Preparation method of cathode slurry of secondary battery

Abstract

A method of preparing a cathode slurry for a secondary battery includes a binder material including a copolymer P1 and a copolymer P2. Each of the two copolymers independently comprises a structural unit derived from a monomer containing an acid group; a structural unit derived from a monomer selected from a group consisting of an amide group-containing monomer, a hydroxyl group-containing monomer and a combination thereof; and a structural unit derived from a monomer selected from a group consisting of a nitrile group-containing monomer, an ether group-containing monomer, an epoxy group-containing monomer and a combination thereof. Due to the chemical components of each copolymer and the method itself, the cathode slurry is well dispersed, and the battery prepared from the cathode slurry has good cycle stability.

Description

Technical Field

[0001] The present invention relates to the field of batteries. In particular, the present invention relates to a method for preparing a cathode slurry for a secondary battery. Background Art

[0002] In the past decades, lithium-ion batteries (LIBs) have been widely used in various applications, especially in consumer electronics, due to their excellent energy density, long cycle life, and high discharge capacity. Due to the rapid market development of electric vehicles (EVs) and grid energy storage, high-performance, low-cost LIBs currently provide one of the most promising options for large-scale energy storage devices.

[0003] In general, the cathode of a lithium-ion battery includes an electrode layer and a current collector, wherein the electrode layer includes a cathode active material and a binder material. The cathode may also include a conductive agent. The binder material fixes the cathode components (cathode active material, binder material, and optional conductive agent) together and adheres them to the current collector, and will greatly affect the cycle stability of the battery. A common method for making a cathode is to prepare a cathode slurry consisting of cathode components and a solvent, and then coat the cathode slurry on a metal current collector and dry it. In the cathode slurry, it is crucial to disperse the cathode components well in the solvent. Otherwise, local changes in the coated slurry may cause defects in the cathode, which will have a negative impact on the electrochemical performance of the battery. Therefore, a binder material suitable for the cathode needs to be well dispersed in the solvent and produce good battery cycle stability when used.

[0004] One of the most common methods for producing cathode slurry is to use polyvinylidene fluoride (PVDF) as a binder material. PVDF does bring good battery cycle stability when used. However, PVDF can only be dissolved in some specific organic solvents, such as N-methyl-2-pyrrolidone (NMP), which is flammable and toxic. A recovery system must be installed during the drying process to recover NMP vapor. This generates high costs in the manufacturing process because it requires a large amount of capital investment.

[0005] The method of using water as a solvent to produce cathode slurry has been explored. These methods use binder materials such as carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR), which have good dispersibility in water. However, SBR and CMC show poor adhesion and battery cycle stability. In particular, SBR is unstable in high voltage environments such as the cathode of a battery and is easily decomposed during the cycle.

[0006] It is worth noting that the above problems are not unique to lithium-ion batteries. Other types of batteries, such as sodium-ion batteries, may also encounter similar problems.

[0007] Therefore, it is necessary to develop a new method to produce cathode slurries for secondary batteries so that the binder material can be well dispersed in the solvent of the cathode slurry and the binder material itself can also promote the cycling ability of the battery. Summary of the invention

[0008] The above needs are met by various aspects and embodiments disclosed herein. A method for preparing a cathode slurry for a secondary battery is provided herein, comprising the following steps: 1) dispersing the binder composition A and the cathode active material in an aqueous solvent to form a first mixture; 2) adding the binder composition B to the first mixture to form a second mixture; and 3) homogenizing the second mixture to obtain a cathode slurry; The adhesive composition A comprises a copolymer P1, and the adhesive composition B comprises a copolymer P2; wherein the copolymer P1 comprises a structural unit (a1), a structural unit (b1) and a structural unit (c1); wherein the copolymer P2 comprises a structural unit (a2), a structural unit (b2) and a structural unit (c2); wherein the structural unit (a1) and the structural unit (a2) are each independently derived from a monomer containing an acid group; wherein the structural unit (b1) and the structural unit (b2) are each independently derived from a monomer selected from the group consisting of an amide group-containing monomer, a hydroxyl group-containing monomer and a combination thereof; and wherein the structural unit (c1) and the structural unit (c2) are each independently derived from a monomer selected from the group consisting of a nitrile group-containing monomer, an ether group-containing monomer, an epoxy group-containing monomer and a combination thereof.

[0009] The invention disclosed herein solves important problems associated with cathode slurries. First, the binder material in the slurry is well dispersed, reducing the risk of cathode defect formation. Second, the binder material in the slurry can also promote good battery cycle stability. Therefore, when the cathode slurry produced using the method disclosed herein is used to make a cathode, the battery including the cathode will have good electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a flow diagram of one embodiment illustrating a method of producing a cathode slurry disclosed herein. DETAILED DESCRIPTION

[0011] The present invention provides a method for preparing a cathode slurry for a secondary battery, comprising the following steps: 1) dispersing the binder composition A and the cathode active material in an aqueous solvent to form a first mixture; 2) adding the binder composition B to the first mixture to form a second mixture; and 3) The second mixture is homogenized to obtain a cathode slurry.

[0012] The term "electrode" refers to either a "cathode" or an "anode".

[0013] The term "cathode composition" refers to any material present in the electrode layers of the cathode, including but not limited to cathode active materials, conductive agents, and binder materials.

[0014] The terms "positive electrode" and "cathode" are used interchangeably. Likewise, the terms "negative electrode" and "anode" are used interchangeably.

[0015] The term "binder material" refers to a compound, mixture of compounds, or polymer used to hold the electrode active material and / or conductive agent in place and adhere it to the current collector to form an electrode. In some embodiments, the electrode does not include any conductive material or conductive agent.

[0016] The term "binder composition" refers to a material for manufacturing an electrode including a binder material. In some embodiments, the binder composition includes a binder material and a dispersion medium.

[0017] The term "conductive agent" refers to a material with good electrical conductivity. Therefore, the conductive agent is usually mixed with the electrode active material when forming the electrode to improve the conductivity of the electrode. In some embodiments, the conductive agent is chemically active. In other embodiments, the conductive agent is chemically inert.

[0018] The term "aqueous" with respect to a solvent means that the solvent contains water as a major component and one or more minor components other than water, or consists only of water.

[0019] The term "unsaturated" refers to a moiety having one or more units of unsaturation.

[0020] The term "alkyl" or "alkyl group" refers to a radical having the general formula C n H 2n+1 A monovalent radical derived from a saturated, unbranched or branched aliphatic hydrocarbon by removing a hydrogen atom, wherein n is an integer.

[0021] The term "cycloalkyl" or "cycloalkyl group" refers to a saturated or unsaturated cyclic non-aromatic hydrocarbon group having a monocyclic or multiple condensed rings. The cycloalkyl group may be unsubstituted or substituted with one or two suitable substituents. In addition, the cycloalkyl group may be monocyclic or polycyclic.

[0022] The term "alkenyl" refers to a monovalent group derived from the removal of a hydrogen atom from any carbon atom of an unsaturated aliphatic hydrocarbon having at least one carbon-carbon double bond. Similarly, the term "alkynyl" refers to a monovalent group derived from the removal of a hydrogen atom from any carbon atom of an unsaturated aliphatic hydrocarbon having at least one carbon-carbon triple bond. In addition, the term "alkenynyl" refers to a monovalent group derived from the removal of a hydrogen atom from any carbon atom of an unsaturated aliphatic hydrocarbon having at least one carbon-carbon double bond and at least one carbon-carbon triple bond. The unsaturated aliphatic hydrocarbon of the alkenyl, alkynyl or alkenynyl group may be branched or unbranched.

[0023] The term "alkoxy" refers to an alkyl group attached to the main carbon chain through an oxygen atom. Alkoxy groups can be substituted or unsubstituted.

[0024] The term "aryl" or "aryl group" refers to an organic group derived from a monocyclic or polycyclic aromatic hydrocarbon by removing a hydrogen atom. The aryl group may be unsubstituted or substituted with one or more suitable substituents. In addition, the aryl group may be monocyclic or polycyclic.

[0025] The term "alkylamino" refers to a group derived from a primary or secondary amine by removing a hydrogen atom. Alkylamino includes the terms "N-alkylamino" and "N,N-dialkylamino", wherein the amino groups are independently substituted with one or two alkyl groups. Alkylamino may be optionally substituted with one or more substituents.

[0026] The term "alkylthio" refers to a group containing a branched or unbranched alkyl group attached to a divalent sulfur atom. The alkylthio group may be optionally substituted with one or more substituents.

[0027] The term "heteroatom" refers to one or more of oxygen (O), sulfur (S), nitrogen (N), phosphorus (P) or silicon (Si), including any oxidized form of nitrogen (N), sulfur (S) or phosphorus (P); any basic nitrogen that is quaternized; or a nitrogen in a heterocyclic ring that may be substituted.

[0028] The term "aliphatic" refers to non-aromatic hydrocarbons or radicals derived therefrom.

[0029] The term "aromatic" refers to a group comprising an aromatic hydrocarbon ring, which optionally includes heteroatoms or substituents.

[0030] The term "substituted" used to describe a compound or chemical moiety means that at least one hydrogen atom of the compound or chemical moiety is replaced by a second chemical moiety. Examples of substituents include, but are not limited to, halogen; alkyl; heteroalkyl; alkenyl; alkynyl; alkenynyl; aryl; heteroaryl; hydroxy; alkoxy; amine; nitro; thiol; thioether; imino; cyano; amide; phosphonato; phosphinato; carboxyl; thiocarbonyl; sulfonyl; sulfonamide; acyl; formyl; acyloxy; alkoxycarbonyl; carbonyl; haloalkyl; carbocyclic cycloalkyl; carbocyclic or heterocyclic; amino, monoalkylamino and dialkylamino; ortho-lower alkyl ; ortho-aryl, aryl; aryl-low alkyl; -CO2CH3; -CONH2; -OCH2CONH2; -NH2; -SO2NH2; -OCHF2; -CF3; -OCF3; -NH(alkyl); -N(alkyl)2; -NH(aryl); -N(alkyl)(aryl); -N(aryl)2; -CHO; -CO(alkyl); -CO(aryl); -CO2(alkyl); and -CO2(aryl); and these parts may also be optionally substituted by fused ring structures or bridge structures. These substituents may be optionally further substituted by one or more substituents. Unless otherwise indicated, all chemical groups disclosed herein may be substituted.

[0031] The term "halogen" or "halo" refers to F, Cl, Br or I.

[0032] The abbreviation "(meth)acrylic" includes both "acrylic" and "methacrylic".

[0033] The term "polymer" refers to a compound prepared by polymerizing monomers, whether of the same or a different type. The generic term "polymer" embraces the terms "homopolymer" and "copolymer."

[0034] The term "homopolymer" refers to a polymer prepared by polymerizing the same type of monomers.

[0035] The term "copolymer" refers to polymers prepared by polymerizing two or more different types of monomers.

[0036] The term "monomer unit" refers to a constitutional unit contributed to the structure of a polymer by a single monomer.

[0037] The term "structural unit" refers to the total monomer units derived from the same monomer type in a polymer.

[0038] The term "homogenizer" refers to a device that can be used to homogenize a material, ie, to evenly distribute the material throughout a fluid. In the homogenization process disclosed herein, any conventional homogenizer can be used in the homogenization process.

[0039] The term "solids content" refers to the amount of non-volatile matter remaining after evaporation.

[0040] The term "apply" refers to the act of laying or spreading a substance on a surface.

[0041] The term "current collector" refers to any conductive substrate that is in contact with the electrode layer and can conduct current to the electrode during discharge or charging of the secondary battery. Some non-limiting examples of current collectors include a single metal layer or a single substrate and a single metal layer or substrate covered with a conductive coating (e.g., a carbon black-based coating). The metal layer or substrate can be in the form of a foil or a porous body having a three-dimensional mesh structure, and can be a polymer or a metal material or a metallized polymer.

[0042] The term "electrode layer" refers to a layer that is in contact with a current collector and contains an electrochemically active material. In some embodiments, the electrode layer is made by applying a slurry to the current collector. In some embodiments, the electrode layer is located on the surface of the current collector. In other embodiments, the three-dimensional porous current collector is covered with a conformal electrode layer.

[0043] The term "room temperature" refers to a room temperature of about 18°C ​​to about 30°C, such as 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30°C. In some embodiments, room temperature refers to a temperature of about 20°C + / - 1°C, or + / - 2°C, or + / - 3°C. In other embodiments, room temperature refers to a temperature of about 22°C or about 25°C.

[0044] The term "peel strength" refers to the amount of force required to separate two materials that are adhered to each other, such as a current collector and an electrode layer. It is a measure of the strength of the adhesion between the two materials and is usually expressed in N / cm.

[0045] The term "adhesion strength" refers to the amount of force required to separate a substrate from an adhesive material adhered to the substrate. It is a measure of the adhesion performance of the adhesive material to the substrate, usually expressed in N / cm.

[0046] The term "C-rate" refers to the charge or discharge rate of a battery expressed in ampere-hours (Ah) or milliampere-hours (mAh) based on its total storage capacity. For example, a 1C rate means that all the stored energy is used in one hour; 0.1C means that 10% of the energy is used in one hour or the entire energy is used in 10 hours; and 5C means that the entire energy is used in 12 minutes.

