Adhesive, negative pole piece and electrochemical energy storage device

Abstract

The invention belongs to the technical field of batteries, and particularly relates to an adhesive, a negative pole piece and an electrochemical energy storage device. The adhesive provided by the invention comprises a polymer formed by a first monomer, a second monomer and other polymerizable monomers, the first monomer is unsaturated alkane or unsaturated aromatic hydrocarbon or unsaturated carboxylic ester with a cyclic ether structure, and the cyclic ether structure contains a plurality of oxygen; and the second monomer is selected from one or two of a vinyl hydrocarbon monomer and an ethylenically unsaturated carboxylic ester monomer. The binding agent provided by the invention is beneficial to improving the dynamic performance of the electrochemical energy storage device.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and particularly to an adhesive, a negative electrode sheet and an electrochemical energy storage device Background Art

[0002] Secondary batteries are widely used in various consumer electronic products and electric vehicles due to their outstanding characteristics such as light weight, pollution-free, and no memory effect. Among them, lithium-ion batteries are very widely used in the fields of portable electronic devices, electric vehicles, etc

[0003] With the increasingly wide application range of secondary batteries, the market not only has higher and higher requirements for the improvement of the energy density of lithium-ion batteries, but also pays more and more attention to their kinetic functions including fast charging

[0004] There are many factors affecting the rate performance of lithium-ion batteries, and the adhesive is one of them. The adhesive is the main carrier that connects the electrode active material, the lithium-conducting agent and the electrode current collector. By making the components inside the electrode integral, a stable electrode structure is formed to reduce the impedance of the electrode

[0005] At present, water-soluble adhesives represented by polyacrylic acid (PAA), styrene-butadiene rubber (SBR) or carboxymethyl cellulose (CMC) are widely used in negative electrode materials. PAA is an amorphous polymer with a chain-like cross-linked structure, and it has better adhesion uniformity and flexibility with the negative electrode material. SBR is usually polymerized from butadiene and styrene monomers. To improve its ionic conductivity, other functional monomers are also selected during preparation. CMC has good hydrophilicity, but it is brittle. The prior art discloses the combined use of CMC and SBR to improve the mechanical properties of the adhesive. Therefore, the performance of the existing water-soluble adhesives still needs to be improved Summary of the Invention

[0006] In view of the above problems, the present invention provides an adhesive, a negative electrode sheet and an electrochemical energy storage device. The adhesive provided by the present invention is beneficial to improving the kinetic performance of the electrochemical energy storage device

[0007] The first aspect of the present invention is to provide an adhesive, which comprises a polymer formed by a first monomer, a second monomer and other polymerizable monomers. The first monomer is an unsaturated alkane or unsaturated aromatic hydrocarbon or unsaturated carboxylic acid ester having a cyclic ether structure, and the cyclic ether structure contains multiple oxygen atoms

[0008] The second monomer is selected from one or two of vinyl hydrocarbon monomers and ethylenically unsaturated carboxylic acid ester monomers

[0009] The first monomer in the binder of the present application has a cyclic ether structure, which not only exhibits a small charge transfer resistance but also facilitates the transport of lithium ions. The second monomer has a certain adhesiveness, which is beneficial to improving the adhesion between the binder and other substances in the negative electrode sheet. The addition of other polymerizable monomers is conducive to adjusting the adsorption between the polymer and the solvent and improving the flexibility of the polymer. Therefore, a flexible binder with good adhesiveness is finally prepared in the present application. This flexible binder with good adhesiveness is beneficial to improving the kinetic performance of the electrochemical energy storage device.

[0010] In some embodiments, the cyclic ether structure is selected from C2-C20 cycloalkanes containing two or more oxygen atoms;

[0011] The cycloalkane is any one of a monocyclic ring, a fused ring, and a spiro ring.

[0012] In some embodiments, the cyclic ether structure has the following general formula:

[0013]

[0014] In the general formula (I-1), n1, n2, n3, n4, and n5 each independently selected from 0, 1, 2, or 3;

[0015] X 1 、X 2 、X 3 、X 4 、X 5 each independently selected from CH 2 or O.

