WO2022160383A1 - 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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WO2022160383A1
WO2022160383A1 PCT/CN2021/076033 CN2021076033W WO2022160383A1 WO 2022160383 A1 WO2022160383 A1 WO 2022160383A1 CN 2021076033 W CN2021076033 W CN 2021076033W WO 2022160383 A1 WO2022160383 A1 WO 2022160383A1
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negative electrode
polymer
block
binder
polymer block
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PCT/CN2021/076033
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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 JP2022578868A priority Critical patent/JP7497469B2/ja
Priority to EP21921982.1A priority patent/EP4287323A1/en
Priority to US18/010,465 priority patent/US20230207814A1/en
Publication of WO2022160383A1 publication Critical patent/WO2022160383A1/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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
    • C08F293/005—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
    • 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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F212/02—Monomers containing only one unsaturated aliphatic radical
    • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F212/06—Hydrocarbons
    • C08F212/08—Styrene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2438/00—Living radical polymerisation
    • C08F2438/03—Use of a di- or tri-thiocarbonylthio compound, e.g. di- or tri-thioester, di- or tri-thiocarbamate, or a xanthate as chain transfer agent, e.g . Reversible Addition Fragmentation chain Transfer [RAFT] or Macromolecular Design via Interchange of Xanthates [MADIX]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the embodiments of the present invention relate to the field of 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 lithium ion batteries, 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 purpose of the embodiments of the present invention is to provide a binder, which has strong ion conductivity and better adhesion, so that the prepared negative electrode has higher peel strength, and the lithium ion battery using the binder has better fast charging ability. and high and low temperature performance.
  • the first aspect of the present invention provides a binder, the binder includes a lithiated block polymer, and the lithiated block polymer is a block polymer with a structure shown in B-C-B-A
  • 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 degree of polymerization of the polymer block A is 10-50
  • the degree of polymerization of the polymer block B is 200-500
  • the degree of polymerization of the polymer block C is 400-500. 1000.
  • the structure of the alkenyl formic acid monomer is wherein, R 11 and R 12 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 aromatic vinyl monomer structure 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 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 block polymer of the present invention can be prepared by a conventional step-by-step feed polymerization method in the art.
  • the step-by-step feed polymerization method is to add each polymer block in steps according to the specific block structure of the block polymer. A, polymer block B or polymer block C, realize the step-by-step polymerization of each polymer block.
  • the lithiated 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 groups, and the C 1-4 alkyl phenyl group 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 lithiated block polymer is Wherein, n is 10-50; x is 200-500; y is 400-1000; z is 200-500.
  • the lithiated block polymer of the present invention can be prepared by lithiation of the block polymer, and the block polymer can be prepared by a conventional step-by-step addition polymerization method in the art.
  • the step-by-step addition polymerization method is based on For the specific block structure of the block polymer, each polymer block (A), polymer block (B) or polymer block (C) is added in steps to realize the step-by-step polymerization of each polymer block .
  • the step of preparing a block polymer B-C-B-A comprises: (1) polymer block (A) undergoes a polymerization reaction with the polymer block (B) to obtain a polymer block (B-A); (2) the polymer block (C) undergoes a polymerization reaction with the polymer block (B-A) to obtain a polymer block block (C-B-A); (3) polymer block B and polymer block (C-B-A) react to obtain block polymer B-C-B-A.
  • a second aspect of the present invention provides a preparation method of a binder, the preparation method comprising the steps of:
  • PAA-PSt-PEHA polyacrylic acid-styrene-acrylic acid isooctanoate
  • PAA-PSt polyacrylic acid-styrene-acrylic acid isooctanoate-styrene
  • n 10-50
  • x is 200-500
  • y is 400-1000
  • z is 200-500.
  • the mass ratio of the polyacrylic acid-styrene-acrylic acid iso-octanoate-styrene (PAA-PSt-PEHA-PSt) and the styrene monomer is preferably (0.01-0.3):1 ; more preferably (0.02 to 0.27):1.
  • step (1) the polymerization reaction is preferably carried out in the presence of an initiator, and the initiator is preferably potassium persulfate, sodium persulfate or ammonium persulfate.
