Polymer alkali metal salt polymolecular substance and preparation method therefor, polymer alkali metal salt material, electrode slurry, electrode sheet, use thereof in preparation of secondary battery, secondary battery, and electric device

Abstract

Provided in the present application is a polymer alkali metal salt polymolecular substance, comprising a plurality of polymer alkali metal salt molecules. The polymer alkali metal salt molecules have a linear structure and comprise a carbon main chain and a plurality of side groups Q grafted along the carbon main chain, any side group Q independently being -COOH or -COOM, at least part of the side groups Q being -COOM, and M being an alkali metal element. In the polymer alkali metal salt polymolecular substance, the mass percentage of element M ≥3 wt%, the number-average molecular mass is selected from 3 kDa-1000 kDa, and the polydispersity index is selected from 1-1.5.

Description

Polymer alkali metal salt multimolecule and preparation method thereof, polymer alkali metal salt material, electrode slurry, electrode plate and application in preparing secondary battery, secondary battery, and electrical device

[0001] Related applications

[0002] This application claims priority to Chinese patent application number CN2023116336717, filed on December 1, 2023, entitled “Polymer Alkali Metal Salts and Their Application in the Preparation of Secondary Batteries,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of secondary batteries, and in particular to multi-molecules of polymer alkali metal salts and their applications in the preparation of secondary batteries, and further to multi-molecules of polymer alkali metal salts, polymer alkali metal salt materials, electrode slurries, electrode plates, secondary batteries, electrical devices, preparation methods and applications. Background Art

[0004] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0005] In recent years, with the advancement of secondary battery technology, lithium-ion batteries, a leading example, have been widely used in a variety of fields, including power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. They are also widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants. With the increasing application of secondary batteries, higher requirements are being placed on their cycle performance. Improving the cycle performance and rate capability of secondary batteries has been a key issue in the field of secondary batteries in recent years.

[0006] Summary of the Invention

[0007] According to various embodiments and examples of the present application, the present application provides a polymer alkali metal salt multi-molecule and its use in the preparation of a secondary battery. Further provided are a polymer alkali metal salt multi-molecule, a polymer alkali metal salt material, an electrode slurry, an electrode plate, a secondary battery, an electrical device, a preparation method, and applications. The polymer alkali metal salt multi-molecule and the polymer alkali metal salt material containing the multi-molecule can be used in the electrode plate of a secondary battery to play at least one of the roles of a binder and a dispersant, thereby improving the cycle performance and rate performance of the secondary battery.

[0008] In a first aspect of the present application, a multimolecular compound of a polymer alkali metal salt is provided, comprising a plurality of polymer alkali metal salt molecules, wherein the polymer alkali metal salt molecules have a linear structure, the polymer alkali metal salt molecules comprising a carbon backbone and a plurality of side groups Q branched along the carbon backbone, any of the side groups Q independently being -COOH or -COOM, and at least a portion of the side groups Q being -COOM, and M being an alkali metal element;

[0009] The mass percentage of the M element in the multi-molecule compound of the polymer alkali metal salt is greater than or equal to 3 wt %; the number average molecular weight of the multi-molecule compound of the polymer alkali metal salt is selected from 3 kDa to 1000 kDa, and the polydispersity coefficient of the multi-molecule compound of the polymer alkali metal salt is selected from 1 to 1.5.