[0016] In some embodiments, the cyclic ether structure has any one of the following structural formulas:

[0017]

[0018] In some embodiments, the first monomer has any one of the following general formulas:

[0019]

[0020] In the general formula, m is selected from 0, 1, 2, 3, 4, or 5;

[0021] R 1 is selected from hydrogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C5-C10 aryl, substituted or unsubstituted C5-C10 heteroaryl, halogen, or cyano;

[0022] R 2Selected from substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl;

[0023] R 3 Selected from substituted or unsubstituted C2-C10 alkenyl;

[0024] Preferably, m is selected from 1, 2, 3 or 4;

[0025] Preferably, R 1 is selected from hydrogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl.

[0026] Preferably, R 2 is selected from substituted or unsubstituted C2-C10 alkenyl.

[0027] In some embodiments, the cyclic ether structure is selected from fused rings containing two or more oxygen atoms, such as:

[0028] etc.

[0029] In some embodiments, the cyclic ether structure has the following general formula:

[0030]

[0031] In the general formula (I-2), n6, n7, n8, n9, n6’, n7’, n8’, n9’ are each independently selected from 0, 1, 2 or 3;

[0032] X 6 、X 7 、X 8 、X 9 、X 6 ’、X 7 ’、X 8 ’、X 9 ’ are each independently selected from CH 2 or O;

[0033] Preferably, the cyclic ether structure has any one of the following structural formulas:

[0034]

[0035] In some embodiments, the first monomer has the following general formula:

[0036]

[0037] In the general formula (II-3), R 4 、R 4 ’ are each independently selected from substituted or unsubstituted C2-C10 alkenyl.

[0038] In some embodiments, based on the total mass of the polymer, the mass percentages of each monomer are as follows:

[0039] The first monomer: 5 wt% to 95 wt%;

[0040] The second monomer: 5 wt% to 95 wt%;

[0041] Other polymerizable monomers: 0.1 wt% to 15 wt%;

[0042] Preferably, the mass percentage of the first monomer is 10 wt% to 90%;

[0043] Preferably, the mass percentage of the second monomer is 10 wt% to 90%;

[0044] Preferably, the mass percentage of the other polymerizable monomers is 0.1 wt% to 10%.

[0045] In some embodiments, the ethylenically unsaturated carboxylate monomer is an acrylate monomer, and the acrylate monomer includes an alkyl acrylate and / or an alkyl methacrylate monomer;

[0046] Preferably, the acrylate monomer includes any one or a combination of two or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acrylate, isooctyl acrylate, and octyl methacrylate;

[0047] and / or;

[0048] The vinyl hydrocarbon monomer includes any one or a combination of two or more of vinyl benzene monomers and C5-C10 linear or branched olefins;

[0049] Preferably, the vinyl benzene monomers include any one or a combination of two or more of styrene, α-methylstyrene, and sodium styrene sulfonate;

[0050] and / or;

[0051] The other polymerizable monomers include any one or a combination of two or more of monoethylenically unsaturated carboxyl monomers, monoethylenically unsaturated ether monomers, monoethylenically unsaturated nitrile monomers, or monoethylenically unsaturated amide monomers;

[0052] Preferably, the other polymerizable monomers include any one or a combination of two or more of acrylamide, N-hydroxymethylacrylamide, acrylic acid, and methacrylic acid.

[0053] In some embodiments, the second monomer comprises a mixture of a vinyl hydrocarbon monomer and an ethylenically unsaturated carboxylic acid ester monomer, and the mass ratio of the vinyl hydrocarbon monomer to the ethylenically unsaturated carboxylic acid ester monomer is 1:

[0054] (0.5 to 2), preferably 1:(0.5 to 1.5).

[0055] In some embodiments, the other polymerizable monomer comprises a mixture of acrylic acid and methacrylic acid,

[0056] In some embodiments, the adhesive comprises latex particles formed from a polymer and a solvent;

[0057] Preferably, the particle size of the latex particles ≤ 1000 nm;

[0058] Preferably, the solid content of the adhesive is 10% to 60%;

[0059] Preferably, the solvent comprises water.

[0060] In the present invention, the particle size distribution can be directly measured using a particle size analyzer. For example, in the present invention, a certain amount of the emulsion is placed in a beaker, and after standing for several minutes, first visually check whether there is precipitation at the bottom of the beaker, then pick up the emulsion with a glass rod and observe whether there is a uniformly dispersed liquid on the glass rod. Finally, take a small amount of the sample, dilute it, and use a particle size analyzer produced by Zhuhai Omic Instrument Co., Ltd. to measure the particle size and its distribution of the emulsion.