  • the temperature of the polymerization reaction is preferably 50-90°C, more preferably 60-80°C.
  • step (1) the time of the polymerization reaction is preferably 2 to 8 hours.
  • step (1) after the polymerization reaction, the polymerization reaction product polyacrylic acid-styrene-isooctanoate acrylate-styrene (PAA-PSt-PEHA-PSt) is washed with deionized water to a pH of 3-6. .
  • PAA-PSt-PEHA-PSt polyacrylic acid-styrene-isooctanoate acrylate-styrene
  • the lithium hydroxide is preferably an aqueous solution of lithium hydroxide, and in the aqueous lithium hydroxide solution, the mass fraction of lithium hydroxide is preferably 5%-15%.
  • step (1) the preparation of the polyacrylic acid-styrene-acrylic acid isooctanoate (PAA-PSt-PEHA) includes the steps:
  • PAA-PSt polyacrylic acid-styrene
  • PAA-PSt-PEHA polyacrylic acid-styrene-iso-octyl acrylate
  • step (A) the mass ratio of the polyacrylic acid-styrene (PAA-PSt) to the isooctyl acrylate is preferably (0.6-0.9):1; more preferably (0.6-0.7):1.
  • step (A) the polymerization reaction is preferably carried out in the presence of an initiator, and the initiator is preferably potassium persulfate, sodium persulfate or ammonium persulfate; for example: potassium persulfate.
  • the initiator is preferably potassium persulfate, sodium persulfate or ammonium persulfate; for example: potassium persulfate.
  • step (A) the temperature of the polymerization reaction is preferably 50-90°C, more preferably 60-80°C.
  • step (A) the time of the polymerization reaction is preferably 2 to 8 hours, more preferably 2 to 6 hours.
  • the preparation of the polyacrylic acid-styrene (PAA-PSt) comprises the steps:
  • the mass ratio of the polyacrylic acid and the styrene monomer is preferably 1:(3-90); more preferably 1:(5-75).
  • step (I) the polymerization reaction is preferably carried out in the presence of an initiator, and the initiator is preferably potassium persulfate, sodium persulfate or ammonium persulfate.
  • the temperature of the polymerization reaction is preferably 50-90°C, more preferably 60-80°C.
  • the polymerization reaction time is preferably 2 to 10 hours, more preferably 2 to 8 hours.
  • the preparation method of the polyacrylic acid is not limited, but preferably: the preparation method of the polyacrylic acid is that in the presence of a RAFT reagent and an initiator, the polyacrylic acid monomer is subjected to a polymerization reaction, that is, the polyacrylic acid is ;
  • the mass ratio of the RAFT reagent, the initiator and the acrylic monomer is preferably (0.5-1.0): (0.2-0.5): (10-20);
  • the temperature is preferably 50-90°C, more preferably 60-80°C;
  • the polymerization time is preferably 10-22 hours, more preferably 12-20 hours;
  • the initiator is preferably potassium persulfate, sodium persulfate , ammonium persulfate;
  • the RAFT reagent is preferably Wherein, R is isopropionic acid group, acetic acid group, 2-cyanoacetic acid group or 2-aminoacetic acid group; Z is C 4-12 alkyl group, C 4-12 al
  • a third aspect of the present invention provides a negative electrode slurry for lithium ion batteries, the negative electrode slurry includes a negative electrode active material, a conductive agent, a binder and a thickener, and the binder includes the above-mentioned lithiated block polymer thing.
  • a fourth 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, 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 Si-based active materials 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 aforementioned dense inter-crosslinked network structure.
  • 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 fifth 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 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 lithiated block polymer provided by the present invention has at least the following advantages:
  • the present invention provides a lithiated block polymer, which has good ion-conducting ability and is beneficial to reduce the internal impedance of the electrode.
  • the lithiated block polymer of the present invention has low cost, is compatible with various negative electrode systems, and is easy to be popularized on a large scale.
  • the prepared lithium ion battery has better fast charging capability, better low temperature discharge capability, and less gas generation at high temperature.
  • 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).
