B表示聚合物嵌段B，C表示聚合物嵌段C；
    所述聚合物嵌段A由烯基甲酸单体聚合而成；
    所述聚合物嵌段B由芳香基乙烯单体聚合而成；
    所述聚合物嵌段C由丙烯酸酯单体聚合而成；且
    所述第二嵌段聚合物为锂化的三嵌段聚合物，所述三嵌段聚合物具有E-F-E所示的结构，其中，E表示聚合物嵌段E，F表示聚合物嵌段F；
    所述聚合物嵌段E由烯基甲酸单体聚合而成；
    所述聚合物嵌段F由丙烯酸酯单体聚合而成。
  2. 根据权利要求1所述的粘结剂，其特征在于，所述四嵌段聚合物中，所述烯基甲酸单体的结构为
    Figure PCTCN2021076032-appb-100001
    其中，R 11、R 12独立地为氢或C 1～4烷基；
    和/或，所述四嵌段聚合物中，所述芳香基乙烯单体结构为
    Figure PCTCN2021076032-appb-100002
    其中，R 21、R 22、R 23、R 24、R 25、R 26独立地为氢或C 1～4烷基；
    和/或，所述四嵌段聚合物中，所述丙烯酸酯单体的结构为
    Figure PCTCN2021076032-appb-100003
    其中，R 31为直链或含支链的C 1～10烷基；
    和/或，所述三嵌段聚合物中，所述烯基甲酸为
    Figure PCTCN2021076032-appb-100004
    其中，R 51、R 52独立地为氢或C 1～4烷基；
    和/或，所述三嵌段聚合物中，所述丙烯酸酯为
    Figure PCTCN2021076032-appb-100005
    其中，R 61为C 1～4烷基。
  3. 根据权利要求2所述的粘结剂，其特征在于，所述四嵌段聚合物中，所述烯基甲酸单体为丙烯酸；
    和/或，所述四嵌段聚合物中，所述芳香基乙烯单体为苯乙烯；
    和/或，所述四嵌段聚合物中，所述丙烯酸酯单体的结构为
    Figure PCTCN2021076032-appb-100006
    其中，R 31为直链或含支链的C 4～8烷基；
    和/或，所述三嵌段聚合物中，所述烯基甲酸为丙烯酸；
    和/或，所述三嵌段聚合物中，所述丙烯酸酯为丙烯酸甲酯。
  4. 根据权利要求1所述的粘结剂，其特征在于，所述第一嵌段聚合物具有通式(Ⅰ)所示的结构，其中，n为10～50；x为200～500；y为400～1000；z为200～500，R 41为C 4～8烷基，R 42和R 43为苯基或C 1～4烷基取代的苯基；
    Figure PCTCN2021076032-appb-100007
    和/或，所述第二嵌段聚合物具有通式(Ⅱ)所示的结构，其中，k为70～700，l为70～700，m为70～700；
    Figure PCTCN2021076032-appb-100008
  5. 根据权利要求4所述的粘结剂，其特征在于，所述第一嵌段聚合物为
    Figure PCTCN2021076032-appb-100009
    其中，n为10～50；x为200～500；y为400～1000；z为200～500。
  6. 根据权利要求1～5中任一项所述的粘结剂，其特征在于，所述第一嵌段聚合物和第二嵌段聚合物的质量比为99:1～1:99。
  7. 根据权利要求1～5中任一项所述的粘结剂，其特征在于，所述第一嵌段聚合物和第二嵌段聚合物的质量比为9:1。
  8. 根据权利要求1～3中任一项所述的粘结剂，其特征在于，所述四嵌段聚合物中，所述聚合物嵌段A的聚合度为10～50，所述聚合物嵌段B的聚合度为200～500，所述聚合物嵌段C的聚合度为400～1000；
    和/或，所述三嵌段聚合物中，所述聚合物嵌段E的聚合度为70～700，所述聚合物嵌F的聚合度为70～700。
  9. 一种锂离子电池用负极浆料，其特征在于，所述负极浆料包括负极活性材料、导电剂以及权利要求1～8中任一项所述的粘结剂。
  10. 根据权利要求9所述的负极浆料，其特征在于，负极活性材料、导电剂以及粘结剂的质量比为a:b:c，其中，a为93～97，b为3～5，c为3～5，且a+b+c＝100。
  11. 一种负极，其特征在于，所述负极包括集流体以及覆于所述集流体上的负极活性材料层，所述负极活性材料层由负极浆料涂覆于所述集流体上形成。
  12. 根据权利要求11所述的负极，其特征在于，所述负极活性材料包括石墨和/或含石墨的化合物。
  13. 一种锂离子电池，其特征在于，所述锂离子电池包括正极、隔膜、电解液以及权利要求11或12所述负极。
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CN111668485A (zh) * 2020-05-22 2020-09-15 远景动力技术(江苏)有限公司 锂离子电池用粘结剂及其制备方法和应用
CN111662418A (zh) * 2020-05-22 2020-09-15 远景动力技术(江苏)有限公司 锂离子电池用锂化功能聚合物及其制备方法和应用

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