[0010] The aforementioned polymer alkali metal salt multi-molecule is an aggregate of multiple polymer alkali metal salt molecules, wherein the polymer alkali metal salt is an alkali metal salt of a polymer carboxylic acid, and at least a portion of the carboxyl groups (-COOH) grafted on the linear carbon backbone are alkali metal salted, that is, at least a portion of the carboxyl groups are converted into alkali metal carboxyl groups (-COOM), so that the side chains of the multi-molecule are grafted with alkali metal carboxyl groups. By simultaneously controlling the average molecular weight, molecular weight distribution and mass percentage of the "M element in the polymer alkali metal salt multi-molecule (which can be recorded as F M or n wt%, where n is a suitable positive number and wt% represents weight percentage). When a multi-molecule polymer alkali metal salt or a polymer alkali metal salt material containing the same is used in an electrode plate of a secondary battery and plays at least one of the roles of a binder and a dispersant, during the stirring stage of the electrode slurry, the polymer alkali metal salt achieves chain segment stretching under the dispersion effect. Due to the mutual electrostatic repulsion between the alkali metal ions, the segments carrying alkali metal carboxyl groups in the polymer alkali metal salt molecules repel each other under the electrostatic effect and become more dispersed. By controlling the polymer alkali metal salt to have a relatively narrow molecular weight distribution and a certain average molecular weight, and further combining it with a certain alkali metal content control, the polymer alkali metal salt can be uniformly distributed around the electrode active material in the electrode active material layer, which is beneficial to providing uniformly distributed alkali metal carboxyl groups at the molecular level and in the electrode active material layer, improving the uniform stability of active ion conduction, and thus improving the cycle performance and rate performance of the battery.

[0011] Based on any suitable embodiment of the present application, further, in some embodiments, in any -COOM, M is independently Li, Na or K;

[0012] Optionally, in any -COOM, M is independently Li or Na.

[0013] When the M element is Li, Na, or K, it can improve the uniformity and stability of active ion conduction at the molecular level and in the electrode active material layer, thereby improving the battery's cycle performance and rate performance. In addition, when the active ions in the secondary battery include the M element, the M element in the polymer alkali metal salt can also serve as a supplement for the active ions.

[0014] Based on any suitable embodiment of the present application, further, in some embodiments, the carbon backbone of the polymer alkali metal salt molecule is formed by sequentially bonding the units represented by formula (I);

[0015] In the units represented by formula (I) in the multi-molecule compound of the polymer alkali metal salt, any Q is independently -COOH or -COOM, and at least a portion of Q is -COOM; any R1 is independently H or C 1-3 alkyl;

[0016] Alternatively, any R1 is independently H or methyl.

[0017] When the carbon backbone of the polymer alkali metal salt molecule is composed of units represented by formula (I) linked sequentially, the polymer alkali metal salt may include one or both of polyacrylic acid alkali metal salts and poly(α-alkyl acrylate alkali metal salts). In this case, the side groups Q are evenly spaced on the carbon backbone, which helps to further improve the uniformity of the distribution of alkali metal carboxyl groups around the electrode active material, thereby improving the uniformity and stability of active ion conduction and the cycle performance and rate performance of the battery.

[0018] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer alkali metal salt includes at least one of polyacrylic acid alkali metal salt and polymethacrylic acid alkali metal salt.

[0019] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer alkali metal salt includes at least one of lithium polyacrylate and lithium polymethacrylate.

[0020] When R1 in formula (I) is one or both of H and methyl, the polymer alkali metal salt may include one or both of polyacrylic acid alkali metal salt and polymethacrylic acid alkali metal salt. In this case, the main chain carbon to which the side group Q is bonded is less affected by the steric hindrance of R1, and the overall flexibility of the polymer alkali metal salt is better. In addition, the side group Q is evenly spaced on the carbon main chain. When the multi-molecule of the polymer alkali metal salt or the polymer alkali metal salt material containing it is used in the electrode active material layer, it is more conducive to improving the uniformity of the distribution of the alkali metal carboxyl group around the electrode active material, and is more conducive to improving the uniform stability of the active ion conduction, and thus is more conducive to improving the cycle performance and rate performance of the battery. When the polymer alkali metal salt includes at least one of lithium polyacrylate and lithium polymethacrylate, it can also play a role in supplementing active ions in secondary batteries whose active ions include lithium ions.

[0021] Based on any suitable embodiment of the present application, further, in some embodiments, the multi-molecules of the polymer alkali metal salt meet one or more of the following characteristics:

[0022] The number average molecular weight of the multi-molecule compound of the polymer alkali metal salt is selected from 100 kDa to 500 kDa;

[0023] The mass percentage of the M element in the multi-molecule material of the polymer alkali metal salt is greater than or equal to 5wt%;

[0024] The M element includes lithium, and the mass percentage of lithium in the multi-molecule of the polymer alkali metal salt is selected from 5wt% to 7.5wt%;

[0025] The polydispersity coefficient of the multi-molecule compound of the polymer alkali metal salt is selected from 1 to 1.3.