[0061] In the present invention, the solid content has any conventional meaning in the art, which includes the ratio of the mass of the solid matter in the emulsion to the total mass. The test methods for the solid content include any conventional forms in the art, such as the drying method, the combustion method, etc.

[0062] The water in the present invention includes but is not limited to deionized water.

[0063] The second aspect of the present invention is to provide a method for preparing a polymer, comprising: mixing a first monomer, a second monomer, other polymerizable monomers, an initiator, and a solvent, and then reacting, controlling the reaction temperature to be 50 °C to 95 °C, and reacting for 1 h to 12 h to obtain the polymer;

[0064] Preferably, based on the total mass of the polymer, the mass percentage of the initiator is 0.05% to 5%.

[0065] Preferably, the method further includes adjusting the pH value of the reaction mixture to neutral.

[0066] In some embodiments, the initiator is one or two of an organic peroxide or an inorganic peroxide.

[0067] In some embodiments, the initiator includes, but is not limited to, at least one of ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide (BPO), lauroyl peroxide (LPO), lauroyl peroxide, dicumyl peroxide, tert-butyl peroxybenzoate, or tert-butyl peroxy pivalate, and preferably at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0068] In some embodiments, an alkaline substance is used to adjust the pH value of the mixture to 5-9, preferably 7-9.

[0069] In some embodiments, the alkaline substance includes, but is not limited to, an inorganic strong base or an inorganic weak base, and preferably an aqueous solution of lithium hydroxide.

[0070] The third aspect of the present invention is to provide a negative electrode plate, which includes a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector, and the binder described in the second aspect is included in the negative electrode film.

[0071] In some embodiments of the present invention, based on the total mass of the negative electrode film, the mass percentage of the binder is 0.5%-3.0%, preferably 1.0%-2.5%.

[0072] In some embodiments of the present invention, the negative electrode film further includes a negative electrode active material, a conductive agent, a dispersant, etc.

[0073] In some embodiments of the present invention, the negative electrode active material includes a carbonaceous material, and the carbonaceous material includes one or a combination of two or more of artificial graphite, natural graphite, soft carbon, and hard carbon. Among them, artificial graphite, natural graphite, soft carbon, hard carbon, etc. include any conventional form of materials in the art, and include any conventional manufacturers and models in the art. At the same time, the negative electrode active material may also include a silicon-based material, and the silicon-based material includes one or two of a silicon-oxygen material or a silicon-carbon material. In addition, the negative electrode active material may also include a silicon-carbon composite, a Li-Sn alloy, a Li-Sn-O alloy, Sn, SnO, SnO 2 、TiO 2 -Li 4 Ti 5 O 12 、Li-Al alloy. However, the present invention is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for lithium ion batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0074] In some embodiments of the present invention, the negative electrode current collector can be a metal foil or a composite current collector. The metal foil can be a copper foil, and the composite current collector can include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy on a substrate of a polymer material such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0075] In some embodiments of the present invention, based on the total mass of the negative electrode film, the mass percentage content of the conductive agent is 0.2% to 2.0%. The conductive agent includes but is not limited to one or a combination of two or more of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0076] In some embodiments of the present invention, based on the total mass of the negative electrode film, the mass percentage content of the dispersant is 0.2% to 2.0%. The dispersant includes but is not limited to cellulose and its salts, specifically, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, etc.

[0077] The fourth aspect of the present invention is to provide an electrochemical energy storage device, including the binder described in the first aspect or the binder prepared by the preparation method described in the second aspect or the negative electrode sheet described in the third aspect.

[0078] In some embodiments of the present invention, the electrochemical energy storage device includes any one or two or more of a lithium-ion battery, a sodium-ion battery, a supercapacitor, a fuel cell, or a solar cell.

[0079] In some embodiments of the present invention, the electrochemical energy storage device includes a lithium-ion battery.