[0047] The term "Ah" refers to the unit used in describing the storage capacity of a battery. For example, a battery with a capacity of 1Ah can provide a current of 1 ampere for 1 hour or a current of 0.5 amperes for two hours, etc. Therefore, 1 Ah is equivalent to 3,600 coulombs of charge. Similarly, the term "milliampere-hour (mAh)" also refers to the unit used in describing the storage capacity of a battery and is 1 / 1,000 of an Ah.

[0048] The term "capacity" is a property of an electrochemical cell and refers to the total amount of charge that an electrochemical cell (e.g., a battery) can hold. Capacity is usually expressed in units of ampere-hours. The term "specific capacity" refers to the capacity output of an electrochemical cell (e.g., a battery) per unit weight, usually expressed in Ah / kg or mAh / g.

[0049] In the following description, all numerical values ​​disclosed herein are approximate values, regardless of whether the word "about" or "approximately" is used in conjunction with them. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a value with a lower limit R is disclosed, L and upper limit R U When a numerical range of R=R is specified, any value within the range is specifically disclosed. Specifically, the following values ​​within the range are specifically disclosed: L +k*(R U -R L ), wherein k is a variable from 0% to 100%. Also, any numerical range defined by two R values ​​determined in the above manner is also specifically disclosed.

[0050] In this specification, all references to the singular include references to the plural and vice versa.

[0051] Currently, the cathode of lithium-ion batteries is usually prepared by dispersing the cathode active material, binder material and conductive agent in a solvent to form a cathode slurry, and then coating the cathode slurry on a current collector and drying. PVDF is usually used as a binder material because it can bring good battery cycle stability, but it can only be dissolved in specific organic solvents such as NMP. However, NMP is hazardous and the cost of mitigating these hazards is high. In order to avoid these disadvantages, methods for manufacturing cathodes using slurries containing aqueous solvents have been designed, but the electrochemical performance of batteries containing these cathodes has yet to be improved.

[0052] The present invention provides a method for preparing a cathode slurry for a secondary battery. Figure 1 is a flow chart illustrating the steps of method 100, which is one embodiment of the present invention. In some embodiments, in step 101, a first mixture is formed by dispersing a binder composition A and a cathode active material in an aqueous solvent.

[0053] In some embodiments, the binder composition A includes a copolymer P1 as a binder material. In certain embodiments, the binder composition A further includes a dispersion medium. There are no particular restrictions on the dispersion medium in the binder composition A, but the dispersion medium should be miscible with the aqueous solvent of the cathode slurry so that the cathode slurry can become uniform. Any material suitable for use as an aqueous solvent can also be used as the dispersion medium in the binder composition A. In some embodiments, the aqueous solvent of the cathode slurry and the dispersion medium in the binder composition A are the same, different, or partially different.

[0054] In some embodiments, copolymer P1 includes structural units (a1), (b1) and (c1). In some embodiments, structural unit (a1) is derived from a monomer containing an acid group. In certain embodiments, the acid group is selected from the group consisting of carboxylic acid, sulfonic acid, sulfuric acid, phosphonic acid, phosphoric acid, nitric acid and combinations thereof. The acids listed above also include their salts and derivatives. In some embodiments, the salt of the acid includes an alkali metal cation. Examples of alkali metals that form alkali metal cations include lithium, sodium and potassium. In some embodiments, the salt of the acid includes an ammonium cation.

[0055] In some embodiments, the carboxylic acid is acrylic acid, methacrylic acid, crotonic acid, 2-butyl crotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, 4,4-dimethyl itaconic acid (tetraconic acid) or a combination thereof. In certain embodiments, the carboxylic acid is 2-ethylacrylic acid, isocrotonic acid, cis-2-pentenoic acid, trans-2-pentenoic acid, angelic acid, tiglic acid (tiglic acid) acid), 3,3-dimethylacrylic acid, 3-propylacrylic acid, trans-2-methyl-3-ethylacrylic acid, cis-2-methyl-3-ethylacrylic acid, 3-isopropylacrylic acid, trans-3-methyl-3-ethylacrylic acid, cis-3-methyl-3-ethylacrylic acid, 2-isopropylacrylic acid, trimethylacrylic acid, 2-methyl-3,3-diethylacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, 2-methyl-2-hexenoic acid, trans-3-methyl-2-hexenoic acid, 3-methyl-3-propylacrylic acid, 2-ethyl-3-propylacrylic acid, 2,3-diethylacrylic acid, 3,3-diethylacrylic acid, 3-methyl-3-hexylacrylic acid, 3-methyl-3-tert-butylacrylic acid, 2-methyl-3-pentylacrylic acid, 3-methyl-3-pentylacrylic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-hexenoic acid, 3-methyl-2-ethyl-2-hexenoic acid, 3-tert-butylacrylic acid, 2,3-dimethyl-3-ethylacrylic acid, 3,3-dimethyl-2-ethylacrylic acid, 3-methyl-3-isopropylacrylic acid, 2-methyl-3-isopropylacrylic acid, trans-2-octenoic acid, cis-2-octenoic acid, trans-2-decenoic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid or a combination thereof.

[0056] In some embodiments, the sulfonic acid is vinyl sulfonic acid, methyl vinyl sulfonic acid, allyl vinyl sulfonic acid, allyl sulfonic acid, methyl allyl sulfonic acid, styrene sulfonic acid, 2-sulfoethyl methacrylic acid, 2-methyl-2-propylene-1-sulfonic acid, 2-acrylamido-2-methyl-1-propane sulfonic acid, 3-allyloxy-2-hydroxy-1-propane sulfonic acid, or a combination thereof.

[0057] In some embodiments, the sulfuric acid is allyl hydrogen sulfate, vinyl hydrogen sulfate, 4-allylphenol sulfate, or a combination thereof.

[0058] In some embodiments, the phosphonic acid is phosphonoxyethyl acrylate, phosphonoxyethyl methacrylate, vinylphosphonic acid, allylphosphonic acid, 3-butenylphosphonic acid, styrenephosphonic acid, vinylbenzylphosphonic acid, (2-chloro-2-phenyl-vinyl)-phosphonic acid, acrylamidoalkylphosphonic acid, methacrylamidoalkylphosphonic acid, acrylamidoalkyldiphosphonic acid, acrylphosphonic acid, 2-methacryloyloxyethylphosphonic acid, bis(2-methacryloyloxyethyl)phosphonic acid, 2-methacryloyloxyethylphosphonic acid, ethyl-methacryloyloxyethylphosphonic acid, or a combination thereof.

[0059] In some embodiments, the phosphonic acid is mono(2-acryloyloxyethyl)phosphate, mono(2-methacryloyloxyethyl)phosphate, diphenyl(2-acryloyloxyethyl)phosphate, diphenyl(2-methacryloyloxyethyl)phosphate, phenyl(2-acryloyloxyethyl)phosphate, methacrylate phosphorooxyethyl, methacrylate-3-chloro-2-phosphorooxypropyl, monomethacrylate phosphorooxypoly(ethylene glycol), methacrylate phosphorooxypoly(propylene glycol), (meth)acryloyloxyethylphosphonic acid. Ester, (meth)acryloxypropyl phosphate, (meth)acryloxy-2-hydroxypropyl phosphate, (meth)acryloxy-3-hydroxypropyl phosphate, (meth)acryloxy-3-chloro-2-hydroxypropyl phosphate, allyl hydrogen phosphate, vinyl hydrogen phosphate, allyl hydrogen pyrophosphate, vinyl hydrogen pyrophosphate, allyl hydrogen tripolyphosphate, vinyl hydrogen tripolyphosphate, allyl hydrogen tetrapolyphosphate, vinyl hydrogen tetrapolyphosphate, allyl hydrogen trimetaphosphate, vinyl hydrogen trimetaphosphate, isopentenyl phosphate, isopentenyl pyrophosphate, or a combination thereof.

[0060] In some embodiments, the nitric acid is allyl hydrogen nitrate, vinyl hydrogen nitrate, or a combination thereof.

[0061] In some embodiments, the proportion of structural unit (a1) in copolymer P1 is about 45% to about 80%, about 46% to about 80%, about 47% to about 80%, about 48% to about 80%, about 49% to about 80%, about 50% to about 80%, about 52% to about 80%, about 55% to about 80%, about 58% to about 60%, about 60% to about 80%, about 62% to about 80%, about 65% to about 80%, about 68% to about 80%, about 70% to about 80%, about 45% to about 70%, about 50% to about 70%, about 55% to about 70%, about 60% to about 70%, about 45% to about 60%, about 50% to about 60%, or about 55% to about 60% by mole, based on the total moles of monomer units in the copolymer.

[0062] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (a1) in copolymer P1 is less than 80%, less than 79%, less than 78%, less than 77%, less than 76%, less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, less than 50%, less than 49%, less than 48%, less than 47% or less than 46% by mole. In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (a1) in copolymer P1 is more than 45%, more than 46%, more than 47%, more than 48%, more than 49%, more than 50%, more than 55%, more than 60%, more than 65%, more than 70%, more than 75%, more than 76%, more than 77%, more than 78% or more than 79% by mole.

[0063] In some embodiments, the structural unit (b1) is derived from a monomer selected from the group consisting of an amide group-containing monomer, a hydroxyl group-containing monomer, and a combination thereof.

[0064] In some embodiments, the amide-containing monomer is acrylamide, methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, N-n-propyl methacrylamide, N-isopropyl methacrylamide, isopropyl acrylamide, N-n-butyl methacrylamide, N-isobutyl methacrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide, N,N-diethyl acrylamide, N,N-diethyl methacrylamide, N-hydroxymethyl methacrylamide, N-(methoxymethyl) methacrylamide, N-(ethoxymethyl) methacrylamide, ) methacrylamide, N-(propyloxymethyl) methacrylamide, N-(butoxymethyl) methacrylamide, N-(3-(dimethylamino)propyl) methacrylamide, N-(2-(dimethylamino)ethyl) methacrylamide, N,N-(dihydroxymethyl) methacrylamide, diacetone methacrylamide, diacetone acrylamide, methacryl morpholine, N-hydroxymethyl acrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N,N'-methylenebisacrylamide (MBA), N-hydroxymethyl acrylamide, or a combination thereof.

[0065] In some embodiments, the hydroxyl group-containing monomer is a hydroxyl group-containing monomer having a C1 to C 20 Alkyl group or C5 to C 20In some embodiments, the monomer containing a hydroxyl group is 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl acrylate, 6-hydroxyhexyl methacrylate, 1,4-cyclohexanedimethanol monoacrylate, 1,4-cyclohexanedimethanol monomethacrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, allyl alcohol, or a combination thereof.

[0066] In some embodiments, based on the total moles of the monomer units in the copolymer, the proportion of the structural unit (b1) in the copolymer P1 is about 10% to about 35%, about 13% to about 35%, about 15% to about 35%, about 18% to about 35%, about 20% to about 35%, about 23% to about 35%, about 25% to about 35%, about 28% to about 35%, about 30% to about 35%, about 10% to about 32%, about 13% to about 32%, about 15% to about 32%, about 18% to about 32%, about 20% to about 32%, about 23% to about 32%, about 25% to about 32%, about 28% to about 32%, about 10% to about 30%, about 13% to about 30%, about 15% to about 30%, about 18% to about 30%, about 20% to about 30%, about 23% to about 30%, about 25% to about 30%, about 10% to about 28%, about 13% to about 28%, about 15% to about 28%, about 18% to about 28%, about 20% to about 28%, about 10% to about 25%, about 13% to about 25%, about 15% to about 25%, about 18% to about 25%, about 20% to about 25%, about 10% to about 22%, about 13% to about 22%, about 15% to about 22%, about 10% to about 20%, about 13% to about 20%, or about 15% to about 20%.

[0067] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (b1) in copolymer P1 is less than 35%, less than 32%, less than 30%, less than 28%, less than 25%, less than 23%, less than 20%, less than 18%, less than 15%, or less than 13% by mole. In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (b1) in copolymer P1 is more than 10%, more than 13%, more than 15%, more than 18%, more than 20%, more than 23%, more than 25%, more than 28%, or more than 30% by mole.

[0068] In some embodiments, the structural unit (c1) is derived from a monomer selected from the group consisting of a nitrile group-containing monomer, an ester group-containing monomer, an epoxy group-containing monomer, and a combination thereof.

[0069] In some embodiments, the monomer containing nitrile groups is or includes α,β-ethylenically unsaturated nitrile monomers. In some embodiments, the monomer containing nitrile groups is acrylonitrile, α-haloacrylonitrile, α-alkylacrylonitrile or a combination thereof. In some embodiments, the monomer containing nitrile groups is α-chloroacrylonitrile, α-bromoacrylonitrile, α-fluoroacrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-n-hexylacrylonitrile, α-methoxyacrylonitrile, 3-methoxyacrylonitrile, 3-ethoxyacrylonitrile, α-acetoxyacrylonitrile, α-phenylacrylonitrile, α-tolylacrylonitrile, α-(methoxyphenyl)acrylonitrile, α-(chlorophenyl)acrylonitrile, α-(cyanophenyl)acrylonitrile, vinylidene cyanide or a combination thereof.

