WO2024259966A1 - 聚合物、负极极片、电池和用电装置 - Google Patents

聚合物、负极极片、电池和用电装置 Download PDF

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WO2024259966A1
WO2024259966A1 PCT/CN2024/072543 CN2024072543W WO2024259966A1 WO 2024259966 A1 WO2024259966 A1 WO 2024259966A1 CN 2024072543 W CN2024072543 W CN 2024072543W WO 2024259966 A1 WO2024259966 A1 WO 2024259966A1
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negative electrode
group
substituted
unsubstituted
formula
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French (fr)
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柴思瑀
魏志婷
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Contemporary Amperex Technology Co Ltd
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    • 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
    • C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
    • C08F251/02—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof on to cellulose or derivatives thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/137—Electrodes based on electro-active polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
    • H01M4/606—Polymers containing aromatic main chain polymers
    • H01M4/608—Polymers containing aromatic main chain polymers containing heterocyclic rings
    • 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 present application relates to a polymer, a negative electrode sheet, a battery and an electrical device.
  • Battery cells are widely used because of their reliable working performance, no pollution, and no memory effect. For example, as environmental protection issues are increasingly valued and new energy vehicles become more popular, the demand for power battery cells will show explosive growth.
  • the present application provides a polymer, a negative electrode plate, a battery and an electrical device.
  • the performance of the electrode plate of the battery described in the present application can be improved.
  • an embodiment of the present application proposes a polymer, wherein the polymer includes a modified carboxymethyl cellulose salt, wherein the modified carboxymethyl cellulose salt is a carboxymethyl cellulose salt in which a hydrogen atom of at least one hydroxyl group is substituted with a grafted group, and the grafted group includes at least one of a substituted or unsubstituted polyamide group and a substituted or unsubstituted polyester group.
  • the polymer of the embodiment of the present application can be regarded as a modified carboxymethyl cellulose salt, that is, a polymer obtained by grafting and modifying the side chain of carboxymethyl cellulose salt (CMC-M).
  • CMC-M carboxymethyl cellulose salt
  • the grafted group replaces the hydrogen atom in the hydroxyl group, destroys the hydroxyl structure in the carboxymethyl cellulose salt, thereby destroying the regular hydrogen bond structure and weakening the hydrogen bond effect;
  • the group replacing the hydrogen atom in the hydroxyl group includes a polyamide group, a polyester group, etc., and even if such a group forms a hydrogen bond, the hydrogen bond effect formed in this way is weaker than the hydrogen bond effect formed by the carboxymethyl cellulose salt itself, thereby reducing the interaction force between the polymer molecular chains, increasing the free volume of the polymer network, and promoting the relative movement between the polymer molecular chains, thereby reducing the stress generated during drying, and improving the flexibility of the negative electrode film layer
  • the main structure of the polymer is still carboxymethyl cellulose salt, it still has a good dispersing effect, which can effectively reduce the interfacial tension between the negative electrode active material and the solvent, so that the negative electrode active material is evenly dispersed in the negative electrode slurry.
  • the polymer comprises a repeating unit represented by formula (A),
  • M includes at least one of Li, Na or NH 4 ;
  • R1 to R5 each independently include at least one of hydrogen atoms, substituted or unsubstituted polyamide groups, substituted or unsubstituted polyester groups, and at least one of R1 and R5 includes at least one of substituted or unsubstituted polyamide groups, substituted or unsubstituted polyester groups, wherein the grafted group includes non-hydrogen atom groups in R1 to R5 ; n represents the degree of polymerization of the modified carboxymethyl cellulose salt; optionally, n includes any positive integer from 1500 to 3000.
  • the above material has good dispersibility and weak hydrogen bonding, which is conducive to further improving the flexibility of the polymer applied to the negative electrode film layer.
  • the grafted group includes a substituted or unsubstituted polyamide group
  • the substituted or unsubstituted polyamide group includes the structural formula shown in formula (1)
  • R 11 includes at least one of a single bond, a substituted or unsubstituted C1 to C5 methylene group;
  • R 12 to R 16 each independently include at least one of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkenyl group, and a substituted or unsubstituted C1 to C10 alkynyl group;
  • n includes any positive integer from 1 to 30.
  • the polyamide group of the embodiment of the present application is grafted to the side chain of the carboxymethyl cellulose salt, which can replace the hydrogen atom at the original hydroxyl position, thereby destroying the regular O-H-O hydrogen bond structure of the carboxymethyl cellulose salt and forming a new N-H-O hydrogen bond structure.
  • the N-H-O hydrogen bond structure is weaker than the O-H-O hydrogen bond, so that the intermolecular force of the grafted modified carboxymethyl cellulose salt is weakened, the flexibility is increased, and the interface performance of the negative electrode film layer is improved.
  • the highly electronegative element nitrogen can form a complex with the active ions (such as lithium ions or sodium ions) in the battery system, accelerate the transmission rate of the active ions, and improve the dynamic performance of the battery monomer.
  • the grafted group includes at least one of the structural formulas shown in formula (1-11) to formula (1-15),
  • the grafted group includes at least one of the structural formulas shown in formula (1-21) to formula (1-24),
  • the grafted group includes a substituted or unsubstituted polyester group
  • the substituted or unsubstituted polyester group includes the structural formula shown in formula (2)
  • R 21 includes at least one of a single bond, a substituted or unsubstituted C1 to C5 methylene group;
  • R 22 includes substituted or unsubstituted C1-C5 alkyl
  • R 23 to R 25 each independently include at least one of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkenyl group, and a substituted or unsubstituted C1 to C10 alkynyl group;
  • s includes any positive integer from 1 to 30.
  • the polyester group of the embodiment of the present application is grafted to the side chain of the carboxymethyl cellulose salt, it can replace the hydrogen atom at the original hydroxyl position, thereby destroying the regular O-H-O hydrogen bond structure of the carboxymethyl cellulose salt, weakening the hydrogen bonding effect of the carboxymethyl cellulose salt itself, so that the intermolecular force of the grafted modified carboxymethyl cellulose salt is weakened, the flexibility is increased, and the interface performance of the negative electrode film layer is improved.
  • the polyester group itself has good flexibility, and after replacing the hydroxyl position, it can further improve the flexibility of the carboxymethyl cellulose salt, thereby improving the interface performance of the negative electrode film layer.
  • R 21 includes a single bond
  • R 1 to R 5 each independently include the structure represented by formula (2-1),
  • R1 to R5 each independently include at least one of the structural formulas shown in formula (2-11) to formula (2-16),
  • R 21 includes substituted or unsubstituted C1 to C5 methylene, and R 1 to R 5 each independently include the structural formula shown in formula (2-2),
  • p includes any positive integer from 1 to 5.
  • R1 to R5 each independently include at least one of the structural formulas shown in formula (2-21) to formula (2-28),
  • the weight average molecular weight of R1 to R5 is less than or equal to 2500Da, and can be 71Da to 2500Da.
  • the molecular weight of the grafted group in the polymer is relatively small, which can reduce the hydrogen bonding effect between the polymer molecular chains and make the polymer have better dispersibility.
  • the weight average molecular weight of the polymer is 40 wDa to 80 wDa.
  • the polymer can have excellent dispersibility.
  • the elongation at break of the reference film made of sodium carboxymethyl cellulose is 100%
  • the elongation at break of the film made of the polymer is 170% to 300%
  • the width of the reference film and the film made of the polymer is 2.5 cm
  • the length is 5 cm
  • the thickness is 1 mm.
  • the elongation at break of the polymer is higher than that of conventional sodium carboxymethyl cellulose.
  • the polymer When the polymer is applied to the negative electrode plate, it has better flexibility and is not prone to breakage.
  • the present application also proposes a dispersant, which includes a polymer as described in any embodiment of the first aspect of the present application.
  • the dispersant can be used in the negative electrode film layer of the negative electrode plate to reduce the risk of cracking of the negative electrode film layer and improve the interface performance of the negative electrode film layer; in addition, since the grafted group includes heteroatoms such as nitrogen atoms, oxygen atoms, etc., such atoms are conducive to the transmission of active ions such as lithium ions and sodium ions, thereby increasing the transmission rate of active ions and facilitating Improve the electrical performance of the negative electrode film layer.
  • the dispersant may also include carboxymethyl cellulose salts.
  • the ratio of the mass content of the carboxymethyl cellulose salt to the mass content of the polymer can be 0.5 to 2.
  • the mass content ratio of the carboxymethyl cellulose salt to the polymer is within the above range, it can work together with the polymer to improve the flexibility of the film formed by itself.
  • the present application also proposes a negative electrode plate, which includes a negative electrode collector and a negative electrode film layer arranged on at least one surface of the negative electrode collector, and the negative electrode film layer includes the polymer described in any embodiment of the first aspect of the present application or the dispersant described in any embodiment of the second aspect.
  • the mass content of the polymer is 1.0% to 1.3%, and optionally 1.0% to 1.2%.
  • the coating weight of the negative electrode film layer is 190 mg/1540.25 mm 2 to 230 mg/1540.25 mm 2 , and can be 200 mg/1540.25 mm 2 to 230 mg/1540.25 mm 2 .
  • the coating weight of the negative electrode film layer is relatively high, which is conducive to achieving thick coating.
  • the present application further proposes a battery, wherein the battery cell comprises a negative electrode plate as described in any embodiment of the third aspect of the present application.
  • the battery comprises a battery cell/battery module and a battery pack.
  • an embodiment of the present application further proposes an electrical device, comprising a battery as described in any embodiment of the fourth aspect of the present application.
  • FIG. 1 is a schematic diagram of an embodiment of a battery cell of the present application.
  • FIG. 2 is an exploded schematic diagram of an embodiment of the battery cell of FIG. 1 .
  • FIG. 3 is a schematic diagram of an embodiment of a battery module of the present application.
  • FIG. 4 is a schematic diagram of an embodiment of a battery pack of the present application.
  • FIG. 5 is an exploded schematic diagram of the embodiment of the battery pack shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of an embodiment of an electric device including the battery cell of the present application as a power source.
  • “Scope” disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application are open-ended or closed-ended.
  • the “include” and “comprising” may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • polyamide-like group refers to a group formed when a terminal group of polyacrylamide loses a hydrogen atom.
  • polyester group refers to a group formed by loss of a hydrogen atom from a terminal group of a polyester.
  • alkyl encompasses straight and branched alkyl groups.
  • the alkyl group may be a C5-C100 alkyl group, a C1-C50 alkyl group, a C1-C40 alkyl group, a C1-C30 alkyl group, a C1-C20 alkyl group, a C1-C12 alkyl group, a C1-C10 alkyl group, a C1-C6 alkyl group, a C1-C5 alkyl group, a C1-C4 alkyl group.
  • the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a heptyl group, a cycloheptyl group, an octyl group, a cyclooctyl group, a nonyl group, and a decyl group.
  • alkyl group may be optionally substituted.
  • haloalkyl refers to an alkyl group in which a hydrogen atom is partially or completely replaced by a halogen atom, and the term “halogen atom” refers to a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.
  • Methylene refers to a group formed by losing two hydrogen atoms from the same carbon atom.
  • the methylene group can be C5-C500 methylene, C20-C400 methylene, C1-C50 methylene, C1-C40 methylene, C1-C30 methylene, C1-C20 methylene, C1-C12 methylene, C1-C10 methylene, C1-C6 methylene, C1-C4 methylene.
  • Methylene includes methylene, ethylene, propylene, butylene, isobutylene, pentylene, hexylene, heptylene, octylene, nonylene and decylene etc.
  • methylene can be optionally substituted.
  • halomethylene refers to a methylene group in which hydrogen atoms are partially or completely replaced by halogen atoms
  • halogen atom refers to fluorine atoms, chlorine atoms, bromine atoms, iodine atoms etc.
  • hydrogen refers to 1H (protium, H), 2H (deuterium, D) or 3H (tritium, T). In various embodiments, “hydrogen” may be 1H (protium, H).
  • C1-C8 alkyl discloses C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7 and C7-C8 alkyl individually.
  • the integers in the range of 5-40 are specifically intended to disclose individually 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40; the integers in the range of 1-20 are specifically intended to disclose individually 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Accordingly, other groups or ranges are specifically contemplated.
  • the substituents may be independently selected from halogen atoms or heteroatoms.
  • polymer refers to a molecular complex consisting of more than ten monomer units and generally includes, but is not limited to, homopolymers, copolymers, such as block, graft, random and alternating copolymers, terpolymers, and higher order "x" polymers, further including their analogs, derivatives, combinations and mixtures.
  • polymer shall include all possible isomeric configurations of the molecule, including but not limited to isotactic, syndiotactic and random symmetry and combinations thereof.