[0080] In some embodiments of the present invention, the lithium-ion battery further includes a positive electrode sheet, a separator, an electrolyte, etc. Among them, the positive electrode active material in the positive electrode sheet includes but is not limited to LiCoO 2 、LiNiO 2 、LiMnO 2 、LiMn 2 O 4 、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6 CO 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 CO 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.85 CO 0.15 Al 0.05 O 2 , LiFePO 4 (LFP) and LiMnPO 4 One or more of the above. The separator is located between the positive electrode plate and the negative electrode plate, and any well-known porous separator with good chemical stability and mechanical stability can be selected. For example, the material of the separator may include, but is not limited to, one or more combinations of the following group: glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without any particular limitation. The electrolyte is used to conduct ions between the positive electrode plate and the negative electrode plate. The electrolyte includes an electrolyte salt and a solvent. Among them, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluorooxalate phosphate. The solvent may include at least one selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone, or an ether solvent such as triethylene glycol dimethyl ether, etc.

[0081] The electrical device using the electrochemical energy storage device provided by the present invention as a power source may include, but is not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys may include stationary or mobile electric toys. For example, game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc. The spacecraft may include airplanes, rockets, space shuttles, and spaceships, etc.

[0082] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are hereinafter given. Specific Embodiments

[0083] The compounds and derivatives provided in the present invention can be named according to the IUPAC (International Union of Pure and Applied Chemistry) or CAS (Chemical Abstracts Service, Columbus, OH) nomenclature system.

[0084] "Substituted" means that a hydrogen atom in a molecule is replaced by other different atoms or molecules. The "substituted" is selected from hydrogen, halogen, cyano, nitro, C1-C20 straight-chain or branched-chain alkyl, C1-C20 straight-chain or branched-chain alkoxy, C2-C20 straight-chain or branched-chain alkenyl, C2-C20 straight-chain or branched-chain alkynyl, C6-C20 aryl, C6-C20 heteroaryl, C3-C20 heterocyclic group

[0085] The minimum and maximum carbon atom contents in a hydrocarbon group are indicated by a prefix. For example, the prefix Ca~b alkyl indicates any alkyl containing "a" to "b" carbon atoms. Thus, for example, "C1~4 alkyl" means an alkyl containing 1 to 4 carbon atoms.

[0086] "Alkyl" refers to a saturated hydrocarbon chain having a specified number of member atoms. For example, C1-C6 alkyl refers to an alkyl group having 1 to 6 member atoms, such as 1 to 4 member atoms. The alkyl group can be straight-chain or branched-chain. Representative branched-chain alkyl groups have one, two, or three branches. The alkyl group can be optionally substituted with one or more substituents as defined herein. Alkyl includes methyl, ethyl, propyl (n-propyl and isopropyl), butyl (n-butyl, isobutyl, and tert-butyl), pentyl (n-pentyl, isopentyl, and neopentyl), and hexyl. "C3-C12 alkyl" should be understood to preferably represent a straight-chain or branched-chain saturated monovalent hydrocarbon group having 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms. The alkyl is, for example, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl, or 1,2-dimethylbutyl, etc. or their isomers. In particular, the group has 4, 5, 6, 7, 8 carbon atoms ("C4-C8 alkyl"), such as butyl, isopropyl, pentyl, hexyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-ethylhexyl, etc. The alkyl group can also be part of other groups, such as C1-C6 alkoxy.

[0087] "Alkenyl" refers to a straight-chain or branched-chain hydrocarbon group having 2 to 10 carbon atoms and in some embodiments 2 to 6 carbon atoms or 2 to 4 carbon atoms and having at least 1 vinyl unsaturation site (>C=C<). For example, (Ca-Cb) alkenyl refers to an alkenyl group having a to b carbon atoms and is intended to include, for example, vinyl, propenyl, isopropenyl, 1,3-butadienyl, etc.

[0088] "Alkynyl" refers to a straight-chain monovalent hydrocarbon group or a branched-chain monovalent hydrocarbon group containing at least one triple bond. The term "alkynyl" is also intended to include those hydrocarbon groups having one triple bond and one double bond. For example, (C2-C6) alkynyl is intended to include ethynyl, propynyl, etc.

[0089] "Halogen" is fluorine, chlorine, bromine, or iodine.

[0090] "Heterocycle", "heterocyclic group", "heterocycloalkyl", "heterocycloalkane" refer to a saturated ring or a non-aromatic unsaturated ring containing at least one heteroatom; wherein the heteroatom includes but is not limited to a nitrogen atom, an oxygen atom, a sulfur atom.