[0070] In some embodiments, the monomer containing an ester group is C1-C 20 Alkyl acrylate, C1-C 20 Alkyl methacrylate, cycloalkyl acrylate or a combination thereof. In some embodiments, the monomer containing an ester group is methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 3,3,5-trimethylhexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, n-tetradecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, methoxymethyl acrylate, methoxyethyl acrylate, ethoxymethyl acrylate, ethoxyethyl acrylate, perfluorooctyl acrylate, stearyl acrylate or a combination thereof.

[0071] In some embodiments, the epoxy group-containing monomer is vinyl glycidyl ether, allyl glycidyl ether, allyl-2,3-epoxypropyl ether, butenyl glycidyl ether, butadiene monoepoxide, chloroprene monoepoxide, 3,4-epoxy-1-butene, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexane, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylethylene, epoxy-4-vinylcyclohexene, 1,2-epoxy-5,9-cyclododecadiene, or a combination thereof.

[0072] In some embodiments, based on the total moles of the monomer units in the copolymer, the proportion of the structural unit (c1) in the copolymer P1 is about 10% to about 40%, about 12% to about 40%, about 15% to about 40%, about 18% to about 40%, about 20% to about 40%, about 22% to about 40%, about 25% to about 40%, about 28% to about 40%, about 30% to about 40%, about 10% to about 38%, about 12% to about 38%, about 14% to about 38%, about 16% to about 38%, about 18% to about 38%, about 20% to about 38%, about 22% to about 38%, about 25% to about 38%, about 28% to about 38%, about 10% to about 35%, about From about 12% to about 35%, from about 15% to about 35%, from about 18% to about 35%, from about 20% to about 35%, from about 22% to about 35%, from about 25% to about 35%, from about 10% to about 32%, from about 12% to about 32%, from about 15% to about 32%, from about 18% to about 32%, from about 20% to about 32%, from about 22% to about 32%, from about 10% to about 30%, from about 12% to about 30%, from about 15% to about 30%, from about 18% to about 30%, from about 20% to about 30%, from about 10% to about 28%, from about 12% to about 28%, from about 15% to about 28%, from about 18% to about 28%, from about 10% to about 25%, from about 12% to about 25%, or from about 15% to about 25%.

[0073] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (c1) in copolymer P1 is less than 40%, less than 38%, less than 35%, less than 32%, less than 30%, less than 28%, less than 25%, less than 22%, less than 20%, less than 18% or less than 15% by mole. In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (c1) in copolymer P1 is more than 10%, more than 12%, more than 15%, more than 18%, more than 20%, more than 22%, more than 25%, more than 28%, more than 30%, more than 32% or more than 35% by mole.

[0074] The weight average molecular weight (M) of the copolymer binder material w ) is one of the factors that affect the adhesion performance of the copolymer, which affects the ability of the electrode layer to maintain adhesion on the current collector, thereby affecting the cycle stability of the battery. w It also affects the dispersibility of the copolymer in an aqueous solvent. When the weight average molecular weight of the copolymer P1 is within the following range, the adhesion performance and dispersibility of the copolymer P1 are improved.

[0075] In some embodiments, the M of copolymer P1 w is about 10,000 g / mol to about 600,000 g / mol, about 50,000 g / mol to about 600,000 g / mol, about 100,000 g / mol to about 600,000 g / mol, about 200,000 g / mol to about 600,000 g / mol, about 400,000 g / mol to about 600,000 g / mol, about 10,000 g / mol to about 400,000 g / mol, about 50,000 g / mol to about 400,000 g / mol, about 100,000 g / mol to about 400,000 g / mol, about 200,000 g / mol to about 400,000 g / mol, about 10,000 g / mol to about 300,000 g / mol, about 30,000 g / mol to about 300,000 g / mol, about 50,000 g / mol to about 300,000 g / mol, about 75,000 g / mol to about 300,000 g / mol, about 100,000 g / mol to about 300,000 g / mol, about 150,000 g / mol to about 300,000 g / mol, about 200,000 g / mol to about 300,000 g / mol, about 10,000 g / mol to about 250,000 g / mol, about 30,000 g / mol to about 250,000 g / mol, about 50,000 g / mol to about 250,000 g / mol, about 100,000 g / mol to about 250,000 g / mol, about 150,000 g / mol to about 250,000 g / mol, about 10,000 g / mol to about 200,000 g / mol, about 30,000 g / mol to about 200,000 g / mol, about 50,000 g / mol to about 200,000 g / mol, about 100,000 g / mol to about 200,000 g / mol, about 10,000 g / mol to about 150,000 g / mol, about 30,000 g / mol to about 150,000 g / mol, about 50,000 g / mol to about 150,000 g / mol, or about 75,000 g / mol to about 150,000 g / mol.

[0076] In some embodiments, the M of copolymer P1 wIn some embodiments, the M of copolymer P1 is less than 600,000 g / mol, less than 500,000 g / mol, less than 400,000 g / mol, less than 300,000 g / mol, less than 250,000 g / mol, less than 200,000 g / mol, less than 175,000 g / mol, less than 150,000 g / mol, less than 125,000 g / mol, less than 100,000 g / mol, less than 90,000 g / mol, less than 80,000 g / mol, less than 70,000 g / mol, less than 60,000 g / mol, or less than 50,000 g / mol. w is greater than 10,000 g / mol, greater than 15,000 g / mol, greater than 20,000 g / mol, greater than 25,000 g / mol, greater than 30,000 g / mol, greater than 35,000 g / mol, greater than 40,000 g / mol, greater than 50,000 g / mol, greater than 60,000 g / mol, greater than 70,000 g / mol, greater than 80,000 g / mol, greater than 100,000 g / mol, greater than 150,000 g / mol, greater than 175,000 g / mol, greater than 200,000 g / mol, greater than 300,000 g / mol, greater than 400,000 g / mol, or greater than 500,000 g / mol.

[0077] In some embodiments, the solid content of the binder composition A is about 5% to about 25%, about 6% to about 25%, about 7% to about 25%, about 8% to about 25%, about 9% to about 25%, about 10% to about 25%, about 11% to about 25%, about 12% to about 25%, about 13% to about 25%, about 14% to about 25%, about 15% to about 25%, about 5% to about 22%, about 6% to about 22%, about 7% to about 22%, about 8% to about 22%, about 9% to about 25%, about 10% to about 22%, about 11% to about 25%, about 12% to about 25%, about 13% to about 25%, about 14% to about 25%, about 15% to about 25%, about 5% to about 22%, about 6% to about 22%, about 7% to about 22%, about 8% to about 22%, about 9% to about 22%, about 10% to about 22%, about 11% to about 25%, about 12% to about 25%, about 13% to about 25%, about 14% to about 25%, about 15% to about 25%, about 15% to about 22%, about 11% to about 22%, about 12% to about 25%, about 13 ... 2%, about 12% to about 22%, about 13% to about 22%, about 14% to about 22%, about 15% to about 22%, about 5% to about 20%, about 6% to about 20%, about 7% to about 20%, about 8% to about 20%, about 9% to about 20%, about 10% to about 20%, about 5% to about 17%, about 6% to about 17%, about 7% to about 17%, about 8% to 17%, about 9% to about 17%, about 10% to about 17%, about 5% to about 15%, about 6% to about 15%, about 7% to about 15%, about 8% to 15%, about 9% to about 15%, or about 10% to about 15%.

[0078] In some embodiments, the solid content of binder composition A is less than 25%, less than 23%, less than 20%, less than 19%, less than 18%, less than 17%, less than 16%, less than 15%, less than 14%, less than 13%, or less than 10% by weight, based on the total weight of binder composition A. In some embodiments, the solid content of binder composition A is greater than 5%, greater than 6%, greater than 7%, greater than 8%, greater than 9%, greater than 10%, greater than 11%, greater than 12%, greater than 13%, greater than 14%, greater than 15%, greater than 16%, greater than 17%, greater than 18%, greater than 19%, or greater than 20% by weight, based on the total weight of binder composition A.

[0079] One of the advantages of the present invention is that an aqueous solvent can be used in the cathode slurry, which minimizes the impact on the environment and improves the safety of the cathode manufacturing process. In some embodiments, the aqueous solvent is water. In some embodiments, the aqueous solvent is selected from the group consisting of tap water, bottled water, purified water, pure water, distilled water, deionized water (DI water), D2O and combinations thereof.

[0080] In some embodiments, the aqueous solvent includes water and a minor component other than water. In some embodiments, the volume ratio of water to the minor component is about 51:49 to about 99:1. Any water-miscible or volatile solvent can be used as a minor component. Some non-limiting examples of minor components include alcohols, lower aliphatic ketones, lower alkyl acetates and combinations thereof. Adding minor components can improve the processability of the cathode slurry.

[0081] Some non-limiting examples of alcohol include C1-C4 alcohols, such as methanol, ethanol, isopropanol, n-propanol, tert-butyl alcohol, n-butyl alcohol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, ethylene glycol, propylene glycol, glycerine and combinations thereof. Some non-limiting examples of lower aliphatic ketones include acetone, dimethyl ketone, methyl ethyl ketone (MEK) and combinations thereof. Some non-limiting examples of lower alkyl acetates include ethyl acetate (EA), isopropyl acetate, propyl acetate, butyl acetate (BA), and combinations thereof. Some other non-limiting examples of water-miscible or volatile solvents include 1,4-dioxane, diethyl ether, methyl tert-butyl ether, cyclopentyl methyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran, acetonitrile, dimethyl sulfoxide (DMSO), sulfolane, nitromethane, propylene carbonate, ethylene carbonate, dimethyl carbonate, pyridine, acetaldehyde, formic acid, acetic acid, propionic acid, butyric acid, gamma-valerolactone (GVL), furfuryl alcohol, methyl lactate, ethyl lactate, diethanolamine, dimethylacetamide (DMAc), dimethylformamide (DMF), N-methylpyrrolidone (NMP), dihydrolevorotatory glucosone (Cyrene TM), N,N'-dimethylpropylene urea (DMPU) and dimethyl isosorbide (DMI). In some embodiments, no minor components are present in the aqueous solvent.

[0082] The cathode active material should be selected according to the type of battery produced. In some embodiments, the type of battery can be a primary battery or a secondary battery. Some non-limiting examples of battery types include alkaline batteries, aluminum air batteries, lithium batteries, lithium air batteries, magnesium batteries, silver oxide batteries, zinc air batteries, aluminum ion batteries, lead acid batteries, lithium ion batteries, magnesium ion batteries, potassium ion batteries, sodium ion batteries, sodium air batteries, silicon air batteries, zinc ion batteries, and sodium sulfur batteries.

[0083] In some embodiments, the cathode active material is for a lithium ion battery. In some embodiments, the cathode active material for a lithium ion battery is selected from the group consisting of LiCoO2, LiNiO2, LiNi 1-x M x O2、LiNi x Mn y O2、LiCo x Ni y O2、Li 1+ z Ni x Mn y Co 1-x-y O2、LiNi x Co y Al z O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4 and a combination thereof, wherein each x is independently 0.1 to 0.9; each y is independently 0 to 0.9; each z is independently 0 to 0.4; and M is selected from the group consisting of Co, Mn, Al, Fe, Ti, Ga, Mg and a combination thereof.

[0084] In certain embodiments, the cathode active material for lithium ion batteries is selected from LiNi x Mn y O2、Li 1+ z Ni x Mn y Co 1-x-y O2(NMC), LiNi x Co y Al z O2(NCA), LiCo x Ni yA group consisting of O2 and its combinations, where each x is independently from 0.4 to 0.6; each y is independently from 0.2 to 0.4; and each z is independently from 0 to 0.1. In other embodiments, the cathode active material for a lithium-ion battery is not LiCoO2, LiNiO2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, LiFeO2 or LiFePO4. In further embodiments, the cathode active material for a lithium-ion battery is not LiNi x Mn y O2, Li 1+z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al z O2 or LiCo x Ni y O2, where each x is independently from 0.1 to 0.9; each y is independently from 0 to 0.45; and each z is independently from 0 to 0.2. In certain embodiments, the cathode active material for a lithium-ion battery is Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2; where -0.2 ≤ x ≤ 0.2, 0 ≤ a < 1, 0 ≤ b < 1, 0 ≤ c < 1, and a + b + c ≤ 1. In some embodiments, the cathode active material for a lithium-ion battery has the general formula Li 1+ x Ni a Mn b Co c Al (1-a-b-c) O2, where 0.33 ≤ a ≤ 0.92, 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.5. In some embodiments, the cathode active material for a lithium-ion battery has the general formula LiMPO4, where M is selected from the group consisting of Fe, Co, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge and their combinations.

[0085] In some embodiments, the cathode active material for a lithium-ion battery is selected from the group consisting of LiFePO4, LiCoPO4, LiNiPO4, LiMnPO4, LiMnFePO4, LiMn x Fe (1-x) PO4, and their combinations; where 0 < x < 1. In some embodiments, the cathode active material for a lithium-ion battery is LiNi x Mn yO4; where 0.1 ≤ x ≤ 0.9 and 0 ≤ y ≤ 2. In certain embodiments, the cathode active material for a lithium-ion battery is xLi2MnO3·(1-x)LiMO2, where M is selected from the group consisting of Ni, Co, Mn, and combinations thereof; and where 0 < x < 1. In some embodiments, the cathode active material for a lithium-ion battery is Li3V2(PO4)3 or LiVPO4F. In certain embodiments, the cathode active material for a lithium-ion battery has the general formula Li2MSiO4, where M is selected from the group consisting of Fe, Co, Mn, Ni, and combinations thereof.

