Aqueous coating composition, aqueous pole piece, and aqueous battery

Abstract

An aqueous coating composition, an aqueous pole piece, and an aqueous battery. The aqueous coating composition comprises an aqueous binder and a solvent, the aqueous binder comprises a first polymer, and the first polymer comprises a structural unit represented by formula (1) and a structural unit represented by formula (2); in formula (1), R1, R2 and R3 are each independently hydrogen, a halogen, an alkyl, a hydroxyalkyl, an alkoxylate, a cycloalkyl, an alkenyl, an alkynyl, a heterocycloalkyl, an aryl, a heteroaryl, a hydroxyl, a cyano group or a nitro group, and L is a connecting bond or a C1-10 alkylene group; in formula (2), R4, R5 and R6 are each independently hydrogen, a halogen, an alkyl, a hydroxyalkyl, an alkoxylate, a cycloalkyl, an alkenyl, an alkynyl, a heterocycloalkyl, an aryl, a heteroaryl, a hydroxyl, a cyano group or a nitro group, and n＝2-12. The aqueous coating composition can improve the adhesion and water resistance of an aqueous coating, thereby improving the safety performance and cycle performance of an aqueous battery.

Description

Aqueous coating composition, aqueous electrode and aqueous battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202311021430.7 and application date August 14, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to an aqueous coating composition, an aqueous electrode, and an aqueous battery. Background Art

[0004] In recent years, the application scope of secondary batteries has become increasingly extensive. Secondary batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As secondary batteries have achieved great development, higher requirements have been placed on their performance.

[0005] Aqueous batteries are currently attracting widespread attention due to their environmentally friendly and pollution-free properties. However, aqueous batteries place high demands on the water resistance of their electrodes. Therefore, how to ensure excellent water resistance in aqueous electrodes and improve the safety and recyclability of aqueous batteries has become a pressing issue in this field.

[0006] Summary of the Invention

[0007] The present application is made in view of the above-mentioned problems, and its purpose is to provide an aqueous coating composition, an aqueous electrode and an aqueous battery, thereby improving the adhesion and water resistance of the aqueous electrode, reducing the risk of the aqueous coating falling off, and further improving the safety performance and cycle performance of the aqueous battery.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a water-based coating composition, characterized in that it contains an aqueous binder and a solvent, the aqueous binder contains a first polymer, and the first polymer contains a structural unit represented by formula (1) and a structural unit represented by formula (2).

[0009] In formula (1), R1, R2, and R3 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro, and L is a connecting bond or a C1-10 alkylene group.

[0010] In formula (2), R4, R5, and R6 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano, or nitro, and n=2-12.

[0011] The carboxyl group in the structural unit represented by formula (1) and the hydroxyl group in the structural unit represented by formula (2) in the aqueous coating composition of the present application can form hydrogen bonds and / or cross-linked structures, thereby improving its adhesion in the aqueous electrode, enabling the aqueous electrode to obtain excellent water resistance, reducing the risk of demolding, and improving the safety and cyclability of the battery.

[0012] In any embodiment, in formula (1), R1, R2, and R3 are each independently hydrogen, an alkyl group, a hydroxyalkyl group, an alkoxy group, a hydroxyl group, or a cyano group, L is a linker or a C3-4 alkylene group, and in formula (2), R4, R5, and R6 are each independently hydrogen, an alkyl group, a hydroxyalkyl group, an alkoxy group, a hydroxyl group, or a cyano group, and n = 3 to 6. By including the above-mentioned functional groups in the structural units represented by formulas (1) and (2), the adhesion between the aqueous coating and the current collector can be improved. Moreover, as the battery is used for a longer time, the improved adhesion is conducive to further improving the cycle performance.

[0013] In any embodiment, in the first polymer, the mass proportion of the structural unit represented by formula (1) is 10% to 75%, and the mass proportion of the structural unit represented by formula (2) is 5% to 40%. By setting the content of each structural unit within the above range, a high-density cross-linked network structure can be formed.

[0014] In any embodiment, the first polymer further comprises a structural unit represented by formula (3) and / or a structural unit represented by formula (4),

[0015] In formula (3), R7, R8, and R9 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano, or nitro.

[0016] R 10 is a rigid group, optionally a cyano group, an amido group or an aryl group, optionally a cyano group,

[0017] In formula (4), R 11 、R 12 、R 13 Each is independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano or nitro, and m=2-12.

[0018] The structural unit shown in formula (3) is a hard segment that can provide strength to the material, and the structural unit shown in formula (4) is a soft segment that can provide flexibility to the material. As a result, the wetting and spreading of the water-based coating on the substrate, especially the oil-containing substrate (for example, oil-containing aluminum foil) can be enhanced, which is beneficial to improving the adhesion and water resistance.

[0019] In any embodiment, the mass proportion of the structural unit represented by formula (3) in the first polymer is 5% to 40%. In any embodiment, the mass proportion of the structural unit represented by formula (4) in the first polymer is 10% to 75%. This allows the water-based coating to have appropriate hardness and flexibility, which helps improve the adhesion and water resistance of the water-based coating.

[0020] In any embodiment, in the first polymer, the mass proportion of the structural unit represented by formula (1) is 30% to 55%, the mass proportion of the structural unit represented by formula (2) is 5% to 15%, the mass proportion of the structural unit represented by formula (3) is 10% to 20%, and the mass proportion of the structural unit represented by formula (4) is 30% to 55%. By making the content of each structural unit within the above range, it is beneficial to improve the bonding strength and water resistance.

[0021] In any embodiment, the number average molecular weight of the first polymer is 200,000 to 1,000,000, and optionally 300,000 to 600,000. By setting the number average molecular weight within this range, the binder molecular chains can be partially entangled within the water-based coating, which is conducive to the formation of a three-dimensional network structure in the water-based coating and improves the adhesive strength. Furthermore, by setting the number average molecular weight within this range, the entanglement can be controlled within a moderate range, thereby achieving excellent flexibility.

[0022] In any embodiment, the aqueous binder further comprises a second polymer, which, unlike the first polymer, comprises a group reactive with the first polymer, wherein the group is capable of forming hydrogen bonds and / or crosslinking structures with the first polymer. By further including the second polymer, which forms hydrogen bonds and / or crosslinking structures with the first polymer, a high-density three-dimensional crosslinked network can be formed, further enhancing the adhesive strength and improving the water resistance of the aqueous coating.

[0023] In any embodiment, the second polymer includes a flexible group, wherein the flexible group is a group including an ester bond or a group including an ether bond. By including the flexible group in the polymer, the flexibility of the binder can be increased, the brittleness of the coating can be improved, and the water resistance of the water-based coating can be improved.

[0024] In any embodiment, the second polymer comprises a structural unit represented by formula (5), a structural unit represented by formula (6), and a structural unit represented by formula (7).

[0025] In formula (5), R'1, R'2, and R'3 are the same as or different from R1, R2, and R3, respectively, and are independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro; L' is the same as or different from L, and is a connecting bond or a C1-10 alkylene group.

[0026] In formula (6), R'4, R'5, and R'6 are the same as or different from R4, R5, and R6, respectively, and are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro; n' is the same as or different from n, and n'=2 to 12.

[0027] In formula (7), R' 11 , R' 12 , R' 13 With R 11 、R 12 、R 13 are the same or different, and are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano or nitro, m' is the same as or different from m, and m'=2-12.