  • polymer shall include all possible geometric configurations of the molecule.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector.
  • the negative electrode film layer is formed by coating the negative electrode slurry on the negative electrode current collector and drying. In the process of forming the negative electrode film layer by the negative electrode slurry, cracking and other phenomena may occur, resulting in the negative electrode film layer not meeting the production requirements.
  • the related technology adds plasticizers such as butanediol to the negative electrode slurry.
  • the plasticizer is usually a small molecule compound (whose molecular weight is relatively small).
  • the plasticizer can enter between the molecular chains of the binder polymer, reduce the intermolecular stress of the binder polymer, and reduce the crystallinity of the polymer molecular chain, thereby improving the shaping and flexibility of the negative electrode film layer and improving the cracking phenomenon of the negative electrode film layer.
  • the residual plasticizer easily leads to uneven thickness of the negative electrode film layer, resulting in dark marks, metal precipitation and other interface problems in the negative electrode film layer.
  • the embodiment of the present application proposes a polymer, which can be used as a dispersant in the negative electrode film layer.
  • the polymer includes modified carboxymethyl cellulose salts, that is, the carboxymethyl cellulose salts are grafted and modified so that the polymer has good flexibility.
  • modified carboxymethyl cellulose salts that is, the carboxymethyl cellulose salts are grafted and modified so that the polymer has good flexibility.
  • the present application provides a polymer, wherein the polymer includes a modified carboxymethyl cellulose salt, wherein the modified carboxymethyl cellulose salt is a carboxymethyl cellulose salt in which at least one hydrogen atom of a hydroxyl group is replaced with a grafted group, wherein the grafted group includes at least one of a substituted or unsubstituted polyamide group and a substituted or unsubstituted polyester group.
  • the polymer includes a modified carboxymethyl cellulose salt, wherein the modified carboxymethyl cellulose salt is a carboxymethyl cellulose salt in which at least one hydrogen atom of a hydroxyl group is replaced with a grafted group, wherein the grafted group includes at least one of a substituted or unsubstituted polyamide group and a substituted or unsubstituted polyester group.
  • Carboxymethyl cellulose salts are a type of anionic water-soluble cellulose ether derivatives. When used in negative electrode slurry, they can reduce the interfacial tension between the negative electrode active material and the solvent, and have a good dispersing effect on the negative electrode active material. Under stirring, it is beneficial for the negative electrode active material to be evenly dispersed in the solvent to form a stable slurry system.
  • the molecular chains of carboxymethyl cellulose salts are rich in hydroxyl groups (-OH).
  • hydroxyl groups enables the molecular chains of carboxymethyl cellulose salts to form strong van der Waals forces or hydrogen bonds.
  • carboxymethyl cellulose salts may be able to form strong van der Waals forces or hydrogen bonds with negative electrode active materials, etc., so that the negative electrode slurry has strong drying stress during the drying process and warps, and may crack during further rolling, causing cracking of the negative electrode film layer.
  • the polymer of the embodiment of the present application can be regarded as a modified carboxymethyl cellulose salt, that is, a polymer obtained by grafting the side chain of carboxymethyl cellulose salt (CMC-M), and the hydrogen atoms in the hydroxyl group are replaced by grafting the side chain of the carboxymethyl cellulose salt, thereby destroying the hydroxyl structure in the carboxymethyl cellulose salt, thereby destroying the regular hydrogen bond structure and weakening the hydrogen bond effect;
  • the group replacing the hydrogen atom in the hydroxyl group includes a polyamide group, a polyester group, etc., and even if such a group forms a hydrogen bond, the hydrogen bond effect formed in this way is weaker than the hydrogen bond effect formed by the carboxymethyl cellulose salt itself, thereby reducing the interaction force between the polymer molecular chains, increasing the free volume of the polymer network, and promoting the relative movement between the polymer molecular chains, thereby reducing the stress generated during drying, and improving the flexibility of the negative electrode film layer, reducing
  • the main structure of the polymer is still carboxymethyl cellulose salt, it still has a good dispersing effect, which can effectively reduce the interfacial tension between the negative electrode active material and the solvent, so that the negative electrode active material is evenly dispersed in the negative electrode slurry. Therefore, the polymer can be used in the negative electrode slurry (or the negative electrode film layer of the negative electrode sheet) as a dispersant.
  • the modified carboxymethyl cellulose salts may include modified carboxymethyl cellulose potassium salt and the like.
  • the modified carboxymethyl cellulose salts may include at least one of modified carboxymethyl cellulose lithium salt, modified carboxymethyl cellulose sodium salt or modified carboxymethyl cellulose ammonium salt; specifically, the modified carboxymethyl cellulose salts include the compound represented by formula (A),
  • M includes at least one of Li, Na or NH 4 ;
  • R1 to R5 each independently include at least one of a hydrogen atom, a substituted or unsubstituted polyamide group, and a substituted or unsubstituted polyester group, and at least one of R1 and R5 includes at least one of a substituted or unsubstituted polyamide group, and a substituted or unsubstituted polyester group, wherein the grafted group includes a non-hydrogen atom group among R1 to R5 ; n represents the degree of polymerization of the modified carboxymethyl cellulose salt.
  • the above materials have good dispersibility and weak hydrogen bonding, which is conducive to further improving the application of polymers in negative electrodes. Flexibility in the membrane.
  • n includes any positive integer from 1500 to 3000.
  • n may be 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900 or 3000.
  • the non-hydrogen atom group refers to a non-hydrogen atom group, that is, when R 1 to R 5 all replace the hydrogen atoms in the hydroxyl group, R 1 to R 5 can be considered as grafted groups; if one of R 1 to R 5 , for example R 1, is a hydrogen atom, then R 1 is not a grafted group.
  • the repeating unit in the modified carboxymethyl cellulose salts may include one or more, and the polymer may include one or more modified carboxymethyl cellulose salts.
  • R 1 to R 5 includes at least one of a substituted or unsubstituted polyamide group and a substituted or unsubstituted polyester group, which can be understood as at least one hydroxyl group in the polymer being substituted, that is, at least one of R 1 to R 5 is not a hydrogen atom, for example, four of R 1 to R 5 are hydrogen atoms, or three of them are hydrogen atoms, or two of them are hydrogen atoms, and one of them is a hydrogen atom, or even R 1 to R 5 may not be hydrogen atoms. As the number of hydrogen atoms decreases, it means that the number of substituted hydroxyl groups in the polymer increases.
  • the polyamide group includes nitrogen, a strongly electronegative element. After the polyamide group is grafted to the side chain of carboxymethyl cellulose salt, it can replace the hydrogen atom at the original hydroxyl position and thus destroy the regular O-H-O hydrogen bond structure of the carboxymethyl cellulose salt, forming a new N-H-O hydrogen bond structure.
  • the N-H-O hydrogen bond structure is weaker than the O-H-O hydrogen bond, which weakens the intermolecular force of the grafted carboxymethyl cellulose salt, increases flexibility, and improves the interface performance of the negative electrode film layer.
  • the strongly electronegative element nitrogen can form a complex with the active ions (such as lithium ions or sodium ions) in the battery system, accelerate the transmission rate of the active ions, and improve the kinetic performance of the battery monomer.
  • R1 to R5 each independently include a substituted or unsubstituted polyamide group, and the substituted or unsubstituted polyamide group includes the structural formula shown in formula (1),
  • R 11 includes at least one of a single bond, a substituted or unsubstituted C1 to C5 methylene group;
  • R 12 to R 16 each independently include at least one of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkenyl group, and a substituted or unsubstituted C1 to C10 alkynyl group.
  • the substituent may include at least one of a halogen atom, a hydroxyl group and a carboxyl group, wherein the halogen atom may include at least one of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
  • n includes any positive integer from 1 to 30.
  • m can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30.
  • R 11 includes a single bond
  • the substituted or unsubstituted polyamide group includes the structural formula shown in formula (1-a)
  • the structural formula represented by formula (1-a) includes at least one of the structural formula represented by formula (1-11) to the structural formula represented by formula (1-15),
  • R 11 includes substituted or unsubstituted C1 to C5 methylene groups, and the substituted or unsubstituted polyamide group includes the structural formula shown in formula (1-b),
  • q includes any positive integer from 1 to 5.
  • q may be 1, 2, 3, 4 or 5.
  • the structural formula represented by formula (1-b) includes at least one of the structural formula represented by formula (1-21) to the structural formula represented by formula (1-24),
  • the polyester group After the polyester group is grafted onto the side chain of the carboxymethyl cellulose salt, it can replace the original hydroxyl position and thus destroy the regular O-H-O hydrogen bond structure of the carboxymethyl cellulose salt, weaken the hydrogen bonding effect of the carboxymethyl cellulose salt itself, so that the intermolecular force of the grafted modified carboxymethyl cellulose salt is weakened, the flexibility is increased, and the interface performance of the negative electrode film layer is improved; and the migration rate of active ions such as lithium ions can be improved.
  • the polyester group itself has good flexibility, and after replacing the hydroxyl position, it can further improve the flexibility of the carboxymethyl cellulose salt, thereby improving the interface performance of the negative electrode film layer.
  • R1 to R5 each independently include a substituted or unsubstituted polyester group, and the substituted or unsubstituted polyester group includes the structural formula shown in formula (2),
  • R 21 includes at least one of a single bond, a substituted or unsubstituted C1 to C5 methylene group;
  • R 22 to and including substituted or unsubstituted C1-C5 alkyl
  • R 23 to R 25 each independently include at least one of a hydrogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkenyl group, and a substituted or unsubstituted C1 to C10 alkynyl group.
  • the substituent may include at least one of a halogen atom, a hydroxyl group and a carboxyl group, wherein the halogen atom may include at least one of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
  • s includes any positive integer from 1 to 30.
  • s can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30.
  • R 21 includes a single bond
  • the substituted or unsubstituted polyester group includes the structural formula shown in formula (2-1),
  • R1 to R5 each independently include at least one of the structural formulas shown in formula (2-11) to formula (2-16),
  • R 21 includes substituted or unsubstituted C1 to C5 methylene, and R 1 to R 5 each independently include the structural formula shown in formula (2-2),
  • p includes any positive integer from 1 to 5.
  • p may be 1, 2, 3, 4 or 5.
  • R1 to R5 each independently include at least one of the structural formulas shown in formula (2-21) to formula (2-28),
  • the halogen atom may include at least one of a fluorine atom, a chlorine atom, and a bromine atom.
  • the above atoms can improve the voltage resistance of the polymer.
  • the weight average molecular weight of R1 to R5 is less than or equal to 2500Da, and can be 71Da to 2500Da.
  • the molecular weight of the grafted group in the polymer is relatively small, which can reduce the hydrogen bonding effect between the polymer molecular chains and make the polymer have better dispersibility.
  • the weight average molecular weight of R1 to R5 can be 71 Da, 78 Da, 80 Da, 85 Da, 90 Da, 95 Da, 100 Da, 120 Da, 150 Da, 180 Da, 200 Da, 220 Da, 250 Da, 280 Da, 300 Da, 320 Da, 350 Da, 380 Da, 400 Da, 450 Da, 500 Da, 600 Da, 700 Da, 800 Da, 900 Da, 1000 Da, 1100 Da, 1200 Da, 1300 Da, 1400 Da, 1500 Da, 1600 Da, 1700 Da, 1800 Da, 1900 Da, 2000 Da, 2100 Da, 2200 Da, 2300 Da, 2400 Da, 2500 Da, or a range consisting of any two of the above values.
  • the weight average molecular weight of the polymer is 40 wDa to 80 wDa.
  • the polymer can have excellent dispersibility.
  • the weight average molecular weight of the polymer can be 40wDa, 42wDa, 45wDa, 46wDa, 48wDa, 50wDa, 52wDa, 55wDa, 58wDa, 60wDa, 62wDa, 65wDa, 68wDa, 70wDa, 72wDa, 75wDa, 78wDa, 80wDa or a range consisting of any two of the above values.
  • the weight average molecular weight of the polymer can be tested by methods known in the art, such as gel chromatography, such as Waters 2695 Isocratic HPLC gel chromatograph (differential refractive index detector 2141).
  • Conventional sodium carboxymethyl cellulose is a solid polymer at room temperature. Sodium carboxymethyl cellulose is dissolved in solvent water with a mass content of 1%. After stirring at 1200 rpm for 2 hours, it is dried in an oven at, for example, 40°C for more than 24 hours to obtain a reference film with a width of 2.5 cm, a length of 5 cm, and a thickness of about 1 mm. The elongation at break of the reference film is tested, and the elongation at break of the reference film is defined as 100%. It should be noted that conventional sodium carboxymethyl cellulose refers to sodium carboxymethyl cellulose whose side chains are not substituted by other groups, especially the hydrogen atoms at the hydroxyl position are not substituted.
