Binder, electrode sheet, battery, and electrical device

Abstract

The present invention relates to a binder, an electrode plate, a battery and an electrical device. The components of the binder include hydrogenated nitrile rubber modified with a first active group and a crosslinking agent, wherein the first active group includes at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group and an amidoxime group; the crosslinking agent contains at least two second active groups, and the second active groups can chemically react with the first active groups on the hydrogenated nitrile rubber modified with the first active group. The binder can inhibit the swelling of the electrode plate, thereby inhibiting the volume expansion of the battery and improving the cycle performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a binder, an electrode plate, a battery and an electrical device. Background Art

[0002] Secondary batteries are increasingly widely used due to their clean and renewable characteristics. Lithium batteries have excellent cycle performance, excellent safety performance, low cost and environmental friendliness, and are a hot topic for secondary batteries. With the development of science and technology, in order to adapt to the needs of different environments and application scenarios, such as to meet the development trend of miniaturization and thinness of various electrical appliances and to improve the driving range of electric vehicles, people have put forward higher and higher requirements on the energy density and cycle life of lithium batteries.

[0003] Secondary batteries such as lithium-ion batteries are mainly composed of five parts: positive electrode, negative electrode, separator, electrolyte and shell. They mainly rely on the movement of lithium ions between the positive and negative electrodes to generate electricity. When charging, lithium ions are deintercalated from the positive electrode and embedded in the negative electrode through the electrolyte, and the opposite is true when discharging. In the process of trying to improve the energy density or cycle life of lithium batteries, technicians found that lithium-ion batteries have a problem of volume expansion during the charging and discharging process, which seriously hinders the improvement of the cycle performance of secondary batteries.

[0004] Therefore, the traditional technology still needs to be improved. Summary of the invention

[0005] Based on this, it is necessary to provide a binder, an electrode plate, a battery and an electrical device, wherein the binder can inhibit the swelling of the electrode plate, thereby inhibiting the volume expansion of the battery and improving the cycle performance of the battery.

[0006] The present application is implemented through the following technical solutions.

[0007] In a first aspect of the present application, a binder is provided, wherein the components of the binder include a hydrogenated nitrile rubber modified with a first active group and a crosslinking agent, wherein the first active group includes at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group and an amidoxime group;

[0008] The cross-linking agent contains at least two second active groups, and the second active groups can chemically react with the first active groups on the hydrogenated nitrile rubber modified by the first active groups.

[0009] The components of the above-mentioned binder include hydrogenated nitrile rubber modified with a first active group and a cross-linking agent. The cross-linking agent contains at least two second active groups, and the second active group can chemically react with the first active group. Thus, the hydrogenated nitrile rubber modified with the first active group and the cross-linking agent can form a three-dimensional network structure through chemical reaction. The formed three-dimensional network structure has a small swelling degree in solvents such as electrolytes. When applied to prepare the electrode active layer on the electrode sheet, while maintaining excellent binding performance, it can inhibit the swelling degree of the electrode active layer in the electrolyte, thereby inhibiting the swelling of the electrode sheet, further reducing the volume expansion of the battery, and improving the cycle performance of the battery.

[0010] In some embodiments, the second active group includes at least one of an amino group, a hydroxyl group, a carbodiimide group, an aziridine group, and an isocyanate group.

[0011] In some embodiments, the hydrogenated nitrile rubber modified with the first active group includes a structural unit shown in formula (A):

[0012]

[0013] Wherein, X1 represents the first active group, and X2 is selected from H or an alkyl group with 1 to 10 carbon atoms;

[0014] * represents the connection site.

[0015] In some embodiments, the mass ratio of the structural unit shown in formula (A) in the hydrogenated nitrile rubber modified with the first active group is 0.1 wt% to 20 wt%.

[0016] In some embodiments, the hydrogenated nitrile rubber modified with the first active group includes a chain segment structure shown in formula (1):

[0017]

[0018] Both x and z are arbitrary integers greater than 0, and both y and w are arbitrary integers greater than or equal to 0.

[0019] In some embodiments, the weight average molecular weight of the hydrogenated nitrile rubber modified with the first active group is 300,000 to 600,000.

[0020] In some embodiments, in the binder, the mass ratio of the hydrogenated nitrile rubber modified with the first active group to the cross-linking agent is (1 to 3):(0.01 to 0.5).

[0021] In the second aspect of the present application, an electrode paste is provided. The electrode paste includes an electrode active material and the binder of the first aspect of the present application.

[0022] When the electrode slurry is used to prepare the electrode active layer on the electrode plate, the hydrogenated nitrile rubber modified by the first active group in the binder and the cross-linking agent can form a three-dimensional network structure through a chemical reaction between the first active functional group in the hydrogenated nitrile rubber modified by the first active group and the second active group in the cross-linking agent. The formed three-dimensional network structure has a small swelling degree in solvents such as electrolytes. Therefore, while maintaining excellent bonding properties, it can inhibit the swelling degree of the electrode active layer in the electrolyte, thereby inhibiting the swelling of the electrode plate, thereby reducing the volume expansion of the battery and improving the cycle performance of the battery.

[0023] In some of the embodiments, the electrode slurry further includes a conductive agent, wherein the conductive agent includes a carbon material modified with a third active group, and the third active group can chemically react with the first active group and / or the second active group.

[0024] Any two of the third active group in the above-mentioned functionalized modified conductive material, the first active group in the hydrogenated nitrile rubber modified by the first active group, and the second active group in the cross-linking agent can undergo a chemical reaction, so that the conductive material modified by the third active group, the hydrogenated nitrile rubber modified by the first active group, and the binder form a three-dimensional network structure. On the one hand, the swelling degree of the electrode active layer in the electrolyte can be further suppressed, thereby suppressing the swelling of the electrode pole piece; on the other hand, the functionalized modified carbon material, as a two-dimensional conductive material, can play a certain role in long-range conductivity, so that the electrode active layer maintains excellent conductivity even in a swollen state.

[0025] In some embodiments, the third reactive group includes at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group and an amidoxime group; and / or

[0026] The mass percentage of the third active group in the conductive material modified by the third active group is 0.01wt% to 5wt%; and / or

[0027] The conductive material modified by the third active group includes at least one of a carbon material modified by the third active group and a conductive metal material modified by the third active group.