[0028] The carboxyl group of the structural unit represented by formula (5) and / or the hydroxyl group of the structural unit represented by formula (6) in the above-mentioned second polymer can form hydrogen bonds and / or cross-linked structures with the carboxyl group of the structural unit represented by formula (1) and / or the hydroxyl group of the structural unit represented by formula (2) in the above-mentioned first polymer, forming a high-density three-dimensional network cross-linked structure, which is beneficial to improving the adhesion and water resistance of the water-based coating.

[0029] In any embodiment, in formula (5), R'1, R'2, and R'3 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, L' is a linker or a C3-4 alkylene group, in formula (6), R'4, R'5, and R'6 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, n'=3-6, in formula (7), R' 11 , R' 12 , R' 13 Each independently represents hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl or cyano, and m' is 3 to 6. By optimizing the structure of the structural units, a high-density three-dimensional network system is formed, which is beneficial to improving adhesion and water resistance.

[0030] In any embodiment, in the second polymer, the mass proportion of the structural unit represented by formula (5) is 10% to 60%, the mass proportion of the structural unit represented by formula (6) is 5% to 20%, and the mass proportion of the structural unit represented by formula (7) is 20% to 60%. By setting the content of each structural unit within the above range, it is beneficial to form a high-density three-dimensional network cross-linked system, which is conducive to further improving the bonding strength and water resistance.

[0031] In any embodiment, the number average molecular weight of the second polymer is 200,000 to 1.2 million, optionally 250,000 to 600,000. By setting the number average molecular weight within this range, the binder molecular chains can be partially entangled within the water-based coating, which is conducive to the formation of a three-dimensional network structure in the water-based coating and improves the adhesive strength. At the same time, by setting the number average molecular weight within this range, the entanglement can be controlled within a moderate range, thereby achieving excellent flexibility.

[0032] In any embodiment, the structural unit of formula (2) and the structural unit of formula (6) are By making the above structural unit into this specific structure, the bonding force of the adhesive in the water-based electrode is greatly improved, thereby improving the water resistance of the water-based electrode.

[0033] In any embodiment, the mass ratio of the first polymer to the second polymer is 9:1 to 1:9, and optionally 4:1 to 1:4. By ensuring the mass ratio of the first polymer to the second polymer is within this range, high-density hydrogen bonds can be formed, which facilitates the formation of a high-density three-dimensional network system and further improves water resistance.

[0034] In any embodiment, the solvent is water. Using water as a solvent is low-cost and environmentally friendly. In any embodiment, the composition further comprises an insulating material and / or a dispersant. Optionally, the insulating material is a ceramic material, optionally the ceramic material is boehmite powder, and optionally the dispersant is a polyacrylamide-based dispersant. This improves insulation and battery safety.

[0035] A second aspect of the present application further provides an aqueous electrode, characterized by comprising an aqueous coating formed from the aqueous coating composition of the first aspect of the present application and having a three-dimensional network cross-linked structure. The inclusion of the three-dimensional network cross-linked structure in the aqueous coating enhances the adhesive strength and water resistance of the aqueous coating, thereby improving the cycling performance and safety of the battery.

[0036] In any embodiment, the water-based coating contains 10% to 30% by mass of an aqueous binder, preferably 15% to 25% by mass, relative to the total mass of the water-based coating. By adjusting the binder content within this range, the adhesion of the water-based coating can be enhanced, improving water resistance, and contributing to an increase in the content of the insulating material, thereby enhancing the insulation effect.

[0037] In any embodiment, the aqueous coating layer contains 65% to 80% by mass of an insulating material and 0.2% to 1.0% by mass of a dispersant relative to the total mass of the aqueous coating layer. This contributes to improved insulation properties and battery safety.

[0038] In any embodiment, the contact angle between the aqueous coating and water is less than or equal to 90°, and optionally is 40° to 80°. This improves the wettability of the aqueous coating in the aqueous electrode, allowing the coating to spread more fully on the substrate, increasing the contact area, and improving the adhesion of the aqueous coating to the substrate surface, thereby reducing the risk of detachment.

[0039] In any embodiment, the peel strength of the aqueous coating on the aqueous electrode is greater than or equal to 10 N / m, optionally greater than or equal to 17 N / m, and the peel strength is obtained by performing a peel test based on the national standard GB / T41511-2022.

[0040] In any embodiment, the aqueous electrode is an aqueous positive electrode or an aqueous negative electrode.

[0041] The third aspect of the present application also provides an aqueous battery, which includes the aqueous electrode of the second aspect of the present application. Therefore, the aqueous battery of the present application has excellent safety performance and cycle performance.

[0042] The fourth aspect of the present application also provides an electrical device, which includes the aqueous battery of the third aspect of the present application.

[0043] Effects of the Invention

[0044] The aqueous coating composition of the present application includes a polymer with a specific structure as an aqueous binder, forming a three-dimensional network cross-linked structure within the aqueous coating. This improves the adhesion of the aqueous coating to the electrode, thereby enhancing the coating's water resistance. Furthermore, the polymer contains flexible structural units with an ester structure, which increases the coating's flexibility and contributes to further improving the coating's water resistance. By including a coating with high adhesion and high water resistance, the aqueous electrode of the present application achieves the application of aqueous electrode technology and improves the safety and cycling performance of aqueous batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a partial schematic cross-sectional view of a pole piece according to some embodiments of the present application.

[0046] FIG2 is an infrared spectrum obtained by performing infrared testing on the first polymer 1-20 obtained in the preparation example of this application.

[0047] Figure 3 is an infrared spectrum obtained by performing infrared testing on the aqueous coating of the positive electrode plate after disassembling the battery prepared in Example 24 of the present application.

[0048] DESCRIPTION OF REFERENCE NUMERALS 1 - Current collector; 11 - Conductive layer; 12 - Insulating layer; 13 - Substrate; 2 - Active material layer DETAILED DESCRIPTION

[0049] The following describes in detail the embodiments of the aqueous coating composition, aqueous electrode, aqueous battery, and electrical device of the present application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially identical structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0050] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] Unless otherwise indicated, the following terms used in the specification and claims have the following meanings:

[0052] "Halogen" refers to fluorine, chlorine, bromine or iodine, optionally fluorine or chlorine.

[0053] "Alkyl" refers to a saturated aliphatic hydrocarbon group, including straight and branched chain groups of 1 to 20 carbon atoms. Optionally, it is a medium-sized alkyl group containing 1 to 10 carbon atoms, such as methyl, ethyl, propyl, 2-propyl, n-butyl, isobutyl, tert-butyl, pentyl, etc. Furthermore, it is optionally a lower alkyl group containing 1 to 4 carbon atoms, such as methyl, ethyl, propyl, 2-propyl, n-butyl, isobutyl, or tert-butyl, etc. The alkyl group may be substituted or unsubstituted. When substituted, the group may optionally be halogen, hydroxy, lower alkoxy, aryl, aryloxy, heteroaryl, or heterocycloalkyl.

[0054] The "hydroxyalkyl group" refers to a group in which a hydrogen atom in the above-mentioned alkyl group is substituted with a hydroxy group.

[0055] "Cycloalkyl" refers to a 3-8 membered all-carbon monocyclic ring, an all-carbon 5-membered / 6-membered or 6-membered / 6-membered fused ring, or a polycyclic fused ring ("fused ring" means that each ring in the system shares a pair of adjacent carbon atoms with the other rings in the system), wherein one or more rings may contain one or more double bonds, but no ring has a completely conjugated π electron system. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclopentene, cyclohexane, cyclohexadiene, adamantane, cycloheptane, cycloheptatriene, etc. Cycloalkyl groups may be substituted or unsubstituted. When substituted, they may be one or more substituents independently selected from lower alkyl, trihaloalkyl, halogen, hydroxy, lower alkoxy, aryl, aryloxy, 6-membered heteroaryl, 5-membered heteroaryl, or 5- or 6-membered heterocycloalkyl, sulfhydryl, (lower alkyl)sulfanyl, cyano, nitro, carboxyl, and ester groups.