[0026] Based on any suitable embodiment of the present application, further, in some embodiments, the M element includes lithium element, and the mass percentage of lithium element in the multi-molecule of the polymer alkali metal salt is selected from 5.5 wt % to 7 wt %.

[0027] By adjusting the average molecular weight of the polymer alkali metal salt's multi-molecules, the polymer alkali metal salt is more fully dispersed in the electrode active material layer of the electrode pole piece, and the alkali metal carboxyl groups carried by the polymer alkali metal salt are more evenly distributed around the electrode active material, which is more conducive to improving the cycle performance and rate performance of the battery.

[0028] By adjusting the mass percentage of M element in the polymer alkali metal salt multi-molecule (F M) Within the aforementioned range, more carboxyl groups of the carbon backbone side groups can be converted into alkali metal carboxyl groups, which is beneficial for the alkali metal carboxyl groups to disperse the molecular chains better at the slurry level through electrostatic repulsion, which is more beneficial to the cycle performance of the battery. On the other hand, it is beneficial to better improve the active ion conduction and more beneficial to improve the battery rate performance. As a non-limiting example, when the M element includes lithium, the mass percentage of lithium in the multi-molecule of the polymer alkali metal salt (F Li ) to better optimize battery cycle performance and rate performance.

[0029] By adjusting the polydispersity coefficient of the polymer alkali metal salt, the molecular weight uniformity of the polymer alkali metal salt can be adjusted, which is beneficial to improving the dispersion uniformity of the alkali metal carboxyl groups in the polymer alkali metal salt in the electrode pole piece, and is more beneficial to improving the cycle performance and rate performance of the battery.

[0030] By adjusting the average molecular weight, molecular weight distribution and the mass percentage of the "M element in the polymer alkali metal salt multi-molecule (F M )" within the aforementioned range is conducive to a more uniform distribution of the alkali metal carboxyl groups in the electrode plate, which is more conducive to improving the uniform stability of active ion conduction, and further more conducive to improving the cycle performance and rate performance of the battery.

[0031] In a second aspect of the present application, a polymer alkali metal salt material is provided, which comprises a multi-molecule substance of the polymer alkali metal salt described in the first aspect of the present application.

[0032] In a third aspect of the present application, an electrode slurry is provided.

[0033] In some embodiments, the electrode slurry contains an electrode active substance and a multi-molecular substance of the polymer alkali metal salt described in the first aspect of the present application, or the electrode slurry contains an electrode active substance and the polymer alkali metal salt material described in the second aspect of the present application; the electrode slurry is a positive electrode slurry or a negative electrode slurry.

[0034] The multi-molecule polymer alkali metal salt provided in the first aspect of the present application or the polymer alkali metal salt material provided in the second aspect can be used to prepare an electrode slurry, which can be used to prepare a positive electrode slurry or a negative electrode slurry. The multi-molecule polymer alkali metal salt can be used as at least one of a binder and a dispersant, which can improve the dispersion uniformity and stability of the electrode slurry system and prevent the electrode slurry from settling for a long time. The multi-molecule polymer alkali metal salt and the polymer alkali metal salt in the polymer alkali metal salt material have a certain average molecular weight and a certain molecular weight distribution, and have a certain content of alkali metal carboxyl groups, so that they can be more evenly and stably dispersed in the electrode slurry. In the electrode active material layer prepared using the electrode slurry, the polymer alkali metal salt is evenly coated around the electrode active material and has a uniform distribution in the electrode active material layer. A good connection can be formed between the electrode active material and the current collector, providing good adhesion performance, reducing the polarization impedance between the electrodes, and helping to better improve the uniform stability of active ion conduction, and better improve the cycle performance and rate performance of the battery.

[0035] Based on any suitable embodiment of the present application, further, in some embodiments, the mass proportion of the multi-molecules of the polymer alkali metal salt in the dry weight of the electrode slurry is 0.1 wt% to 5 wt%;

[0036] Optionally, the mass proportion of the multi-molecules of the polymer alkali metal salt in the dry weight of the electrode slurry is 0.5 wt% to 2 wt%.