[0028] In some embodiments, based on the total mass of the components in the electrode slurry excluding the solvent, the mass proportion of the conductive agent is 0.1% to 5%; and / or

[0029] The conductive material modified by the third active group accounts for 0.01% to 5% of the conductive agent; and / or

[0030] The conductive material modified by the third active group is selected from carbon materials modified by the third active group.

[0031] In some of these embodiments, the electrode active material is a positive electrode active material or a negative electrode active material; and / or

[0032] Based on the total mass of the components other than the solvent in the electrode paste, the mass proportion of the electrode active material is 95% to 99%.

[0033] In some of these embodiments, the electrode active material includes at least one of lithium iron phosphate and lithium manganese iron phosphate.

[0034] In a third aspect of the present application, there is provided an electrode tab, which includes a current collector and an active layer located on the surface of the current collector, and the preparation raw materials of the active layer include the binder of the first aspect of the present application; or

[0035] The active layer is prepared from the electrode paste of the second aspect of the present application.

[0036] In a fourth aspect of the present application, there is provided an electrode tab, which includes a current collector and an active layer located on the surface of the current collector, and the active layer has a three-dimensional network structure in which the hydrogenated nitrile rubber modified with the first active group in the binder of the first aspect of the present application is connected to the cross-linking agent through cross-linking sites, and the cross-linking sites include groups formed by chemical reactions between the first active group in the hydrogenated nitrile rubber modified with the first active group and the second active group in the cross-linking agent.

[0037] In some of these embodiments, the components of the active layer further include a conductive agent, and the conductive agent includes a conductive material modified with a third active group, and the third active group can undergo a chemical reaction with the first active group and / or the second active group;

[0038] The active layer further has a three-dimensional network structure in which the hydrogenated nitrile rubber modified with the first active group, the cross-linking agent, and the conductive material modified with the third active group are connected through cross-linking sites, and the cross-linking sites include groups formed by chemical reactions between any two of the first active group, the second active group, and the third active group.

[0039] In a fifth aspect of the present application, there is provided a battery, including: the battery includes the electrode tab of the third aspect of the present application or the electrode tab of the fourth aspect of the present application.

[0040] In a sixth aspect of the present application, there is provided an electrical device, including the battery of the fifth aspect of the present application. Description of the Drawings

[0041] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiments. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0042] Figure 1 is a schematic diagram of a battery according to an embodiment of the present application;

[0043] Figure 2 is a schematic diagram of an electrical device using the battery as a power source according to an embodiment of the present application.

[0044] Description of reference numerals:

[0045] 10 Battery; 20 Electrical device. Detailed embodiments

[0046] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is provided. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0047] In the present invention, unless otherwise clearly defined and limited, terms such as "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0050] In the present application of this invention, the term "alkyl group" refers to a group formed by an alkane losing one hydrogen atom. For example, methane loses one hydrogen atom to form a methyl group.

[0051] The term "alkane" refers to an alkane in which all carbon atoms are connected by single carbon-carbon bonds and do not form a ring, and the remaining valence bonds are all combined with hydrogen atoms, including straight-chain alkanes and branched-chain alkanes.

[0052] As described in the background art, lithium-ion batteries have the problem of volume expansion during the charging and discharging process, which seriously hinders the improvement of the cycle performance of secondary batteries. Those skilled in the art believe that there are two main reasons: on the one hand, the volume of the active material on the electrode plate changes before and after charging and discharging of the lithium-ion battery; on the other hand, during the charging process, after the interface of the electrode plate is in contact with the electrolyte for a long time, side reactions will occur, generating side reaction products, which will accumulate at the interface, resulting in battery volume expansion.

[0053] Therefore, those skilled in the art have focused on developing new active materials or adding substances to inhibit side reactions. However, the technicians in this application have found during the long-term development and production process of lithium-ion batteries that: after the active layer on the electrode plate comes into contact with the electrolyte, swelling will occur, which largely contributes to the volume expansion of the battery. Further research on the components of the active layer reveals that the binder component in the active layer generally contains macromolecular substances, which are prone to swelling after contact with the electrolyte, thus further contributing to the expansion of the electrode plate and reducing the cycle performance of the battery.

[0054] In traditional technologies, hydrogenated nitrile rubber binder and PVDF are often used to prepare electrode plates. Among them, hydrogenated nitrile rubber is a copolymer synthesized from acrylonitrile and butadiene. It not only has excellent bonding performance but also can improve the flexibility of the electrode plate. Moreover, the electrode paste prepared with hydrogenated nitrile rubber binder has a lower viscosity, good fluidity of the electrode paste, and can increase the solid content of the electrode paste at a fixed viscosity, reducing the production cost. However, the technicians in this application have found through research that: hydrogenated nitrile rubber contains a cyano group, and the cyano group has a high polarity, resulting in a high swelling degree of the hydrogenated nitrile rubber binder in the electrolyte, thereby increasing the expansion rate of the electrode plate, further affecting the conductivity between the active material, the conductive agent, and the current collector, causing battery capacity attenuation, and reducing the cycle performance of the battery.

[0055] Based on this, the technicians of the present application creatively use modified hydrogenated nitrile rubber and a crosslinking agent so that the modified hydrogenated nitrile rubber and the crosslinking agent can be crosslinked through a chemical reaction to form a three-dimensional network structure, thereby inhibiting the swelling of the binder in the electrolyte.

[0056] An embodiment of the present application provides an adhesive, the components of which include hydrogenated nitrile rubber modified with a first active group and a crosslinking agent, wherein the first active group includes at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group and an amidoxime group.

[0057] The cross-linking agent contains at least two second active groups, and the second active groups can chemically react with the first active groups on the hydrogenated nitrile rubber modified by the first active groups.

[0058] The components of the above-mentioned adhesive include hydrogenated nitrile rubber modified by a first active group and a cross-linking agent, the cross-linking agent contains at least two second active groups, and the second active groups can chemically react with the first active groups. In this way, the hydrogenated nitrile rubber modified by the first active group and the cross-linking agent can form groups to form a three-dimensional network structure through chemical reaction. The formed three-dimensional network structure has a small swelling degree in solvents such as electrolytes. When used to prepare an electrode active layer on an electrode plate, while maintaining excellent bonding properties, it can inhibit the swelling degree of the electrode active layer in the electrolyte, thereby inhibiting the swelling of the electrode plate, thereby reducing the volume expansion of the battery and improving the cycle performance of the battery.

[0059] The second active group may be a functional group that can react with various first active groups on the first active group-modified hydrogenated nitrile rubber, and the specific type may be selected according to the type of the first active group on the first active group-modified hydrogenated nitrile rubber.