  • the polymer is prepared into a film, the polymer is dissolved in solvent water, the mass content of the polymer is 1%, and after stirring at 1200 rpm for 2 hours, it is dried in an oven, for example, at 40° C. for more than 24 hours to obtain a film, the width of the film is 2.5 cm, the length is 5 cm, and the thickness is about 1 mm; the elongation at break of the film is calculated by testing the elongation at break of the reference film as 100%, and the elongation at break of the film is 170% to 300%.
  • the thickness deviation of the film can be controlled within the range of 0.5%.
  • the elongation at break of the polymer is higher than that of conventional sodium carboxymethyl cellulose.
  • the polymer When the polymer is applied to the negative electrode plate, it has better flexibility and is not prone to breakage.
  • the elongation at break of the film may be 170%, 180%, 190%, 200%, 210%, 220%, 230%, 240%, 250%, 260%, 270%, 280%, 290%, 300% or a range consisting of any two of the above values.
  • the elongation at break of the film has a well-known meaning in the art and can be tested using equipment and methods known in the art. Specifically, the test can be performed with reference to the standard GB/T36363-2018.
  • an embodiment of the present application provides a method for preparing a polymer, the method comprising step S100 of alkalization treatment and step S200 of substitution treatment.
  • the alkalization treatment specifically includes: providing carboxymethyl cellulose salts, and subjecting the carboxymethyl cellulose salts to alkalization treatment with alkali to activate the hydroxyl sites of the carboxymethyl cellulose salts to form active reaction sites.
  • Carboxymethyl cellulose salts include compounds represented by formula (B),
  • M includes at least one of Li, Na or NH 4 ;
  • n represents the degree of polymerization of carboxymethyl cellulose salts.
  • the hydrogen atoms at the hydroxyl positions are activated.
  • sodium hydroxide NaOH or potassium hydroxide KOH is used for alkalization, and at least one hydrogen atom at the hydroxyl position in the carboxymethyl cellulose salt is activated.
  • Atom substitution for example, the hydrogen atoms at all hydroxyl positions of carboxymethyl cellulose salts are substituted by Na, and the intermediate product after substitution is a compound shown in formula (C),
  • the substitution treatment specifically includes: adding a substitution compound into the system to carry out a substitution reaction.
  • the substitution compound will replace the sodium Na atom at the hydroxyl position, and the product after substitution is a polymer, and the polymer is shown in the above formula (A).
  • the substituted compound includes at least one of a substituted or unsubstituted polyamide group and a substituted or unsubstituted polyester group.
  • the substituted compound includes a polyamide compound, wherein the polyamide compound includes a compound represented by formula (11):
  • R 11 includes at least one of a single bond, a substituted or unsubstituted C1 to C5 methylene group
  • R 12 to R 16 each independently include at least one of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkenyl group, and a substituted or unsubstituted C1 to C10 alkynyl group.
  • n includes any positive integer from 1 to 30.
  • the substituted compound includes a substituted or unsubstituted polyester group
  • the substituted or unsubstituted polyester group includes a compound represented by formula (21),
  • R 21 includes at least one of a single bond, a substituted or unsubstituted C1 to C5 methylene group
  • R 22 to and including substituted or unsubstituted C1-C5 alkyl
  • R 23 to R 25 each independently include at least one of a hydrogen atom, a halogen atom, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkenyl group, and a substituted or unsubstituted C1 to C10 alkynyl group.
  • s includes any positive integer from 1 to 30.
  • the reaction can be carried out under the reaction conditions commonly used in the art, and the molar ratio of each raw material can also be selected according to the molar ratio commonly used in the art.
  • the present application provides a dispersant, which includes a polymer as described in any embodiment of the first aspect of the present application or a polymer obtained by the preparation method described in any embodiment of the second aspect of the present application.
  • the dispersant can be used in the negative electrode film layer of the negative electrode plate.
  • the dispersant may also include carboxymethyl cellulose salts.
  • the ratio of the mass content of the carboxymethyl cellulose salt to the mass content of the polymer can be 0.5 to 2.
  • the mass content ratio of the carboxymethyl cellulose salt to the polymer is within the above range, it can work together with the polymer to improve the flexibility of the film formed by itself.
  • the ratio of the mass content of the carboxymethyl cellulose salt to the mass content of the polymer can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or a range consisting of any two of the above values.
  • the embodiment of the present application proposes a negative electrode plate, which includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a polymer as described in any embodiment of the first aspect of the present application or a polymer obtained by the preparation method described in any implementation of the second aspect of the present application.
  • the polymer can be used as a dispersant in the negative electrode film layer, which can make the negative electrode active material evenly dispersed in the negative electrode film layer, so that the performance of the negative electrode film layer is uniform, and the dispersant can also improve the flexibility of the negative electrode film layer and reduce the risk of cracking of the negative electrode film layer.
  • the negative electrode current collector has two surfaces opposite to each other in the thickness direction thereof, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the mass content of the polymer is 0.8% to 1.3%, optionally 1.0% to 1.3%, optionally 1.0% to 1.2%.
  • the mass content of the polymer is within the above range, it can effectively improve the performance uniformity and flexibility of the negative electrode film layer, and its proportion is relatively low, which basically does not affect the proportion of the negative electrode active material, thereby making the battery cell have a higher energy density.
  • the polymer can significantly improve The flexibility of the negative electrode film layer, etc., so no additives such as plasticizers need to be added to the negative electrode slurry, thereby reducing the adverse effects caused by the introduction of plasticizers.
  • the mass content of the polymer can be 0.8%, 0.85%, 0.9%, 1.00%, 1.01%, 1.02%, 1.03%, 1.04%, 1.05%, 1.06%, 1.07%, 1.08%, 1.09%, 1.10%, 1.11%, 1.12%, 1.13%, 1.14%, 1.15%, 1.16%, 1.17%, 1.18%, 1.19%, 1.2%, 1.3% or a range consisting of any two of the above values.
  • the negative electrode film layer may also include carboxymethyl cellulose salts, such as at least one of sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.
  • carboxymethyl cellulose salts such as at least one of sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.
  • the difference between this type of carboxymethyl cellulose salt and the above-mentioned polymer is that the hydroxyl groups in this type of carboxymethyl cellulose salt are not replaced, and the carboxymethyl cellulose salt can play a dispersing role together with the above-mentioned polymer, and on this basis, the polymer can also additionally improve the flexibility of the negative electrode film layer.
  • the mass content of the carboxymethyl cellulose salt can be 0.05% to 1.0%; optionally 0.05% to 0.3%.
  • the mass content of the carboxymethyl cellulose salt is within the above range, it can work together with the polymer to improve the performance uniformity and flexibility of the negative electrode film layer.
  • the mass content of carboxymethyl cellulose salts can be 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.3%, 0.35%, 0.4%, 0.42%, 0.45%, 0.46%, 0.48%, 0.50%, 0.52%, 0.55%, 0.56%, 0.58%, 0.60%, 0.62%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.70%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.80%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.90%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%, 0.99%, 0.91%, 0.99%, 0 6%, 0.68%, 0.70%,
  • the ratio of the mass content of the carboxymethyl cellulose salt to the mass content of the polymer can be 0.5 to 2.
  • the mass content ratio of the carboxymethyl cellulose salt to the polymer is within the above range, it can work together with the polymer to improve the performance uniformity and flexibility of the negative electrode film layer.
  • the ratio of the mass content of the carboxymethyl cellulose salt to the mass content of the polymer can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2 or a range consisting of any two of the above values.
  • the negative electrode active material may be a negative electrode active material for a battery cell known in the art.
  • the negative electrode active material may include but is not limited to at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.
  • the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.
  • the tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.
  • the negative electrode film layer may further include a negative electrode conductive agent.
  • a negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the mass percentage of the negative electrode conductive agent is ⁇ 5%.
  • the negative electrode film layer may also optionally include a negative electrode binder.
  • the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • SR-1B water-soluble unsaturated resin
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • CMCS carboxymethyl chitosan
  • the negative electrode film layer may also optionally include other additives.
  • other additives may include Including thickeners, for example, PTC thermistor materials, etc.
  • the mass percentage of the other additives is ⁇ 2%.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).
  • the negative electrode film layer is usually formed by coating the negative electrode slurry on the negative electrode current collector, drying and cold pressing.
  • the negative electrode slurry is usually formed by dispersing the negative electrode active material, polymer, optional conductive agent, optional binder, and other optional auxiliary agents in a solvent and stirring them uniformly.
  • the solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.
  • the negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer.
  • the negative electrode plate described in the embodiments of the present application further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode collector and the negative electrode film layer and disposed on the surface of the negative electrode collector.
  • the negative electrode plate described in the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.
  • the present application proposes a battery cell, the battery cell comprising a negative electrode sheet.
  • the negative electrode sheet comprises the negative electrode sheet of any embodiment of the fourth aspect of the present application, and the use of the negative electrode sheet can extend the dynamic performance of the battery cell.
  • the battery cell further includes a positive electrode tab.
  • the positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may include but is not limited to at least one of a lithium-containing transition metal oxide, a lithium-containing phosphate, and their respective modified compounds.
  • the lithium transition metal oxide may include but are not limited to at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.
  • lithium-containing phosphate may include but are not limited to at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon, and their respective modified compounds.
  • the positive electrode film layer includes a positive electrode active material
  • the positive electrode active material can be a positive electrode active material for a battery cell known in the art.
  • the positive electrode active material may include at least one of the following materials: a layered structure positive electrode active material (such as ternary, lithium nickelate/sodium, lithium cobaltate/sodium, lithium manganate/sodium, lithium/sodium-rich layered and rock salt phase layered materials), an olivine-type phosphate active material, a spinel structured positive electrode active material (such as spinel lithium manganate, spinel nickel lithium manganate, lithium-rich spinel lithium manganate, and lithium nickel lithium manganate, etc.).
  • a layered structure positive electrode active material such as ternary, lithium nickelate/sodium, lithium cobaltate/sodium, lithium manganate/sodium, lithium/sodium-rich layered and rock salt phase layered materials
  • an olivine-type phosphate active material such as spinel lithium manganate,
  • the general formula of the layered positive electrode active material is: LixAyNiaCobMncM (1-abc) Yz , wherein 0 ⁇ x ⁇ 2.1, 0 ⁇ y ⁇ 2.1, and 0.9 ⁇ x+y ⁇ 2.1; 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1 , 0 ⁇ c ⁇ 1, and 0.1 ⁇ a+b+c ⁇ 1; 1.8 ⁇ z ⁇ 3.5;
  • A is selected from one or more of Na, K, and Mg;
  • M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce;
  • Y is selected from one or more of O and F.
  • the layered structure positive active material may include one or more of lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), and LiNi 0.5 Co0.2 Mn 0.3 O 2 (NCM523).
  • the general formula of the olivine -type phosphate active material is: LixAyMeaMbP1 - cXcYz , wherein 0 ⁇ x ⁇ 1.3, 0 ⁇ y ⁇ 1.3, and 0.9 ⁇ x+y ⁇ 1.3; 0.9 ⁇ a ⁇ 1.5, 0 ⁇ b ⁇ 0.5, and 0.9 ⁇ a + b ⁇ 1.5; 0 ⁇ c ⁇ 0.5; 3 ⁇ z ⁇ 5;
  • A is selected from one or more of Na, K, and Mg;
  • Me is selected from one or more of Mn , Fe, Co, and Ni;
  • M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce;
  • X is selected from one or more of S, Si, Cl, B, C, and N; and Y is selected from one or more of
  • the general formula of the positive electrode active material with a spinel structure is: LixAyMnaM2 - aYz , wherein 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 1, and 0.9 ⁇ x+y ⁇ 2; 0.5 ⁇ a ⁇ 2; 3 ⁇ z ⁇ 5;
  • A is selected from one or more of Na, K, and Mg;
  • M is selected from one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is selected from one or more of O and F.
  • the positive electrode active material of the spinel structure includes one or more of LiMn 2 O 4 , LiNi 0.5 Mn 1.5 O 4 , LiCr 0.3 Mn 1.7 O 4 , Li 1.1 Al 0.1 Mn 1.9 O 4 , Li 2 Mn 2 O 4 , and Li 1.5 Mn 2 O 4 .
  • the modified compound of each positive electrode active material mentioned above may be a compound obtained by doping and/or surface coating the positive electrode active material.
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • tetrafluoroethylene-hexafluoropropylene copolymer tetrafluor
  • the positive electrode film layer may further include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the mass percentage of the conductive agent is ⁇ 5%.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the optional conductive agent, the optional binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the battery cell further includes an electrolyte.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.