[0037] Based on any suitable embodiment of the present application, further, in some embodiments, the alkali metal carboxyl groups in the multi-molecules of the polymer alkali metal salt are distributed along the carbon backbone in a manner such that the electrode slurry does not settle within 24 hours at 20° C. to 30° C.; wherein the alkali metal carboxyl groups refer to -COOM;

[0038] Optionally, the alkali metallated carboxyl groups in the polymer alkali metal salt multimolecule are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 36 hours at 20° C. to 30° C.;

[0039] Further optionally, the alkali metallated carboxyl groups in the multi-molecules of the polymer alkali metal salt are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 48 hours at 20° C. to 30° C.

[0040] In a third aspect of the present application, an electrode slurry is further provided, wherein the electrode slurry contains an electrode active material and a multi-molecule substance of a polymer alkali metal salt; the electrode slurry is a positive electrode slurry or a negative electrode slurry;

[0041] The multi-molecule compound of the polymer alkali metal salt is prepared by a method comprising the following steps:

[0042] A polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution are provided respectively; wherein the polymer carboxylic acid solution is an aqueous solution containing a polymer carboxylic acid, the polymer carboxylic acid having a linear structure, the polymer carboxylic acid comprising a carbon backbone and a plurality of carboxyl groups branched along the carbon backbone; the alkali metal hydroxide aqueous solution is an aqueous solution containing an alkali metal hydroxide, wherein the alkali metal element in the alkali metal hydroxide is denoted as element M;

[0043] The polymer carboxylic acid solution is mixed with the alkali metal hydroxide aqueous solution, and an alkali metalization reaction is performed so that the hydrogen atoms of at least a portion of the multiple carboxyl groups included in the polymer carboxylic acid are replaced by the M element, thereby preparing a polymer alkali metal salt multimolecular compound containing n wt% of the M element; wherein n ≥ 3; the number average molecular weight of the polymer alkali metal salt multimolecular compound is 3 kDa to 1000 kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecular compound is 1 to 1.5.

[0044] Based on any suitable embodiment of the present application, further, in some embodiments, the ratio of the molar amount of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution to the molar amount of the carboxyl group in the polymer carboxylic acid solution is denoted as m, then 0.27≤m≤1.3;

[0045] Optionally, 0.3≤m≤1.253;

[0046] Further optionally, 0.4≤m≤1.1;

[0047] Further optionally, 0.4≤m≤1.0.

[0048] Based on any suitable embodiment of the present application, further, in some embodiments, 3.886≤n≤8.974;

[0049] Optionally, 5≤n≤7.5;

[0050] Further optionally, 5.5≤n≤7.

[0051] Based on any suitable embodiment of the present application, further, in some embodiments, 0.977≤n-5.965m≤1.583;

[0052] Optionally, 1≤n-5.965m≤1.5;

[0053] Further optionally, 1 <n-5.965m<1.5。

[0054] Based on any suitable embodiment of the present application, further, in some embodiments, the alkali metal hydroxide includes one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;

[0055] Optionally, the alkali metal hydroxide comprises lithium hydroxide;

[0056] Optionally, the alkali metal hydroxide is lithium hydroxide.

[0057] Based on any suitable embodiment of the present application, further, in some embodiments, the carbon backbone of the polymer carboxylic acid is formed by sequentially linking units represented by formula (II);

[0058] In the unit represented by formula (II) of the polymer carboxylic acid, any one R1 is independently H or C 1-3 alkyl.

[0059] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid satisfies at least one of the following characteristics:

[0060] In the polymer carboxylic acid, any R1 is independently H or methyl;

[0061] The polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid. Optionally, the polymer carboxylic acid is at least one of polyacrylic acid and polymethacrylic acid.