[0086] In certain embodiments, the cathode active material for a lithium-ion battery is doped with a dopant selected from the group consisting of Co, Cr, V, Mo, Nb, Pd, F, Na, Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In some embodiments, the cathode active material for a lithium-ion battery is not doped with Co, Cr, V, Mo, Nb, Pd, F, Na, Fe, Ni, Mn, Mg, Zn, Ti, La, Ce, Ru, Si, or Ge. In certain embodiments, the cathode active material for a lithium-ion battery is not doped with Al, Sn, or Zr.

[0087] In some embodiments, the cathode active material for a lithium-ion battery is LiNi 0.33 Mn 0.33 Co 0.33 O2 (NMC333), LiNi 0.4 Mn 0.4 Co 0.2 O2, LiNi 0.5 Mn 0.3 Co 0.2 O2 (NMC532), LiNi 0.6 Mn 0.2 Co 0.2 O2 (NMC622), LiNi 0.7 Mn 0.15 Co 0.15 O2, LiNi 0.7 Mn 0.1 Co 0.2 O2, LiNi 0.8 Mn 0.1 Co 0.1 O2 (NMC811), LiNi 0.92 Mn 0.04 Co 0.04 O2, LiNi 0.85 Mn 0.075 Co 0.075 O2, LiNi0.8 Co 0.15 Al 0.05 O2、LiNi 0.88 Co 0.1 Al 0.02 O2, LiNiO2 (LNO) or a combination thereof.

[0088] In other embodiments, the cathode active material for the lithium ion battery is not LiCoO2, LiNiO2, LiMnO2, LiMn2O4 or Li2MnO3. In further implementations, the cathode active material for the lithium ion battery is not LiNi 0.33 Mn 0.33 Co 0.33 O2、LiNi 0.4 Mn 0.4 Co 0.2 O2、LiNi 0.5 Mn 0.3 Co 0.2 O2、LiNi 0.6 Mn 0.2 Co 0.2 O2、LiNi 0.7 Mn 0.15 Co 0.15 O2、LiNi 0.7 Mn 0.1 Co 0.2 O2、LiNi 0.8 Mn 0.1 Co 0.1 O2、LiNi 0.92 Mn 0.04 Co 0.04 O2、LiNi 0.85 Mn 0.075 Co 0.075 O2、LiNi 0.8 Co 0.15 Al 0.05 O2 or LiNi 0.88 Co 0.1 Al 0.02 O2.

[0089] In certain embodiments, the cathode active material for a lithium ion battery includes or is a core-shell composite material having a core and shell structure, wherein the core includes a selected from the group consisting of Li 1+x Ni a Mn b Co c Al (1-a-b-c) O2, LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li2MnO3, LiCrO2, Li4Ti5O 12, LiV2O5, LiTiS2, LiMoS2, LiCo a Ni b O2、LiMn a Ni b O2 and a combination thereof; wherein -0.2≤x≤0.2, 0≤a<1, 0≤b<1, 0≤c<1 and a+b+c≤1. In some embodiments, the shell further comprises a lithium transition metal oxide. In certain embodiments, the lithium transition metal oxide of the shell is selected from the group of lithium transition metal oxides for the core described above. In other embodiments, the shell comprises a transition metal oxide. In certain embodiments, the transition metal oxide of the shell is selected from the group consisting of Fe2O3, MnO2, Al2O3, MgO, ZnO, TiO2, La2O3, CeO2, SnO2, ZrO2, RuO2 and a combination thereof. In certain embodiments, the shell comprises a lithium transition metal oxide and a transition metal oxide.

[0090] In some embodiments, the core and shell for lithium ion batteries each independently include two or more lithium transition metal oxides. In some embodiments, one of the core or shell includes only one lithium transition metal oxide, and the other includes two or more lithium transition metal oxides. The lithium transition metal oxides in the core and shell can be the same, or they can be different or partially different. In some embodiments, two or more lithium transition metal oxides are uniformly distributed on the core. In some embodiments, two or more lithium transition metal oxides are unevenly distributed on the core.

[0091] In some embodiments, each metal oxide in the core and shell is independently doped with a dopant selected from the group consisting of Co, Cr, V, Mo, Nb, Pd, F, Na, Fe, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge, and combinations thereof. In some embodiments, the cathode active material is not a core-shell composite.

[0092] In some embodiments, the cathode active material is for a sodium ion battery. In some embodiments, the cathode active material for a sodium ion battery is a Prussian blue type sodium compound that satisfies the formula Na x M y A z, wherein M is one or more metals and A is one or more anions including one or more of O, P, N, C, H or halogen. In certain embodiments, the cathode active material for the sodium ion battery is a sodium analog of the cathode active material for the lithium ion battery discussed above, with sodium replacing lithium. In some embodiments, the cathode active material for the sodium ion battery is selected from the group consisting of NaCoO2, NaFeO2, NaNiO2, NaCrO2, NaVO2, NaTiO2, NaFePO4, Na3V2(PO4)3, Na3V2(PO4)2F3, NMC-type mixed oxides and combinations thereof. In some embodiments, the cathode active material for the sodium ion battery is an organic material, such as disodium naphthalene diimide, doped quinones, pteridine derivatives, polyimides, polyamino acids or combinations thereof.

[0093] In some embodiments, the cathode active material for a sodium ion battery includes or is a core-shell composite material having a core and shell structure. In some embodiments, the cathode active material for a sodium ion battery is doped with a dopant. The same dopants listed above for the cathode active material for a lithium ion battery can be used to dope the cathode active material for a sodium ion battery.

[0094] In some embodiments, the average diameter of the cathode active material particles is about 0.1 μm to about 100 μm, about 0.1 μm to about 50 μm, about 0.5 μm to about 50 μm, about 0.5 μm to about 30 μm, about 0.5 μm to about 20 μm, about 1 μm to about 20 μm, about 2.5 μm to about 50 μm, about 2.5 μm to about 20 μm, about 5 μm to about 50 μm, about 5 μm to about 20 μm, about 7.5 μm to about 20 μm, about 10 μm to about 50 μm, about 10 μm to about 20 μm, about 15 μm to about 50 μm, about 15 μm to about 20 μm, about 20 μm to about 50 μm, or about 50 μm to about 100 μm.

[0095] In some embodiments, the average diameter of the cathode active material particles is less than 100 μm, less than 80 μm, less than 60 μm, less than 50 μm, less than 40 μm, less than 30 μm, less than 20 μm, less than 15 μm, less than 10 μm, less than 7.5 μm, less than 5 μm, less than 2.5 μm, less than 1 μm, less than 0.75 μm, or less than 0.5 μm. In some embodiments, the average diameter of the cathode active material particles is greater than 0.1 μm, greater than 0.25 μm, greater than 0.5 μm, greater than 0.75 μm, greater than 1 μm, greater than 2.5 μm, greater than 5 μm, greater than 7.5 μm, greater than 10 μm, greater than 15 μm, greater than 20 μm, greater than 30 μm, greater than 40 μm, or greater than 50 μm.

[0096] In some embodiments, in addition to the binder composition A and the cathode active material, a conductive agent is dispersed in the aqueous solvent in step 101. When the conductive agent is added to the cathode slurry, the conductive properties of the cathode produced therefrom will be enhanced. Therefore, it may be advantageous for step 101 to further include the addition of a conductive agent.

[0097] In some embodiments, the conductive agent is selected from the group consisting of natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesophase carbon microbeads (MCMB), carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon tubes, carbon nanotubes, activated carbon, Super P, KS6, vapor grown carbon fibers (VGCF), mesoporous carbon, and combinations thereof.

[0098] In some embodiments, the conductive agent includes a conductive polymer selected from the group consisting of polypyrrole, polyaniline, polyacetylene, polyphenylene sulfide (PPS), polyphenylacetylene (PPV), poly(3,4-ethylenedioxythiophene) (PEDOT), polythiophene, and combinations thereof. In some embodiments, the conductive polymer plays two roles at the same time, not only as a conductive agent, but also as a binder material. In other embodiments, the conductive agent does not include a conductive polymer.

[0099] There is no particular restriction on the particular method for producing the first mixture, except that all the ingredients of the first mixture (e.g., conductive material, cathode active material, binder composition A, aqueous solvent) should be uniformly mixed to form a homogeneous mixture. In some embodiments, the first mixture is produced by using a homogenizer. Any homogenizer that can reduce or eliminate particle aggregation and / or promote uniform distribution of cathode components can be used here. Some non-limiting examples of homogenizers include planetary stirring mixers, stirring mixers, mixers and ultrasonic generators. In some embodiments, all the ingredients of the first mixture are added to the homogenizer at one time. In other embodiments, each ingredient of the first mixture can be added to the homogenizer in one or more batches, and each batch can include one or more ingredients.

[0100] There are no particular restrictions on the stirring speed, time required, and temperature used to produce the first mixture, but they should be sufficient to evenly disperse the first mixture. This will help ensure that a homogeneous cathode slurry is produced in the subsequent steps. As non-limiting examples of suitable conditions for producing the first mixture, the stirring speed may be in the range of about 100 rpm to about 3000 rpm; the time required may be in the range of about 5 minutes to about 24 hours; the temperature used may be in the range of about 15° C. to about 95° C.

[0101] In some embodiments, the second mixture is formed by adding the binder composition B to the first mixture in step 102 .

[0102] In some embodiments, the binder composition B includes a copolymer P2 as a binder material. In some embodiments, the chemical compositions of copolymer P1 and copolymer P2 are different. In certain embodiments, the binder composition B further includes a dispersion medium. There are no particular restrictions on the dispersion medium in the binder composition B, but the dispersion medium should be miscible with the aqueous solvent of the cathode slurry so that the cathode slurry can be homogeneous. Any substance suitable for use as an aqueous solvent for the cathode slurry can also be used as the dispersion medium in the binder composition B. In some embodiments, the aqueous solvent of the cathode slurry and the dispersion medium in the binder composition B are the same, different, or partially different. In some embodiments, the dispersion medium in the binder composition A and the dispersion medium in the binder composition B are the same, different, or partially different.

[0103] In some embodiments, copolymer P2 includes structural units (a2), (b2) and (c2). In some embodiments, structural unit (a2) is derived from a monomer containing an acid group. In certain embodiments, the acid group is selected from the group consisting of carboxylic acid, sulfonic acid, sulfuric acid, phosphonic acid, phosphoric acid, nitric acid and combinations thereof. The acids listed above also include their salts and derivatives. In some embodiments, the salt of the acid includes an alkali metal cation. In some embodiments, the salt of the acid includes an ammonium cation. Any embodiment of the monomer from which structural unit (a1) is derived is also a suitable embodiment of the derived structural unit (a2). In certain embodiments, structural unit (a1) and structural unit (a2) are derived from the same, different or partially different monomers, respectively.

[0104] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (a2) in copolymer P2 is about 15% to about 30%, about 18% to about 30%, about 20% to about 30%, about 23% to about 30%, about 25% to about 30%, about 28% to about 30%, about 15% to about 28%, about 18% to about 28%, about 20% to about 28%, about 23% to about 28%, about 25% to about 28%, about 15% to about 25%, about 18% to about 25%, about 20% to about 25%, about 23% to about 25%, about 15% to about 23% or about 18% to about 23% by mole.

[0105] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (a2) in copolymer P2 is less than 30%, less than 28%, less than 25%, less than 23%, less than 20% or less than 18% by mole. In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (a2) in copolymer P2 is more than 15%, more than 18%, more than 20%, more than 23%, more than 25% or more than 28% by mole.

[0106] In some embodiments, structural unit (b2) is derived from a monomer selected from an amide-containing monomer, a hydroxyl-containing monomer, and a combination thereof. Any embodiment of the monomer from which structural unit (b1) is derived is also a suitable embodiment for deriving structural unit (b2). In certain embodiments, structural unit (b1) and structural unit (b2) are derived from the same, different, or partially different monomers, respectively.

[0107] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (b2) in copolymer P2 is about 5% to about 30%, about 8% to about 30%, about 10% to about 30%, about 12% to about 30%, about 15% to about 30%, about 18% to about 30%, about 20% to about 30%, about 5% to about 28%, about 8% to about 28%, about 10% to about 28%, about 12% to about 28%, about 15% to about 28%, about 18% to about 28%, about 20% to about 28%, about 5% to about 25%, about 8% to about 25%, about 10% to about 25%, about 12% to about 25%, about 15% to about 25%, about 18% to about 25%, about 5% to about 22%, about 8% to about 22%, about 10% to about 22%, about 12% to about 22%, about 15% to about 22%, about 5% to about 20%, about 8% to about 20%, about 10% to about 20%, about 12% to about 20%, about 15% to about 20%, about 5% to about 18%, about 8% to about 18%, about 10% to about 18%, about 12% to about 18%, about 5% to about 15%, about 8% to about 15% or about 5% to about 15%.