  • the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl s
  • the electrolyte may further include additives, for example, the additives may include positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.
  • the battery cell further includes a separator.
  • the present application has no particular limitation on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer may be the same or different, without particular limitation.
  • the positive electrode sheet, the separator, and the negative electrode sheet may be formed into an electrode assembly by a winding process and/or a lamination process.
  • the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the battery cell may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).
  • FIG1 is a battery cell 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are combined to form a receiving cavity.
  • the shell 51 has an opening communicating with the receiving cavity.
  • the cover plate 53 is used to cover the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the separator can form an electrode assembly 52 through a winding process and/or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to needs.
  • the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell.
  • the positive electrode sheet, the separator and the negative electrode sheet can be formed into an electrode assembly through a winding process and/or a lamination process, and the electrode assembly is placed in an outer package, and the electrolyte is injected after drying, and the battery cell is obtained through vacuum packaging, standing, forming, shaping and other processes.
  • the battery cells according to the present application may be assembled into a battery module.
  • the battery module may contain multiple battery cells, and the specific number may be adjusted according to the application and capacity of the battery module.
  • FIG3 is a schematic diagram of an exemplary battery module 4.
  • a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.
  • the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.
  • FIG4 and FIG5 are schematic diagrams of a battery pack 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, wherein the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 may be arranged in the battery box in any manner.
  • the battery according to the embodiment of the present application may include one battery cell or a plurality of battery cells.
  • the battery may include a battery module or a battery pack.
  • the sixth aspect of the embodiments of the present application provides an electric device, which includes at least one of the battery cells, battery modules or battery packs of the present application.
  • the battery cells, battery modules or battery packs can be used as the power source of the electric device, and can also be used as the energy storage unit of the electric device.
  • the electric device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.
  • the electrical device may select a battery cell, a battery module or a battery pack according to its usage requirements.
  • Fig. 6 is a schematic diagram of an exemplary electric device 6.
  • the electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • the electric device may be a mobile phone, a tablet computer, a notebook computer, etc.
  • the electric device is usually required to be light and thin, and a battery cell may be used as a power source.
  • Aluminum foil with a thickness of 13 ⁇ m was used as the positive electrode current collector.
  • the positive electrode active material lithium cobalt oxide LiCoO 2 , the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are uniformly mixed in a proper amount of solvent N-methylpyrrolidone (NMP) at a mass ratio of 97.2:1.3:1.5 to obtain a positive electrode slurry; the positive electrode slurry is coated on a positive electrode current collector aluminum foil, and a positive electrode sheet is obtained through processes such as drying, cold pressing, slitting, and cutting.
  • NMP N-methylpyrrolidone
  • a copper foil with a thickness of 6 ⁇ m was used as the negative electrode current collector.
  • Artificial graphite as negative electrode active material, conductive carbon, adhesive styrene acrylic emulsion, and dispersant are mixed evenly in deionized water to prepare negative electrode slurry.
  • the mass ratio of artificial graphite, conductive carbon, adhesive styrene acrylic emulsion, and dispersant in the solid components of the negative electrode slurry is 96.7:0.7:1.5:1.1.
  • the negative electrode slurry is coated on the current collector copper foil and dried at 85°C and cold pressed to obtain a negative electrode sheet containing a negative electrode active material layer.
  • organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an electrolyte solvent, and then lithium salt lithium hexafluorophosphate and the mixed solvent are mixed, and the mass content of the lithium salt relative to the total mass of the electrolyte is 12.5%.
  • the positive electrode sheet, polyethylene PE separator (7 ⁇ m thickness), and negative electrode sheet are stacked and wound in order to obtain an electrode assembly; the electrode assembly is placed in an outer package, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a lithium-ion battery is obtained.
  • Example 1 The difference from Example 1 is that the type of dispersant in the negative electrode slurry is different.
  • Example 1 The difference from Example 1 is that the amount of dispersant added to the negative electrode slurry is different; specifically:
  • Example 3-1 the mass ratio of artificial graphite, conductive agent conductive carbon, binder styrene acrylic emulsion, and dispersant modified CMC-Na in the solid components of the negative electrode slurry is 96.8:0.7:1.5:1.0.
  • Example 3-2 the mass ratio of artificial graphite, conductive agent conductive carbon, binder styrene acrylic emulsion, and dispersant modified CMC-Na in the solid components of the negative electrode slurry is 96.6:0.7:1.5:1.2.
  • Example 3-3 the mass ratio of artificial graphite, conductive agent conductive carbon, binder styrene acrylic emulsion, and dispersant modified CMC-Na in the solid components of the negative electrode slurry is 96.5:0.7:1.5:1.3.
  • Example 3-4 the mass ratio of artificial graphite, conductive agent conductive carbon, binder styrene acrylic emulsion, dispersant modified CMC-Na, and CMC-Na in the solid components of the negative electrode slurry is 96.7:0.7:1.5:0.8:0.3.
  • Example 2 Different from Example 1, the molecular weight of the dispersant in the negative electrode slurry is different.
  • Example 1 The difference from Example 1 is that the cations of the dispersant in the negative electrode slurry are different.
  • Example 2 Different from Example 1, the grafting group of the dispersant in the negative electrode slurry is different;
  • the modified CMC-Na includes a first repeating unit and a second repeating unit of copolymerization.
  • the first repeating unit is formed by grafting modification of CMC by formula (1-11), and the degree of polymerization of the first repeating unit is 5.
  • the second repeating unit is formed by grafting modification of CMC by formula (2-11), and the degree of polymerization of the second repeating unit is 5.
  • the degree of polymerization of the modified CMC-Na can be considered to be the sum of the two repeating units, and the degree of polymerization of the modified CMC-Na is 10.
  • the modified CMC-Na includes a copolymerized first repeating unit and a second repeating unit, the first repeating unit is formed by grafting modification of CMC by formula (1-11), and the degree of polymerization of the first repeating unit is 5, the second repeating unit is formed by grafting modification of CMC by formula (1-24), and the degree of polymerization of the second repeating unit is 5.
  • the degree of polymerization of the modified CMC-Na can be considered to be the sum of the two repeating units, and the degree of polymerization of the modified CMC-Na is 10.
  • a dispersant is added to the negative electrode slurry, and the dispersant is replaced by sodium carboxymethyl cellulose.
  • the mass ratio of artificial graphite, conductive carbon, adhesive styrene acrylic emulsion, and dispersant CMC-Na in the solid components of the negative electrode slurry is 96.7:0.7:1.5:1.1.
  • a dispersant is added to the negative electrode slurry, the dispersant is replaced by sodium carboxymethyl cellulose, and a plasticizer is added to the negative electrode slurry, and the mass ratio of artificial graphite, conductive carbon, adhesive styrene acrylic emulsion, dispersant CMC-Na, and plasticizer butanediol in the solid components of the negative electrode slurry is 96.55:0.7:1.5:1.1:0.15.
  • the filter screen is 150 mesh and is cut into 25cm*25cm pieces with scissors.
  • the coating window measures the approximate critical range of the quality stability of the coated product. Exceeding this range will lead to defects such as cracking.
  • the coating is carried out using an extrusion coater at a speed of 50 m/min. As the coating quality of the negative electrode sheets of the comparative examples and the embodiments gradually improves, observe whether the film layer has cracks. If there are no cracks, continue to increase the weight until the film layer on the surface of the sheet cracks. Record the coating weight that the negative electrode film layer can bear without cracking, which is the coating weight of the negative electrode film layer in Table 1.
  • the battery DC impedance test process is as follows: at 25°C, the lithium ion batteries prepared in the examples and comparative examples are charged to 4.2V at a constant current of 1/3C, and then charged to a current of 0.05C at a constant voltage of 4.2V, and after standing for 5 minutes, the voltage V1 is recorded. Then, the battery is discharged at 1/3C for 30 seconds, and the voltage V2 is recorded. Then, (V2-V1)/(1/3C) is used to obtain the internal resistance DCR of the lithium ion battery.
  • the negative electrode slurry has no sedimentation and no gel, and the state of the negative electrode slurry is relatively stable.
  • a dispersant sodium carboxymethyl cellulose CMC-Na
  • Sodium carboxymethyl cellulose has not been modified by side chains. It is beneficial to improve the dispersion performance of negative electrode active materials in negative electrode slurry.
  • due to the hydrogen bonding effect of sodium carboxymethyl cellulose itself it is not conducive to thick coating of negative electrode slurry. Its coating weight is small, and in the process of drying the negative electrode slurry into a negative electrode film layer, it is easy to cause cracking of the negative electrode film layer.
  • Comparative Example 2 also adds a plasticizer to the negative electrode slurry.
  • the plasticizer can effectively improve the shaping ability and flexibility of the negative electrode film layer, which is beneficial to the thick coating of the negative electrode slurry.
  • the coating weight is improved and the cracking phenomenon of the negative electrode film layer can be improved.
  • the dispersant sodium carboxymethyl cellulose is modified by side chain grafting, which can reduce the hydrogen bonding effect of the dispersant, improve the flexibility of the negative electrode film layer, and reduce the cracking of the negative electrode film layer.
  • the grafted group contains at least one of nitrogen atoms and oxygen atoms, it is beneficial to improve the migration rate of lithium ions, reduce the impedance of the negative electrode film layer, and improve the dynamic performance of the lithium ion battery.
  • Example 1, Example 3-1 to Example 3-4 regulate the amount of dispersant added to the negative electrode slurry, which can effectively adjust the thickness of the negative electrode slurry and improve the flexibility and impedance of the negative electrode film layer.
  • the dispersant of Example 3-4 includes two types, one is the polymer (modified sodium carboxymethyl cellulose) of the present application, and the other is sodium carboxymethyl cellulose. Compared with Example 3-4, the amount of dispersant added in Example 1 is the same as that of the dispersant added in Example 3-4, but the coating performance of Example 1 and the performance of the lithium ion battery are significantly further improved.
  • the present application performs multiple tests on the negative electrode plate in Example 1. For example, ion polishing cross-sectional element analysis (CP) is performed at 10 locations of the negative electrode plate in accordance with GB/T17359-2012 to confirm the thickness of the negative electrode film layer in the negative electrode plate.
  • the thickness deviation of the negative electrode film layer obtained from the 10 tests is controlled within the range of 0.5%. It can be considered that the thickness of the negative electrode film layer in the negative electrode plate is uniform and the thickness consistency is high.
  • the present application adopts the method described in Example 1 to prepare 10 lithium-ion batteries, and measures the average thickness of the negative electrode film layer of each lithium-ion battery, that is, ion polishing cross-sectional element analysis (CP) is performed with reference to GB/T 17359-2012, and the thickness of the negative electrode film layer at 10 locations in the negative electrode sheet is measured, and the average value is calculated as the average thickness of the lithium-ion battery.
  • the thickness deviation of the negative electrode film layer of the 10 lithium-ion batteries is controlled within 0.5%.