  • a 1Ah pouch battery was prepared using the lithiated polyacrylic acid-styrene-isooctyl acrylate-styrene (PAA-PSt-PEHA-PSt) prepared in Example 1 as a battery binder.
  • PAA-PSt-PEHA-PSt lithiated polyacrylic acid-styrene-isooctyl acrylate-styrene
  • the cathode active material NCM811, 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 at a constant current of 0.33C, and after being left at room temperature for 24 hours, it was discharged to 3.0V at a constant current of 0.2C.
  • Example 3 A lithium ion battery was prepared in the same manner as in Example 2, except that in the preparation of the negative electrode pole piece, the negative electrode active material used was artificial graphite.
  • the cathode active material NCM811, 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.
  • the composite negative active material (98% artificial graphite + 2% silicon oxide negative electrode), conductive carbon black Super-P, SBR and thickener sodium carboxymethyl cellulose in a mass ratio of 95:2:2:1, and then They were dispersed in deionized water to obtain 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 a glove box, sealed in vacuum, and left to stand for 24 hours. Then carry out the conventional formation of the first charge according to the following steps: 0.02C constant current charge to 3.05V, 0.05C constant current charge to 3.75V, 0.2C constant current charge to 4.05V, vacuum sealing. Then, it was further charged to 4.2V at a constant current of 0.33C, and after being left at room temperature for 24 hours, it was discharged to 3.0V at 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 electrode pole piece, the negative electrode active material used was artificial graphite.
  • the negative pole pieces made of the embodiment and the comparative example are cut into strips with a width of 2cm ⁇ 10cm, and the 3M VHB double-sided tape of the same size is pasted on the rectangular stainless steel plate of the same size (wipe clean with alcohol before sticking), Roll back and forth three times with a certain weight of roller to make the tape and steel plate closely fit, and then precisely fit the pole piece (active material side) to the other side of the tape, and roll the same three times with the roller, and finally put it in the universal material test In-machine test for peel strength.
  • the batteries prepared in the examples and comparative examples were weighed and their initial weights and initial volumes (measured by the drainage method) were then placed in a 60°C environment, taken out every 7 days, lowered to room temperature to measure the volume, and the volume growth rate was calculated. After the first measurement, it was put back into 60°C and charged with a current of 0.03C until the end of 28 days. The results obtained are shown in Table 4.