[0060] In some embodiments, the chemical reaction may be at least one of a condensation reaction and a ring-opening reaction.

[0061] Condensation reaction refers to the reaction in which two organic substances interact with each other to form a new molecule. Some condensation reactions are accompanied by the release of small molecules, such as water, while some do not release small molecules. The specific pathways of condensation reactions include, but are not limited to, substitution, addition, and elimination. For example, carboxylic acid and hydroxyl, carboxylic acid and amine are condensed through substitution, which can also be called esterification or amidation, and dihydroxyl and hydroxyl are condensed through dehydration elimination.

[0062] In some embodiments, the second reactive group includes at least one of an amine group, a hydroxyl group, a carbodiimide group, an aziridine group, and an isocyanate group.

[0063] Among the above-mentioned second active groups, the amino group can undergo condensation reaction or ring-opening reaction with functional groups such as carboxyl group and epoxy group, the hydroxyl group can undergo condensation reaction or ring-opening reaction with functional groups such as carboxyl group, epoxy group and hydroxyl group, the carbodiimide group can react with carboxyl group or epoxy group, the aziridine group can react with functional groups such as carboxyl group, amino group, hydroxyl group, epoxy group, ester group and amidoxime group, the isocyanate group can react with functional groups such as carboxyl group, amino group and hydroxyl group, and the hydroxyl groups can also undergo dehydration condensation reaction with each other.

[0064] In some of these embodiments, the hydrogenated nitrile rubber modified with the above-mentioned first active group includes a structural unit shown in formula (A):

[0065]

[0066] Among them, X1 represents the first active group, and * represents the connection site.

[0067] In some of these embodiments, X1 is selected from at least one of the following structures:

[0068]

[0069] Among them, * represents the connection site, and R1 is selected from an alkyl group or a polyether group having 1 to 20 carbon atoms.

[0070] In some of these embodiments, R1 is selected from a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms or

[0071] Among them, j represents the degree of polymerization.

[0072] In some of these embodiments, R1 is selected from a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms or

[0073] In some of these embodiments, R1 is selected from a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms or Specific examples include but are not limited to: methyl, ethyl, propyl, butyl or

[0074] Among the above-mentioned "1 to 20 carbon atoms", the number of carbon atoms can be: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

[0075] In some of these embodiments, X2 is selected from a straight-chain alkyl group having 1 to 10 carbon atoms.

[0076] In some of these embodiments, X2 is selected from a straight-chain alkyl group having 1 to 5 carbon atoms. Specific examples include but are not limited to: methyl, ethyl, propyl, butyl.

[0077] In some of these embodiments, the mass percentage of the structural unit shown in the above formula (A) in the hydrogenated nitrile rubber modified with the first active group is 0.1 wt% to 20 wt%.

[0078] The mass percentage of the structural unit shown in the above formula (A) can be measured by methods such as elemental analysis, chemical titration, infrared spectroscopy, etc.

[0079] By regulating the mass percentage of the structural unit shown in formula (A) in the hydrogenated nitrile rubber modified with the first active group, that is, regulating the number of the first active groups contained in the hydrogenated nitrile rubber modified with the first active group, the adhesion of the binder can be further improved, and it is ensured that a sufficient number of the first active groups react with the binder to form a good three-dimensional network structure, further improving the ability to inhibit swelling.

[0080] In the above “0.1 wt% to 20 wt%”, the value can be any value between the two endpoints including the endpoints, and non-limiting examples include but are not limited to: the carbon atom number can be: 0.1 wt%, 0.5 wt%, 1 wt%, 0.1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 13.5 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%.

[0081] In some of these embodiments, the hydrogenated nitrile rubber modified with the first active group includes a chain segment structure shown in formula (1):

[0082]

[0083] Both x and z are any integers greater than 0, and both y and w are any integers greater than or equal to 0.

[0084] It should be noted that the values of the above x, z, y, and w can be the same or different.

[0085] Furthermore, the hydrogenated nitrile rubber modified with the first active group further includes at least one of the following unsaturated structural units:

[0086]

[0087] It can be understood that hydrogenated nitrile rubber is a product obtained by hydrogenating and saturating the carbon-carbon double bonds on the molecular chain of nitrile rubber. During the hydrogenation process, due to process limitations, double bonds may still remain.

[0088] The specific content of the above unsaturated structural unit can be inferred from the hydrogenation saturation of the hydrogenated nitrile rubber modified by the first active group, and further can be inferred from the hydrogenation saturation of the hydrogenated nitrile rubber used as the raw material for preparation.

[0089] Furthermore, the hydrogenation saturation of the hydrogenated nitrile rubber modified by the first active group is 90% - 99.5%; it can be obtained by testing methods commonly used in the art for measuring the degree of hydrogenation, including but not limited to: infrared method, iodometric method, etc.

[0090] Furthermore, the mass percentage of the structural unit containing a cyano group in the hydrogenated nitrile rubber modified by the first active group does not exceed 45%.

[0091] In some embodiments, the mass percentage of the structural unit containing a cyano group in the hydrogenated nitrile rubber modified by the first active group does not exceed 25%.

[0092] In some embodiments, the mass percentage of the structural unit containing a cyano group in the hydrogenated nitrile rubber modified by the first active group is 15% - 25%.

[0093] The structural unit containing a cyano group is as follows:

[0094]

[0095] In some embodiments, the weight-average molecular weight of the hydrogenated nitrile rubber modified by the first active group is 300,000 - 600,000.

[0096] By regulating the weight-average molecular weight of the hydrogenated nitrile rubber modified by the first active group, while further improving the anti-swelling performance of the binder, good adhesiveness and dispersibility can be maintained, which is beneficial to pulping and further applications.

[0097] In some embodiments, the mass ratio of the above hydrogenated nitrile rubber modified by the first active group to the crosslinking agent is (1 - 3):(0.01 - 0.5).

[0098] The preparation of the above hydrogenated nitrile rubber modified by the first active group can refer to the preparation methods of modified hydrogenated nitrile rubber in the art. Here, examples of the preparation of the hydrogenated nitrile rubber modified by the first active group are given, and there are mainly the following two methods:

[0099] (1) Polymerize butadiene, acrylonitrile and a monomer corresponding to the structural unit shown in formula (A) to form a modified nitrile rubber, and then hydrogenate the modified nitrile rubber to obtain the hydrogenated nitrile rubber modified by the first active group; for example, for the carboxyl group-modified hydrogenated nitrile rubber, butadiene, acrylonitrile and methacrylic acid are polymerized to form a modified nitrile rubber, and then hydrogenated to obtain the modified hydrogenated nitrile rubber.