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Abstract

本申请涉及一种聚合物、负极极片、电池和用电装置。所述聚合物包括改性羧甲基纤维素盐类，所述改性羧甲基纤维素盐类是羧甲基纤维素盐类中至少一个羟基的氢原子取代为接枝基团，所述接枝基团包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种。

Description

聚合物、负极极片、电池和用电装置
相关申请的交叉引用
本申请要求享有于2023年06月20日提交的名称为“聚合物、负极极片、电池和用电装置”的中国专利申请202310732524.9的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及一种聚合物、负极极片、电池和用电装置。
背景技术
电池单体具有工作性能可靠，以及无污染、无记忆效应等优点，因而被广泛应用。例如，随着环境保护问题日益受到重视，新能源汽车日益普及，动力型电池单体的需求将呈现爆发式增长。
随着电池应用范围越来越广泛，对电池性能的要求也逐渐严苛。但是，目前对于高速涂布以及厚涂布的强烈需求，使得在制备极片过程中，极片具有发生开裂的风险，导致极片性能无法满足生产需求。
发明内容
本申请提供一种聚合物、负极极片、电池和用电装置，本申请所述的电池的极片性能能够得到提升。
第一方面，本申请实施方式提出了一种聚合物，所述聚合物包括改性羧甲基纤维素盐类，所述改性羧甲基纤维素盐类是羧甲基纤维素盐类中至少一个羟基的氢原子取代为接枝基团，所述接枝基团包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种。
本申请实施方式的聚合物可以看作是改性羧甲基纤维素盐类，即通过对羧甲基纤维素盐类(CMC-M)的侧链进行接枝改性得到的聚合物，通过对羧甲基纤维素盐类的侧链接枝，接枝基团取代羟基中的氢原子，破坏羧甲基纤维素盐类中的羟基结构，从而破坏规整的氢键结构，减弱氢键作用；对羟基中的氢原子取代的基团包括聚酰胺类基团、聚酯基团等，该类基团即使形成氢键，如此形成的氢键作用比羧甲基纤维素盐自身形成的氢键作用更弱，从而能够降低聚合物分子链之间的作用力，提高聚合物网络的自由体积，促进聚合物分子链之间的相对运动，由此减少干燥时产生应力，并提升负极膜层的柔韧性，降低负极膜层发生开裂的风险，改善负极膜层的界面性能；另外，由于接枝基团包括杂原子例如氮原子、氧原子等，该类原子有利于活性离子例如锂离子、钠离子的传输，从而提高活性离子的传输速率，有利于提高负极膜层的电性能。而且聚合物由于主体结构仍为羧甲基纤维素盐类，故其仍具有较好的分散作用，能够有效降低负极活性材料和溶剂之间的界面张力，使得负极活性材料均匀分散于负极浆料中。
在一些实施方式中，所述聚合物包括式(A)所示的重复单元，
式(A)中，M包括Li、Na或NH4中的至少一种；
R1至R5各自独立地包括氢原子、取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，且R1和R5中的至少一者包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，其中，所述接枝基团包括R1至R5中的非氢原子基团；n表示所述改性羧甲基纤维素盐类的聚合度；可选地，n包括1500至3000的任一正整数。上述材质具有良好的分散性和较弱的氢键作用，有利于进一步提高聚合物应用于负极膜层中的柔性作用。
在一些实施方式中，接枝基团包括取代或未取代的聚酰胺类基团，所述取代或未取代的聚酰胺类基团包括式(1)所示结构式，
式(1)中，R11包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
R12至R16各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种；
m包括1至30中的任一正整数。
本申请实施方式的聚酰胺类基团接枝到羧甲基纤维素盐类的侧链，能够取代原有羟基位置上的氢原子，进而破坏羧甲基纤维素盐类规整的O-H-O氢键结构，形成新的N-H-O氢键结构，而N-H-O氢键结构比O-H-O氢键作用更弱，使得接枝改性后的羧甲基纤维素盐类的分子间作用力减弱，柔性增加，提升负极膜层的界面性能。并且强电负性元素氮元素能够与电池体系中的活性离子(例如锂离子或钠离子)形成络合作用，加快活性离子的传输速率，提升电池单体的动力学性能。
在一些实施方式中，接枝基团包括式(1-11)所示结构式至式(1-15)所示结构式中的至少一种，
在一些实施方式中，接枝基团包括式(1-21)所示结构式至式(1-24)所示结构式中的至少一种，
在一些实施方式中，接枝基团包括取代或未取代的聚酯基团，所述取代或未取代的聚酯基团包括式(2)所示结构式，
式(2)中，R21包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
R22包括取代或未取代的C1-C5烷基；
R23至R25各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种；
s包括1至30中的任一正整数。
由此，本申请实施方式的聚酯基团接枝到羧甲基纤维素盐类的侧链后，能够取代原有羟基位置上的氢原子，进而破坏羧甲基纤维素盐类规整的O-H-O氢键结构，减弱羧甲基纤维素盐类自身的氢键作用，使得接枝改性后的羧甲基纤维素盐类的分子间作用力减弱，柔性增加，提升负极膜层的界面性能。并且聚酯基团自身具有较好的柔性，在取代羟基位置后还能够进一步提升羧甲基纤维素盐类的柔性，由此提升负极膜层的界面性能。
在一些实施方式中，R21包括单键，R1至R5各自独立地包括式(2-1)所示结构式，
在一些实施方式中，R1至R5各自独立地包括式(2-11)所示结构式至式(2-16)所示结构式中的至少一种，

在一些实施方式中，R21包括取代或未取代的C1至C5亚甲基，R1至R5各自独立地包括式(2-2)所示结构式，
p包括1至5中的任一正整数。
在一些实施方式中，R1至R5各自独立地包括式(2-21)所示结构式至式(2-28)所示结构式中的至少一种，

在一些实施方式中，R1至R5的重均分子量小于等于2500Da；可选为71Da至2500Da。聚合物中的接枝基团的分子量相对较小，在降低聚合物分子链之间的氢键作用的同时，能够使得聚合物具有较好的分散性。
在一些实施方式中，所述聚合物的重均分子量为40wDa至80wDa。聚合物的重均分子量在上述范围时，可以使得聚合物具有优异的分散性能。
在一些实施方式中，以羧甲基纤维素钠制成的参照胶膜的断裂伸长率为100％，所述聚合物制成的胶膜的断裂伸长率为170％至300％，所述参照胶膜和聚合物制成的胶膜的宽度为2.5cm，长度为5cm，厚度为1mm。
由此，聚合物的断裂伸长率较常规羧甲基纤维素钠的断裂伸长率较高，聚合物在应用于负极极片时，其柔性较好，不易发生断裂。
第二方面，本申请还提出了一种分散剂，分散剂包括如本申请第一方面任一实施方式所述的聚合物。该分散剂可以用于负极极片的负极膜层中，降低负极膜层发生开裂的风险，改善负极膜层的界面性能；另外，由于接枝基团包括杂原子例如氮原子、氧原子等，该类原子有利于活性离子例如锂离子、钠离子的传输，从而提高活性离子的传输速率，有利于 提高负极膜层的电性能。
在一些实施方式中，分散剂还可以包括羧甲基纤维素盐类。
在一些实施方式中，羧甲基纤维素盐类的质量含量和聚合物的质量含量的比值可以为0.5至2。羧甲基纤维素盐类和聚合物的质量含量的比值和在上述范围时，其能够和聚合物共同作用，提升其自身所形成的胶膜的柔韧性。
第三方面，本申请还提出了一种负极极片，所述负极极片包括负极集流体和设置于所述负极集流体至少一个表面上的负极膜层，所述负极膜层包括如本申请第一方面任一实施方式所述的聚合物或第二方面任一实施方式的所述的分散剂。
在一些实施方式中，基于所述负极膜层的总质量计，所述聚合物的质量含量为1.0％至1.3％，可选为1.0％至1.2％。
在一些实施方式中，所述负极膜层的涂布克重为190mg/1540.25mm2至230mg/1540.25mm2；可选为200mg/1540.25mm2至230mg/1540.25mm2。负极膜层的涂布克重相对较高，有利于实现厚涂布。
第四方面，本申请还提出了一种电池，所述电池单体包括如本申请第三方面任一实施方式所述的负极极片。所述电池包括电池单体/电池模组和电池包。
第五方面，本申请实施方式还提出了一种用电装置，包括如本申请第四方面任一实施方式的所述的电池。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请的电池单体的一实施方式的示意图。
图2是图1的电池单体的实施方式的分解示意图。
图3是本申请的电池模块的一实施方式的示意图。
图4是本申请的电池包的一实施方式的示意图。
图5是图4所示的电池包的实施方式的分解示意图。
图6是包含本申请的电池单体作为电源的用电装置的一实施方式的示意图。
附图未必按照实际的比例绘制。
附图标记说明如下：
1、电池包；2、上箱体；3、下箱体；4、电池模块；
5、电池单体；51、壳体；52、电极组件；53、盖板；
6、用电装置。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的聚合物、负极极片、电池单体、电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技 术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
术语“聚酰胺类基团”是指聚丙烯酰胺的端基失去氢原子后形成的基团。
术语“聚酯基团”是指聚酯的端基失去氢原子后形成的基团。
术语“烷基”涵盖直链和支链烷基。例如，烷基可为C5-C100烷基、C1-C50烷基、C1-C40烷基、C1-C30烷基、C1-C20烷基、C1-C12烷基、C1-C10烷基、C1-C6烷基、C1-C5烷基、C1-C4烷基。在一些实施例中，烷基包括甲基、乙基、丙基、异丙基、丁基、异丁基、仲丁基、叔丁基、环丁基、戊基、异戊基、新戊基、叔戊基、环戊基、己基、环己基、庚基、环庚基、辛基、环辛基、壬基和癸基等。另外，烷基可以是任选地被取代的。术语“卤代烷基”是指烷基中，氢原子部分或全部被卤素原子所取代，术语“卤素原子”是指氟原子、氯原子、溴原子、碘原子等。
术语“亚甲基”是指同一个碳原子失去两个氢原子后的基团。例如，亚甲基可为C5-C500亚甲基、C20-C400亚甲基、C1-C50亚甲基、C1-C40亚甲基、C1-C30亚甲基、C1-C20亚甲基、C1-C12亚甲基、C1-C10亚甲基、C1-C6亚甲基、C1-C4亚甲基。在一些实施例中， 亚甲基包括亚甲基、亚乙基、亚丙基、亚丁基、异丁基、亚戊基、亚己基、亚庚基、亚辛基、亚壬基和亚癸基等。另外，亚甲基可以是任选地被取代的。术语“卤代亚甲基”是指亚甲基中，氢原子部分或全部被卤素原子所取代，术语“卤素原子”是指氟原子、氯原子、溴原子、碘原子等。
术语“氢”是指1H(氕，H)、2H(氘，D)或3H(氚，T)。在各实施例中，“氢”可以是1H(氕，H)。
在本说明书的各处，化合物的取代基以组或范围公开。明确地预期这种描述包括这些组和范围的成员的每一个单独的子组合。例如，明确地预期术语“C1-C8烷基”单独地公开C1、C2、C3、C4、C5、C6、C7、C8、C1-C8、C1-C7、C1-C6、C1-C5、C1-C4、C1-C3、C1-C2、C2-C8、C2-C7、C2-C6、C2-C5、C2-C4、C2-C3、C3-C8、C3-C7、C3-C6、C3-C5、C3-C4、C4-C8、C4-C7、C4-C6、C4-C5、C5-C8、C5-C7、C5-C6、C6-C8、C6-C7和C7-C8烷基。
作为其它实例，明确地预期范围为5-40的整数单独地公开5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20、21、22、23、24、25、26、27、28、29、30、31、32、33、34、35、36、37、38、39和40；明确地预期范围为1-20的整数单独地公开1、2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19和20。据此，可明确地预期其它组或范围。
当上述基团经取代时，取代基可独立地选自卤素原子或杂原子。
如本文所用，术语“聚合物”是指由多于十个单体单元组成的分子复合物并且通常包括但不限于均聚物、共聚物，例如嵌段、接枝、无规和交替共聚物、三元共聚物、和更高级的“x”聚体，进一步包括它们的类似物、衍生物、组合和混合物。此外，除非另有具体限制，术语“聚合物”应包括分子的所有可能的异构构型，包括但不限于全同立构、间同立构和随机对称及其组合。此外，除非另有具体限制，否则术语“聚合物”应包括分子的所有可能的几何构型。
负极极片包括负极集流体和设置于负极集流体至少一侧的负极膜层，负极膜层由负极浆料涂覆于负极集流体上干燥形成，负极浆料形成负极膜层的过程中可能会发生开裂等现象，导致负极膜层不满足生产要求。为了改善负极膜层开裂现象，相关技术在负极浆料中添加增塑剂例如丁二醇等，增塑剂通常为小分子化合物(其分子量相对较小)，增塑剂能够进入粘结剂聚合物分子链之间，降低粘结剂聚合物分子间应力，降低聚合物分子链的结晶度，由此提升负极膜层塑形和柔韧性，改善负极膜层开裂现象，但是残留的增塑剂容易导致负极膜层厚度不均匀，使得负极膜层出现暗痕、析出金属等界面问题。
鉴于上述问题，本申请实施方式提出了一种聚合物，该聚合物可以作为负极膜层中的分散剂，聚合物包括改性羧甲基纤维素盐类，即对羧甲基纤维素盐类进行接枝改性，使得聚合物具有较好的柔性，在应用于负极浆料时，能够对负极活性材料等起到分散作用，并能够对负极浆料起到增稠作用，改善负极膜层的柔韧性，改善负极膜层开裂现象。
聚合物
第一方面，本申请实施方式提出了一种聚合物，所述聚合物包括改性羧甲基纤维素盐类，所述改性羧甲基纤维素盐类是羧甲基纤维素盐类中至少一个羟基的氢原子取代为接枝基团，所述接枝基团包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至 少一种。
羧甲基纤维素盐类(CMC-M)是一类阴离子型水溶性纤维素醚化衍生物，在其应用于负极浆料时，能够降低负极活性材料和溶剂之间的界面张力，对负极活性材料等起到良好的分散作用，在搅拌作用下，有利于负极活性材料均匀分散于溶剂中形成稳定的浆料体系。