[0056] "Alkoxy" refers to -O-(alkyl) and -O-(unsubstituted cycloalkyl). Here, alkyl and cycloalkyl are defined as above. Representative examples include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, and the like.

[0057] "Alkenyl" refers to an alkyl group as defined above consisting of at least two carbon atoms and at least one carbon-carbon double bond. Representative examples include, but are not limited to, ethenyl, 1-propenyl, 2-propenyl, 1-, 2- or 3-butenyl, and the like.

[0058] "Alkynyl" refers to an alkyl group as defined above consisting of at least two carbon atoms and at least one carbon-carbon triple bond. Representative examples include, but are not limited to, ethynyl, 1-propynyl, 2-propynyl, 1-, 2- or 3-butynyl, and the like.

[0059] "Heterocycloalkyl" refers to a monocyclic or fused ring group having 5 to 9 ring atoms, one or two of which are selected from nitrogen, oxygen, or sulfur, and the remaining ring atoms are carbon. These rings may also have one or more double bonds, however, these rings do not have a completely conjugated π electron system. Unsubstituted heterocycloalkyl groups include, but are not limited to, pyrrolidinyl, piperidino, morpholinyl, thiomorpholinyl, homopiperazinyl, and the like. Heterocycloalkyl groups may be substituted or unsubstituted. When substituted, the substituents are preferably optionally substituted with one or more substituents selected from the group consisting of halogen, trihalomethyl, hydroxy, nitro, cyano, alkoxy, alkyl, carboxyl, and ester groups.

[0060] "Aryl" refers to a group having at least one aromatic ring structure, i.e., an aromatic ring having a conjugated π-electron system, including carbocyclic aromatic groups, heteroaryl groups, and biaryl groups. The aromatic group may be optionally substituted with one or more substituents selected from the group consisting of halogen, trihalomethyl, hydroxy, nitro, cyano, alkoxy, alkyl, carboxyl, and ester groups.

[0061] "Heteroaryl" refers to an aromatic group having from one to three heteroatoms as ring atoms, with the remaining ring atoms being carbon, including oxygen, sulfur, and nitrogen. The ring may be a five-membered or six-membered ring. Examples of heterocyclic aromatic groups include furanyl, thienyl, pyridyl, pyrrolyl, N-alkylpyrrolyl, pyrimidinyl, pyrazinyl, imidazolyl, and the like. The heteroaryl group may be optionally substituted with one or more substituents selected from the group consisting of halogen, trihalomethyl, hydroxy, nitro, cyano, alkoxy, alkyl, carboxylic acid, and ester groups.

[0062] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0063] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0064] At present, battery electrodes are gradually turning to environmentally friendly and pollution-free water-based electrode systems. However, the existing insulation coating formulation system is not suitable for water-based electrode systems. The reason is that the existing insulation coating formulation system is mostly an oily system, that is, N-methylpyrrolidone (NMP) is used as a solvent, and the binders used are mainly soluble in NMP, such as polyvinylidene fluoride (PVDF), polyimide, etc. Because NMP is a petroleum-derived chemical product, its synthesis and post-processing processes are complicated. Moreover, when preparing electrodes, a large amount of NMP toxic gas will evaporate into the air, polluting the environment and causing harm to the human body. This is contrary to one of the main purposes of the water-based electrode system, environmental protection. In addition, the above-mentioned oily formulation system of the insulation coating is incompatible with the water-based electrode. The solvent water in the water-based electrode system has a different drying efficiency than the solvent NMP in the existing insulation coating formulation system, resulting in poor electrode coating and drying. During the continuous heating process, the film layer area is prone to over-drying, resulting in cracking or even falling off.

[0065] Therefore, there is an urgent need for an aqueous insulating coating in the current aqueous electrode, which not only needs to have excellent adhesion but also needs to have water resistance to adapt to the application of aqueous batteries.

[0066] Based on this, the present application proposes a water-based coating composition suitable for water-based electrodes, wherein the composition comprises a water-based binder and a solvent. The water-based binder comprises a first polymer.

[0067] First polymer

[0068] The first polymer includes a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2).

[0069] In formula (1), R1, R2, and R3 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano, or nitro, and L is a linking bond or a C1-10 alkylene group.

[0070] The so-called C1-10 alkylene group refers to an alkylene group with 1 to 10 carbon atoms, for example, it can include but is not limited to methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene and decylene.

[0071] In formula (2), R4, R5, and R6 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano, or nitro, and n=2-12.

[0072] The water-based binder in the present application has a special cross-linkable structure and carries a certain number of ester structures shown in formula (2), which changes the binder molecular chain from a linear structure to a more solid three-dimensional network structure, thereby improving the water resistance of the water-based coating. At the same time, the ester structure shown in formula (2) acts as a lipophilic group, which enables the water-based coating to better infiltrate and spread on the substrate (aluminum foil, etc.), thereby obtaining a better bonding effect. As a result, the water-based membrane layer has high bonding strength and high water resistance, thereby improving the safety and cyclability of the battery.

[0073] In some embodiments, in formula (1), R1, R2, and R3 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, L is a linker or a C3-4 alkylene group, and in formula (2), R4, R5, and R6 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, and n = 3-6, for example, 3, 4, 5, or 6. By providing the above-mentioned structural units with the above-mentioned functional groups, the adhesion between the coating and the current collector can be further improved. Moreover, as the battery is used for a longer time, the improvement in adhesion is conducive to further improving the cycle performance of the battery.

[0074] In some embodiments, in the first polymer, the mass proportion of the structural unit represented by the above formula (1) is 10% to 75%, and the value can be an end point value or any value between the end points, for example, it can be: 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, but not limited to this. The mass proportion of the structural unit represented by the above formula (2) is 5% to 40%, and the value can be an end point value or any value between the end points, for example, it can be: 5%, 10%, 20%, 25%, 30%, 40%, but not limited to this. By making the mass proportion of the structural unit within the above range, a high-density cross-linked structure can be formed, which is beneficial to improving the water resistance of the water-based coating.

[0075] In some embodiments, the first polymer further comprises a structural unit represented by formula (3) and / or a structural unit represented by formula (4).

[0076] In formula (3), R7, R8, and R9 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano, or nitro.

[0077] R 10 is a rigid group, optionally a cyano group, an amido group or an aryl group, optionally a cyano group.

[0078] In formula (4), R 11 、R 12 、R 13Each is independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano or nitro, and m=2-12.

[0079] The structural unit shown in formula (3) is a hard segment that can provide strength to the material, and the structural unit shown in formula (4) is a soft segment that can provide flexibility to the material. As a result, the coating can be enhanced infiltrated and spread on the substrate, especially the oil-containing substrate (for example, oil-containing aluminum foil), which is beneficial to improving the adhesion and water resistance.

[0080] In some embodiments, in the first polymer, the mass percentage of the structural unit represented by formula (3) is 5% to 40%. The values ​​can be either endpoints or any value between the endpoints, such as, but not limited to, 10%, 20%, 30%, or 40%. By ensuring that the content of the structural unit is within the above range, the water-based coating has a moderate hardness and is conducive to improving adhesion.