[0100] Furthermore, the carboxyl-modified hydrogenated nitrile rubber can further react with an organic alcohol to form an ester group, thereby obtaining an esterification-modified hydrogenated nitrile rubber. The organic alcohol can be polyethylene glycol monomethyl ether or the like.

[0101] (2) Directly modify the hydrogenated nitrile rubber to form a first active group-modified hydrogenated nitrile rubber. For example, perform a glyoximation reaction on the hydrogenated nitrile rubber to convert the cyano group therein into a glyoxime group; or prepare it from nitrile rubber as a starting material. For example, epoxidize the nitrile rubber to obtain an epoxidized modified nitrile rubber, and then hydrogenate the epoxidized modified nitrile rubber to obtain an epoxidized modified hydrogenated nitrile rubber.

[0102] The above preparation methods are only illustrative.

[0103] An embodiment of the present application provides an electrode paste, which includes an electrode active material and the above binder.

[0104] When the above electrode paste is applied to prepare an electrode active layer on an electrode pole piece, the first active group-modified hydrogenated nitrile rubber and the crosslinking agent in the binder can form a three-dimensional network structure through a chemical reaction between the first active group in the first active group-modified hydrogenated nitrile rubber and the second active group in the crosslinking agent. The formed three-dimensional network structure has a small swelling degree in solvents such as electrolyte. Thus, while maintaining excellent bonding performance, it can inhibit the swelling degree of the electrode active layer in the electrolyte, thereby inhibiting the swelling of the electrode pole piece, and further reducing the volume expansion of the battery and improving the cycle performance of the battery.

[0105] In some of these embodiments, based on the total mass of the components other than the solvent in the electrode paste, the mass ratio of the above first active group-modified hydrogenated nitrile rubber is 1% - 3%, and the mass ratio of the crosslinking agent is 0.01% - 0.5%.

[0106] In the binder, if the content of the first active group-modified hydrogenated nitrile rubber binder is too low, the adhesiveness decreases, and the active material and the conductive agent are likely to fall off, affecting the battery life and safety. If the content of the binder is too high, the proportion of the active material decreases, and the energy density of the battery cell decreases. Similarly, if the proportion of the crosslinking agent is too small, the crosslinking effect cannot be achieved, and the swelling cannot be inhibited. If the amount of the crosslinking agent used is too much, the energy density of the battery cell will decrease, and at the same time, it will also cause the gelation of the electrode paste.

[0107] In some of these embodiments, the above electrode paste further includes a conductive agent, and the conductive agent includes a third active group-modified conductive material, and the third active group can chemically react with the first active group and / or the second active group.

[0108] Any two of the third active group in the above-mentioned third active group-modified conductive material, the third active group in the first active group-modified hydrogenated nitrile rubber and the second active group in the cross-linking agent can undergo a chemical reaction, so that the third active group-modified conductive material, the first active group-modified hydrogenated nitrile rubber and the binder form a three-dimensional network structure. On the one hand, the swelling degree of the electrode active layer in the electrolyte can be further suppressed, thereby suppressing the swelling of the electrode pole piece; on the other hand, the functionalized modified carbon material, as a two-dimensional conductive material, can play a certain role in long-range conductivity, so that the electrode active layer maintains excellent conductivity even in a swollen state.

[0109] In some embodiments, the third reactive group includes at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group, and an amidoxime group.

[0110] In some embodiments, the mass percentage of the third active group in the conductive material modified by the third active group is 0.01 wt % to 5 wt %.

[0111] The mass proportion of the third active group in the third active group-modified carbon material reflects the degree of modification of the third active group of the third active group-modified conductive material. The mass proportion can be determined by elemental analysis, chemical titration, infrared spectroscopy and the like.

[0112] In some embodiments, the mass percentage of the third active group in the conductive material modified by the third active group is 1 wt % to 5 wt %.

[0113] In some embodiments, the mass percentage of the third active group in the conductive material modified by the third active group is 1 wt % to 4.5 wt %.

[0114] By adjusting the mass proportion of the third active group in the carbon material modified by the third active group, the swelling degree of the prepared electrode plate can be further suppressed.

[0115] In some of the embodiments, based on the total mass of the components in the electrode slurry excluding the solvent, the mass proportion of the conductive agent is 0.1% to 5%.

[0116] Furthermore, the carbon material modified by the third active group accounts for 0.01% to 5% of the conductive agent.

[0117] In some of the embodiments, the conductive material modified with the third active group includes at least one of a carbon material modified with the third active group and a conductive metal material modified with the third active group.

[0118] Further, based on the total mass of the components other than the solvent in the electrode paste, the mass ratio of the third active group-modified conductive material is 0.01% to 0.5%.

[0119] In some embodiments, the third active group-modified carbon material includes at least one of third active group-modified graphite, third active group-modified graphene, third active group-modified carbon nanofibers, and third active group-modified carbon nanotubes. Specific examples include, but are not limited to: third active group-modified carbon black, third active group-modified natural graphite, third active group-modified artificial graphite, third active group-modified acetylene black, third active group-modified Ketjen black, third active group-modified carbon nanofibers, third active group-modified carbon nanotubes, and third active group-modified graphene.

[0120] The third active group-modified conductive metal materials include, but are not limited to: third active group-modified gold nanofibers, third active group-modified copper nanofibers, third active group-modified nickel nanofibers, third active group-modified aluminum nanofibers, third active group-modified silver nanofibers, third active group-modified TiN nanofibers, third active group-modified gold nanotubes, third active group-modified copper nanotubes, third active group-modified nickel nanotubes, third active group-modified aluminum nanotubes, third active group-modified silver nanotubes, and third active group-modified TiN nanotubes, etc.

[0121] In some embodiments, the third active group-modified conductive material is selected from third active group-modified carbon materials.

[0122] The third active group-modified carbon material can also act as a reinforcing material, which can improve the mechanical properties of the electrode sheet.

[0123] The third active group-modified carbon material is selected from third active group-modified carbon nanofibers or third active group-modified carbon nanotubes and functionalized modified graphene.