羧甲基纤维素盐类的分子链中富含羟基(-OH)，羟基的存在使得羧甲基纤维素盐类自身的分子链之间能够形成较强的范德华力或氢键，而且羧甲基纤维素盐类可能能够与负极活性材料等形成较强的范德华力或氢键，使得负极浆料在干燥过程中具有较强的干燥应力而发生翘曲，并在进一步过辊过程中可能会发生开裂，使得负极膜层发生开裂现象。
而本申请实施方式的聚合物可以看作是改性羧甲基纤维素盐类，即通过对羧甲基纤维素盐类(CMC-M)的侧链进行接枝改性得到的聚合物，通过对羧甲基纤维素盐类的侧链接枝，取代羟基中的氢原子，破坏羧甲基纤维素盐类中的羟基结构，从而破坏规整的氢键结构，减弱氢键作用；对羟基中的氢原子取代的基团包括聚酰胺类基团、聚酯基团等，该类基团即使形成氢键，如此形成的氢键作用比羧甲基纤维素盐自身形成的氢键作用更弱，从而能够降低聚合物分子链之间的作用力，提高聚合物网络的自由体积，促进聚合物分子链之间的相对运动，由此减少干燥时产生应力，并提升负极膜层的柔韧性，降低负极膜层发生开裂的风险，改善负极膜层的界面性能；另外，由于接枝基团包括杂原子例如氮原子、氧原子等，该类原子有利于活性离子例如锂离子、钠离子的传输，从而提高活性离子的传输速率，有利于提高负极膜层的电性能。而且聚合物由于主体结构仍为羧甲基纤维素盐类，故其仍具有较好的分散作用，能够有效降低负极活性材料和溶剂之间的界面张力，使得负极活性材料均匀分散于负极浆料中。由此，聚合物可以应用于负极浆料(或负极极片的负极膜层)中作为分散剂。
在一些实施方式中，改性羧甲基纤维素盐类可以包括改性羧甲基纤维素钾盐等。
在另一些实施方式中，改性羧甲基纤维素盐类可以包括改性羧甲基纤维素锂盐、改性羧甲基纤维素钠盐或改性羧甲基纤维素铵盐中的至少一种；具体地，改性羧甲基纤维素盐类包括式(A)所示的化合物，
式(A)中，M包括Li、Na或NH4中的至少一种；
R1至R5各自独立地包括氢原子、取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，且R1和R5中的至少一者包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，其中，所述接枝基团包括R1至R5中的非氢原子基团；n表示所述改性羧甲基纤维素盐类的聚合度。
上述材质具有良好的分散性和较弱的氢键作用，有利于进一步提高聚合物应用于负极 膜层中的柔性作用。
可选地，n包括1500至3000中的任一正整数。示例性地，n可以为1500、1600、1700、1800、1900、2000、2100、2200、2300、2400、2500、2600、2700、2800、2900或3000。
非氢原子基团表示不是氢原子基团，即R1至R5均取代羟基中的氢原子时，R1至R5可以认为均是接枝基团；若R1至R5中的其中一个，例如R1为氢原子，则R1并非接枝基团。
改性羧甲基纤维素盐类中的重复单元可以包括一种或多种，聚合物可以包括一种或多种改性羧甲基纤维素盐类。
需要说明的是，R1至R5中的至少一者包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，可以理解为聚合物中至少一个羟基被取代，即R1至R5中的至少一者不为氢原子，例如R1至R5中的其中四个为氢原子、或其中三个为氢原子、或其中两个为氢原子、其中一个为氢原子，甚至R1至R5可以均不为氢原子，随着氢原子数量的减少，意味着聚合物中被取代的羟基数量增多，被取代的羟基数量越多，聚合物分子链之间的作用力越小，负极浆料的干燥应力越小，负极膜层不易发生开裂等现象，其界面性能得到提升。在R1至R5可以均不为氢原子的情况下，聚合物的氢键作用较弱，聚合物分子链之间的作用较小，干燥应力明显下降，负极膜层不易发生开裂等现象，其界面性能得到提升。
聚酰胺类基团包括强电负性元素氮元素，在聚酰胺类基团接枝到羧甲基纤维素盐类的侧链后，能够取代原有羟基位置的氢原子进而破坏羧甲基纤维素盐类规整的O-H-O氢键结构，形成新的N-H-O氢键结构，而N-H-O氢键结构比O-H-O氢键作用更弱，使得接枝改性后的羧甲基纤维素盐类的分子间作用力减弱，柔性增加，提升负极膜层的界面性能。并且强电负性元素氮元素能够与电池体系中的活性离子(例如锂离子或钠离子)形成络合作用，加快活性离子的传输速率，提升电池单体的动力学性能。
在一些实施方式中，R1至R5各自独立地包括取代或未取代的聚酰胺类基团，所述取代或未取代的聚酰胺类基团包括式(1)所示结构式，
式(1)中，R11包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
R12至R16各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种。
可选地，上述基团经取代时，取代基可以包括卤素原子、羟基和羧基中的至少一种，其中卤素原子可以包括氟原子、氯原子、溴原子、碘原子中的至少一种。
m包括1至30中的任一正整数。
在一些实施方式中，m可以为1、2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20、21、22、23、24、25、26、27、28、29或30。
在一些实施方式中，R11包括单键，取代或未取代的聚酰胺类基团包括式(1-a)所示结构式，
示例性地，式(1-a)所示结构式包括式(1-11)所示结构式至式(1-15)所示结构式中的至少一种，
在一些实施方式中，R11包括取代或未取代的C1至C5亚甲基，取代或未取代的聚酰胺类基团包括式(1-b)所示结构式，
q包括1至5中的任一正整数。示例性地，q可以为1、2、3、4或5。
示例性地，式(1-b)所示结构式包括式(1-21)所示结构式至式(1-24)所示结构式中的至少一种，
聚酯基团接枝到羧甲基纤维素盐类的侧链后，能够取代原有羟基位置进而破坏羧甲基纤维素盐类规整的O-H-O氢键结构，减弱羧甲基纤维素盐类自身的氢键作用，使得接枝改性后的羧甲基纤维素盐类的分子间作用力减弱，柔性增加，提升负极膜层的界面性能；并且能够提升活性离子例如锂离子的迁移速率。并且聚酯基团自身具有较好的柔性，在取代羟基位置后还能够进一步提升羧甲基纤维素盐类的柔性，由此提升负极膜层的界面性能。
在一些实施方式中，R1至R5各自独立地包括取代或未取代的聚酯基团，所述取代或未取代的聚酯基团包括式(2)所示结构式，
式(2)中，R21包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
R22至包括取代或未取代的C1-C5烷基；
R23至R25各自独立地包括氢原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种。
可选地，上述基团经取代时，取代基可以包括卤素原子、羟基和羧基中的至少一种，其中卤素原子可以包括氟原子、氯原子、溴原子、碘原子中的至少一种。
s包括1至30中的任一正整数。
在一些实施方式中，s可以为1、2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20、21、22、23、24、25、26、27、28、29或30。
在一些实施方式中，R21包括单键，所述取代或未取代的聚酯基团包括式(2-1)所示结构式，
示例性地，R1至R5各自独立地包括式(2-11)所示结构式至式(2-16)所示结构式中的至少一种，

在一些实施方式中，R21包括取代或未取代的C1至C5亚甲基，R1至R5各自独立地包括式(2-2)所示结构式，
p包括1至5中的任一正整数。示例性地，p可以为1、2、3、4或5。
示例性地，R1至R5各自独立地包括式(2-21)所示结构式至式(2-28)所示结构式中的至少一种，

上述各实施方式中，卤素原子可以包括氟原子、氯原子、溴原子中的至少一者。上述原子能够提升聚合物的耐电压性。
上述各实施方式中，R1至R5的重均分子量小于等于2500Da；可选为71Da至2500Da。聚合物中的接枝基团的分子量相对较小，在降低聚合物分子链之间的氢键作用的同时，能够使得聚合物具有较好的分散性。
示例性地，R1至R5的重均分子量可以为71Da、78Da、80Da、85Da、90Da、95Da、100Da、120Da、150Da、180Da、200Da、220Da、250Da、280Da、300Da、320Da、350Da、380Da、400Da、450Da、500Da、600Da、700Da、800Da、900Da、1000Da、1100Da、1200Da、1300Da、1400Da、1500Da、1600Da、1700Da、1800Da、1900Da、2000Da、2100Da、2200Da、2300Da、2400Da、2500Da或是上述任意两个数值组成的范围。
在一些实施方式中，所述聚合物的重均分子量为40wDa至80wDa。聚合物的重均分子量在上述范围时，可以使得聚合物具有优异的分散性能。
示例性地，聚合物的重均分子量可以为40wDa、42wDa、45wDa、46wDa、48wDa、50wDa、52wDa、55wDa、58wDa、60wDa、62wDa、65wDa、68wDa、70wDa、72wDa、75wDa、78wDa、 80wDa或是上述任意两个数值组成的范围。
在本申请中，聚合物的重均分子量的测试可以选用本领域已知的方法进行测试，例如采用凝胶色谱法进行测试，如采用Waters2695IsocraticHPLC型凝胶色谱仪(示差折光检测器2141)进行测试。
常规羧甲基纤维素钠在常温下为固态聚合物，将羧甲基纤维素钠溶解于溶剂水中，羧甲基纤维素钠的质量含量为1％，于1200rpm下搅拌2h后于烘箱例如40℃下干燥24h以上，可以得到参照胶膜，参照胶膜的宽度为2.5cm，长度为5cm，厚度约为1mm；测试参照胶膜的断裂伸长率，将参照胶膜的断裂伸长率定义为100％。需要说明的是，常规羧甲基纤维素钠是指羧甲基纤维素钠的侧链未被其他基团进行取代，尤其是羟基位置的氢原子未被取代。
在一些实施方式中，将所述聚合物制备为胶膜，将聚合物溶解于溶剂水中，聚合物的质量含量为1％，于1200rpm下搅拌2h后于烘箱例如40℃下干燥24h以上，可以得到胶膜，胶膜的宽度为2.5cm，长度为5cm，厚度约为1mm；以参照胶膜的断裂伸长率100％测试计算胶膜的断裂伸长率，所述胶膜的断裂伸长率为170％至300％。在制备胶膜时，胶膜的厚度偏差可以控制在0.5％范围内。
由此，聚合物的断裂伸长率较常规羧甲基纤维素钠的断裂伸长率较高，聚合物在应用于负极极片时，其柔性较好，不易发生断裂。
示例性地，胶膜的断裂伸长率可以为170％、180％、190％、200％、210％、220％、230％、240％、250％、260％、270％、280％、290％、300％或是上述任意两个数值组成的范围。
在本申请中，胶膜的断裂伸长率为本领域公知的含义，可以采用本领域已知的设备和方法进行测试，具体可以参照标准GB/T36363-2018进行测试。
制备聚合物的方法
第二方面，本申请实施方式提出了一种制备聚合物的方法，所述方法包括步骤S100碱化处理和步骤S200取代处理。
在步骤S100中，碱化处理具体包括：提供羧甲基纤维素盐类，将羧甲基纤维素盐类通过碱进行碱化处理，以使羧甲基纤维素盐类的羟基位点进行活化，形成活性反应位点。
羧甲基纤维素盐类包括式(B)所示的化合物，
式(B)中，M包括Li、Na或NH4中的至少一种；
n表示羧甲基纤维素盐类的聚合度。
羧甲基纤维素盐类碱化处理后，其羟基位置的氢原子被活化，例如采用氢氧化钠NaOH或氢氧化钾KOH进行碱化处理，羧甲基纤维素盐类中至少一处羟基位置的氢原子被钠Na 原子取代，例如，羧甲基纤维素盐类的所有羟基位置的氢原子被Na取代，取代后的中间产物如式(C)所示的化合物，
在步骤S200中，取代处理具体包括：将取代化合物加入体系中进行取代反应。取代化合物将取代位于羟基位置的钠Na原子，取代后的产物即为聚合物，聚合物如上述式(A)所示。
取代化合物包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种。
在一些实施方式中，取代化合物包括聚酰胺类化合物，所述聚酰胺类化合物包括式(11)所示化合物，
式(11)中，
R11包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
至R12至R16各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种。
m包括1至30中的任一正整数。
在一些实施方式中，取代化合物包括取代或未取代的聚酯基团，所述取代或未取代的聚酯基团包括式(21)所示化合物，
式(21)中，
R21包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
R22至包括取代或未取代的C1-C5烷基；
R23至R25各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种。
s包括1至30中的任一正整数。
在制备聚合物中，可以在本领域常用的反应条件下进行反应，各原料的摩尔比也可以根据本领域常用的摩尔比进行选取。
分散剂
第三方面，本申请实施方式提出了一种分散剂，分散剂包括如本申请第一方面任一实施方式所述的聚合物或本申请第二方面任一实施所述的制备方法得到的聚合物。该分散剂可以用于负极极片的负极膜层中。
在一些实施方式中，分散剂还可以包括羧甲基纤维素盐类。
在一些实施方式中，羧甲基纤维素盐类的质量含量和聚合物的质量含量的比值可以为0.5至2。羧甲基纤维素盐类和聚合物的质量含量的比值和在上述范围时，其能够和聚合物共同作用，提升其自身所形成的胶膜的柔韧性。
示例性地，羧甲基纤维素盐类的质量含量和聚合物的质量含量的比值可以为0.5、0.6、0.7、0.8、0.9、1、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9、2或是上述任意两个数值组成的范围。
负极极片
第四方面，本申请实施方式提出了一种负极极片，负极极片包括负极集流体和设置于所述负极集流体至少一个表面上的负极膜层，所述负极膜层包括如本申请第一方面任一实施方式所述的聚合物或本申请第二方面任一实施所述的制备方法得到的聚合物。聚合物可以用作负极膜层中的分散剂，能够使得负极活性材料均匀分散于负极膜层中，使得负极膜层的性能均一，且分散剂还能够提升负极膜层的柔韧性，降低负极膜层开裂的风险。例如，所述负极集流体具有在自身厚度方向相对的两个表面，所述负极膜层设置在所述负极集流体的两个相对表面中的任意一者或两者上。