[0108] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (b2) in copolymer P2 is less than 30%, less than 28%, less than 25%, less than 22%, less than 20%, less than 18%, less than 15%, less than 12%, less than 10% or less than 8% by mole. In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (b2) in copolymer P2 is more than 5%, more than 8%, more than 10%, more than 12%, more than 15%, more than 18% or more than 20% by mole.

[0109] In some embodiments, structural unit (c2) is derived from a monomer selected from the group consisting of a nitrile-containing monomer, an ester-containing monomer, an epoxy-containing monomer, and a combination thereof. Any embodiment of the monomer from which structural unit (c1) is derived is also a suitable embodiment of the derived structural unit (c2). In certain embodiments, structural unit (c1) and structural unit (c2) are derived from the same, different, or partially different monomers, respectively.

[0110] In some embodiments, based on the total moles of the monomer units in the copolymer, the proportion of the structural unit (c2) in the copolymer P2 is about 50% to about 75%, about 52% to about 75%, about 55% to about 75%, about 58% to about 75%, about 60% to about 75%, about 62% to about 75%, about 65% to about 75%, about 68% to about 75%, about 70% to about 75%, about 50% to about 72%, about 52% to about 72%, about 55% to about 72%, about 58% to about 72%, about 60% to about 72%, about 62% to about 72%, about 65% to about 72%, about 50% to about 70%, about 52% to about 70%, about 55% to about 70%, about 58% to about 70%, about 60% to about 70%, about 62% to about 70%, about 65% to about 70%, about 50% to about 68%, about 52% to about 68%, about 55% to about 68%, about 58% to about 68%, about 60% to about 68%, about 50% to about 65%, about 52% to about 65%, about 55% to about 65%, about 58% to about 65%, about 60% to about 65%, about 50% to about 62%, about 52% to about 62%, about 55% to about 62%, or about 50% to about 60%.

[0111] In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (c2) in copolymer P2 is less than 75%, less than 72%, less than 70%, less than 68%, less than 65%, less than 62%, less than 60%, less than 58% or less than 55% by mole. In some embodiments, based on the total moles of monomer units in the copolymer, the proportion of structural unit (c2) in copolymer P2 is more than 50%, more than 52%, more than 55%, more than 58%, more than 60%, more than 62%, more than 65%, more than 68% or more than 70% by mole.

[0112] In some embodiments, the M of copolymer P2 w With copolymer P1 M w When the weight average molecular weight of the copolymer P2 is within this range, the bonding performance and dispersibility of the copolymer P2 are improved.

[0113] In certain embodiments, the solid content of binder composition B is within the same range as the solid content of binder composition A.

[0114] In some embodiments, in addition to the binder composition B, an additive is added to the first mixture in step 102. In certain embodiments, the additive may include a surfactant, a dispersant, an elasticity enhancing additive, a salt, an ion conductive polymer, and an inorganic solid electrolyte. Adding these additives can enhance the characteristics of the cathode produced by the cathode slurry of the present invention. Except that all additives (if any) and the binder composition B should be added to the first mixture, there is no particular restriction on the specific order of adding to the first mixture.

[0115] In some embodiments, the cathode slurry is formed by homogenizing the second mixture in step 103. The cathode slurry produced as a result of the methods disclosed herein includes a cathode active material, a binder material including copolymer P1 and copolymer P2, and may additionally include a conductive agent.

[0116] There are no particular restrictions on the stirring speed, required time and temperature used for homogenizing the second mixture, but they should be sufficient to ensure that the cathode slurry formed is homogenous and the cathode components are well dispersed. When the cathode components are well dispersed in the cathode slurry, the formed electrode layer is uniform and smooth, and there is no local unevenness that may affect the cathode performance. As non-limiting examples of suitable conditions for homogenizing the second mixture, the stirring speed can be in the range of about 100 rpm to about 3000 rpm; the required time can be in the range of about 5 minutes to about 24 hours; and the temperature used can be in the range of about 15°C to about 95°C.

[0117] Structural units (a1), (a2), (b1) and (b2) are hydrophilic, while structural units (c1) and (c2) are hydrophobic. Therefore, copolymer P1, which is mainly composed of structural units (a1) and (b1), is hydrophilic and therefore has good dispersibility in the aqueous solvent of the cathode slurry. Surprisingly, it was also found that the presence of copolymer P2 improves the cycle stability of the battery. Therefore, the method of the present invention requires the use of binder composition A and binder composition B at the same time to obtain the two advantages brought by the use of the respective copolymers.

[0118] The order of adding binder composition A and binder composition B is crucial. It is found that by first adding and dispersing binder composition A without adding binder composition B, the cathode active material (and conductive agent) can be kept well dispersed in the cathode slurry. Then binder composition B can be added and dispersed without affecting the dispersion of the cathode active material (and conductive agent) in the slurry. In this way, the battery produced therefrom will have good battery cycle stability.

[0119] On the other hand, if binder composition B is added and dispersed first without adding binder composition A, or both binder compositions are added simultaneously, the cathode components may aggregate. The dispersibility of the cathode components in the cathode slurry will be poor. Applying such a cathode slurry on a substrate will result in surface defects in the cathode, which will have a negative impact on battery performance. Therefore, binder composition A should be added and dispersed before adding binder composition B.

[0120] The proportion of copolymer P1 present in the cathode slurry is critical. If the proportion of copolymer P1 is too low, the dispersion of the cathode ingredients in the slurry may be poor. Conversely, if the proportion of copolymer P1 is too high, the cycling stability of the battery may be poor.

[0121] Likewise, the proportion of copolymer P2 present in the cathode slurry is also critical. If the proportion of copolymer P2 is too low, the cycling stability of the battery may be poor. Conversely, if the proportion of copolymer P2 is too high, the dispersion of the cathode components in the slurry may be poor.

[0122] In some embodiments, the proportion of each of copolymer P1 and copolymer P2 in the cathode slurry is independently about 0.5% to about 3.5%, about 0.5% to about 2.5%, about 0.5% to about 2%, about 0.5% to about 1.5%, about 1% to about 3%, about 1% to about 2.8%, about 1% to about 2.5%, about 1% to about 2.2%, about 1% to about 2%, about 1% to about 1.8%, about 1% to about 1.5%, about 1.2% to about 3%, about 1.2% to about 2.8%, about 1.2% to about 2.5%, about 1% to about 2.2%, about 1% to about 2%, about 1% to about 1.8%, about 1% to about 1.5%, about 1.2% to about 3%, about 1.2% to about 2.5%, about 1.2% to about 2.8%, about 1.2% to about 2.5%. , about 1.2% to about 2.2%, about 1.2% to about 2%, about 1.2% to about 1.8%, about 1.5% to about 3%, about 1.5% to about 2.8%, about 1.5% to about 2.5%, about 1.5% to about 2.2%, about 1.5% to about 2%, about 1.8% to about 3%, about 1.8% to about 2.8%, about 1.8% to about 2.5%, about 1.8% to about 2.2%, about 2% to about 3%, about 2% to about 2.8%, about 2% to about 2.5%, about 2.2% to about 3%, about 2.2% to about 2.8%, or about 2.5% to about 3%.

[0123] In some embodiments, the proportion of each of copolymer P1 and copolymer P2 in the cathode slurry is independently less than 3.5%, less than 3.2%, less than 3%, less than 2.8%, less than 2.5%, less than 2%, less than 1.8%, less than 1.5%, less than 1.2%, less than 1% or less than 0.8% by weight based on the solid content of the cathode slurry. In some embodiments, the proportion of each of copolymer P1 and copolymer P2 in the cathode slurry is independently more than 0.5%, more than 0.8%, more than 1%, more than 1.2%, more than 1.5%, more than 1.8%, more than 2%, more than 2.2%, more than 2.5% or more than 3% by weight based on the solid content of the cathode slurry.

[0124] The proportion of binder material (i.e. the sum of copolymer P1 and copolymer P2) present in the cathode slurry is also critical. If the proportion of binder material is too low, the adhesion of the electrode layer and the cycling stability of the battery may be poor. Conversely, if the proportion of binder material is too high, the conductivity of the cathode may be poor.

[0125] In some embodiments, the proportion of the binder material in the cathode slurry is about 2% to about 5%, about 2.2% to about 5%, about 2.5% to about 5%, about 2.8% to about 5%, about 3% to about 5%, about 3.2% to about 5%, about 3.5% to about 5%, about 3.8% to about 5%, about 4% to about 5%, about 4.2% to about 5%, about 4.5% to about 5%, about 2% to about 4.5%, about 2.2% to about 4.5%, about 2.5% to about 4.5%, about 2.8% to about 4.5%, about 3 ....2% to about 5%, about 3.5% to about 5%, about 3.8% to about 5%, about 4% to about 5%, about 4.2% to about 5%, about 4.5% to about 5%, about 4.5% to about 4.5%, about 3% to about 4.5%, about 3.2% to about 5%, about 3.5% to about 5%, about 3.8% to about %, about 3.2% to about 4.5%, about 3.5% to about 4.5%, about 3.8% to about 4.5%, about 4% to about 4.5%, about 2% to about 4%, about 2.2% to about 4%, about 2.5% to about 4%, about 2.8% to about 4%, about 3% to about 4%, about 3.2% to about 4%, about 3.5% to about 4%, about 2% to about 3.5%, about 2.2% to about 3.5%, about 2.5% to about 3.5%, about 2.8% to about 3.5%, about 3% to about 3.5%, about 2% to about 3%, about 2.2% to about 3%, or about 2.5% to about 3%.

[0126] In some embodiments, based on the solid content of the cathode slurry, the proportion of the binder material in the cathode slurry is less than 5%, less than 4.8%, less than 4.5%, less than 4.2%, less than 4%, less than 3.8%, less than 3.5%, less than 3.2%, less than 3%, less than 2.8% or less than 2.5% by weight. In some embodiments, based on the solid content of the cathode slurry, the proportion of the binder material in the cathode slurry is more than 2%, more than 2.2%, more than 2.5%, more than 2.8%, more than 3%, more than 3.2%, more than 3.5%, more than 3.8%, more than 4%, more than 4.2% or more than 4.5% by weight.

[0127] In some embodiments, the proportion of cathode active material in the cathode slurry is about 75% to about 98%, about 78% to about 98%, about 80% to about 98%, about 82% to about 98%, about 85% to about 98%, about 88% to about 98%, about 90% to about 98%, about 75% to about 95%, about 78% to about 95%, about 80% to about 95%, about 82% to about 95%, about 85% to about 95%, about 75% to about 92%, about 78% to about 92%, about 80% to about 92%, about 82% to about 92%, about 75% to about 90%, about 78% to about 90%, about 80% to about 90%, about 75% to about 88%, about 78% to about 88%, or about 75% to about 85% by weight, based on the solid content of the cathode slurry.

[0128] In some embodiments, the proportion of cathode active material in the cathode slurry is less than 98%, less than 95%, less than 92%, less than 90%, less than 88%, less than 85%, less than 82%, or less than 80% by weight based on the solid content of the cathode slurry. In some embodiments, the proportion of cathode active material in the cathode slurry is greater than 75%, greater than 80%, greater than 85%, greater than 90%, or greater than 95% by weight based on the solid content of the cathode slurry.

[0129] In some embodiments, the proportion of the conductive agent in the cathode slurry is about 1% to about 20%, about 2% to about 20%, about 3% to about 20%, about 4% to about 20%, about 5% to about 20%, about 6% to about 20%, about 7% to about 20%, about 8% to about 20%, about 9% to about 20%, about 10% to about 20%, about 11% to about 20%, about 12% to about 20%, about 13% to about 20% by weight based on the solid content of the cathode slurry. , about 14% to about 20%, about 15% to about 20%, about 1% to about 15%, about 2% to about 15%, about 3% to about 15%, about 4% to about 15%, about 5% to about 15%, about 6% to about 15%, about 7% to about 15%, about 8% to 15%, about 9% to about 15%, about 10% to about 15%, about 1% to about 10%, about 2% to about 10%, about 3% to about 10%, about 4% to about 10% or about 5% to about 10%.

[0130] In some embodiments, based on the solid content of the cathode slurry, the proportion of the conductive agent in the cathode slurry is less than 20%, less than 19%, less than 18%, less than 17%, less than 16%, less than 15%, less than 14%, less than 13%, less than 12%, less than 11%, less than 10%, less than 9%, less than 8%, less than 7%, or less than 6% by weight. In some embodiments, based on the solid content of the cathode slurry, the proportion of the conductive agent in the cathode slurry is more than 1%, more than 2%, more than 3%, more than 4%, more than 5%, more than 6%, more than 7%, more than 8%, more than 9%, more than 10%, more than 11%, more than 12%, more than 13%, more than 14%, or more than 15% by weight.

[0131] In some embodiments, the solids content of the cathode slurry is about 40% to about 80%, about 40% to about 75%, about 40% to about 70%, about 40% to about 65%, about 40% to about 60%, about 40% to about 55%, about 45% to about 80%, about 45% to about 50%, about 40% to about 65%, about 40% to about 60%, about 40% to about 55%, about 45% to about 8 ...5%, about 40% to about 60%, about 40% to about 55%, about 45% to about 80%, about 40% to about 65%, about 40% to about 65%, about 40% to about 60%, about 40% to about 55%, about 45% to about 80%, about 40% to about 65%, about 40% to about 65%, about 40% to about 65%, about 40% to about 60%, about 40% to about 55%, about 45% to about 80%, about 40% to about 65%, about 40% to about 65%, about 40% to about 65%, about 40% to about 65%, about 40% to about 65%, 45% to about 75%, about 45% to about 70%, about 45% to about 65%, about 45% to about 60%, about 50% to about 80%, about 50% to about 75%, about 50% to about 70%, about 50% to about 65%, about 55% to about 80%, about 55% to about 75%, about 55% to about 70%, about 60% to about 80%, about 60% to about 75%, about 65% to about 80%, about 65% to about 75% or about 70% to about 80%.