[0081] In some embodiments, in the first polymer, the mass percentage of the structural unit represented by formula (4) is 10% to 75%. The value can be an endpoint or any value between the endpoints, for example, 10%, 15%, 20%, 30%, 40%, 50%, 60%, or 70%, but is not limited thereto. By ensuring that the content of the structural unit is within the above range, the water-based coating is more conducive to having appropriate flexibility and improving water resistance.

[0082] In some embodiments, in the first polymer, the mass proportion of the structural unit represented by formula (1) is 30% to 55%, the mass proportion of the structural unit represented by formula (2) is 5% to 15%, the mass proportion of the structural unit represented by formula (3) is 10% to 20%, and the mass proportion of the structural unit represented by formula (4) is 30% to 55%. By ensuring that the content of each structural unit is within the above range, it is beneficial to form a three-dimensional network cross-linked structure, improve the adhesion of the water-based coating, and improve water resistance.

[0083] In some embodiments, the connecting bonds on both sides of each structural unit in the first polymer are connected to each other to form a polymer chain as shown below, but the connection method of each structural unit in the first polymer is not limited thereto.

[0084] a and d are both any integer greater than 0, and b and c are both any integer greater than 0. The values ​​of a, b, c and d may be the same or different.

[0085] In some embodiments, the number average molecular weight of the first polymer is 200,000 to 1,000,000, and optionally 300,000 to 600,000. By setting the number average molecular weight within this range, the binder molecular chains can be partially entangled within the water-based coating, which is conducive to the formation of a three-dimensional network structure in the water-based coating and improves the adhesive strength. At the same time, by setting the number average molecular weight within this range, the entanglement can be controlled within a moderate range, thereby achieving excellent flexibility and thus improving the water resistance of the water-based coating.

[0086] Second polymer

[0087] In some embodiments, the aqueous binder in the aqueous coating composition of the present application further includes a second polymer, which is different from the first polymer and contains a group capable of reacting with the first polymer, and the above-mentioned group can form hydrogen bonds and / or cross-linked structures with the first polymer. By further including the second polymer to form hydrogen bonds and / or cross-linked structures with the first polymer, a high-density three-dimensional network cross-linked structure can be formed, further improving the adhesion and further improving the water resistance of the aqueous coating. The so-called "the second polymer is different from the first polymer" includes: the various structural units of the second copolymer are different from the first copolymer; the various structural units of the second copolymer are the same as the first copolymer but the connection method of the various structural units is different; and the various structural units of the second copolymer are the same as the first copolymer but the mass proportion of the various structural units is different, etc.

[0088] In some embodiments, the second polymer includes a flexible group, which is an ester or ether group. These flexible groups include, but are not limited to, methyl acrylate, ethyl acrylate, propyl acrylate, methoxy, and ethoxy groups. These groups can enhance the coating's flexibility, effectively reducing the risk of tab folding, improving the coating's water resistance, and enhancing battery safety.

[0089] In some embodiments, the second polymer comprises a structural unit represented by formula (5), a structural unit represented by formula (6), and a structural unit represented by formula (7).

[0090] In formula (5), R'1, R'2, and R'3 are the same as or different from R1, R2, and R3, respectively, and are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano, or nitro. L' is the same as or different from L and is a linker or a C1-10 alkylene group. Here, the definition of "C1-10 alkylene group" is the same as that in the first polymer.

[0091] In formula (6), R'4, R'5, and R'6 are the same as or different from R4, R5, and R6, respectively, and are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro; n' is the same as or different from n, and n'=2 to 12.

[0092] In formula (7), R' 11 , R' 12 , R' 13 With R 11 、R 12 、R 13 are the same or different, and are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano or nitro, m' is the same as or different from m, and m'=2-12.

[0093] The present application adopts a mixture of two polymers, wherein the carboxyl group of the structural unit represented by formula (1) and / or the hydroxyl group of the structural unit represented by formula (2) in the first polymer interacts with the carboxyl group of the structural unit represented by formula (5) and / or the hydroxyl group of the structural unit represented by formula (6) in the second polymer to form hydrogen bonds, or can further react with each other to form new chemical bonds such as ester bonds through treatments such as heating, thereby constructing a high-density three-dimensional network cross-linked structure inside the coating, thereby providing more sufficient adhesion for the water-based coating and further improving the water resistance of the water-based coating.

[0094] In addition, the structural unit represented by formula (3) in the first polymer, i.e., the acrylonitrile monomer, is a hard monomer that provides strength to the material. The structural unit represented by formula (7) in the second polymer, i.e., the acrylate monomer, is a soft monomer that provides flexibility to the coating. As lipophilic groups, these monomers can better enable the aqueous coating to infiltrate and spread on a substrate, particularly an oil-containing substrate (e.g., oil-containing aluminum foil), thereby improving water resistance and enhancing battery safety.

[0095] In some embodiments, in formula (5), R'1, R'2, and R'3 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, L' is a connecting bond or a C3-4 alkylene group, in formula (6), R'4, R'5, and R'6 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, n'=3-6, in formula (7), R' 11 , R' 12 , R' 13 Each independently represents hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl or cyano, and m'=3 to 6. Here, by providing the structural units with the functional groups, the adhesion between the coating and the current collector is further improved, and as the battery is used for a longer time, the improved adhesion is conducive to further improving the cycle performance.

[0096] In some embodiments, in the second polymer, the mass proportion of the structural unit represented by formula (5) is 10% to 60%, the mass proportion of the structural unit represented by formula (6) is 5% to 20%, and the mass proportion of the structural unit represented by formula (7) is 20% to 60%. By ensuring that the mass proportions of the structural units are within the above ranges, a high-density three-dimensional network system is formed, which is conducive to further improving the bonding strength and water resistance.

[0097] In some embodiments, the structural unit represented by formula (2) in the first polymer and the structural unit represented by formula (6) in the second polymer are both By using a structure of hydroxypropyl ester, that is, by controlling the length of the alkane chain, the swelling rate of the binder material in the electrolyte can be effectively reduced compared to the case of longer chains such as hydroxybutyl ester and hydroxyhexyl ester, so that the coating effectively adheres to the substrate during long-term use, thereby further reducing the possibility of shedding. In addition, compared with the case of shorter chains such as hydroxymethyl ester and hydroxyethyl ester, because the carbon chain becomes longer, the pole piece coating is more flexible, reducing the risk of bending and brittle fracture of the coating, which is conducive to improving water resistance. In addition, by making the structural unit shown in formula (2) consistent with the structural unit shown in formula (6), the intermolecular force will be further enhanced, thereby improving the bonding force and improving water resistance.

[0098] In some embodiments, the structural units in the second polymer are connected to each other to form a polymer chain as shown below, but the connection method of the structural units in the second polymer is not limited thereto.

[0099] e and g are any integer greater than 0, and f is any integer greater than 0. The values ​​of e, f and g may be the same or different.

[0100] In some embodiments, the number average molecular weight of the second polymer is 200,000 to 1.2 million, optionally 250,000 to 600,000. By setting the number average molecular weight within this range, the binder molecular chains can be partially entangled within the water-based coating, which is conducive to the formation of a three-dimensional network structure in the water-based coating and improves the adhesive strength. At the same time, by setting the number average molecular weight within this range, the entanglement can be controlled within a moderate range, thereby achieving excellent flexibility and thus improving the water resistance of the water-based coating.

[0101] In some embodiments, the mass ratio of the first polymer to the second polymer is 9:1 to 1:9, or alternatively 4:1 to 1:4. By ensuring that the mass ratio of the first polymer to the second polymer is within the above range, a high-density three-dimensional network system is formed, which further improves the bonding strength.