[0124] The above-mentioned third active group-modified carbon material, as a two-dimensional conductive material, can play a role in long-range conduction to a certain extent, and can still play a conductive role even in the case of swelling, ensuring that the conductivity of the battery is not affected by swelling.

[0125] In some embodiments, the above-mentioned conductive agent further includes non-functional group-modified conductive materials, and common conductive agents in the art can be used, including but not limited to: at least one of graphite, carbon nanotubes, nanofibers, carbon black, and graphene. Specifically, it can be selected from at least one of SP, KS-6, acetylene black, branched-chain Ketjen black ECP, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotubes CNTs, and graphene and their composite conductive agents.

[0126] In some of these embodiments, the above electrode active material is a positive electrode active material or a negative electrode active material.

[0127] It can be understood that when the electrode active material is a positive electrode active material, the prepared electrode paste is a positive electrode paste, and the prepared electrode sheet is a positive electrode sheet.

[0128] Similarly, when the electrode active material is a negative electrode active material, the prepared electrode paste is a negative electrode paste, and the prepared electrode sheet is a negative electrode sheet.

[0129] In some of these embodiments, based on the total mass of the components other than the solvent in the electrode paste, the mass percentage of the electrode active material is 95% to 99%.

[0130] The above positive electrode active material can adopt the commonly used positive electrode active materials in this application; further, as an example, the positive electrode active material can include at least one of the following materials: lithium phosphate with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides can 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 (which can also be abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM523), LiNi 0.5 Co 0. 25Mn 0.25 O2 (which can also be abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05At least one of O2) and its modified compounds, etc. Examples of the lithium-containing phosphate with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), lithium manganese phosphate (such as LiMnPO4), and lithium manganese iron phosphate.

[0131] In some of these embodiments, the molecular formula of the positive electrode active material is: LiFe x Mn (1-x) PO4, where x takes any number from 0 to 1.

[0132] It can be understood that when x = 0, LiFe x Mn (1-x) PO4 is lithium manganese phosphate LiMnPO4, and when x = 1, LiFePO4 is lithium iron phosphate LiFePO4.

[0133] The above-mentioned negative electrode active material uses the common negative electrode active material in this application; further, 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, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material can be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0134] In some of these embodiments, the above-mentioned electrode active material is a positive electrode active material.

[0135] In some of these embodiments, the electrode active substance includes at least one of lithium iron phosphate and lithium manganese iron phosphate.

[0136] The above-mentioned solvents are each independently selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylformamide, ethanol, ethylene glycol, methanol, and isopropanol. Specifically, the solvent is selected from N-methylpyrrolidone (NMP).

[0137] In one embodiment of this application, an electrode pole piece is further provided. The electrode pole piece includes a current collector and an active layer located on the surface of the current collector. The preparation raw materials of the active layer include the binder as described above; or

[0138] The active layer is prepared from the electrode slurry as described above.

[0139] The preparation steps of the above-mentioned electrode pole piece include the following step S10.

[0140] Step S10: Form an electrode active substance layer on the surface of the current collector.

[0141] It is understandable that in the present application, the above step of forming the electrode active material layer is carried out by coating, and the coating includes but is not limited to printing coating, knife coating, spin coating or inkjet coating.

[0142] In an embodiment of the present application, an electrode plate is provided, which includes a current collector and an active layer on the surface of the current collector. The active layer has a three-dimensional network structure in which hydrogenated nitrile rubber modified with the first active group in the above binder is connected to the above cross-linking agent through cross-linking sites. The cross-linking sites include groups formed by chemical reaction between the first active group in the hydrogenated nitrile rubber modified with the first active group and the second active group in the cross-linking agent.

[0143] In some of these embodiments, the components of the active layer further include a conductive agent, and the conductive agent includes a conductive material modified with a third active group, and the third active group can undergo a chemical reaction with the first active group and / or the second active group.

[0144] The active layer also has a three-dimensional network structure in which hydrogenated nitrile rubber modified with the first active group, a cross-linking agent, and a conductive material modified with a third active group are connected through cross-linking sites. The cross-linking sites include groups formed by chemical reaction between any two of the first active group, the second active group, and the third active group.

[0145] The above electrode plate has excellent anti-swelling performance and high conductivity, can inhibit the volume expansion rate of the battery, and improve its cycling performance.

[0146] In some of these embodiments, the mass ratio of the conductive agent in the active layer is 0.1% - 5%.

[0147] In some of these embodiments, the mass ratio of the electrode active material in the active layer is 95% - 99%.

[0148] In some of these embodiments, the above current collector can be a metal foil or a composite current collector, and the composite current collector has at least one metal surface. For example, as the metal foil, aluminum foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0149] An embodiment of the present application also provides a battery, including the above electrode plate.

[0150] The battery has a small volume expansion rate and excellent cycling performance.

[0151] In some of these embodiments, the above battery includes a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet and / or the negative electrode sheet adopt the above electrode sheet.

[0152] It is understandable that in the above battery, at least one of the positive electrode sheet and the negative electrode sheet adopts the above electrode sheet.

[0153] The positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a stacking process.

[0154] In some of the above, the electrode sheet is a positive electrode sheet, and the negative electrode sheet is made using a conventional binder.

[0155] The conventional binder can be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, hydrogenated nitrile rubber, 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), and fluorinated acrylate resin.

[0156] This application does not particularly limit the type of the separator, and any well-known porous structure separator with good chemical stability and mechanical stability can be selected.

[0157] In some of these 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.

[0158] In some of these embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be made into an electrode assembly by a winding process or a stacking process. Further, the above battery further includes: a housing and an electrolyte, and the electrolyte and the electrode assembly are accommodated in the housing.

[0159] The above housing can be used to encapsulate the electrode assembly and the electrolyte.

[0160] In some embodiments, the above housing can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. It can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as plastics, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed, etc.

[0161] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square or any other shape. For example, Figure 1 is a battery 10 with a square structure as an example.

[0162] In some embodiments, the above electrolyte includes an electrolyte salt and a solvent.

[0163] In some embodiments, the electrolyte salt can 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 difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0164] 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, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0165] In some embodiments, the above electrolyte may also optionally include functional additives. For example, the functional additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives that can improve certain battery performances, such as additives that improve the overcharge performance of the battery, additives that improve the high-temperature or low-temperature performance of the battery, etc.

[0166] The above battery is a secondary battery or a lithium battery.

[0167] In addition, the present application also provides an electrical device, which includes the battery provided by the present application.