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Abstract

一种粘结剂、负极浆料、负极及锂离子电池，所述粘结剂包括锂化嵌段聚合物，所述锂化嵌段聚合物为具有B-C-B-A所示的结构嵌段聚合物的锂化产物，其中，A表示聚合物嵌段A，B表示聚合物嵌段B，和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。所述粘结剂的导离子能力强，粘结性更好，使得制备的负极的剥离强度更高，使用了其的锂离子电池具有更优的快速充电能力和高低温性能。

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2021101176951、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领域，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材料与活性材料，集流体与活性材料粘结在一起。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，使用导离子性能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。
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，同时兼容多种负极体 系，且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粘结剂，其导离子能力强，粘结性更好，使得制备的负极的剥离强度更高，使用了其的锂离子电池具有更优的快速充电能力和高低温性能。
为解决上述技术问题，本发明第一方面提供了一种粘结剂，所述粘结剂包括锂化嵌段聚合物，所述锂化嵌段聚合物为具有B-C-B-A所示的结构嵌段聚合物的锂化产物，其中，A表示聚合物嵌段A，B表示聚合物嵌段B，和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。
在一些优选的方案中，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。
在一些优选的方案中，所述烯基甲酸单体的结构为
Figure PCTCN2021076033-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，所述芳香基乙烯单体结构为
Figure PCTCN2021076033-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，所述丙烯酸酯单体的结构为
Figure PCTCN2021076033-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 PCTCN2021076033-appb-000004
本发明所述嵌段聚合物可通过本领域常规的分步加料聚合法制备，所述分步加料聚合法为根据所述嵌段聚合物的具体嵌段结构，分步加入各聚合物嵌段A、聚合物嵌段B或聚合物嵌段C，实现各聚合物嵌段的分步聚合。
在一些优选的方案中，所述锂化嵌段聚合物具有通式(Ⅰ)所示的结构；
Figure PCTCN2021076033-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 PCTCN2021076033-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，所述锂化嵌段聚合物为
Figure PCTCN2021076033-appb-000007
其中，n为10～50；x为200～500；y为400～1000；z为200～500。
本发明所述锂化嵌段聚合物可通过嵌段聚合物进行锂化处理制备，所述嵌段聚合物可通过本领域常规的分步加料聚合法制备，所述分步加料聚合法为根据所述嵌段聚合物的具体嵌段结构，分步加入各聚合物嵌段(A)、聚合物嵌段(B)或聚合物嵌段(C)，实现各聚合物嵌段的分步聚合。例如，制备嵌段聚合物B-C-B-A(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))的步骤包括：(1)聚合物嵌段(A)和聚合物嵌段(B)发生聚合反应，获得聚合物嵌段(B-A)；(2)聚合物嵌段(C)和聚合物嵌段(B-A)发生聚合反应，获得聚合物嵌段(C-B-A)；(3)聚合物嵌段B和聚合物嵌段(C-B-A)反应，获得嵌段聚合物B-C-B-A。
本发明第二方面提供了一种粘结剂的制备方法，所述制备方法包括步骤：
(1)取聚丙烯酸-苯乙烯-丙烯酸异辛酸酯(PAA-PSt-PEHA)和苯乙烯单体进行聚合反应，获得聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAA-PSt-PEHA-PSt)；和
(2)用氢氧化锂处理聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAA-PSt-PEHA-PSt)，获得所述粘结剂；
Figure PCTCN2021076033-appb-000008
其中，n为10～50，x为200～500，y为400～1000，步骤(2)中，z为200～500。
步骤(1)中，所述聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAA-PSt-PEHA-PSt)和所述苯乙烯单体的质量比优选为(0.01～0.3):1；更优选为(0.02～0.27):1。
步骤(1)中，所述聚合反应优选在引发剂存在下进行，所述引发剂优选为过硫酸钾、过硫酸钠或过硫酸铵。
步骤(1)中，所述聚合反应的温度优选为50～90℃，更优选为60～80℃。
步骤(1)中，所述聚合反应的时间优选为2～8小时。
步骤(1)中，所述聚合反应后还包括使用去离子水洗涤聚合反应产物聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAA-PSt-PEHA-PSt)至pH为3～6。
步骤(2)中，所述氢氧化锂优选为氢氧化锂的水溶液，所述氢氧化锂水溶液中，氢氧化锂的质量分数优选为5％-15％。