[0102] Water-based coating composition

[0103] In some embodiments, the aqueous coating composition further comprises an insulating material and / or a dispersant in addition to the aqueous binder. Optionally, the insulating material is a ceramic material. Ceramic materials include but are not limited to aluminum oxide, boehmite, zirconium oxide, titanium oxide, silicon nitride, boron carbide, etc., and boehmite powder is optional. The dispersant may be, for example, a polyacrylamide-based dispersant. In the coating, the carboxyl group of the structural unit represented by formula (1) in the first polymer and the carboxyl group of the structural unit represented by formula (5) in the second polymer can form hydrogen bonds with the insulating material boehmite, further improving the adhesion of the aqueous coating.

[0104] In some embodiments, water, such as deionized water, is used as a solvent. Compared with oil-based electrode systems using NMP as a solvent, the use of water as a solvent can reduce costs, be pollution-free, and be environmentally friendly.

[0105] The water-based coating slurry may be prepared by the following method, but is not limited thereto.

[0106] (1) adding the dispersant to deionized water, and stirring the mixture for 5 min to 30 min at a dispersion speed of 500 rpm to 2000 rpm to obtain a dispersion (1);

[0107] (2) adding boehmite to the above dispersion (1), and stirring the mixture at a dispersion speed of 500 rpm to 2000 rpm for 30 min to 120 min to obtain dispersion (2);

[0108] (3) Add the first polymer as a binder to the above dispersion (2), and stir for 30 min to 120 min at a dispersion speed of 500 rpm to 2000 rpm to obtain a dispersion (3) as a water-based coating slurry.

[0109] When the water-based binder further comprises a second copolymer, the following steps are further performed:

[0110] (4) adding the second polymer as a binder to the above dispersion (3), stirring at a dispersion speed of 200 rpm to 1000 rpm for 15 min to 60 min to obtain a coating slurry; further, stirring at a dispersion speed of 500 to 800 rpm for 20 min to 40 min to obtain a water-based coating slurry.

[0111] Water electrode

[0112] The present application also provides an aqueous electrode, comprising an aqueous coating. The aqueous coating is formed from the aqueous coating composition of the first aspect of the present application and has a three-dimensional cross-linked network structure. The inclusion of the three-dimensional cross-linked network structure in the aqueous coating improves the water resistance of the aqueous coating and reduces the risk of delamination.

[0113] In some embodiments, the water-based coating contains 10% to 30% by mass of an aqueous binder, and optionally 15% to 25% by mass, relative to the total mass of the water-based coating. By ensuring that the binder content is within the above range, the adhesion of the water-based coating can be increased, thereby improving water resistance.

[0114] In some embodiments, the water-based coating contains 65% to 80% by mass of insulating material, preferably 70% to 80% by mass, relative to the total mass of the water-based coating. Furthermore, the water-based coating contains 0.2% to 1.0% by mass of a dispersant, preferably 0.5% to 0.8% by mass, relative to the total mass of the water-based coating, thereby contributing to improved insulation performance.

[0115] In some embodiments, the contact angle of the aqueous coating with water is less than or equal to 90°, and optionally is between 40° and 80°. The contact angle (θ) refers to the angle θ between the tangent line of the gas-liquid interface at the intersection of the gas, liquid, and solid phases and the solid-liquid boundary line, and is a measure of wettability. If θ < 90°, the solid is lyophilic, i.e., the liquid wets the solid, and the smaller the angle, the better the wettability. If θ > 90°, the solid is lyophobic, i.e., the liquid does not wet the solid, easily moves on the surface, and cannot enter the pores.

[0116] The present application makes the contact angle between the aqueous coating and water within the above-mentioned range, so that the aqueous coating has good wettability in the aqueous electrode, the coating spreads more fully on the substrate, and the contact area is increased, which is beneficial to improving the adhesion of the aqueous coating to the substrate surface, improving the water resistance of the aqueous coating, and reducing the risk of falling off.

[0117] In some embodiments, the peel strength of the aqueous coating on the aqueous electrode is greater than or equal to 10 N / m, and optionally greater than or equal to 17 N / m. The peel strength can be obtained by performing a peel test in accordance with the national standard GB / T 41511-2022.

[0118] In some embodiments, the aqueous electrode is an aqueous positive electrode or an aqueous negative electrode.

[0119] The aqueous coating composition of the present application can be used to form an insulating coating in an aqueous positive electrode plate. The following describes an exemplary method for preparing a plate with reference to FIG1 .

[0120] In the preparation of the aqueous positive electrode of the battery, an insulating material, an aqueous binder, a dispersant, and deionized water can be prepared into an aqueous coating slurry according to the above method. The insulating coating slurry and the conductive layer slurry are respectively coated on at least one surface of the substrate 13 (aluminum foil). After drying, the insulating coating 12 and the conductive layer 11 are formed on the substrate 13 to obtain a composite positive electrode current collector 1. Then, a slurry containing an active material is coated on the conductive layer 11 to form an active material layer 2, thereby producing a pole piece.

[0121] During the electrode drying process, the heat causes the carboxyl and hydroxyl groups in the aqueous binder to react, forming hydrogen bonds and / or crosslinks, resulting in a three-dimensional crosslinked network. This results in an aqueous electrode with excellent adhesion and improved water resistance, significantly reducing the risk of film release and enhancing battery safety.

[0122] The thickness of a single insulating coating layer formed from the aqueous coating slurry ranges from 1 to 20 μm, and optionally from 2 to 8 μm. A thickness of 1 μm or greater provides excellent insulation protection, while a thickness of 20 μm or less contributes to improved battery energy density. Furthermore, the width of the insulating coating ranges from 1 to 20 mm, and optionally from 3 to 10 mm, thereby achieving both excellent insulation protection and improved battery energy density.

[0123] The surface density of the positive electrode film layer of the aqueous positive electrode plate of this application is 250mg / 1540.25mm 2 ~500mg / 1540.25mm 2 , which can reach or even exceed the coating weight of oil-based electrodes. In addition, the drying temperature of water-based electrodes is 60℃-120℃, while the drying temperature of conventional oil-based electrodes is 110℃-140℃. Therefore, the application of water-based electrodes can greatly save energy.

[0124] Aqueous batteries

[0125] In one embodiment of the present application, an aqueous battery is provided.

[0126] The term "battery" mentioned herein refers to a battery cell, a battery module or a battery pack.

[0127] Typically, a battery cell consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0128] [Positive electrode]

[0129] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes the aqueous coating of the present application as an insulating coating.

[0130] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0131] In some embodiments, the positive electrode current collector is a composite current collector, which may include a substrate layer, a conductive layer, and an insulating layer disposed on at least one surface of the substrate layer.

[0132] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may adopt the positive electrode active material for lithium-ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0133] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene polymer, and a fluorine-containing acrylate resin.

[0134] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0135] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the aqueous positive electrode sheet, such as the positive electrode active material, the conductive agent, the aqueous binder and any other components, are dispersed in a solvent (such as water) to form an aqueous positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0136] [Negative electrode]

[0137] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0138] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0139] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector includes a substrate layer and a conductive layer and an insulating layer disposed on at least one surface of the substrate layer.

[0140] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0141] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0142] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0143] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0144] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0145] [Electrolyte]

[0146] The electrolyte conducts ions between the positive and negative electrodes. The electrolyte includes an electrolyte salt and a solvent. This application does not specifically limit the types of electrolyte salt and solvent; they can be selected based on needs.

[0147] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0148] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0149] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0150] [Isolation film]

[0151] In some embodiments, the aqueous battery further includes an isolation membrane. This application has no particular restrictions on the type of isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.

[0152] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0153] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0154] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0155] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0156] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape.