[0168] The above battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device.

[0169] Furthermore, the above electrical device can 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, satellites, energy storage systems, etc., but not limited thereto.

[0170] As the electrical device, the above battery can be selected according to its usage requirements.

[0171] Figure 2 is an electrical device 20 as an example. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0172] Another example of the device can be a mobile phone, a tablet computer, a laptop computer, etc. The device usually requires being thin and light, and a secondary battery can be used as the power source.

[0173] The present invention will be described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. It should be understood that the appended claims define the scope of the present invention. Under the guidance of the inventive concept of the present invention, those skilled in the art should realize that certain changes made to the embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

[0174] The following are specific embodiments. Specific Embodiments

[0176] Example 1

[0177] (1) Preparation of carboxylated hydrogenated nitrile rubber: 700 g of acrylonitrile, 70 g of methacrylic acid, and 800 g of butadiene were added to 10 kg of chlorobenzene to form a mixed material. The mixed material was added to a high-pressure reactor, stirred well, and the reactor was degassed with H2 three times. Then the temperature of the reactor was raised to 130 °C. The hydrogenation catalyst tris(triphenylphosphine)-rhodium chloride and the polymerization initiator triphenylphosphine were dissolved in a chlorobenzene solution to obtain a catalyst solution. Under a hydrogen atmosphere, the catalyst solution was added to the reactor and the temperature was raised to 138 °C, and the internal pressure of the reactor was adjusted to 8.27 MPa. After reacting for a period of time, a sample was taken for infrared test to analyze its hydrogenation degree until the hydrogenation degree of the sample reached 99.5%. Finally, the chlorobenzene was removed by injecting steam and dried to obtain carboxylated hydrogenated nitrile rubber.

[0178] The prepared carboxylated hydrogenated nitrile rubber was tested by external spectroscopy and its functionalization degree was analyzed and calculated: It represents the mass ratio of the acrylic acid structural unit containing carboxyl groups in the carboxylated hydrogenated nitrile rubber. The specific results are shown in Table 1.

[0179] The prepared carboxylated hydrogenated nitrile rubber was tested by gel permeation chromatography to measure its weight-average molecular weight. The specific results are shown in Table 1.

[0180] Carboxylated carbon nanotubes were provided: 5 g of single-walled carbon nanotubes were added to 450 mL of mixed acid, and the single-walled carbon nanotubes were dispersed evenly by ultrasonic treatment. Then it was refluxed in a water bath at 70 °C for 0.5 h, 3 h, 7 h, and 9 h. After the reaction, it was diluted with deionized water, filtered by suction, washed to neutral, and then dried in vacuum at 60 °C for 24 h to obtain functionalized carbon nanotubes as carboxylated carbon nanotubes. Among them, the mixed acid was obtained by mixing concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1. The carboxylated carbon nanotubes were tested by external spectroscopy and their functionalization degree was calculated: It represents the mass ratio of carboxyl groups in the carboxylated carbon nanotubes. The specific results are shown in Table 1.

[0181] (2) Preparation of the positive electrode plate: The positive active material lithium iron phosphate, conductive agent carbon black, carboxylated hydrogenated nitrile rubber, cross-linking agent (polyaziridine SAC-100), and carboxylated carbon nanotubes are mixed evenly according to a mass ratio of 97.8:1:1:0.01:0.01. Then, NMP is added as a solvent, and the mixture is stirred under a vacuum mixer until the system becomes homogeneous, obtaining a positive electrode slurry with a solid content of 70 wt%. The positive electrode slurry is evenly coated on one surface of an aluminum foil with a thickness of 12 μm, dried at 90 °C, and cold-pressed to obtain a positive electrode plate with a thickness of 110 μm for the positive active material layer. Then, after processes such as tab forming and slitting, the positive electrode plate is obtained.

[0182] (3) Preparation of the negative electrode plate: The negative active material artificial graphite, conductive agent conductive carbon black, binder styrene-butadiene rubber (SBR), and thickener carboxymethyl cellulose (CMC) are mixed according to a mass ratio of 96:0.9:1.6:1.5, and deionized water is added as a solvent. The mixture is stirred under a vacuum mixer until the system becomes homogeneous, obtaining a negative electrode slurry with a solid content of 54 wt%. The negative electrode slurry is evenly coated on one surface of an aluminum foil copper foil with a thickness of 8 μm, dried at 110 °C, and cold-pressed to obtain a negative electrode plate with a thickness of 110 μm for the negative active material layer. Then, after processes such as tab forming and slitting, the negative electrode plate is obtained.

[0183] (4) Preparation of the electrolyte: In an environment with a water content of less than 10 ppm, ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate, which are non-aqueous organic solvents, are mixed according to a volume ratio of 1:1:1 to obtain an electrolyte solvent. Subsequently, lithium salt LiPF6 is dissolved in the mixed solvent to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0184] (5) Preparation of the separator: A polyethylene film with a thickness of 14 μm is selected as the separator, and before use, it is cut into a suitable size according to the sizes of the positive electrode plate and the negative electrode plate.

[0185] (6) Preparation of the lithium-ion battery: The above-mentioned positive electrode plate, separator, and negative electrode plate are stacked in sequence, with the separator placed between the positive electrode plate and the negative electrode plate to play an isolation role, and then wound to obtain an electrode assembly; the electrode assembly is placed in an outer packaging shell, dried, and then injected with the electrolyte. After processes such as vacuum packaging, standing, forming, and shaping, the lithium-ion battery is obtained.

[0186] (7) The performance of the lithium-ion battery is tested, including the following:

[0187] 1. Test the swelling rate of the positive electrode plate:

[0188] (1) At 25 °C, the initial thickness of the positive electrode plate is tested and denoted as H0.

[0189] (2) The lithium-ion battery prepared with this positive electrode sheet is charged at a constant current of 1.0 C to 3.65 V at 45°C, allowed to stand for 5 min, and then discharged at a constant current of 1 / 3 C to 2.5 V. This is taken as one cycle. After 300 cycles, the lithium-ion battery is disassembled and the thickness of the positive electrode sheet at this time is measured and denoted as H1.

[0190] The thickness growth rate (%) of the positive electrode sheet = (H1 - H0) / H0 × 100%.

[0191] The thickness of the electrode sheet is measured using a micrometer.