[0062] Based on any suitable embodiment of the present application, further, in some embodiments, the method for preparing the multi-molecule compound of the polymer alkali metal salt satisfies one or more of the following characteristics:

[0063] In the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution;

[0064] The number average molecular weight of the polymer carboxylic acid is selected from 97 kDa to 485 kDa;

[0065] The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10 wt% to 40 wt%;

[0066] The solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture, and the alcohol-water mixture is C 1-3 A mixture of alkyl alcohol and water, wherein C 1-3 The volume ratio of alkyl alcohol to water is selected from 5% to 30%;

[0067] The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5wt% to 11.5wt%;

[0068] After the alkali metalization reaction is completed, the steps of drying and dispersing the liquid phase reaction system are also included, and the dispersion is carried out by ball milling.

[0069] Based on any appropriate embodiment of the present application, further, in some embodiments, the prepared multi-molecule compound of the polymer alkali metal salt is the multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application.

[0070] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode slurry meets the following characteristics:

[0071] The alkali metal carboxyl groups in the polymer alkali metal salt multimolecule are distributed along the carbon backbone in a manner such that the electrode slurry does not settle within 24 hours at 20° C. to 30° C.; wherein the alkali metal carboxyl groups refer to -COOM;

[0072] Optionally, the alkali metallated carboxyl groups in the polymer alkali metal salt multimolecule are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 36 hours at 20° C. to 30° C.;

[0073] Further optionally, the alkali metallated carboxyl groups in the multi-molecules of the polymer alkali metal salt are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 48 hours at 20° C. to 30° C.

[0074] In a fourth aspect of the present application, an electrode plate is provided, comprising an electrode active material layer, wherein the electrode plate is a positive electrode plate or a negative electrode plate;

[0075] The electrode active material layer satisfies any one of the following characteristics:

[0076] The electrode active material layer comprises an electrode active substance and a multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application, or the electrode active material layer comprises an electrode active substance and the polymer alkali metal salt material described in the second aspect of the present application;

[0077] The electrode active material layer is a film layer made using the electrode slurry described in the third aspect of the present application.

[0078] When the aforementioned polymer alkali metal salt multi-molecule or polymer alkali metal salt material is provided in the electrode active material layer, by controlling the polymer alkali metal salt to have a relatively narrow molecular weight distribution and a certain average molecular weight, and further combining a certain alkali metal content control, the polymer alkali metal salt can be uniformly distributed around the electrode active substance in the electrode active material layer, which is beneficial to provide uniformly distributed alkali metal carboxyl groups at the molecular level and in the electrode active material layer, improving the uniform stability of active ion conduction, thereby improving the cycle performance and rate performance of the battery.

[0079] In the positive electrode sheet, the multi-molecule compound of polymer alkali metal salt or polymer alkali metal salt material can play the role of coating the positive electrode electrolyte interface film (CEI film), which can alleviate the dissolution of metal ions in the positive electrode, inhibit the decomposition of the electrolyte at high voltage, and improve the battery cycle performance.

[0080] In the negative electrode plate, the multi-molecule substance of the polymer alkali metal salt or the polymer alkali metal salt material can play the role of coating the negative electrode plate and participating in the formation of the negative electrode electrolyte interface film (SEI film), which can accelerate the conduction of active ions, reduce polarization, and be beneficial to reduce the cumulative polarization, thereby improving the rate performance of the battery.

[0081] When the electrode slurry is used to prepare the electrode active material layer, the dispersion uniformity and stability of the electrode slurry system can be improved, thereby making the polymer alkali metal salt and the alkali metal carboxyl groups contained therein uniformly distributed in the electrode active material layer, which is beneficial to better improve the uniform stability of active ion conduction and better improve the cycle performance and rate performance of the battery.

[0082] Based on any suitable embodiment of the present application, further, in some embodiments, the mass proportion of the polymer alkali metal salt multimolecule or the polymer alkali metal salt material in the electrode active material layer is 0.1 wt% to 5 wt%.

[0083] Based on any suitable embodiment of the present application, further, in some embodiments, the mass proportion of the polymer alkali metal salt multimolecule or the polymer alkali metal salt material in the electrode active material layer is 0.5 wt % to 2 wt %.