[0157] In some embodiments, battery cells may be assembled into a battery module. The battery module may contain one or more battery cells. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0158] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0159] Electrical devices

[0160] In addition, the present application also provides an electrical device, which includes the battery provided in the present application. The battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0161] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0162] Example

[0163] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0164] Preparation Example

[0165] At 20°C, nitrogen was introduced into the reactor for deoxygenation, and then 4.2g of the surfactant sodium dodecylbenzenesulfonate was added to 90g of deionized water, stirred and dissolved evenly, and then the monomers of formula (1) CH2=CHCOOH, formula (2) CH2=CHCOO(CH2)3OH, formula (3) CH2=CHCN, formula (4) CH2=CHCOO(CH2)3CH3 and 0.05g of the chain transfer agent n-dodecyl mercaptan were added in sequence and mixed evenly; then the temperature was raised to 85°C and stirred evenly to obtain a pre-emulsion.

[0166] Next, 1.5 g of ammonium persulfate (initiator) and 2.8 g of sodium dodecylbenzenesulfonate (surfactant) were added dropwise to the pre-emulsion. After the additions were complete, the mixture was stirred at 300 rpm for 120 minutes to obtain a polymer seed solution. An additional 1.5 g of ammonium persulfate (initiator) was added, and stirring continued at 300 rpm for 120 minutes to obtain a polymer.

[0167] The polymer was then post-treated by cooling the reactor to room temperature, evacuating the reactor for 30 minutes, and then returning the reactor to normal pressure. Finally, the polymer was filtered through a 300-mesh filter and the pH was adjusted to 7-8 using lithium hydroxide to obtain a first polymer 1-20, the composition of which is shown in Table 1 below.

[0168] Referring to the above method, the first polymer and the second polymer in Table 1 and Table 2 were prepared according to the compositions shown in Table 1 and Table 2 below.

[0169] Table 1

[0170] In the table, “-” means not added.

[0171] Table 2

[0172] Example 1

[0173] (1) Preparation of water-based coating slurry

[0174] 91g of insulating material aluminum oxide, 2g of dispersant polyacrylamide (purchased from Dow Chemical, model 4045N, solid content 50%), and 16g of first polymer 1-1 (solid content 50%) as a water-based binder were added to deionized water to prepare an insulating coating slurry. The specific operation is as follows.

[0175] (1-1) adding a dispersant to deionized water, and stirring the mixture at a dispersion speed of 1500 rpm for 30 minutes to obtain a dispersion (1);

[0176] (1-2) adding aluminum oxide to the above dispersion (1), and stirring the mixture at a dispersion speed of 1500 rpm for 60 minutes to obtain dispersion (2);

[0177] (1-3) The first polymer 1-1 as a water-based binder is added to the above dispersion (2), and stirred at a dispersion speed of 1200 rpm for 90 minutes to obtain a dispersion (3) as a water-based coating slurry.

[0178] When the water-based binder further comprises a second copolymer, the second polymer is added to the above dispersion (3) and stirred at a dispersion speed of 800 rpm for 30 minutes to obtain a water-based coating slurry.

[0179] (2) Preparation of current collector

[0180] Conductive graphite (purchased from Shanghai Kaiyin Chemical Co., Ltd., brand SP5000) as a conductive material, dispersant xanthan gum (molecular weight of about 1,000,000 g / mol, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.), aqueous binder polyacrylic acid (number average molecular weight of 300,000-800,000), curing agent polycarbodiimide (number average molecular weight of 10,000-40,000) and water are used to make a conductive slurry.

[0181] Then, the water-based coating slurry prepared in (1) is evenly coated on one surface of the positive electrode aluminum foil substrate, and is coated in the edge area extending 10 mm from the edge of the substrate to the middle. The above-mentioned conductive slurry is evenly coated on the blank area of ​​the positive electrode aluminum foil substrate except the above-mentioned edge area, and the coating speed is 50-150 m / min. Thereafter, it is dried at 60°C-150°C. During the drying and heating process, the binder in the water-based coating forms a three-dimensional network cross-linked structure. Thus, a composite positive electrode current collector comprising a water-based coating (insulating layer) and a conductive layer is obtained. The composition of the formed water-based coating is shown in Table 3.

[0182] (3) Preparation of aqueous positive electrode sheets

[0183] The positive electrode active material lithium iron phosphate, the conductive agent conductive carbon black, the dispersion stabilizer polyethylene and pyrrolidone, and the aqueous binder acrylic polymer are mixed in a solvent deionized water in a weight ratio of 96:1:1.2:1.8. After mixing evenly, an aqueous positive electrode slurry with a deionized water content of 40wt% and a solid content (solid content, including the positive electrode active material, conductive agent, dispersion stabilizer and aqueous binder) of 60wt% is prepared. Then, the aqueous positive electrode slurry is evenly coated on the conductive layer of the composite positive electrode current collector prepared by the above (2) and dried to form an active material layer. After that, it is cold pressed and cut to obtain a positive electrode sheet.

[0184] (4) Preparation of negative electrode sheet

[0185] The negative electrode active material, artificial graphite; the conductive agent, carbon black; the binder, styrene-butadiene rubber (SBR); and the thickener, sodium carboxymethyl cellulose (CMC), were dissolved in deionized water at a weight ratio of 96.2:0.8:0.8:1.2. After mixing, a negative electrode slurry with a deionized water content of 45 wt% and a solid content (solids content, including the negative electrode active material, conductive agent, binder, and thickener) of 55 wt% was prepared. The negative electrode slurry was then evenly coated on the negative electrode current collector copper foil. After drying, cold pressing, and slitting, the negative electrode sheets were obtained.

[0186] (5) Preparation of electrolyte

[0187] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3 / 7, 12.5% ​​LiPF6 lithium salt was added and dissolved in the organic solvent, and stirred uniformly to obtain an electrolyte.

[0188] (6) Preparation of isolation membrane

[0189] A 7-μm thick PE porous film was used as a substrate, and then coated with a 2-μm thick ceramic coating, and the composite film was used as an isolation membrane.

[0190] (7) Preparation of lithium-ion batteries

[0191] The aqueous positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in order, with the separator placed between the positive and negative electrode sheets to act as an isolation layer, and then wound to obtain a battery assembly. The battery assembly is placed in an aluminum shell and baked at 80°C to remove water. The electrolyte obtained in (5) above is then injected and sealed. After that, a lithium-ion battery is obtained through the following processes: standing, hot and cold pressing, formation, shaping, and capacity testing.

[0192] Example 2-36

[0193] The electrode was prepared in the same manner as in Example 1 so that the composition of the aqueous coating was as shown in Table 3, and then a battery was manufactured in the same manner as in Example 1.

[0194] In Table 3, "content (wt%)" refers to the content of the water-based binder, insulating material, and dispersant relative to the total mass of the water-based coating. "Boehmite" was purchased from Zhejiang Jidun New Material Technology Co., Ltd., Dv50 = 1.3 μm.

[0195] Table 3

[0196] In the table, “-” means not added.

[0197] Comparative Example 1

[0198] In the preparation of the coating slurry (1) of Example 1, boehmite (purchased from Zhejiang Jidun New Materials Technology Co., Ltd., Dv50 1.3 μm) and a binder PVDF (purchased from Solvay Chemical, model HSV900) were dispersed in the solvent NMP to prepare an insulating coating slurry having an NMP content of 88 wt% and a solid content (including boehmite + binder) of 12 wt%. Otherwise, the electrode was prepared in the same manner as in Example 1, and then the battery was manufactured.