步骤(1)中，所述聚丙烯酸-苯乙烯-丙烯酸异辛酸酯(PAA-PSt-PEHA)的制备包括步骤：
(A)取聚丙烯酸-苯乙烯(PAA-PSt)和丙烯酸异辛酯单体进行聚合反应，获得聚丙烯酸-苯乙烯-丙烯酸异辛酸酯(PAA-PSt-PEHA)；
Figure PCTCN2021076033-appb-000009
其中，步骤(A)中，n为10～50；x为200～500；y为400～1000。
步骤(A)中，所述聚丙烯酸-苯乙烯(PAA-PSt)和所述丙烯酸异辛酯的质量比优选为(0.6～0.9):1；更优选为(0.6～0.7):1。
步骤(A)中，所述聚合反应优选在引发剂存在下进行，所述引发剂优选为过硫酸钾、过硫酸钠或过硫酸铵；例如：过硫酸钾。
步骤(A)中，所述聚合反应的温度优选为50～90℃，更优选为60～80℃。
步骤(A)中，所述聚合反应的时间优选为2～8小时，更优选为2～6小时。
步骤(A)中，所述聚丙烯酸-苯乙烯(PAA-PSt)的制备包括步骤：
(Ⅰ)取聚丙烯酸和苯乙烯单体进行聚合反应，获得聚丙烯酸-苯乙烯(PAA-PSt)；
Figure PCTCN2021076033-appb-000010
其中，n为10～50；x为200～500。
步骤(Ⅰ)中，所述聚丙烯酸和所述苯乙烯单体的质量比优选为1:(3～90)；更优选为1:(5～75)。
步骤(Ⅰ)中，所述聚合反应优选在引发剂存在下进行，所述引发剂优选为过硫酸钾、过硫酸钠或过硫酸铵。
步骤(Ⅰ)中，所述聚合反应的温度优选为50～90℃，更优选为60～80℃。
步骤(Ⅰ)中，所述聚合反应的时间优选为2～10小时，更优选为2～8小时。
步骤(Ⅰ)中，所述聚丙烯酸的制备方法不作限定，但优选地：所述聚丙烯酸的制备方法为在RAFT试剂和引发剂存在下，丙烯酸单体进行聚合反应即的所述的聚丙烯酸；所述聚合反应中，所述RAFT试剂、所述引发剂和所述丙烯酸单体的质量比优选为(0.5～1.0): (0.2～0.5):(10～20)；所述聚合反应的温度优选为50～90℃，更优选为60～80℃；所述聚合反应的时间优选为10～22小时，更优选为12～20小时；所述引发剂优选为过硫酸钾、过硫酸钠、过硫酸铵；所述RAFT试剂优选为
Figure PCTCN2021076033-appb-000011
其中，R为异丙酸基、乙酸基、2-氰基乙酸基或2-氨基乙酸基；Z为C 4～12烷基、C 4～12烷硫基、苯基或苄基，例如：2-巯基-S-硫代苯甲酰乙酸。
本发明第三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、粘结剂以及增稠剂，所述粘结剂包括上述锂化嵌段聚合物。
在一些优选的方案中，所述负极活性材料、导电剂、粘结剂以及增稠剂的质量比为a:b:c:d，其中，a为93～97；b为3～5；c为3～5；d为0.5～1.5，且a+b+c+d＝100。
本发明第四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。
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。
本发明第五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)。
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。
本发明提供的锂化嵌段聚合物，和现有技术相比，至少具有下述优点：
(1)本发明从分子结构设计角度，提供了一种锂化嵌段聚合物，其具有较好的导离子能力，有利于降低电极内部阻抗。
(2)本发明的锂化嵌段聚合物成本低廉，同时兼容多种负极体系，且易于规模推广。
(3)使用本发明的锂化嵌段聚合物作为粘结剂，其粘结性更好，制备的锂离子电池负极剥离强度更高。
(4)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，更优的低温放电能力，并且高温下产气更少。
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 粘结剂--锂化聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAA-PSt-PEHA-PSt)的制备
步骤一：聚丙烯酸(PAA)的制备
Figure PCTCN2021076033-appb-000012
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 PCTCN2021076033-appb-000013
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 PCTCN2021076033-appb-000014
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 PCTCN2021076033-appb-000015
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 PCTCN2021076033-appb-000016
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 锂离子电池的制备
使用实施例1制备的锂化聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)作为电池粘结剂制备1Ah的软包电池。
正极极片的制备
按96:2:2的质量比混合正极活性材料NCM811、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95:2:2:1的质量比混合复合负极活性材料(98％人造石墨+2％硅氧负极)、导电碳黑Super-P、实施例1制备的锂化聚丙烯酸-苯乙烯-丙烯酸异辛酯-苯乙烯(PAA-PSt-PEHA-PSt)和增稠剂羧甲基纤维素钠，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。
实施例3按照与实施例2相同的方法制备锂离子电池，差别在于负极极片制备中，所用负极活性材料为人造石墨。
对比例1 应用传统SBR粘结剂制备锂离子电池
正极极片的制备