在一些实施方式中，基于所述负极膜层的总质量计，所述聚合物的质量含量为0.8％至1.3％，可选为1.0％至1.3％，可选为1.0％至1.2％。聚合物的质量含量在上述范围时，能够有效提升负极膜层的性能均一性和柔韧性，且其占比相对较低，基本不会对负极活性材料的占比造成影响，从而使得电池单体具有较高的能量密度。而且由于聚合物能够显著改善 负极膜层的柔韧性等，故负极浆料中可以不添加增塑剂等助剂，由此能够降低由于引入增塑剂带来的不利影响。
示例性地，聚合物的质量含量可以为0.8％、0.85％、0.9％、1.00％、1.01％、1.02％、1.03％、1.04％、1.05％、1.06％、1.07％、1.08％、1.09％、1.10％、1.11％、1.12％、1.13％、1.14％、1.15％、1.16％、1.17％、1.18％、1.19％、1.2％、1.3％或是上述任意两个数值组成的范围。
在一些实施方式中，负极膜层还可以包括羧甲基纤维素盐类，例如羧甲基纤维素钠、羧甲基纤维素钾、羧甲基纤维素锂等中的至少一种，该类羧甲基纤维素盐类和上述聚合物的区别在于，该类羧甲基纤维素盐类中的羟基未被取代，羧甲基纤维素盐类能够和上述聚合物共同发挥分散作用，且在此基础上，聚合物还能够额外改善负极膜层的柔韧性。
在一些实施方式中，基于负极膜层的总质量计，羧甲基纤维素盐类的质量含量可以为0.05％至1.0％；可选为0.05％至0.3％。羧甲基纤维素盐类的质量含量在上述范围时，其能够和聚合物共同作用，改善负极膜层的性能均一性和柔韧性等。
示例性地，羧甲基纤维素盐类的质量含量可以为0.05％、0.10％、0.15％、0.20％、0.25％、0.3％、0.35％、0.4％、0.42％、0.45％、0.46％、0.48％、0.50％、0.52％、0.55％、0.56％、0.58％、0.60％、0.62％、0.65％、0.66％、0.68％、0.70％、0.72％、0.75％、0.78％、0.80％、0.82％、0.85％、0.86％、0.88％、0.9％、0.91％、0.92％、0.93％、0.94％、0.95％、0.96％、0.97％、0.98％、0.99％、1.00％或是上述任意两个数值组成的范围。
在一些实施方式中，羧甲基纤维素盐类的质量含量和聚合物的质量含量的比值可以为0.5至2。羧甲基纤维素盐类和聚合物的质量含量的比值和在上述范围时，其能够和聚合物共同作用，改善负极膜层的性能均一性和柔韧性等。
示例性地，羧甲基纤维素盐类的质量含量和聚合物的质量含量的比值可以为0.5、0.6、0.7、0.8、0.9、1、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9、2或是上述任意两个数值组成的范围。
所述负极活性物质可采用本领域公知的用于电池单体的负极活性物质。作为示例，所述负极活性物质可包括但不限于天然石墨、人造石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂中的至少一种。所述硅基材料可包括单质硅、硅氧化物、硅碳复合物、硅氮复合物和硅合金材料中的至少一种。所述锡基材料可包括单质锡、锡氧化物和锡合金材料中的至少一种。
在一些实施方式中，所述负极膜层还可选地包括负极导电剂。本申请实施方式对所述负极导电剂的种类没有特别的限制，作为示例，所述负极导电剂可包括超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的至少一种。在一些实施方式中，基于所述负极膜层的总重量，所述负极导电剂的质量百分含量为≤5％。
在一些实施方式中，所述负极膜层还可选地包括负极粘结剂。本申请实施方式对所述负极粘结剂的种类没有特别的限制，作为示例，所述负极粘结剂可包括丁苯橡胶(SBR)、水溶性不饱和树脂SR-1B、水性丙烯酸类树脂(例如，聚丙烯酸PAA、聚甲基丙烯酸PMAA、聚丙烯酸钠PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)和羧甲基壳聚糖(CMCS)中的至少一种。在一些实施方式中，基于所述负极膜层的总重量，所述负极粘结剂的质量百分含量为≤5％。
在一些实施方式中，所述负极膜层还可选地包括其他助剂。作为示例，其他助剂可包 括增稠剂，例如，PTC热敏电阻材料等。在一些实施方式中，基于所述负极膜层的总重量，所述其他助剂的质量百分含量为≤2％。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铜箔。所述复合集流体可包括高分子材料基层以及形成于所述高分子材料基层至少一个表面上的金属材料层。作为示例，所述金属材料可包括铜、铜合金、镍、镍合金、钛、钛合金、银和银合金中的至少一种。作为示例，所述高分子材料基层可包括聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)和聚乙烯(PE)中的至少一种。
所述负极膜层通常是将负极浆料涂布于负极集流体上，经干燥、冷压而成的。所述负极浆料通常是将负极活性物质、聚合物、可选的导电剂、可选的粘结剂、其他可选的助剂分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水，但不限于此。
所述负极极片并不排除除了所述负极膜层之外的其他附加功能层。例如在某些实施例中，本申请实施方式所述的负极极片还包括夹在所述负极集流体和所述负极膜层之间、设置在所述负极集流体表面的导电底涂层(例如由导电剂和粘结剂组成)。在另外一些实施例中，本申请实施方式所述的负极极片还包括覆盖在所述负极膜层表面的保护层。
电池单体
第五方面，本申请提出了一种电池单体，所述电池单体包括负极极片。负极极片包括本申请第四方面任一实施方式的负极极片，由于采用该负极极片，能够延长电池单体的动力学性能等。
[正极极片]
在一些实施方式中，电池单体还包括正极极片。
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，正极膜层包括正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，当本申请的电池单体为锂离子电池时，所述正极活性材料可包括但不限于含锂过渡金属氧化物、含锂磷酸盐及其各自的改性化合物中的至少一种。所述锂过渡金属氧化物的示例可包括但不限于锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其各自的改性化合物中的至少一种。所述含锂磷酸盐的示例可包括但不限于磷酸铁锂、磷酸铁锂与碳的复合材料、磷酸锰锂、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料及其各自的改性化合物中的至少一种。
所述正极膜层包括正极活性材料，所述正极活性材料可采用本领域公知的用于电池单体的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：层状结构正极活性材料(例如三元、镍酸锂/钠、钴酸锂/钠、锰酸锂/钠、富锂/钠层状和岩盐相层状等材料)、橄榄石型磷酸盐活性材料、尖晶石结构的正极活性材料(例如尖晶石锰酸锂、尖晶石镍锰酸锂、富锂的尖晶石锰酸锂和镍锰酸锂等)。
示例性地，层状结构正极活性材料的通式为：LixAyNiaCobMncM(1-a-b-c)Yz，其中，0≤x≤2.1，0≤y≤2.1，且0.9≤x+y≤2.1；0≤a≤1，0≤b≤1，0≤c≤1，且0.1≤a+b+c≤1；1.8≤z≤3.5；A选自Na、K、Mg中的一种或几种；M选自B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Fe、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；Y选自O、F中的一种或几种。可选地，y＝0。具体地，层状结构正极活性材料可以包括钴酸锂LCO、镍酸锂LNO、锰酸锂LMO、LiNi1/3Co1/3Mn1/3O2(NCM333)、LiNi0.8Co0.1Mn0.1O2(NCM811)和LiNi0.5Co0.2Mn0.3O2(NCM523)中的一种或多种。
示例性地，橄榄石型磷酸盐活性材料的通式为：LixAyMeaMbP1-cXcYz，其中，0≤x≤1.3，0≤y≤1.3，且0.9≤x+y≤1.3；0.9≤a≤1.5，0≤b≤0.5，且0.9≤a+b≤1.5；0≤c≤0.5；3≤z≤5；A选自Na、K、Mg中的一种或几种；Me选自Mn、Fe、Co、Ni中的一种或几种；M选自B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；X选自S、Si、Cl、B、C、N中的一种或几种；Y选自O、F中的一种或几种。具体地，橄榄石型磷酸盐活性材料包括LiFePO4、LiMnPO4、LiNiPO4、和LiCoPO4中的一种或多种。
示例性地，尖晶石结构的正极活性材料的通式为：LixAyMnaM2-aYz，其中，0≤x≤2，0≤y≤1，且0.9≤x+y≤2；0.5≤a≤2；3≤z≤5；A选自Na、K、Mg中的一种或几种；M选自Ni、Co、B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Fe、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；Y选自O、F中的一种或几种。具体地，尖晶石结构的正极活性材料包括LiMn2O4、LiNi0.5Mn1.5O4、LiCr0.3Mn1.7O4、Li1.1Al0.1Mn1.9O4、Li2Mn2O4和Li1.5Mn2O4中的一种或多种。
在本申请中，上述各正极活性材料的改性化合物可以是对所述正极活性材料进行掺杂改性和/或表面包覆改性。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。在一些实施方式中，基于所述正极膜层的总重量，粘结剂的质量百分含量为≤5％。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。在一些实施方式中，基于所述正极膜层的总重量，导电剂的质量百分含量为≤5％。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、可选的导电剂、可选的粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[电解液]
在一些实施方式中，电池单体还包括电解液。
在电池单体充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出，电解液在正极极片和负极极片之间起到传导活性离子的作用。本申请对电解液的种类没有特别的限制，可根据实际需求进行选择。
所述电解液包括电解质盐和溶剂。所述电解质盐和所述溶剂的种类不受具体的限制，可根据实际需求进行选择。
作为示例，所述电解质盐可包括但不限于六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、高氯酸锂(LiClO4)、六氟砷酸锂(LiAsF6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO2F2)、二氟二草酸磷酸锂(LiDFOP)和四氟草酸磷酸锂(LiTFOP)中的至少一种。
作为示例，所述溶剂可包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸乙烯酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)和二乙砜(ESE)中的至少一种。
在一些实施方式中，所述电解液中还可选地包括添加剂。例如，所述添加剂可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温功率性能的添加剂等。
[隔离膜]
在一些实施方式中，电池单体还包括隔离膜。
本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可包括玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，所述正极极片、所述隔离膜和所述负极极片可通过卷绕工艺和/或叠片工艺制成电极组件。
在一些实施方式中，所述电池单体可包括外包装。该外包装可用于封装上述电极组件及电解液。
在一些实施方式中，所述电池单体的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。所述电池单体的外包装也可以是软包，例如袋式软包。所述软包的材质可以是塑料，如聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)和聚丁二酸丁二醇酯(PBS)中的至少一种。
本申请对电池单体的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图1是作为一个示例的方形结构的电池单体5。
在一些实施方式中，如图2所示，外包装可包括壳体51和盖板53。壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口， 盖板53用于盖设所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺和/或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔。电解液浸润于电极组件52中。电池单体5所含电极组件52的数量可以为一个或多个，可根据需求来调节。
本申请的电池单体的制备方法是公知的。在一些实施方式中，可将正极极片、隔离膜、负极极片和电解液组装形成电池单体。作为示例，可将正极极片、隔离膜、负极极片经卷绕工艺和/或叠片工艺形成电极组件，将电极组件置于外包装中，烘干后注入电解液，经过真空封装、静置、化成、整形等工序，得到电池单体。