[0199] Comparative Example 2

[0200] In the preparation of the coating slurry (1) of Example 1, only polyacrylic acid was used as the binder. Otherwise, the electrode sheets were prepared in the same manner as in Example 1, and then the battery was manufactured.

[0201] Comparative Example 3

[0202] In the preparation of the coating slurry (1) in Example 1, only polypropylene hydroxyethyl ester was used as the binder. Otherwise, the electrode sheets were prepared in the same manner as in Example 1, and then the battery was manufactured.

[0203] The following tests were performed on the positive electrode sheets and batteries obtained in the above examples and comparative examples.

[0204] Pole coating inspection

[0205] The aqueous coating (insulating layer) of the positive electrode plate in the above embodiment was analyzed according to the infrared spectroscopy analysis method specified in GB / T6040-2002. The specific method is as follows:

[0206] The first polymers 1-1 to 1-20 were respectively used as test samples and put into an IS10 Fourier transform infrared spectrometer produced by Nicolet Corporation of the United States for analysis.

[0207] The battery obtained in Example 1 was disassembled to obtain a current collector containing an aqueous coating (insulating layer). This current collector was then soaked in diethyl carbonate (DEC), an electrolyte solvent, for 2 hours. The electrode was then rinsed three times with fresh DEC and dried to prepare the test samples. These samples were then analyzed using a Nicolet IS10 Fourier transform infrared spectrometer.

[0208] The infrared spectra of the first polymers 1-1 to 1-20 were compared with the infrared spectra of the examples. In the infrared spectra of the examples, the carbonyl and carbon-oxygen single bond peaks were significantly red-shifted, proving that hydrogen bonds were formed in the aqueous coatings of the examples.

[0209] Specifically, Figure 2 is an infrared spectrum obtained by infrared testing the first polymer 1-20. Figure 3 is an infrared spectrum obtained by infrared testing the aqueous coating of the positive electrode after disassembling the battery prepared in Example 24. By comparing Figures 2 and 3, it can be seen that the carbonyl and carbon-oxygen single bond peaks are significantly red-shifted (1700.17 cm -1 →1732.33cm -1 and 1073.69cm -1 →1162.46cm -1 ), which shows that hydrogen bonds are formed in the aqueous coating of Example 24 and a three-dimensional network cross-linked structure exists.

[0210] Pole performance test

[0211] (Immersion electrolyte performance test)

[0212] Take the electrode to be tested, which should be in good appearance. Use a blade to cut a sample with a width of 10mm and a length of 100mm. Immerse the sample in an electrolyte solvent composed of a mixture of EC, DMC, and DEC in a ratio of 1:1:1. Soak the mixture at 60°C for 24 hours and observe whether the coating has fallen off.

[0213] (Peel strength test)

[0214] The 180° peel strength of the water-based coating was tested using a tensile testing machine based on the national standard GB / T 41511-2022.

[0215] Take the electrode to be tested, and the appearance of the electrode is good. Use a blade to cut a electrode sample with a width of 10mm and a length of 100-160mm. Stick the special double-sided tape NITTO.NO5000NS on the steel plate, with a tape width of 10mm and a length of 90-150mm. Stick the fixed-size electrode sample cut above on the double-sided tape with the test surface facing down, and then use a 3kg pressure roller to roll three times in the same direction along the surface of the positive electrode insulating coating. Insert a paper tape with a width equal to the electrode and a length 80-200mm greater than the sample length under the electrode and fix it with wrinkle glue. The sample is then fixed on the testing machine, and the end of the steel plate without the electrode is fixed with the lower clamp. The paper tape is folded upward and fixed with the upper clamp. The axis direction of the electrode is consistent with the direction of force. The testing machine is loaded at a peeling speed of 10mm / min until the positive electrode breaks. The test is stopped and the maximum load force is recorded as F (unit N). The electrode width L = 20mm. According to f1 = F / L, the peel strength f1 (unit N / m) is calculated. The greater the peel strength, the higher the bonding strength.

[0216] (Water resistance test)

[0217] Take the electrode to be tested, which should be in good condition. Use a blade to cut a 10 mm wide and 100 mm long electrode sample. Immerse the entire sample in a water-containing ultrasonic instrument (BRANSON CPX3800-HC, ultrasonic frequency: 20 kHz, ultrasonic power: 50 W). Simultaneously start a stopwatch and record the dissolution time of the water-based coating.

[0218] (Contact angle test)

[0219] With reference to the GB / T 30693-2014 standard document, the contact angle between the water-based coating (insulating layer) and water was tested, and deionized water was used as the liquid reagent.

[0220] Specifically, the current collector containing the aqueous coating to be tested is placed flat on the load test platform, and then 0.6μL-1.0μL of deionized water is squeezed out through a microsyringe. The knob on the stage base is rotated to move the stage until it contacts the deionized water droplet, and the image is frozen within 10 seconds. The angle between the tangent line of the outer surface of the droplet and the plane of the aqueous coating is measured using the angle measurement method as the contact angle.

[0221] Battery performance test

[0222] (Battery capacity retention test)

[0223] The battery capacity retention rate test process is as follows: At 25°C, the battery in the example is charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C, left for 5 minutes, and then discharged at 1 / 3C to 2.7V. The resulting capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the battery discharge capacity Cn after the nth cycle is recorded. The battery capacity retention rate after each cycle is Pn = Cn / C0 * 100%. In this test process, the first cycle corresponds to n = 1, the second cycle corresponds to n = 2, ..., and the 100th cycle corresponds to n = 100.

[0224] In this application, the battery in the example was cycled 800 times under the above test conditions, and the capacity retention rate was calculated and shown in Table 4.

[0225] (Battery vibration abuse test)

[0226] During the winding process of the battery assembly, the aqueous coating (insulating coating) is folded in half and inserted about 2 mm on the innermost side of the battery assembly so that it contacts the active area of ​​the negative electrode. The battery is obtained by following the same method as the above-mentioned "Preparation of Lithium-ion Batteries".

[0227] The resulting battery was placed on a vibration table and subjected to an 8-hour vibration test in each of the three axes: X, Y, and Z. The battery assembly was then disassembled to confirm whether there was any corrosion at the electrode fold. If there was corrosion, it would indicate an internal short circuit and poor safety performance. If there was no corrosion, the battery had good safety performance.

[0228] The test results of the above examples and comparative examples are shown in Table 4 below.

[0229] Table 4

[0230] As shown in the data in Table 4, the aqueous coating of the positive electrode sheets in Examples 1 to 36 of the present application has high adhesion and high water resistance. Specifically, the aqueous coating does not fall off after the positive electrode sheets are soaked in the electrolyte, and the peel strength of the aqueous coating is greater than 8N / m, indicating that it has high adhesion. In the water resistance test, the coating does not fall off after a long time, and has good water solubility. Moreover, the contact angles of the aqueous coating with water are all less than 90°, indicating that the aqueous coating has good wettability, which is beneficial to improving the adhesion of the aqueous coating to the surface of the substrate. In addition, the aqueous batteries containing the aqueous coating of Examples 1 to 36 have a high capacity retention rate after 800 cycles, and the battery has excellent cycle performance. In addition, the battery has no ablation in the vibration abuse test, and the battery has good safety performance.

[0231] In the embodiments, compared with Examples 1 to 21, Examples 25 to 36 further contain a second polymer as an aqueous binder, and the first polymer and the second polymer form hydrogen bonds and / or cross-linking structures to form a high-density three-dimensional network cross-linking structure. The adhesion and water resistance of the coating are further improved, thereby improving the cyclability and safety of the battery.