[0084] By adjusting the mass ratio of the polymeric alkali metal salt multi-molecule or polymeric alkali metal salt material in the electrode active material layer, the binder effect and active ion conductivity can be adjusted. By regulating the mass ratio of the polymeric alkali metal salt multi-molecule or polymeric alkali metal salt material in the electrode active material layer within the aforementioned range, the binder effect is effectively exerted while also improving the kinetic performance of the battery cell, helping to accelerate the conduction rate of active ions in the electrode during the charge and discharge process, and facilitating a balanced balance between the battery's cycle performance and rate capability.

[0085] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode plate satisfies one or both of the following characteristics:

[0086] Dispersing the electrode active material layer in the positive electrode sheet in a first solvent at a solid content of 40 wt% to 70 wt%, wherein the obtained positive electrode dispersion does not settle within 24 hours at 20° C. to 30° C.; wherein the first solvent comprises one or more of N-methylpyrrolidone, dimethylformamide, and ethylene glycol dimethyl ether;

[0087] The electrode active material layer in the negative electrode plate is dispersed in water according to a solid content of 40 wt% to 70 wt%, and the obtained negative electrode dispersion can be kept from settling within 24 hours at 20° C. to 30° C.

[0088] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode plate satisfies one or both of the following characteristics:

[0089] Dispersing the electrode active material layer in the positive electrode sheet in the first solvent at a solid content of 40 wt % to 70 wt %, wherein the obtained positive electrode dispersion does not settle within 36 hours at 20° C. to 30° C.

[0090] The electrode active material layer in the negative electrode plate is dispersed in water according to a solid content of 40 wt% to 70 wt%, and the obtained negative electrode dispersion can be kept at 20° C. to 30° C. without sedimentation within 36 hours.

[0091] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode plate satisfies one or both of the following characteristics:

[0092] Dispersing the electrode active material layer in the positive electrode sheet in the first solvent at a solid content of 40 wt % to 70 wt %, wherein the obtained positive electrode dispersion does not settle within 48 hours at 20° C. to 30° C.

[0093] The electrode active material layer in the negative electrode plate is dispersed in water according to a solid content of 40 wt% to 70 wt%, and the obtained negative electrode dispersion can be kept from settling within 48 hours at 20° C. to 30° C.

[0094] The electrode plate containing the multi-molecule compound or polymer alkali metal salt material of the aforementioned polymer alkali metal salt can be a positive electrode plate or a negative electrode plate. By adjusting the distribution of the alkali metal carboxyl groups along the linear main chain (such as the carbon main chain) of the polymer alkali metal salt, the system dispersion of the corresponding positive electrode slurry and the negative electrode slurry can be made more uniform and stable, and can avoid sedimentation for a long time. The components in the prepared electrode plate have good dispersion, and the polymer alkali metal salt and the alkali metal carboxyl groups contained therein have a uniform distribution in the electrode active material layer. In addition, it is also beneficial to the uniformity and stability of the active ion transmission channel in the plate, which is conducive to better utilization of the battery capacity. Accordingly, when the electrode active material layer in the electrode plate is resuspended in a solvent, the obtained dispersion also has good dispersibility and can remain stable for a long time.

[0095] In a fifth aspect of the present application, a secondary battery is provided, comprising a positive electrode sheet and a negative electrode sheet, wherein one or more of the positive electrode sheet and the negative electrode sheet is the electrode sheet described in the fourth aspect of the present application.

[0096] Based on any suitable embodiment of the present application, further, in some embodiments, the secondary battery is a lithium-ion secondary battery, and the M element in the polymer alkali metal salt molecule includes lithium.

[0097] For lithium ion secondary batteries whose active ions include lithium ions, when the multi-molecule substance of the polymer alkali metal salt or the M element of the polymer alkali metal salt material includes lithium, it can also play a role in compensating for lithium loss.

[0098] In a sixth aspect of the present application, an electrical device is provided, which includes the secondary battery described in the fifth aspect of the present application.