在本申请的一些实施方式中，根据本申请的电池单体可以组装成电池模块，电池模块所含电池单体的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图3是作为一个示例的电池模块4的示意图。如图3所示，在电池模块4中，多个电池单体5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池单体5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个电池单体5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图4和图5是作为一个示例的电池包1的示意图。如图4和图5所示，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2用于盖设下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
本申请实施方式的电池可以包括一个电池单体或多个电池单体，在电池包括多个电池单体的情况下，电池可以包括电池模块或者电池包。
用电装置
本申请实施方式第六方面提供一种用电装置，所述用电装置包括本申请的电池单体、电池模块或电池包中的至少一种。所述电池单体、电池模块或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
所述用电装置可以根据其使用需求来选择电池单体、电池模块或电池包。
图6是作为一个示例的用电装置6的示意图。该用电装置6为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置6对高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该用电装置通常要求轻薄化，可以采用电池单体作为电源。
实施例
下述实施方式更具体地描述了本申请公开的内容，这些实施方式仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施方式中所报道的所有份、百分比和比值都是基于质量计，而且实施 方式中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施方式中使用的仪器均可商购获得。
实施例和对比例锂离子电池的制备
1、正极极片的制备
采用厚度为13μm的铝箔作为正极集流体。
将正极活性材料钴酸锂LiCoO2、导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按照质量比97.2:1.3:1.5在适量的溶剂N-甲基吡咯烷酮(NMP)中混合均匀，得到正极浆料；将正极浆料涂布于正极集流体铝箔上，通过烘干、冷压、分条、裁切等工序，得到正极极片。
2、负极极片的制备
采用厚度为6μm的铜箔作为负极集流体。
将作为负极活性物质的人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂在去离子水中混合均匀，制成负极浆料。负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂的质量比为96.7:0.7:1.5:1.1。将负极浆料涂布在集流体铜箔上并在85℃下烘干、冷压后得到含有负极活性物质层的负极极片。
3、电解液的制备
在含水量小于10ppm的环境下，将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按体积比1:1:1进行混合得到电解液溶剂，随后将锂盐六氟磷酸锂和混合后的溶剂混合，锂盐相对于电解液总质量的质量含量为12.5％。
4、锂离子电池的制备
将正极极片、聚乙烯PE隔离膜(7μm厚度)、负极极片按顺序堆叠并卷绕，得到电极组件；将电极组件置于外包装中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，得到锂离子电池。
实施例2-1至实施例2-5
与实施例1不同的是，负极浆料中分散剂的种类不同。
实施例3-1至实施例3-4
与实施例1不同的是，负极浆料中分散剂的添加量不同；具体地：
实施例3-1中，负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂改性CMC-Na的质量比为96.8:0.7:1.5:1.0。
实施例3-2中，负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂改性CMC-Na的质量比为96.6:0.7:1.5:1.2。
实施例3-3中，负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂改性CMC-Na的质量比为96.5:0.7:1.5:1.3。
实施例3-4中，负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂改性CMC-Na、CMC-Na的质量比为96.7:0.7:1.5:0.8:0.3。
实施例4-1至实施例4-4
与实施例1不同的是，负极浆料中分散剂的分子量不同。
实施例5-1至实施例5-2
与实施例1不同的是，负极浆料中分散剂的阳离子不同。
实施例6-1至实施例6-2
与实施例1不同的是，负极浆料中分散剂的接枝基团不同；
实施例6-1中，改性CMC-Na包括共聚的第一重复单元和第二重复单元，第一重复单元为CMC经式(1-11)接枝改性形成，第一重复单元的聚合度为5，第二重复单元为CMC经式(2-11)接枝改性形成，第二重复单元的聚合度为5，改性CMC-Na的聚合度可以认为是两种重复单元的加和，改性CMC-Na的聚合度为10。
实施例6-2中，改性CMC-Na包括共聚的第一重复单元和第二重复单元，第一重复单元为CMC经式(1-11)接枝改性形成，第一重复单元的聚合度为5，第二重复单元为CMC经式(1-24)接枝改性形成，第二重复单元的聚合度为5，改性CMC-Na的聚合度可以认为是两种重复单元的加和，改性CMC-Na的聚合度为10。
对比例1
与实施例1不同的是，负极浆料中添加分散剂，分散剂替换为羧甲基纤维素钠，负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂CMC-Na的质量比为96.7:0.7:1.5:1.1。
对比例2
与实施例1不同的是，负极浆料中添加分散剂，分散剂替换为羧甲基纤维素钠，且负极浆料中添加增塑剂，负极浆料的固体成分中人造石墨、导电剂导电碳、粘接剂苯丙乳液、分散剂CMC-Na、增塑剂丁二醇的质量比为96.55:0.7:1.5:1.1:0.15。
实施例和对比例的相关参数如表1所示。
测试部分
1、负极浆料过滤性测试：
过滤网150目，将过滤网用剪刀剪成25cm*25cm。
将150目过滤网折成扇形悬空固定于干净烧杯杯口之上，取负极浆料500mL从过滤网上面全部倒入，从滤网尖端开始流出负极浆料，开始记录时间。记录300mL过滤时间。
2、负极浆料凝胶及沉降状态：
取负极浆料500ml，放置不同时间观察负极浆料是否出现果冻凝胶状态，并且测试其浆料粘度，若测试烧杯上层浆料粘度下降，且下层浆料变稠，则说明出现浆料沉降。
3、负极膜层的涂布克重：
涂布窗口衡量涂布产品的质量稳定性的大致临界范围，超过此范围则导致开裂等缺陷。采用挤压涂布机并以50m/min速度进行涂布，随着对比例和实施例的负极极片涂布质量逐渐质量，观察膜层有无开裂情况，如果没有开裂，继续增加重量，直至极片表面膜层产生开裂，记录负极膜层的所能负载的不开裂涂布重量，即为表1中负极膜层的涂布克重。
4、锂离子电池的直流阻抗测试
电池直流阻抗测试过程如下：在25℃下，将实施例和对比例制备的锂离子电池，分别以1/3C恒流充电至4.2V，再以4.2V恒定电压充电至电流为0.05C，搁置5min后，记录电压V1。然后再以1/3C放电30s，记录电压V2，则(V2-V1)/(1/3C)，得到锂离子电池的内阻DCR。
测试结果
测试结果如表1所示
表1
上述各实施例和对比例，经凝胶及沉降测试，负极浆料无沉降，无凝胶，负极浆料的状态相对稳定。
由表1可知，对比例1在负极浆料中添加有分散剂羧甲基纤维素钠CMC-Na，该羧甲 基纤维素钠并未经过侧链改性，其在负极浆料中有利于提升负极活性物质的分散性能，但是由于羧甲基纤维素钠自身存在的氢键作用，不利于负极浆料的厚涂布，其涂布克重较小，且负极浆料干燥为负极膜层的过程中，容易导致负极膜层发生开裂等问题。
相较于对比例1，对比例2在负极浆料中还添加有增塑剂，增塑剂能够有效改善负极膜层塑形能力和柔韧性，有利于负极浆料的厚涂布，其涂布克重得到提升，并能够改善负极膜层开裂现象；但是经过测试发现，添加有增塑剂的负极膜层，负极膜层的厚度不均匀，且负极膜层的阻抗较高。
而本申请实施例在负极浆料中并未添加增塑剂，但是对分散剂羧甲基纤维素钠进行了侧链接枝改性，能够降低分散剂的氢键作用，提升负极膜层的柔性性能，降低负极膜层发生开裂等问题；并且由于接枝基团包含氮原子和氧原子中的至少一者，有利于锂离子迁移速率的提升，降低负极膜层的阻抗，提升锂离子电池的动力学性能。实施例1、实施例3-1至实施例3-4对负极浆料中的分散剂的添加量进行调控，能够有效调节负极浆料的厚涂布程度，并改善负极膜层的柔韧性和阻抗等。实施例3-4的分散剂包括两类，一类为本申请的聚合物(改性羧甲基纤维素钠)，另一类为羧甲基纤维素钠，相较于实施例3-4，实施例1的分散剂的添加量和实施例3-4的分散剂的添加量相同，但是实施例1的涂布性能和锂离子电池的性能明显有进一步改善。
本申请对实施例1中的负极极片进行多处检测，例如取负极极片的10处参照GB/T17359-2012进行离子抛光断面元素分析(CP)，确认负极极片中负极膜层的厚度，10处测试得到的负极膜层的厚度偏差控制在0.5％范围内，可以认为负极极片中负极膜层的厚度均匀，厚度一致性较高。
本申请采用实施例1所述的方法制备10个锂离子电池，对每个锂离子电池测定其负极膜层的平均厚度，即参照GB/T 17359-2012进行离子抛光断面元素分析(CP)，测定负极极片中10处的负极膜层的厚度，计算其平均值作为该锂离子电池的平均厚度，10个锂离子电池的负极膜层的厚度偏差控制为0.5％范围内。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (15)

  1. 一种聚合物，所述聚合物包括改性羧甲基纤维素盐类，所述改性羧甲基纤维素盐类是羧甲基纤维素盐类中至少一个羟基的氢原子取代为接枝基团，所述接枝基团包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种。
  2. 根据权利要求1所述的聚合物，所述改性羧甲基纤维素盐类包括式(A)所示的化合物，
    式(A)中，M包括Li、Na或NH4中的至少一种；
    R1至R5各自独立地包括氢原子、取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，且R1和R5中的至少一者包括取代或未取代的聚酰胺类基团、取代或未取代的聚酯基团中的至少一种，其中，所述接枝基团包括R1至R5中的非氢原子基团；
    n表示所述改性羧甲基纤维素盐类的聚合度；可选地，n包括1500至3000的任一正整数。
  3. 根据权利要求1或2所述的聚合物，其中，所述接枝基团包括取代或未取代的聚酰胺类基团，所述取代或未取代的聚酰胺类基团包括式(1)所示结构式，
    式(1)中，R11包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
    R12至R16各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种；
    m包括1至30中的任一正整数。
  4. 根据权利要求1至3中任一项所述的聚合物，其中，所述接枝基团包括式(1-11)所示结构式至式(1-15)所示结构式中的至少一种，
    和/或
    所述接枝基团包括式(1-21)所示结构式至式(1-24)所示结构式中的至少一种，

  5. 根据权利要求1至4中任一项所述的聚合物，其中，所述接枝基团包括取代或未取代的聚酯基团，所述取代或未取代的聚酯基团包括式(2)所示结构式，
    式(2)中，R21包括单键、取代或未取代的C1至C5亚甲基中的至少一种；
    R22包括取代或未取代的C1-C5烷基；
    R23至R25各自独立地包括氢原子、卤素原子、取代或未取代的C1至C10烷基、取代或未取代的C1至C10烯基、取代或未取代的C1至C10炔基中的至少一种；
    s包括1至30中的任一正整数。
  6. 根据权利要求5所述的聚合物，其中，R21包括单键，R1至R5各自独立地包括式(2-1)所示结构式，
    可选地，R1至R5各自独立地包括式(2-11)所示结构式至式(2-16)所示结构式中的至少一种，
  7. 根据权利要求5所述的聚合物，其中，R21包括取代或未取代的C1至C5亚甲基，R1至R5各自独立地包括式(2-2)所示结构式，
    p包括1至5中的任一正整数；
    可选地，R1至R5各自独立地包括式(2-21)所示结构式至式(2-28)所示结构式中的至少一种，
  8. 根据权利要求2至7中任一项所述的聚合物，其中，R1至R5的重均分子量小于等于2500Da；可选为71Da至2500Da。
  9. 根据权利要求1至8中任一项所述的聚合物，其中，所述聚合物的重均分子量为40wDa至80wDa。
  10. 根据权利要求1至9中任一项所述的聚合物，其中，
    以羧甲基纤维素钠制成的参照胶膜断裂伸长率为100％，所述聚合物制成的胶膜的断裂 伸长率为170％至300％，所述聚合物制成的胶膜和参照胶膜的宽度为2.5cm，长度为5cm，厚度为1mm。
  11. 一种负极极片，包括负极集流体和设置于所述负极集流体至少一个表面上的负极膜层，所述负极膜层包括如权利要求1至10中任一项所述的聚合物。
  12. 根据权利要求11所述的负极极片，其中，基于所述负极膜层的总质量计，所述聚合物的质量含量为1.0％至1.3％，可选为1.0％至1.2％。
  13. 根据权利要求11或12所述的负极极片，其中，所述负极膜层的涂布克重为190mg/1540.25mm2至230mg/1540.25mm2；可选为200mg/1540.25mm2至230mg/1540.25mm2。
  14. 一种电池，包括如权利要求11至13中任一项所述的负极极片。
  15. 一种用电装置，包括如权利要求14所述的电池。
PCT/CN2024/072543 2023-06-20 2024-01-16 聚合物、负极极片、电池和用电装置 Ceased WO2024259966A1 (zh)

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