[0192] The volume expansion of the positive electrode sheet and the secondary battery can be characterized by the thickness growth rate of the positive electrode sheet. The smaller the thickness growth rate of the positive electrode sheet, the smaller the volume expansion of the positive electrode sheet and the secondary battery.

[0193] 2. Capacity retention rate test:

[0194] (1) At 45°C, the lithium-ion battery is charged at a constant current of 1 / 3 C to 3.65 V, then charged at a constant voltage of 3.65 V until the current is 0.05 C, allowed to stand for 5 min, and then discharged at a constant current of 1 / 3 C to 2.5 V. The discharge capacity C0 is recorded.

[0195] (2) Then the lithium-ion battery is charged at a constant current of 1.0 C to 3.65 V, allowed to stand for 5 min, and then discharged at a constant current of 1 / 3 C to 2.5 V. The discharge capacity C1 is recorded.

[0196] The above step (2) is repeated 200 times. The discharge capacity C200 of the lithium-ion battery after the 200th cycle is recorded. The capacity retention rate P200 = C200 / C0 × 100%.

[0197] Impedance growth rate:

[0198] (1) At 45°C, the lithium-ion battery is charged at a constant current of 1 / 3 C to 4.3 V, then charged at a constant voltage of 4.3 V until the current is 0.05 C. After standing for 5 min, the voltage V1 is recorded. Then it is discharged at a constant current of 1 / 3 C for 30 s, and the voltage V2 is recorded to obtain the impedance DCR1 of the lithium-ion battery after the first cycle.

[0199] The above step (1) is repeated 200 times to obtain the impedance DCR200 of the lithium-ion battery after the 200th cycle. The impedance growth rate = (DCR200 - DCR1) / DCR1 × 100%. The specific results are shown in Table 1.

[0200] Examples 2 - 3

[0201] Examples 2 to 3 are basically the same as Example 1, except that: in the regulation step (2), the mass ratio of the positive electrode active material to the hydrogenated nitrile rubber modified with the first active group is shown in Table 1 specifically.

[0202] The remaining steps are the same as those in Example 1.

[0203] Examples 4 to 8

[0204] Examples 4 to 8 are basically the same as Example 3, except that: in step (1), the feeding ratio of raw materials in the preparation process of carboxylated hydrogenated nitrile rubber is controlled to obtain carboxylated hydrogenated nitrile rubbers with different degrees of functionalization: that is, in the carboxylated hydrogenated nitrile rubber, the mass ratio of the structural unit containing carboxyl is different from that in Example 3, and the specific parameters are shown in Table 1.

[0205] Example 9

[0206] Example 9 is basically the same as Example 3, except that:

[0207] (1) Preparation of amidoximated hydrogenated nitrile rubber: Add 20 g of hydrogenated nitrile rubber and 178 g of chloroform to a three-necked flask, stir until fully dissolved at 40 °C through condensation reflux; pour in 36 ml of ethanol solution, add 10 g of hydroxylamine hydrochloride, dissolve for 15 min, and finally add 28.5 g of sodium carbonate. Stir and reflux at 40 °C for 16 h to obtain amidoximated hydrogenated nitrile rubber. The specific parameters are shown in Table 1

[0208] The remaining steps are the same as those in Example 3.

[0209] Examples 10 to 11

[0210] Examples 10 to 11 are basically the same as Example 9, except that: the process conditions in the preparation process of amidoximated hydrogenated nitrile rubber are controlled to obtain amidoximated hydrogenated nitrile rubbers with different weight average molecular weights, and the specific parameters are shown in Table 1.

[0211] The remaining steps are the same as those in Example 9.

[0212] Examples 12 to 14

[0213] Examples 12 to 14 are basically the same as Example 3, except that: in step (2), on the premise of keeping the total mass ratio of conductive carbon black and carboxylated carbon nanotubes the same as that in Example 3, the mass ratio of carboxylated carbon nanotubes is changed, and the specific parameters are shown in Table 1.

[0214] The remaining steps are the same as those in Example 3.

[0215] Example 15

[0216] Example 15 is basically the same as Example 3, except that: in step (2), the carboxylated carbon nanotubes are replaced with the same mass of unmodified carbon nanotubes. For specific parameters, please refer to Table 1.

[0217] The remaining steps are the same as those in Example 3.

[0218] Example 16

[0219] Example 16 is basically the same as Example 2, except that:

[0220] (1) Preparation of esterified hydrogenated nitrile rubber: Dissolve 20 g of XNBR (carboxylated nitrile rubber) in 500 mL of chlorobenzene, then drop 20 mL of thionyl chloride into the polymer solution, and react at 78 °C for 4 hours. Then, add an appropriate amount of polyethylene glycol monomethyl ether (molar ratio of -COOH in carboxylated nitrile rubber to -OH in polyethylene glycol monomethyl ether = 1:1.2) and triethylamine (molar ratio of -COOH to Et3N = 1:1.2) to the above solution, and react at 55 °C for 5 hours. The whole reaction process is carried out in a nitrogen atmosphere. The hydroxyl group on polyethylene glycol monomethyl ether reacts with the carboxyl group on XNBR to form an ester group. The product is solidified in ethanol, washed 3 times with water, and dried at 55 °C to obtain MPEG-grafted nitrile rubber.

[0221] Add 18 g of MPEG-grafted nitrile rubber and 282 mL of chlorobenzene to an autoclave, then transfer the hydrogenation catalyst tris(triphenylphosphine)-rhodium chloride to the reactor. Slowly heat the autoclave to 120 °C and keep it for 8 hours. The whole reaction process is carried out in a hydrogen atmosphere. The product is solidified in ethanol, thoroughly washed and dried at 55 °C to obtain esterified hydrogenated nitrile rubber with a hydrogenation degree of 99.5%.

[0222] In step (2), the aziridine crosslinking agent is replaced with an equimolar amount of isocyanate crosslinking agent XR-202.

[0223] The remaining steps are the same as those in Example 2.

[0224] Example 17

[0225] Example 17 is basically the same as Example 2, except that:

[0226] (1) Preparation of epoxidized hydrogenated nitrile rubber: Dissolve 20 g of nitrile rubber in 250 g of chlorobenzene in a 500 ml three-necked flask, add CH3COOH to acidify the system, then dropwise add H2O2, stop the reaction after reacting at 60 °C for 6 h, cool to room temperature, precipitate with anhydrous ethanol, wash three times and then put it in an oven to dry to obtain the product epoxidized nitrile rubber.