[0132] In some embodiments, the solid content of the cathode slurry is less than 80%, less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, or less than 50% by weight based on the total weight of the cathode slurry. In some embodiments, the solid content of the cathode slurry is more than 40%, more than 45%, more than 50%, more than 55%, more than 60%, more than 65%, or more than 70% by weight based on the total weight of the cathode slurry.

[0133] In certain embodiments, the proportion of water in the non-solid part of the cathode slurry will exceed 50%. This can be achieved by setting the proportion of water in the aqueous solvent, the dispersion medium of the binder composition A, and the dispersion medium of the binder composition B to be 50% or more.

[0134] In some embodiments, the proportion of water in the non-solid part of the cathode slurry is greater than 50%, greater than 55%, greater than 60%, greater than 65%, greater than 70%, greater than 75%, greater than 80%, greater than 85%, greater than 90%, greater than 95%, greater than 98% or greater than 99%. In some embodiments, the proportion of water in the non-solid part of the cathode slurry is 100%; that is, the non-solid part of the cathode slurry is water.

[0135] In some embodiments, after forming the cathode slurry, the slurry can be coated on one or both sides of the current collector to form an electrode layer film. There are no particular restrictions on the equipment and conditions used for coating the cathode slurry, but a uniform and smooth coating layer should be formed accordingly. Some non-limiting examples of suitable equipment include a knife coater, a slot extrusion coater, a transfer coater, a spray coater, a roll coater, a gravure coater, a dip coater, or a curtain coater.

[0136] The function of the current collector is to collect the electrons generated by the electrochemical reaction of the cathode active material or to provide the electrons required for the electrochemical reaction. There is no particular limitation on the current collector. In some embodiments, the current collector can be in the form of a foil, a sheet or a film. In some embodiments, the current collector is a metal. In some embodiments, the metal is selected from the group consisting of stainless steel, titanium, nickel, aluminum, copper, platinum, gold, silver, chromium, zirconium, tungsten, molybdenum, silicon, tin, vanadium, zinc, cadmium, or alloys thereof. In some embodiments, the current collector further comprises a conductive resin.

[0137] In some embodiments, after the cathode slurry is applied to the current collector, the electrode layer film is heated and dried to form the electrode layer, and the cathode is produced. Any device capable of drying the electrode layer film to adhere the electrode layer to the current collector can be used here. Some non-limiting examples of suitable drying equipment include vacuum drying ovens, batch drying ovens, conveyor belt drying ovens, and microwave drying ovens. There are no particular restrictions on the conditions for drying the electrode layer film, but the drying conditions should be sufficient to ensure that the electrode layer is firmly adhered to the current collector. However, drying the conductive layer film at a temperature above 150°C may cause undesirable deformation of the cathode, thereby affecting the performance of the cathode. In some embodiments, the cathode is mechanically compressed after drying to increase the density of the cathode.

[0138] In certain embodiments, the thickness of the electrode layer is from about 5 μm to about 90 μm, from about 5 μm to about 50 μm, from about 5 μm to about 25 μm, from about 10 μm to about 90 μm, from about 10 μm to about 50 μm, from about 10 μm to about 30 μm, from about 25 μm to about 70 μm, from about 25 μm to about 50 μm, from about 30 μm to about 90 μm, or from about 30 μm to about 80 μm. In some embodiments, the thickness of the electrode layer is greater than 5 μm, greater than 10 μm, greater than 15 μm, greater than 20 μm, greater than 25 μm, greater than 30 μm, greater than 40 μm, greater than 50 μm, greater than 60 μm, greater than 70 μm, or greater than 80 μm. In some embodiments, the thickness of the electrode layer is less than 90 μm, less than 80 μm, less than 70 μm, less than 60 μm, less than 50 μm, less than 40 μm, less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, or less than 10 μm.

[0139] In some embodiments, the surface density of the electrode layer is about 1 mg / cm 2 To about 50mg / cm 2 , about 2.5mg / cm 2 To about 50mg / cm 2 , about 5mg / cm 2 To about 50mg / cm 2 , about 10mg / cm 2 To about 50mg / cm 2 , about 15mg / cm 2 To about 50mg / cm 2 , about 20mg / cm 2 To about 50mg / cm 2 , about 30mg / cm 2 To about 50mg / cm 2 , about 1mg / cm 2 To about 30mg / cm 2 , about 5mg / cm2 To about 30mg / cm 2 , about 10mg / cm 2 To about 30mg / cm 2 , about 15mg / cm 2 To about 30mg / cm 2 , about 20mg / cm 2 To about 30mg / cm 2 , about 1mg / cm 2 To about 20mg / cm 2 , about 5mg / cm 2 To about 20mg / cm 2 , about 10mg / cm 2 To about 20mg / cm 2 , about 1mg / cm 2 To about 15mg / cm 2 , about 5mg / cm 2 To about 15mg / cm 2 or about 10 mg / cm 2 To about 15mg / cm 2 .

[0140] In some embodiments, the surface density of the electrode layer is less than 50 mg / cm 2 Less than 40mg / cm 2 Less than 30mg / cm 2 Less than 20mg / cm 2 Less than 15mg / cm 2 Less than 10mg / cm 2 Less than 5mg / cm 2 or less than 2.5 mg / cm 2 In some embodiments, the surface density of the electrode layer is greater than 1 mg / cm 2 , greater than 2.5mg / cm 2 , greater than 5mg / cm 2 , greater than 10mg / cm 2 , greater than 15mg / cm 2 , greater than 20mg / cm 2 , greater than 30mg / cm 2 or greater than 40 mg / cm 2 .

[0141] The electrode layer of the present invention exhibits strong adhesion to the current collector. It is important that the electrode layer has high peel strength to the current collector because this can prevent the peeling or separation of the cathode, which will greatly affect the mechanical stability of the cathode and the cycle stability of the battery including the cathode. Therefore, the cathode should have sufficient peel strength to withstand the rigors of the battery manufacturing process.

[0142] In some embodiments, the peel strength between the electrode layer and the current collector is about 1.0 N / cm to about 8.0 N / cm, about 1.0 N / cm to about 6.0 N / cm, about 1.0 N / cm to about 5.0 N / cm, about 1.0 N / cm to about 4.0 N / cm, about 1.0 N / cm to about 3.0 N / cm, about 1.0 N / cm to about 2.5 N / cm, about 1.0 N / cm to about 2.0 N / cm, about 2.0 N / cm to about 8.0 N / cm, about 2.0 N / cm to about 6.0 N / cm, about 2.0 N / cm to about 5.0 N / cm, about 2.0 N / cm to about 3.0 N / cm, about 3.0 N / cm to about 8.0 N / cm, about 3.0 N / cm to about 6.0 N / cm, or about 4.0 N / cm to about 6.0 N / cm.

[0143] In some embodiments, the peel strength between the electrode layer and the current collector is greater than 1.0 N / cm, greater than 1.2 N / cm, greater than 1.5 N / cm, greater than 2.0 N / cm, greater than 2.2 N / cm, greater than 2.5 N / cm, greater than 3.0 N / cm, greater than 3.5 N / cm, greater than 4.0 N / cm, greater than 4.5 N / cm, greater than 5.0 N / cm, greater than 5.5 N / cm, greater than 6.0 N / cm, greater than 6.5 N / cm, or greater than 7.0 N / cm. In some embodiments, the peel strength between the electrode layer and the current collector is less than 8.0 N / cm, less than 7.5 N / cm, less than 7.0 N / cm, less than 6.5 N / cm, less than 6.0 N / cm, less than 5.5 N / cm, less than 5.0 N / cm, less than 4.5 N / cm, less than 4.0 N / cm, less than 3.5 N / cm, less than 3.0 N / cm, less than 2.8 N / cm, less than 2.5 N / cm, less than 2.2 N / cm, less than 2.0 N / cm, less than 1.8 N / cm, or less than 1.5 N / cm.

[0144] In some embodiments, once the cathode is formed, the cathode can be assembled with an anode and an electrolyte to form a battery. As long as the battery has good electrochemical performance, there is no particular limitation on the anode or electrolyte used.

[0145] In some embodiments, the electrolyte is a liquid electrolyte. This liquid electrolyte includes an electrolyte solvent and a salt. In some embodiments, the electrolyte solvent is water; the liquid electrolyte is an aqueous electrolyte. In other embodiments, the electrolyte solvent is a liquid composed of one or more organic solvents; the liquid electrolyte is a non-aqueous electrolyte. In some embodiments, various organic solvents are selected from carbonate-based, ester-based, ether-based or other aprotic solvents. Some non-limiting examples of carbonate-based solvents include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and combinations thereof. Some non-limiting examples of ester-based solvents include methyl acetate, methyl propionate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate and combinations thereof. Some non-limiting examples of ether-based solvents include dibutyl ether, tetraethanol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran and combinations thereof. Some non-limiting examples of other aprotic solvents include methyl bromide, ethyl bromide, methyl formate, acetonitrile, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, and combinations thereof.

[0146] In some embodiments, the liquid electrolyte is for a lithium ion battery. The salt in the liquid electrolyte is a lithium salt. In some embodiments, the lithium salt is selected from the group consisting of LiPF6, LiBO2, LiBF4, LiSbF6, LiAsF6, LiAlCl4, LiClO4, LiCl, LiI, LiNO3, LiB(C2O4)2, LiSO3CF3, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2CF2CF3)2, LiC2H3O2, and combinations thereof.

[0147] In some embodiments, the liquid electrolyte is for a sodium ion battery. The salt in the liquid electrolyte is a sodium salt. In some embodiments, the sodium salt is a sodium analog of the lithium salt discussed above, in which the lithium is replaced by sodium. The sodium salt includes NaPF6, NaBF4, NaN(SO2CF3)2, NaN(SO2F)2, NaClO4, NaSO3CF3, and combinations thereof. In some embodiments, the salt present in the liquid electrolyte of the sodium ion battery is one or more NaMF x ; wherein each x is 4 or 6; and wherein each M is selected from Al 3+ , B 3+ , Ga 3+ 、In 3+ Sc 3+ , Y 3+ ,La 3+ , P 5+ 、As 5+ and their combinations.

[0148] In some embodiments, the electrolyte is a solid electrolyte. In some embodiments, the solid electrolyte is a polymer electrolyte. This polymer electrolyte includes an ion-conducting polymer and a salt. Any known polymer electrolyte can be used in the present invention. Some non-limiting examples of ion-conducting polymers include polyethers, polycarbonates, polyacrylates, polysiloxanes, polyphosphazenes, polyethylene derivatives, alkylene oxide derivatives, phosphate polymers, polylysine, polyester sulfides, polyvinyl alcohol and polyvinylidene fluoride. Some non-limiting examples of salts of polymer electrolytes include lithium salts and sodium salts of the liquid electrolytes mentioned above.

[0149] In some embodiments, the solid electrolyte is an inorganic solid electrolyte. Any known inorganic solid electrolyte can be used. Some non-limiting examples include sulfides, lithium superion conductor (LISICON) type compounds, lanthanum lithium titanate (LLTO) type compounds, and perovskite compounds.

[0150] In some embodiments, the solid electrolyte is a gel electrolyte. Such a gel electrolyte includes a polymer electrolyte and an electrolyte solvent.

[0151] When the method disclosed herein is used to produce a cathode slurry, the dispersibility of the cathode slurry is very good. After the slurry is applied to form a cathode, a battery including the cathode will have good cycle stability. Therefore, the method of the present invention successfully produces a cathode slurry that can coordinate the processability of the slurry and the electrochemical performance of the battery.

[0152] Provide the following examples to illustrate embodiments of the present invention, it is not used to limit the present invention to the specific embodiments cited. Unless otherwise indicated, all parts and percentages are by weight. All numerical values ​​are approximate. When providing numerical ranges, it should be understood that the embodiments outside the stated range still fall within the scope of the present invention. The specific details described in each embodiment should not be understood as essential features of the present invention. Example

[0153] The solid content of the binder composition can be determined by measuring the degree of mass change of the binder composition before and after drying. About 1g of the binder composition is weighed in a weighing bottle and dried in a vacuum dryer at 110±5°C and -0.09MPa for more than 5 hours. The binder composition is cooled in the dryer for about 15 minutes, and then its mass is measured. The mass difference of the binder composition before and after drying is determined, and the solid content (%) of the binder composition is calculated according to the following formula:

[0154] The interfacial resistance between the electrode layer and the current collector of the electrode was measured using an electrode resistance measurement system (RM2610, HIOKI).