按96:2:2的质量比混合正极活性材料NCM811、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95:2:2:1的质量比混合复合负极活性材料(98％人造石墨+2％硅氧负极)、导电碳黑Super-P、SBR和增稠剂羧甲基纤维素钠，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24小时。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，所用负极活性材料为人造石墨。
测试例1 锂化聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯(PAA-PSt-PEHA-PSt)的表征
取0.01g聚丙烯酸-苯乙烯-丙烯酸异辛酸酯-苯乙烯溶解在5ml四氢呋喃溶剂中，用凝胶渗透色谱仪测定其分子量和分子量分布曲线，结果见表1。
表1
Figure PCTCN2021076033-appb-000017
测试例2 锂离子电池性能测试
(1)快速充电能力测试
25℃下，采2C的倍率对实施例和对比例制备的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2。
表2
Figure PCTCN2021076033-appb-000018
(2)剥离强度测试
将实施例和对比例制成的负极极片裁切成2cm×10cm宽的长条，在同样尺寸的长方形 不锈钢板上贴上同样尺寸的3M VHB双面胶带(贴之前用酒精擦拭干净)，用一定重量的辊轮来回滚压三次，使胶带与钢板紧密贴合，再将极片(活性材料面)与胶带另一面精准贴合，用辊轮同样滚压三次，最后置于万能材料试验机中测试剥离强度。
将钢板一段置于机器下方夹具，钢板与地面垂直夹紧，从下方轻轻撕开至极片中间位置，180°弯曲至机器上方夹具夹紧，控制机器调节上夹具位置，打开测试软件，设置好测试条件为拉伸速率50mm/min，将初始参数全部归零，开启测试。所得结果见表3。
表3
Figure PCTCN2021076033-appb-000019
(3)高温产气性能测试
将实施例和对比例制备的电池称量初始重量和初始体积(排水法测量)，后置于60℃环境中静置，每隔7天取出，降至常温测量体积，计算体积增长率，每次测量完后再放回60℃中，并且以0.03C的电流充电，直至28天结束。所得结果见表4。
表4
Figure PCTCN2021076033-appb-000020
(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4小时，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5。
表5
Figure PCTCN2021076033-appb-000021
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 (11)

  1. 一种粘结剂，其特征在于，所述粘结剂包括锂化嵌段聚合物，所述锂化嵌段聚合物为具有B-C-B-A所示的结构嵌段聚合物的锂化产物，其中，A表示聚合物嵌段A，B表示聚合物嵌段B，和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。
  2. 根据权利要求1所述的粘结剂，其特征在于，所述烯基甲酸单体的结构为
    Figure PCTCN2021076033-appb-100001
    其中，R 11、R 12独立地为氢或C 1～4烷基；
    和/或，所述芳香基乙烯单体的结构为
    Figure PCTCN2021076033-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，所述丙烯酸酯单体的结构为
    Figure PCTCN2021076033-appb-100003
    其中，R 31为直链或含支链的C 1～10烷基。
  3. 根据权利要求2所述的粘结剂，其特征在于，所述烯基甲酸单体为丙烯酸；
    和/或，所述芳香基乙烯单体为苯乙烯；
    和/或，所述丙烯酸酯单体的结构为
    Figure PCTCN2021076033-appb-100004
    其中，R 31为直链或含支链的C 4～8烷基。
  4. 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。
  5. 根据权利要求1所述的粘结剂，其特征在于，所述锂化嵌段聚合物具有通式(Ⅰ)所示的结构；
    Figure PCTCN2021076033-appb-100005
    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。
  6. 根据权利要求1所述的粘结剂，其特征在于，所述锂化嵌段聚合物为
    Figure PCTCN2021076033-appb-100006
    其中，n为10～50；x为200～500；y为400～1000；z为200～500。
  7. 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、权力要求1～6中任一项所述的粘结剂以及增稠剂。
  8. 根据权利要求7所述的负极浆料，其特征在于，所述负极活性材料、导电剂、粘结剂以及增稠剂的质量比为a:b:c:d，其中，a为93～97；b为3～5；c为3～5；d为0.5～1.5，且a+b+c+d＝100。
  9. 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权利要求7或8所述负极浆料涂覆于所述集流体上形成。
  10. 根据权利要求9所述的负极，其特征在于，所述负极活性材料包括硅和/或石墨。
  11. 一种锂离子电池，其特征在于，所述锂离子电池包括正极、如权力要求9或10所述负极、隔膜以及电解液。
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CN111430667A (zh) * 2019-12-31 2020-07-17 蜂巢能源科技有限公司 负极浆料、负极片、动力电池和电动汽车
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
CN111600033A (zh) * 2020-05-28 2020-08-28 珠海冠宇电池股份有限公司 一种负极粘结剂及其应用

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