[0227] Dissolve 15 g of the prepared epoxidized nitrile rubber in 500 g of chlorobenzene, then put it into a reaction kettle and degas the reaction kettle three times with H2. Raise the temperature of the reaction kettle to 130 °C, dissolve the catalyst tris(triphenylphosphine)-rhodium chloride and triphenylphosphine in the chlorobenzene solution to form a catalyst solution. Under a hydrogen atmosphere, add the catalyst solution to the reaction kettle and raise the temperature to 138 °C, and adjust the internal pressure of the reaction kettle to 8.27 MPa. Take a sample for infrared test to analyze its hydrogenation degree until the hydrogenation degree of the sample reaches 99.5%. Finally, remove the chlorobenzene by injecting steam and dry to obtain epoxidized hydrogenated nitrile rubber.

[0228] In step (2), replace the aziridine crosslinking agent with an equimolar amount of polycarbodiimide crosslinking agent CDI-1171.

[0229] The remaining steps are the same as those in Example 2. Specific parameters are shown in Table 1.

[0230] Comparative Example 1

[0231] Comparative Example 1 is basically the same as Example 1, except that: in step (2), replace the carboxylated hydrogenated nitrile rubber with an equal mass of hydrogenated nitrile rubber. The remaining steps are the same as those in Example 3.

[0232] The relevant physical parameters and test results in each example and comparative example are shown in Table 1:

[0233] Among them, A represents the functionality in the hydrogenated nitrile rubber modified with the first active group, that is, the mass percentage of the structural unit containing the first active group, B represents the weight-average molecular weight of the hydrogenated nitrile rubber modified with the first active group, and C represents the mass percentage of the third active group in the carbon nanotubes modified with the third active group.

[0234] Based on the total mass of the components other than the solvent in the positive electrode slurry, the mass percentage of the hydrogenated nitrile rubber modified with the first active group is denoted as D, the mass percentage of the crosslinking agent is denoted as E, the mass percentage of the carbon nanotubes modified with the third active group is denoted as F, and the mass percentage of the positive electrode active material is K.

[0235] Table 1

[0236]

[0237] From the experimental results in the above table, it can be seen that the positive electrode sheet of this application has excellent flexibility, and even at a relatively high electrode compaction density, it can maintain good flexibility.

[0238] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0239] The above-described embodiments only express several implementation manners of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims, and the specification and drawings can be used to explain the content of the claims.

Claims

1. An electrode paste, characterized in that, The electrode slurry comprises an electrode active material and a binder, wherein the binder comprises a hydrogenated nitrile rubber modified with a first active group and a crosslinking agent, wherein the first active group comprises at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group and an amidoxime group; The cross-linking agent contains at least two second reactive groups, and the second reactive groups can chemically react with the first reactive groups on the hydrogenated nitrile rubber modified by the first reactive groups; the second reactive groups include at least one of an amine group, a hydroxyl group, a carbodiimide group, an aziridine group and an isocyanate group; The first active group-modified hydrogenated nitrile rubber comprises a structural unit represented by formula (A): Wherein, X1 represents the first active group, and X2 is selected from H or an alkyl group having 1 to 10 carbon atoms; * indicates the attachment site; The electrode slurry also includes a conductive agent, which includes a conductive material modified with a third active group, and the third active group can chemically react with the first active group and / or the second active group; the third active group includes at least one of a carboxyl group, an amine group, a hydroxyl group, an epoxy group, an ester group and an amidoxime group.

2. The electrode slurry according to claim 1, characterized in that The mass proportion of the third active group in the conductive material modified by the third active group is 0.01wt% to 5wt%; and / or The conductive material modified by the third active group includes at least one of a carbon material modified by the third active group and a conductive metal material modified by the third active group.

3. The electrode paste according to claim 1, wherein, Based on the total mass of the components in the electrode slurry excluding the solvent, the mass proportion of the conductive agent is 0.1% to 5%; and / or The proportion of the conductive material modified by the third active group in the conductive agent is 0.01% to 5%; and / or The conductive material modified by the third active group is selected from carbon materials modified by the third active group.

4. The electrode paste according to claim 1, characterized in that, 1wt%~20wt%。 The mass proportion of the structural unit represented by formula (A) in the hydrogenated nitrile rubber modified by the first active group is 0. 1wt% ~ 20wt%.

5. The electrode paste according to claim 1, wherein The hydrogenated nitrile rubber modified by the first active group comprises a segment structure shown in formula (1): x and z are both arbitrary integers > 0, and y and w are both arbitrary integers ≥ 0.

6. The electrode paste according to any one of claims 1 to 5, characterized in that The weight average molecular weight of the hydrogenated nitrile rubber modified by the first active group is 300,000 to 600,000.

7. The electrode paste according to any one of claims 1 to 5, characterized in that, In the binder, the mass ratio of the first active group-modified hydrogenated nitrile rubber to the cross-linking agent is (1-3): (0.01-0.5).

8. The electrode paste according to any one of claims 1 to 5, characterized in that, The electrode active material is a positive electrode active material or a negative electrode active material; Based on the total mass of the components in the electrode slurry excluding the solvent, the mass proportion of the electrode active material is 95% to 99%.

9. The electrode paste according to claim 8, wherein The electrode active material includes at least one of lithium iron phosphate and lithium manganese iron phosphate.

10. An electrode sheet, characterized in that, The electrode plate comprises a current collector and an active layer located on the surface of the current collector, and the active layer is made of the electrode slurry according to any one of claims 1 to 9.

11. An electrode tab, characterized in that, The electrode sheet includes a current collector and an active layer located on the surface of the current collector. The active layer has a three-dimensional network structure in which the hydrogenated nitrile rubber modified by the first active group in the binder in the electrode paste according to any one of claims 1 to 9 is connected to the crosslinking agent through crosslinking sites. The crosslinking sites include groups formed by chemical reactions between the first active groups in the hydrogenated nitrile rubber modified by the first active group and the second active groups in the crosslinking agent. The active layer also has a three-dimensional network structure in which the hydrogenated nitrile rubber modified by the first active group, the crosslinking agent, and the conductive material modified by the third active group in the conductive agent in the electrode paste according to any one of claims 1 to 9 are connected through crosslinking sites. The crosslinking sites include groups formed by chemical reactions between any two of the first active group, the second active group, and the third active group.

12. A battery, characterized in that, It includes the electrode sheet according to claim 10 or claim 11.

13. An electrical device, characterized in that, It includes the battery according to claim 12.

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