[0099] In a seventh aspect of the present application, a method for preparing a multimolecular compound of a polymer alkali metal salt is provided, comprising the following steps:

[0100] A polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution are provided respectively; wherein the polymer carboxylic acid solution is an aqueous solution containing a polymer carboxylic acid, the polymer carboxylic acid having a linear structure, the polymer carboxylic acid comprising a carbon backbone and a plurality of carboxyl groups branched along the carbon backbone; the alkali metal hydroxide aqueous solution is an aqueous solution containing an alkali metal hydroxide, wherein the alkali metal element in the alkali metal hydroxide is denoted as element M;

[0101] The polymer carboxylic acid solution is mixed with the alkali metal hydroxide aqueous solution, and an alkali metalization reaction is performed so that the hydrogen atoms of at least a portion of the multiple carboxyl groups included in the polymer carboxylic acid are replaced by the M element, thereby preparing a polymer alkali metal salt multimolecular compound containing n wt% of the M element; wherein n ≥ 3; the number average molecular weight of the polymer alkali metal salt multimolecular compound is 3 kDa to 1000 kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecular compound is 1 to 1.5.

[0102] Using a polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution as raw materials, by controlling the average molecular weight and polydispersity coefficient of the polymer carboxylic acid raw materials and further controlling the proportion of carboxyl groups in the polymer carboxylic acid that are alkali metalized, a multimolecular compound of a polymer alkali metal salt having a certain alkali metal content or a polymer alkali metal salt material containing the multimolecular compound can be obtained.

[0103] Based on any suitable embodiment of the present application, further, in some embodiments, the ratio of the molar amount of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution to the molar amount of the carboxyl group in the polymer carboxylic acid solution is denoted as m, then 0.27≤m≤1.3.

[0104] In some embodiments, 0.3≤m≤1.253;

[0105] Optionally, 0.4≤m≤1.1;

[0106] Further optionally, 0.4≤m≤1.0.

[0107] By controlling the ratio (m) of the molar amount of alkali metal hydroxide in the aqueous alkali metal hydroxide solution to the molar amount of carboxyl groups in the polymer carboxylic acid solution, the mass percentage (n wt%) of the M element in the polymer alkali metal salt multimolecule can be controlled within a certain range, which is beneficial to the uniform distribution of the alkali metal carboxyl groups in the polymer alkali metal salt multimolecule or polymer alkali metal salt material, and further beneficial to the uniform distribution of the alkali metal carboxyl groups in the electrode active material layer.

[0108] Based on any suitable embodiment of the present application, further, in some embodiments, 3.886≤n≤8.974;

[0109] Optionally, 5≤n≤7.5;

[0110] Further optionally, 5.5≤n≤7.

[0111] Among them, n is the same as the aforementioned F M The numerical relationship is as follows: n = 100 × F M .

[0112] Based on any suitable embodiment of the present application, further, in some embodiments, 0.977≤n-5.965m≤1.583;

[0113] Optionally, 1≤n-5.965m≤1.5;

[0114] Further optionally, 1 <n-5.965m<1.5。

[0115] The n-5.965m value range can be used to coordinately control the n value and the m value. By controlling n-5.965m within the above range, it is beneficial to balance the battery performance and cost at different alkali metal contents.

[0116] Based on any suitable embodiment of the present application, further, in some embodiments, the alkali metal hydroxide includes one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;

[0117] Optionally, the alkali metal hydroxide includes one or more of lithium hydroxide and sodium hydroxide;

[0118] Optionally, the alkali metal hydroxide is lithium hydroxide.

[0119] By selecting different kinds of alkali metal hydroxides, it is possible to prepare polymer alkali metal salts containing different alkali metalated carboxyl groups.

[0120] Based on any suitable embodiment of the present application, further, in some embodiments, the carbon backbone of the polymer carboxylic acid is formed by sequentially linking units represented by formula (II);

[0121] In the unit represented by formula (II) of the polymer carboxylic acid, any one R1 is independently H or C 1-3 alkyl.

[0122] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid satisfies at least one of the following characteristics:

[0123] In the polymer carboxylic acid, any R1 is independently H or methyl;

[0124] The polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid.