[0155] The weight average molecular weight of copolymer is measured by gel permeation chromatography. First, the binder composition containing copolymer is dissolved in dimethylformamide at room temperature. Once the binder composition is completely dissolved, the solution is gently filtered through a 0.45 μm filter to prepare a measurement sample. A calibration curve is prepared with polystyrene standards, and the weight average molecular weight of the copolymer is calculated against the curve. The obtained measurement sample is analyzed with an Agilent PLgel 5 μm MIXED-C column. The flow rate is 1 ml / min, and the weight of the sample is 2 mg. The detector used is a Waters 2414 refractive index (RI) detector, and the detection temperature is 35 ° C. Example 1 A) Preparation of Binder Component A

[0156] 18.17 g of sodium hydroxide (NaOH) was added to a round-bottom flask containing 380 g of deionized water. The mixture was stirred at a speed of 80 rpm for 30 minutes to obtain a first suspension.

[0157] 36.08 g of acrylic acid was added to the first suspension. The mixture was further stirred at 80 rpm for 30 minutes to obtain a second suspension.

[0158] 19.05 g of acrylamide was dissolved in 10 g of deionized water to form an acrylamide solution. Thereafter, all of the acrylamide solution was added to the second suspension. The mixture was further heated to 55° C. and stirred at a speed of 80 rpm for 45 minutes to obtain a third suspension.

[0159] 12.88 g of acrylonitrile was added to the third suspension. The mixture was further stirred at 80 rpm for 10 minutes to obtain a fourth suspension.

[0160] Then, 0.015 g of a water-soluble free radical initiator (ammonium persulfate, APS; from Aladdin Industries, China) was dissolved in 3 g of deionized water, and 0.0075 g of a reducing agent (sodium bisulfite; from Tianjin Damao Chemical Reagent Factory, China) was dissolved in 1.5 g of deionized water. All of the APS solution and the sodium bisulfite solution were added to the fourth suspension. The mixture was stirred at 200 rpm at 55° C. for 24 hours to obtain a fifth suspension.

[0161] After the reaction is complete, the temperature of the fifth suspension is reduced to 25° C. 3.72 g of NaOH is dissolved in 400 g of deionized water. Thereafter, all of the sodium hydroxide solution is added dropwise to the fifth suspension for 1 hour to adjust the pH value to 7.3 to form a sixth suspension. The sixth suspension is filtered with a 200 μm nylon mesh to form a binder composition A. The solid content of the binder composition A is 9.00 wt.%. B) Preparation of Binder Composition B

[0162] Binder composition B was prepared in the same manner as binder composition A, except that 7.45 g of NaOH was added when preparing the first suspension, 16.76 g of acrylic acid was added when preparing the second suspension, 7.19 g of acrylamide was added when preparing the third suspension, and 35.96 g of acrylonitrile was added when preparing the fourth suspension. The solid content of binder composition B was 8.07 wt.%. C) Preparation of cathode slurry

[0163] The first mixture was prepared by dispersing 3.00 g of a conductive agent (Super P; from Timcal Ltd, Bodio, Switzerland), 55.80 g of NMC811 (from Shandong Tianjiao New Energy Co., Ltd., China) and 6.67 g of a binder composition A (9.00 wt.% solid content) in 27.10 g of deionized water while stirring with an overhead stirrer (R20, IKA). After addition, the first mixture was further stirred at 1,200 rpm at 25°C for about 2.5 hours.

[0164] Thereafter, a second mixture was prepared by adding 7.43 g of Binder Composition B (solids content 8.07 wt. %) while stirring with an overhead stirrer.

[0165] Then, the second mixture was further stirred at 25° C. at a speed of 1,200 rpm for about 30 minutes to form a cathode slurry. D) Preparation of cathode

[0166] The homogenized cathode slurry was coated on one side of an aluminum foil with a thickness of 16 μm as a current collector using a blade coater with a gap width of 120 μm. The 80 μm coated slurry on the aluminum foil was dried in an electric heating furnace at 70 °C to form an electrode layer. The drying time was about 10 minutes. The electrode was then pressed to reduce the thickness of the electrode layer to 23 μm. The surface density of the electrode layer was 7.00 mg / cm 2 .

[0167] The interfacial resistance between the electrode layer and the current collector in the cathode was measured. E) Assembly of button battery

[0168] CR2032 button-type Li cells were assembled in an argon-filled glove box. A lithium metal foil with a thickness of 500 μm was used as the anode, and the cathode was cut into discs and dried at 105 °C under vacuum in a box-type resistance furnace (DZF-6020, from Shenzhen Kejing Zhida Technology Co., Ltd., China) for about 16 hours. The cathode and anode were separated by a separator. The separator was a non-woven fabric (MPM, Japan) microporous membrane with a ceramic coating, and its thickness was about 25 μm.

[0169] Then, the electrolyte is injected into the casing containing the electrodes in a high-purity argon environment with a humidity and oxygen content of less than 3 ppm respectively. The electrolyte is a solution containing LiPF6 (1M) in a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. After injecting the electrolyte, the button cell is sealed using a punching tool with a standard round shape. F) Electrochemical measurements

[0170] The button cells were analyzed in constant current mode using a multi-channel battery tester (BTS-4008-5V10mA, from China Xinwei Electronics Co., Ltd.). After activation at C / 20, they were charged and discharged at a rate of C / 2. The battery was tested for charge / discharge cycles at a current density of C / 2 between 3.0V and 4.3V at 25°C to obtain the discharge capacity and capacity retention after 50 cycles. The electrochemical properties of the button cells of Example 1 were tested and are shown in Table 1 below. Preparation of Binder Composition A of Examples 2-5 and 9-14 and Comparative Examples 2-7 and 9

[0171] The preparation method of the adhesive composition A of Examples 2-5 and 9-14 and Comparative Examples 2-7 and 9 is the same as that of Example 1. Preparation of Binder Composition A of Example 6

[0172] The binder composition A was prepared in the same manner as in Example 1, except that 29.70 g of NaOH was added when preparing the first suspension, 56.85 g of acrylic acid was added when preparing the second suspension, 7.19 g of acrylamide was added when preparing the third suspension, and 6.44 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the binder composition was 10.40 wt.%. Preparation of Binder Composition A of Example 7

[0173] The binder composition A was prepared in the same manner as in Example 1, except that 17.56 g of NaOH was added when preparing the first suspension, 34.99 g of acrylic acid was added when preparing the second suspension, 12.94 g of acrylamide was added when preparing the third suspension, and 18.25 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the binder composition was 9.19 wt.%. Preparation of Adhesive Composition A of Example 8

[0174] The binder composition A was prepared in the same manner as in Example 1, except that 18.37 g of NaOH was added when preparing the first suspension, 36.44 g of acrylic acid was added when preparing the second suspension, 23.01 g of acrylamide was added when preparing the third suspension, and 9.66 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the binder composition was 9.37 wt.%. Preparation of Adhesive Composition A of Comparative Example 1

[0175] The preparation method of the adhesive composition A is the same as the preparation method of the adhesive composition B in Example 1. Preparation of Adhesive Composition B of Examples 2-8 and 13-14 and Comparative Examples 2-8

[0176] The preparation method of the adhesive composition B of Examples 2-8 and 13-14 and Comparative Examples 2-8 is the same as that of Example 1. Preparation of Binder Composition B of Example 9

[0177] Binder composition B was prepared in the same manner as in Example 1, except that 9.47 g of NaOH was added when preparing the first suspension, 20.41 g of acrylic acid was added when preparing the second suspension, 3.59 g of acrylamide was added when preparing the third suspension, and 35.96 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the binder composition was 7.89 wt.%. Preparation of Adhesive Composition B of Example 10

[0178] Adhesive composition B was prepared in the same manner as in Example 1, except that 5.42 g of NaOH was added when preparing the first suspension, 13.12 g of acrylic acid was added when preparing the second suspension, 12.94 g of acrylamide was added when preparing the third suspension, and 34.35 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the adhesive composition was 7.82 wt.%. Preparation of Adhesive Composition B of Example 11

[0179] Binder composition B was prepared in the same manner as in Example 1, except that 7.04 g of NaOH was added when preparing the first suspension, 16.04 g of acrylic acid was added when preparing the second suspension, 17.97 g of acrylamide was added when preparing the third suspension, and 28.45 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the binder composition was 7.79 wt.%. Preparation of Adhesive Composition B of Example 12

[0180] Adhesive composition B was prepared in the same manner as in Example 1, except that 6.23 g of NaOH was added when preparing the first suspension, 14.58 g of acrylic acid was added when preparing the second suspension, 5.75 g of acrylamide was added when preparing the third suspension, and 38.64 g of acrylonitrile was added when preparing the fourth suspension. The solid content of the adhesive composition was 7.58 wt.%. Preparation of Adhesive Composition B of Comparative Example 1

[0181] The preparation method of the adhesive composition B is the same as the preparation method of the adhesive composition A in Example 1. Preparation of cathode slurry of Example 2

[0182] A cathode slurry was prepared in the same manner as in Example 1, except that 2.40 g of a conductive agent, 55.80 g of NMC811, and 13.33 g of a binder composition A were dispersed in 21.03 g of deionized water to prepare a first mixture. Preparation of cathode slurry of Example 3

[0183] A cathode slurry was prepared in the same manner as in Example 1, except that 1.80 g of a conductive agent, 55.80 g of NMC811, and 6.67 g of a binder composition A were dispersed in 13.43 g of deionized water to prepare a first mixture, and 22.30 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Example 4

[0184] A cathode slurry was prepared in the same manner as in Example 1, except that 1.80 g of a conductive agent, 55.80 g of NMC811, and 20.00 g of a binder composition A were dispersed in 14.97 g of deionized water to prepare a first mixture. Preparation of cathode slurry of Example 5

[0185] A cathode slurry was prepared in the same manner as in Example 1, except that 1.50 g of a conductive agent, 55.74 g of NMC811, and 15.33 g of a binder composition A were dispersed in 9.22 g of deionized water to prepare a first mixture, and 18.21 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Example 6

[0186] A cathode slurry was prepared in the same manner as in Example 1, except that 2.40 g of a conductive agent, 55.80 g of NMC811, and 11.54 g of a binder composition A were dispersed in 22.83 g of deionized water to prepare a first mixture. Preparation of cathode slurry of Example 7

[0187] A cathode slurry was prepared in the same manner as in Example 1, except that 2.40 g of a conductive agent, 55.80 g of NMC811, and 13.06 g of a binder composition A were dispersed in 21.31 g of deionized water to prepare a first mixture. Preparation of cathode slurry of Example 8

[0188] A cathode slurry was prepared in the same manner as in Example 1, except that 2.40 g of a conductive agent, 55.80 g of NMC811, and 12.81 g of a binder composition A were dispersed in 21.56 g of deionized water to prepare a first mixture. Preparation of cathode slurry of Example 9

[0189] A cathode slurry was prepared in the same manner as in Example 2, except that the conductive agent, NMC811 and binder composition A were dispersed in 20.86 g of deionized water to prepare a first mixture, and 7.60 g of binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Example 10

[0190] A cathode slurry was prepared in the same manner as in Example 2, except that the conductive agent, NMC811 and binder composition A were dispersed in 20.79 g of deionized water to prepare a first mixture, and 7.67 g of binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Example 11

[0191] A cathode slurry was prepared in the same manner as in Example 2, except that the conductive agent, NMC811 and binder composition A were dispersed in 20.76 g of deionized water to prepare a first mixture, and 7.70 g of binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Example 12

[0192] A cathode slurry was prepared in the same manner as in Example 2, except that the conductive agent, NMC811 and binder composition A were dispersed in 20.55 g of deionized water to prepare a first mixture, and 7.92 g of binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Example 13

[0193] A cathode slurry was prepared in the same manner as in Example 1, except that 55.80 g of NMC811 was replaced with the same weight of NMC622 (obtained from Shandong Tianjiao New Energy Co., Ltd., China). Preparation of cathode slurry of Example 14

[0194] The cathode slurry was prepared in the same manner as in Example 1, except that the same weight of LiNi 0.5 Mn 1.5 O4 (LNMO; obtained from Chengdu Xingneng New Materials Co., Ltd., China) replaced 55.80 g of NMC811. Preparation of cathode slurry of Comparative Example 1

[0195] A cathode slurry was prepared in the same manner as in Example 1, except that 3.00 g of a conductive agent, 55.80 g of NMC811, and 7.43 g of a binder composition A were dispersed in 27.10 g of deionized water to prepare a first mixture, and 6.67 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Comparative Example 2

[0196] A cathode slurry was prepared in the same manner as in Example 1, except that 3.00 g of a conductive agent, 55.80 g of NMC811, and 2.00 g of a binder composition A were dispersed in 26.56 g of deionized water to prepare a first mixture, and 12.64 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Comparative Example 3

[0197] A cathode slurry was prepared in the same manner as in Example 1, except that 3.00 g of a conductive agent, 55.80 g of NMC811, and 11.33 g of a binder composition A were dispersed in 27.64 g of deionized water to prepare a first mixture, and 2.23 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Comparative Example 4

[0198] A cathode slurry was prepared in the same manner as in Example 1, except that 1.50 g of a conductive agent, 55.80 g of NMC811, and 24.67 g of a binder composition A were dispersed in 12.09 g of deionized water to prepare a first mixture, and 5.95 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Comparative Example 5

[0199] A cathode slurry was prepared in the same manner as in Example 1, except that 1.50 g of a conductive agent, 55.80 g of NMC811, and 5.33 g of a binder composition A were dispersed in 9.86 g of deionized water to prepare a first mixture, and 27.51 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Comparative Example 6

[0200] A cathode slurry was prepared in the same manner as in Example 1, except that 1.50 g of a conductive agent, 55.38 g of NMC811, and 17.33 g of a binder composition A were dispersed in 6.46 g of deionized water to prepare a first mixture, and 19.33 g of a binder composition B was added to the first mixture to prepare a second mixture. Preparation of cathode slurry of Comparative Example 7

[0201] A premix was prepared by mixing 6.67 g of Binder Composition A and 7.43 g of Binder Composition B, and the premix was stirred at 25° C. with an overhead stirrer at a speed of 1,200 rpm for about 30 minutes.