[0092] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The ranges defined in this way can include or exclude the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" are fully listed herein, and "0 to 5" is only an abbreviated representation of these numerical combinations. In addition, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0093] If there is no special instruction, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0094] If there is no special instruction, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0095] If there is no special instruction, all steps of the present invention can be carried out in sequence or randomly, and preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0096] If there is no special instruction, the "including" and "comprising" mentioned in the present invention mean open-ended or can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0097] Unless otherwise specified, in the present invention, the term "or" is inclusive. For example, 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 present) and B is false (or absent); A is false (or absent) while B is true (or present); or both A and B are true (or present).

[0098] Example 1

[0099] A method for preparing an adhesive is provided, comprising the following steps:

[0100] 1) Prepare each monomer compound: the first monomer 2 - vinyl - 1,3 - dioxolane (20 wt%), styrene (48 wt%), ethyl acrylate (30 wt%), and acrylic acid (2 wt%).

[0101] 2) Add 50 parts by mass of the above - mentioned mixed monomers to 200 parts by mass of deionized water, add 0.25 part by mass of ammonium persulfate, react at 70 °C for 6 h, and adjust the pH value to 7.0 with a 10% lithium hydroxide solution after the reaction to obtain the adhesive.

[0102] The present invention also discloses that the first monomer is an unsaturated alkane or unsaturated aromatic hydrocarbon having a cyclic ether structure. Although not specifically listed in Table 1 below, it should actually be within the protection scope of the present invention.

[0103] Except for using the monomers and contents in Table 1, Examples 2 - 7 are prepared according to the same method as Example 1.

[0104] Table 1 Adhesive List

[0105]

[0106] Comparative Example 1

[0107] The difference from Example 1 is that the first monomer does not have a cyclic ether structure and is methyl acrylate.

[0108] Comparative Example 2

[0109] The difference from Example 1 is that the cyclic ether structure contains a single oxygen atom and is tetrahydrofurfuryl acrylate.

[0110] Comparative Example 3

[0111] The difference from Example 1 is that the first monomer is not included.

[0112] Comparative Example 4

[0113] A water - based binder is provided, which is a commercially available SBR binder (AL series of Aigelong, Japan).

[0114] Comparative Example 5

[0115] Provide an aqueous binder, which is a commercially available PAA binder (Research One AONE).

[0116] Comparative Example 6

[0117] Provide an aqueous binder, which is a commercially available PAN binder (Research One BAP-G1501).

[0118] Application Example

[0119] 1. Provide a negative electrode plate, which includes a current collector (Cu foil) and a negative electrode film layer disposed on the current collector. The material of the negative electrode film layer includes a negative electrode active material (graphite, BETRAY New Energy Materials Co., Ltd.), a conductive agent (carbon black SP), a binder, and a thickening agent (sodium carboxymethyl cellulose CMC). The binders are the aqueous binders provided in Examples 1 to 10 and Comparative Examples 1 to 6 respectively.

[0120] The preparation method of the negative electrode plate is as follows: Mix the negative electrode active material, the conductive agent, the binder, and the thickening agent according to a mass ratio of 96.5:1.0:1.0:1.5, add deionized water according to a proportion of 40 wt% of the system solid content, stir and mix well to form a uniform negative electrode slurry. After passing through a 100-mesh sieve, coat it on the negative electrode current collector Cu foil, then dry it, and roll it with a roller at a unit length load of 10×10 4 N / m to obtain the negative electrode plate.

[0121] 2. Provide a secondary battery, which includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. The negative electrode plate is the aforementioned negative electrode plate, and the preparation method is as follows:

[0122] (1) Preparation of the positive electrode plate: Mix the positive electrode active material (lithium iron phosphate material, BETRAY S13), conductive carbon black, and binder (PVDF) according to a mass ratio of 96.5:2.0:2.5 based on the solid content, add N-methylpyrrolidone (NMP) according to a proportion of 50 wt% of the system solid content, stir and mix well to form a uniform positive electrode slurry. After passing through a 100-mesh sieve, coat it on the positive electrode current collector Al foil, then dry it, and roll it with a roller at a unit length load of 10×10 4 N / m to obtain the positive electrode plate;

[0123] (2) Negative electrode plate: As described above;

[0124] (3) Separator: Use a PE porous polymer film (Shenzhen Xingyuan Material Technology Co., Ltd.) as the separator;

[0125] (4) Assembly of secondary battery: The positive electrode sheet, separator, and negative electrode sheet are wound in sequence to obtain an electrode core; the electrode core is encapsulated with an aluminum-plastic film, baked to remove water, and then electrolyte is injected. After vacuum packaging, standing, formation, secondary sealing, shaping and other processes, a secondary battery is obtained.