[0232] In Examples 30 to 36, the structural unit of formula (2) in the first polymer and the structural unit of formula (6) in the second polymer both include a specific structure (hydroxypropyl ester), thereby greatly improving the adhesion of the aqueous coating, improving the water resistance, and enhancing the cyclability and safety of the battery.

[0233] In contrast, in Comparative Examples 1 to 3, the coating cannot take into account both high adhesion and high water resistance, the battery cycle performance is poor, and the battery safety is affected. Specifically, in Comparative Example 1, the oil-based coating slurry (binder PVDF + solvent NMP) is used in the water-based electrode. Although the oily coating shows high water resistance in the water resistance test, it is incompatible with the water-based electrode, the coating falls off, the adhesion is very poor, the cycle performance is poor, local ablation occurs, and the battery safety is poor. In Comparative Example 2, only polyacrylic acid is used as a binder, and in Comparative Example 3, only polypropylene hydroxyethyl is used as a binder. Since a three-dimensional network cross-linked structure is not formed in the coating, the water-based coating cannot obtain sufficient adhesion and water resistance, resulting in poor cycle performance and safety performance of the battery.

[0234] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A water-based coating composition, characterized in that: Contains water-based binder and solvent, The aqueous adhesive comprises a first polymer, wherein the first polymer comprises a structural unit represented by formula (1) and a structural unit represented by formula (2), In formula (1), R1, R2, and R3 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro; L is a linking bond or a C1-10 alkylene group; In formula (2), R4, R5, and R6 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro, and n=2 to 12.

2. The water-based coating composition according to claim 1, wherein In formula (1), R1, R2, and R3 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano; L is a connecting bond or a C3-4 alkylene group; In formula (2), R4, R5, and R6 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxy, or cyano, and n=3-6.

3. The water-based coating composition according to claim 1 or 2, wherein: In the first polymer, the mass percentage of the structural unit represented by the formula (1) is The mass proportion of the structural unit represented by formula (2) is 5% to 40%.

4. The water-based coating composition according to any one of claims 1 to 3, wherein The first polymer further comprises a structural unit represented by formula (3) and / or a structural unit represented by formula (4), In formula (3), R7, R8, and R9 are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano, or nitro. R 10 is a rigid group, optionally a cyano group, an acylamino group or an aryl group, optionally a cyano group, In formula (4), R 11 , R 12 , R 13 Each is independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano or nitro, and m=2-12.

5. The water-based coating composition according to claim 4, wherein In the first polymer, the mass percentage of the structural unit represented by the formula (3) is 5% to 40%.

6. The water-based coating composition according to claim 4, wherein: In the first polymer, the mass proportion of the structural unit represented by the formula (4) is 10% to 75%.

7. The water-based coating composition according to any one of claims 4 to 6, wherein In the first polymer, the mass percentage of the structural unit represented by the formula (1) is The mass proportion of the structural unit represented by formula (2) is 5% to 15%, the mass proportion of the structural unit represented by formula (3) is 10% to 20%, and the mass proportion of the structural unit represented by formula (4) is 30% to 55%.

8. The water-based coating composition according to any one of claims 1 to 7, wherein The number average molecular weight of the first polymer is 200,000 to 1,000,000, and optionally 300,000 to 600,000.

9. The water-based coating composition according to any one of claims 1 to 8, wherein The aqueous binder further comprises a second polymer, which is different from the first polymer and comprises a group capable of reacting with the first polymer. The group is capable of forming a hydrogen bond and / or a cross-linked structure with the first polymer.

10. The water-based coating composition according to claim 9, wherein: The second polymer comprises a flexible group, Optionally, the flexible group is a group including an ester bond or a group including an ether bond.

11. The water-based coating composition according to claim 9 or 10, wherein: The second polymer comprises a structural unit represented by formula (5), a structural unit represented by formula (6) and a structural unit represented by formula (7), In formula (5), R'1, R'2, R'3 are the same as or different from R1, R2, R3, and are independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano or nitro; L' is the same as or different from L, and is a connecting bond or a C1-10 alkylene group; In formula (6), R'4, R'5, R'6 are the same as or different from R4, R5, R6, and are independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxyl, cyano or nitro, n' is the same as or different from n, and n'=2 to 12, In formula (7), R' 11 , R' 12 , R' 13 With R 11 , R 12 , R 13 are the same or different, and are each independently hydrogen, halogen, alkyl, hydroxyalkyl, alkoxy, cycloalkyl, alkenyl, alkynyl, heterocycloalkyl, aryl, heteroaryl, hydroxy, cyano or nitro, m' is the same as or different from m, and m'=2-12.

12. The water-based coating composition according to claim 11, wherein In formula (5), R'1, R'2, and R'3 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, L' is a connecting bond or a C3-4 alkylene group, In formula (6), R'4, R'5, and R'6 are each independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxyl, or cyano, and n'=3 to 6. In formula (7), R' 11 , R' 12 , R' 13 Each is independently hydrogen, alkyl, hydroxyalkyl, alkoxy, hydroxy or cyano, and m'=3-6.

13. The water-based coating composition according to claim 11 or 12, wherein: In the second polymer, the mass proportion of the structural unit represented by formula (5) is 10% to 60%, the mass proportion of the structural unit represented by formula (6) is 5% to 20%, and the mass proportion of the structural unit represented by formula (7) is The mass ratio is 20% to 60%.

14. The water-based coating composition according to any one of claims 11 to 13, wherein The structural unit of formula (2) is The structural unit of formula (6) is 15. The water-based coating composition according to any one of claims 9 to 14, wherein The number average molecular weight of the second polymer is 200,000 to 1.2 million, and optionally 250,000 to 600,000.

16. The water-based coating composition according to any one of claims 9 to 15, wherein The mass ratio of the first polymer to the second polymer is 9:1 to 1:9, and optionally 4:1 to 1:

4.

17. The water-based coating composition according to any one of claims 1 to 16, wherein The solvent is water.

18. The water-based coating composition according to any one of claims 1 to 17, wherein The composition further comprises an insulating material and / or a dispersant, Optionally, the insulating material is a ceramic material. Optionally, the ceramic material is boehmite powder. Optionally, the dispersant is a polyacrylamide-based dispersant.

19. A water-based electrode, characterized in that: Including water-based coatings, The water-based coating is formed from the water-based coating composition according to any one of claims 1 to 18 and has a three-dimensional network cross-linked structure.

20. The water-based electrode according to claim 19, wherein: The water-based coating layer contains 10% to 30% by mass of an aqueous binder relative to the total mass of the water-based coating layer, and optionally 15% to 25% by mass.

21. The water-based electrode according to claim 19 or 20, wherein: The water-based coating layer contains 65% to 80% by mass of an insulating material relative to the total mass of the water-based coating layer, and 0.2% to 1.0% by mass of a dispersant relative to the total mass of the water-based coating layer.

22. The water-based electrode according to any one of claims 19 to 21, wherein: The contact angle between the aqueous coating and water is less than or equal to 90°, and can be optionally 40° to 80°.

23. The water-based electrode according to any one of claims 19 to 22, wherein: The peel strength of the water-based coating in the water-based electrode is greater than or equal to 10 N / m, and optionally greater than or equal to 17 N / m. The peel strength is obtained by performing a peel test based on the national standard GB / T 41511-2022.

24. The water-based electrode according to any one of claims 19 to 23, wherein: The water-based electrode is a water-based positive electrode or a water-based negative electrode.

25. An aqueous battery, characterized in that: The invention comprises the water-based electrode according to any one of claims 19 to 24.

26. An electrical device, characterized in that: Includes the aqueous battery as described in claim 25.

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