[0202] A first mixture was prepared by dispersing 3.00 g of conductive agent, 55.80 g of NMC811 and premix in 27.10 g of deionized water while stirring with an overhead stirrer. After addition, the first mixture was further stirred at 1,200 rpm for about 2.5 hours at 25°C to form a cathode slurry. Preparation of cathode slurry of Comparative Example 8

[0203] A 45% sodium polyacrylate solution (Sigma-Aldrich, USA) was used as the binder composition A, and a cathode slurry was prepared in the same manner as in Example 1, except that 3.00 g of a conductive agent, 55.80 g of NMC811 and 1.33 g of the binder composition A were dispersed in 32.43 g of deionized water to prepare a first mixture. Preparation of cathode slurry of Comparative Example 9

[0204] A 45% sodium polyacrylate solution (Sigma-Aldrich, USA) was used as the binder composition B. A cathode slurry was prepared in the same manner as in Example 1, except that the conductive agent, NMC811 and the binder composition A were dispersed in 33.20 g of deionized water to prepare a first mixture, and 1.33 g of the binder composition B was added to the first mixture to prepare a second mixture. Preparation of positive electrodes of Examples 2-14 and Comparative Examples 1-9

[0205] The positive electrodes of Examples 2-14 and Comparative Examples 1-9 were prepared in the same manner as Example 1. Examples 2-14 and Comparative Examples Assembly of button batteries 1-9

[0206] The button cells of Examples 2-14 and Comparative Examples 1-9 were assembled in the same manner as in Example 1. Electrochemical measurements of Examples 2-14 and Comparative Examples 1-9

[0207] The electrochemical properties of the button cells of Examples 2-14 and Comparative Examples 1-9 were measured in the same manner as in Example 1. The test results are shown in Table 1 below.

[0208] Although the present invention has been described in conjunction with a limited number of embodiments, the specific features of one embodiment should not limit other embodiments of the present invention. In some embodiments, the method may include a plurality of steps not mentioned herein. In other embodiments, the method does not include or substantially does not contain any steps not listed herein. There are variations and changes based on the described embodiments. The attached claims are intended to cover all these variations and changes that fall within the scope of the present invention.

Claims

1. A method for preparing a cathode slurry for a secondary battery, The following steps are involved: 1) dispersing the binder composition A and the cathode active material in an aqueous solvent to form a first mixture; 2) adding the binder composition B to the first mixture to form a second mixture; as well as 3) homogenizing the second mixture to obtain a cathode slurry; The binder composition A comprises a copolymer P 1 , and the binder composition B includes a copolymer P 2 ; wherein the copolymer P 1 Including structural units (a 1 ), structural unit (b 1 ) and structural units (c 1 ); wherein the copolymer P 2 Including structural units (a 2 ), structural unit (b 2 ) and structural units (c 2 ); wherein the structural unit (a 1 ) and the structural unit (a 2 ) are each independently derived from a monomer containing an acid group; wherein the structural unit (b 1 ) and the structural unit (b 2 ) are each independently derived from a monomer selected from the group consisting of an amide-containing monomer, a hydroxyl-containing monomer, and a combination thereof; and wherein the structural unit (c 1 ) and the structural unit (c 2 ) are each independently derived from a monomer selected from the group consisting of a nitrile group-containing monomer, an ether group-containing monomer, an epoxy group-containing monomer, and a combination thereof.

2. The method of claim 1, wherein the acid group is selected from the group consisting of carboxylic acid, sulfonic acid, sulfuric acid, phosphonic acid, phosphoric acid, nitric acid, salts thereof, derivatives thereof, and combinations thereof.

3. The method according to claim 1, wherein the copolymer P 1 and the copolymer P 2 The chemical composition is different.

4. The method according to claim 1, wherein based on the copolymer P 1 The total number of moles of monomer units in the 1 ) in the copolymer P 1 The ratio is about 45% to about 80% by mole.

5. The method according to claim 1, wherein based on the copolymer P 2 The total number of moles of monomer units in the 2 ) in the copolymer P 2 The ratio is about 15% to about 30% by mole.

6. The method according to claim 1, wherein based on the copolymer P 1 The total number of moles of monomer units in the structural unit (b 1 ) in the copolymer P 1 The ratio is about 10% to about 35% by mole.

7. The method according to claim 1, wherein based on the copolymer P 2 The total number of moles of monomer units in the structural unit (b 2 ) in the copolymer P 2 The ratio is about 5% to about 30% by mole.

8. The method according to claim 1, wherein based on the copolymer P 1 The total number of moles of monomer units in the structural unit (c 1 ) in the copolymer P 1 The ratio is about 10% to about 40% by mole.

9. The method according to claim 1, wherein based on the copolymer P 2 The total number of moles of monomer units in the structural unit (c 2 ) in the copolymer P 2 The ratio is about 50% to about 75% by mole.

10. The method according to claim 1, wherein the structural unit (a 1 ) and the structural unit (a 2 ) are different; wherein the monomers derived from the structural unit (b 1 ) and the structural unit (b 2 ) are different; and wherein the monomers derived from the structural unit (c 1 ) and the structural unit (c 2 )'s monomers are different.

11. The method of claim 1, wherein the carboxylic acid is independently selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, 2-butyl crotonic acid, cinnamic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, 4,4-dimethyl itaconic acid (tetraconic acid), 2-ethylacrylic acid, isocrotonic acid, cis-2-pentenoic acid, trans-2-pentenoic acid, angelic acid, tiglic acid (tiglic acid), 2-ethylacrylic acid, 2-pentenoic ... acid), 3,3-dimethylacrylic acid, 3-propylacrylic acid, trans-2-methyl-3-ethylacrylic acid, cis-2-methyl-3-ethylacrylic acid, 3-isopropylacrylic acid, trans-3-methyl-3-ethylacrylic acid, cis-3-methyl-3-ethylacrylic acid, 2-isopropylacrylic acid, trimethylacrylic acid, 2-methyl-3,3-diethylacrylic acid, 3-butylacrylic acid, 2-butylacrylic acid, 2-pentylacrylic acid, 2-methyl-2-hexenoic acid, trans-3-methyl-2-hexenoic acid, 3-methyl-3-propylacrylic acid, 2-ethyl-3-propylacrylic acid, 2,3-diethylacrylic acid, 3,3-diethylacrylic acid, 3-methyl The present invention relates to a group consisting of 2-methyl-3-pentylacrylic acid, 3-methyl-3-pentylacrylic acid, 4-methyl-2-hexenoic acid, 4-ethyl-2-hexenoic acid, 3-methyl-2-ethyl-2-hexenoic acid, 3-tert-butylacrylic acid, 2,3-dimethyl-3-ethylacrylic acid, 3,3-dimethyl-2-ethylacrylic acid, 3-methyl-3-isopropylacrylic acid, 2-methyl-3-isopropylacrylic acid, trans-2-octenoic acid, cis-2-octenoic acid, trans-2-decenoic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid and combinations thereof.

12. The method according to claim 1, wherein the amide-containing monomer is independently selected from the group consisting of acrylamide, methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, N-n-propyl methacrylamide, N-isopropyl methacrylamide, isopropyl acrylamide, N-n-butyl methacrylamide, N-isobutyl methacrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide, N,N-diethyl acrylamide, N,N-diethyl methacrylamide, N-hydroxymethyl methacrylamide, N-(methoxymethyl) methacrylamide, The group consisting of N-(ethoxymethyl)methacrylamide, N-(propoxymethyl)methacrylamide, N-(butoxymethyl)methacrylamide, N-(3-(dimethylamino)propyl)methacrylamide, N-(2-(dimethylamino)ethyl)methacrylamide, N,N-(dihydroxymethyl)methacrylamide, diacetone methacrylamide, diacetone acrylamide, methacryl morpholine, N-hydroxymethylacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N,N'-methylenebisacrylamide, N-hydroxymethylacrylamide and combinations thereof.

13. The method according to claim 1, wherein the nitrile-containing monomer is independently selected from the group consisting of acrylonitrile, α-haloacrylonitrile, α-alkylacrylonitrile, α-chloroacrylonitrile, α-bromoacrylonitrile, α-fluoroacrylonitrile, methacrylonitrile, α-ethylacrylonitrile, α-isopropylacrylonitrile, α-n-hexylacrylonitrile, α-methoxyacrylonitrile, 3-methoxyacrylonitrile, 3-ethoxyacrylonitrile, α-acetoxyacrylonitrile, α-phenylacrylonitrile, α-tolylacrylonitrile, α-(methoxyphenyl)acrylonitrile, α-(chlorophenyl)acrylonitrile, α-(cyanophenyl)acrylonitrile, vinylidene cyanide, and combinations thereof.

14. The method according to claim 1, wherein the aqueous solvent is water, and wherein the proportion of water in the non-solid portion of the cathode slurry exceeds 50%.

15. The method according to claim 14, wherein the aqueous solvent comprises a minor component other than water; wherein the minor component is selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, tert-butyl alcohol, n-butyl alcohol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, ethylene glycol, propylene glycol, glycerol, acetone, dimethyl ketone, methyl ethyl ketone, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate, 1,4-dioxane, diethyl ether, methyl tert-butyl ether, cyclopentyl methyl ether, tetrahydrofuran, 2-methyl The present invention relates to a group consisting of methyltetrahydrofuran, acetonitrile, dimethyl sulfoxide, cyclopentane, nitromethane, propylene carbonate, ethylene carbonate, dimethyl carbonate, pyridine, acetaldehyde, formic acid, acetic acid, propionic acid, butyric acid, γ-valerolactone, furfuryl alcohol, methyl lactate, ethyl lactate, diethanolamine, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, dihydrolevoglucose ketone, N,N'-dimethylpropyleneurea, dimethyl isosorbide and combinations thereof; and wherein the volume ratio of water in the aqueous solvent to the minor component is from about 51:49 to about 99:

1.

16. The method of claim 1, wherein the solid content of the cathode slurry is about 40% to about 80% by weight based on the total weight of the cathode slurry; wherein the copolymer P in the cathode slurry is about 10% to about 10% by weight based on the solid content of the cathode slurry. 1 and the copolymer P 2 The proportion of each independently is about 0.5% to about 3.5% by weight; and wherein based on the solid content of the cathode slurry, the copolymer P in the cathode slurry 1 and the copolymer P 2 The proportion of the sum is at most 5% by weight.

17. The method according to claim 1, wherein the cathode active material is selected from LiCoO 2 、LiNiO 2 、LiNi 1-x (M 1 ) x O 2 、LiNi x Mn y O 2 、LiCo x Ni y O 2 , Li 1+z Ni x Mn y Co 1-x-y O 2 、LiNi x Co y Al z O 2 , LiV 2 O 5 、LiTiS 2 、LiMoS 2 、LiMnO 2 、LiCrO 2 、LiMn 2 O 4 , Li 2 MnO 3 、LiFeO 2 ,LiM 2 PO 4 , Li 1+a Ni b Mn c Co d Al (1-b-c-d) O 2 , Li 3 V 2 (PO 4 ) 3 、LiVPO 4 F. LiNi x Mn e O 4 、LiNi 0.92 Mn 0.04 Co 0.04 O 2 and a group consisting of combinations thereof, wherein 0.1≤x≤0.9; 0≤y≤0.9; 0≤z≤0.4; -0.2≤a≤0.2; 0≤b<1; 0≤c<1; 0≤d<1; 0≤e≤2; and b+c+d≤1; M 1 is selected from the group consisting of Co, Mn, Al, Fe, Ti, Ga, Mg, and combinations thereof; and M 2 Selected from the group consisting of Fe, Co, Ni, Mn, Al, Mg, Zn, Ti, La, Ce, Sn, Zr, Ru, Si, Ge and combinations thereof.

18. The method according to claim 1, wherein a proportion of the cathode active material in the cathode slurry is about 75% to about 98% by weight based on a solid content of the cathode slurry. 19 . The method according to claim 1 , wherein step 1) further comprises dispersing a conductive agent other than the binder composition A and the cathode active material in the aqueous solvent to form the first mixture.

20. The method according to claim 19, wherein the conductive agent is selected from the group consisting of natural graphite particles, synthetic graphite particles, hard carbon, soft carbon, mesophase carbon microbeads, carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon tubes, carbon nanotubes, activated carbon, Super P, KS6, vapor-grown carbon fibers, mesoporous carbon, and combinations thereof; and wherein the proportion of the conductive agent in the cathode slurry is about 1% to about 20% by weight based on the solid content of the cathode slurry.

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