[0126] Performance test:

[0127] ① Battery internal resistance - Performance test of battery DC pulse resistance (DCR):

[0128] First, at 25 °C, the battery prepared above is discharged at a constant current of 0.5C to 2.75V, left standing for 5 min, charged at a constant current of 0.5C for 1 h (adjusting the SOC to 50%), the battery with the adjusted SOC of 50% is left standing at 25 °C for 5 min, discharged at a constant current of 4C for 30 s, left standing for 5 min, and the initial voltage V0 and the voltage V1 after 30 s of discharge are recorded. The calculation formula for the discharge DC internal resistance at 50% SOC is as follows:

[0129] DCR (mΩ) = (V0 - V1) / 4C discharge current × 1000.

[0130] ② Battery rate performance:

[0131] At 25 °C, the lithium-ion battery after initial adjustment is charged at a constant current of 0.5C to 4.2V, then charged at a constant voltage until the cut-off current of 0.02C, left standing for 5 min, then discharged at a constant current of 1C to 2.5V, left standing for 5 min, and the 1C discharge capacity is measured. Then it is charged at a constant current of 0.5C to 4.2V, then charged at a constant voltage until the cut-off current of 0.02C, left standing for 5 min, then discharged at a constant current of 3C to 2.5V, left standing for 5 min, and the discharge capacity at the 3C rate is measured.

[0132] 3C capacity retention rate (%) = 100% × 3C discharge capacity / 1C discharge capacity.

[0133] The performance test results of Examples 1 - 7 and Comparative Examples 1 - 6 are shown in Table 2 below.

[0134] Table 2 List of secondary battery performance

[0135] Internal resistance (25°C, Ω) Capacity retention rate at 3C (25°C, %) Example 1 1.67 96.49 Example 2 3.15 94.38 Example 3 2.17 95.45 Example 4 1.22 98.14 Example 5 1.11 98.75 Example 6 1.67 96.49 Example 7 1.67 96.49 Comparative Example 1 4.34 92.40 Comparative Example 2 4.32 92.50 Comparative Example 3 4.38 92.10 Comparative Example 4 6.96 88.30 Comparative Example 5 4.50 91.40 Comparative Example 6 4.36 92.20

[0136] Combined with the list, it can be seen that the binder provided by this application is beneficial to improving the kinetic performance of the electrochemical energy storage device.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered within the scope of the claims and the specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. An adhesive, characterized in that: it comprises a polymer formed from a first monomer, a second monomer and other polymerizable monomers, the first monomer being an unsaturated alkane or unsaturated aromatic hydrocarbon or unsaturated carboxylic acid ester having a cyclic ether structure, the cyclic ether structure containing a plurality of oxygen atoms; the second monomer is selected from one or two of vinyl hydrocarbon monomers and ethylenically unsaturated carboxylic acid ester monomers.

2. The adhesive according to claim 1, characterized in that: the cyclic ether structure is selected from C2-C20 cycloalkanes containing two or more oxygen atoms; the cycloalkane is any one of a monocyclic, fused ring, or spiro ring.

3. The adhesive according to claim 1 or 2, characterized in that: the cyclic ether structure has the following general formula: in the general formula (I-1), n1, n2, n3, n4, n5 are each independently selected from 0, 1, 2 or 3; X 1 , X 2 , X 3 , X 4 , X 5 Each independently selected from CH 2 or O; preferably, the cyclic ether structure has any one of the following structural formulas:

4. The adhesive according to claim 3, characterized in that: the first monomer has any one of the following general formulas: in the general formula (II-1), m is selected from 0, 1, 2, 3, 4 or 5; R 1 selected from hydrogen, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C2-C10 alkynyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C5-C10 aryl group, a substituted or unsubstituted C5-C10 heteroaryl group, a halogen or a cyano group; R 2 selected from substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl; In the general formula (II-2), R 3 is selected from substituted or unsubstituted C2-C10 alkenyl; preferably, m is selected from 1, 2, 3 or 4; Preferably, R 1 is selected from hydrogen, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C2-C10 alkenyl group; Preferably, R 2 is selected from substituted or unsubstituted C2-C10 alkenyl.

5. The adhesive according to claim 1 or 2, characterized in that: the cyclic ether structure has the following general formula: in the general formula (I-2), n6, n7, n8, n9, n6’, n7’, n8’, n9’ are each independently selected from 0, 1, 2 or 3; X 6 、 X 7 、 X 8 、 X 9 、 X 6 ’、 X 7 ’、 X 8 ’、 X 9 ’ are each independently selected from CH 2 or O; preferably, the cyclic ether structure has any one of the following structural formulas:

6. The adhesive according to claim 5, characterized in that: the first monomer has the following general formula: In the general formula (II-3), R 4 , R 4 ' are each independently selected from substituted or unsubstituted C2-C10 alkenyl.

7. The adhesive according to claim 1 or 2 or 4 or 6, characterized in that: based on the total mass of the polymer, the mass percentages of each monomer are as follows: First monomer: 4.9 wt% - 95 wt%; Second monomer: 4.9 wt% - 95 wt%; Other polymerizable monomers: 0.1% wt - 15 wt%; Preferably, the mass percentage of the first monomer is 10 w% - 90%; Preferably, the mass percentage of the second monomer is 10 w% - 90%; Preferably, the mass percentage of the other polymerizable monomers is 0.1 w% - 10%.

8. The adhesive according to claim 1 or 2 or 4 or 6, characterized in that: the ethylenically unsaturated carboxylic acid ester monomers are acrylate monomers, and the acrylate monomers include acrylic acid alkyl esters and / or methacrylic acid alkyl esters monomers; preferably, the acrylate monomers include any one or a combination of two or more of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, amyl acrylate, amyl methacrylate, hexyl acrylate, hexyl methacrylate, octyl acrylate, isooctyl acrylate, and octyl methacrylate; and / or; the vinyl hydrocarbon monomers include any one or a combination of two or more of vinyl benzene monomers and C5-C10 straight-chain or branched-chain olefins; Preferably, the vinylbenzene monomer includes any one or a combination of two or more of styrene, α-methylstyrene, and sodium styrene sulfonate; and / or; The other polymerizable monomer includes any one or a combination of two or more of monoethylenically unsaturated carboxyl monomers, monoethylenically unsaturated ether monomers, monoethylenically unsaturated nitrile monomers, or monoethylenically unsaturated amide monomers; Preferably, the other polymerizable monomer includes any one or a combination of two or more of acrylamide, N-methylolacrylamide, acrylic acid, and methacrylic acid.

9. The adhesive according to claim 1 or 2 or 4 or 6, characterized in that: The adhesive contains latex particles formed by a polymer and a solvent; Preferably, the particle size of the latex particles ≤ 1000 nm; Preferably, the solid content of the adhesive is 10% to 60%; Preferably, the solvent contains water.

10. A method for preparing an adhesive, characterized in that: comprising: Mixing a first monomer, a second monomer, other polymerizable monomers, an initiator, and a solvent and then reacting, controlling the reaction temperature to be 50°C to 95°C, and reacting for 1 h to 12 h to obtain the polymer; Preferably, based on the total mass of the polymer, the mass percentage of the initiator is 0.05% to 5%. Preferably, the method further includes adjusting the pH value of the reaction mixture to neutral.

11. A negative electrode plate, characterized in that: comprising a negative electrode current collector and a negative electrode film provided on at least one surface of the negative electrode current collector, and the negative electrode film includes the adhesive according to any one of claims 1 to 9 or the adhesive prepared by the preparation method according to claim 10; Preferably, based on the total mass of the negative electrode film, the mass percentage of the adhesive is 0.5% to 3.0%, preferably 1.0% to 2.5%.

12. An electrochemical energy storage device, characterized in that, comprising the adhesive according to any one of claims 1 to 9 or the adhesive prepared by the preparation method according to claim 10 or the negative electrode plate according to claim 11; Preferably, the electrochemical energy storage device includes any one or two or more of a lithium ion battery, a sodium ion battery, a supercapacitor, a fuel cell, or a solar cell; Preferably, the electrochemical energy storage device includes a lithium ion battery.

Images