[0125] By controlling the structure of the polymer carboxylic acid, the structure of the polymer alkali metal salt multi-molecule or the polymer alkali metal salt in the polymer alkali metal salt material can be controlled. When the carbon backbone of the polymer carboxylic acid is composed of units represented by formula (II) linked sequentially, it can react to form the alkali metal structural unit represented by the aforementioned formula (I) to obtain the corresponding polymer alkali metal salt. By controlling any R1 to be independently H or methyl, or by controlling the polymer carboxylic acid to include at least one of polyacrylic acid and polymethacrylic acid, the polymer alkali metal salt can include at least one of polyacrylic acid alkali metal salt and polymethacrylic acid alkali metal salt.

[0126] Based on any suitable embodiment of the present application, further, in some embodiments, the method for preparing the multi-molecule compound of the polymer alkali metal salt satisfies one or more of the following characteristics:

[0127] In the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution;

[0128] The number average molecular weight of the polymer carboxylic acid is selected from 97 kDa to 485 kDa;

[0129] The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10 wt% to 40 wt%;

[0130] The solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture, and the alcohol-water mixture is C 1-3 A mixture of alkyl alcohol and water, wherein C 1-3 The volume ratio of alkyl alcohol to water is selected from 5% to 30%;

[0131] The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5wt% to 11.5wt%;

[0132] After the alkali metalization reaction is completed, the steps of drying and dispersing the liquid phase reaction system are also included, and the dispersion is carried out by ball milling.

[0133] By controlling the average molecular weight of the polymer carboxylic acid, the average molecular weight of the polymer alkali metal salt multimer and the polymer alkali metal salt material can be better controlled. By using a low concentration of the polymer carboxylic acid solution and / or a low concentration of the alkali metal hydroxide aqueous solution, the alkali metallated carboxyl groups are more evenly dispersed in the polymer alkali metal salt.

[0134] Based on any suitable embodiment of the present application, further, in some embodiments, the multi-molecule compound of the polymer alkali metal salt is as defined in the first aspect of the present application; that is, the multi-molecule compound of the polymer alkali metal salt prepared in the seventh aspect of the present application can be the multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application.

[0135] In the eighth aspect of the present application, there is provided the use of a multimolecular compound of a polymer alkali metal salt as described in the first aspect of the present application, or a polymer alkali metal salt material as described in the second aspect of the present application, or an electrode slurry as described in the third aspect of the present application, or an electrode plate as described in the fourth aspect of the present application, or a multimolecular compound of a polymer alkali metal salt as described in the seventh aspect of the present application in the preparation of a secondary battery, wherein the multimolecular compound of a polymer alkali metal salt is used as at least one of a binder and a dispersant in an electrode plate.

[0136] In an eighth aspect of the present application, there is further provided an application of a polymer alkali metal salt multi-molecule substance or a polymer alkali metal salt material in the preparation of a secondary battery, wherein the polymer alkali metal salt multi-molecule substance is the polymer alkali metal salt multi-molecule substance in the electrode slurry described in the second aspect of the present application, and the polymer alkali metal salt material comprises the polymer alkali metal salt multi-molecule substance; the polymer alkali metal salt multi-molecule substance is used as at least one of a binder and a dispersant in an electrode plate;

[0137] The electrode plate comprises an electrode active material layer, and the electrode plate is a positive electrode plate or a negative electrode plate;

[0138] The electrode active material layer is a film layer made using the electrode slurry described in the second aspect of the present application; wherein, the electrode active material layer is prepared by coating and drying the electrode slurry.

[0139] The details of one or more embodiments or examples of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] In order to better describe and illustrate the embodiments, examples, or examples of the applications disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered as limiting the scope of the disclosed applications, the presently described embodiments, examples, or examples, or the best mode currently understood for these applications. Furthermore, the same reference numerals are used throughout the drawings to represent the same components.

[0141] In the attached figure:

[0142] FIG1 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0143] FIG. 2 is an exploded view of the battery cell according to one embodiment of the present application shown in FIG. 1 .

[0144] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0145] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0146] FIG5 is an exploded view of the battery pack shown in FIG4 according to an embodiment of the present application.

[0147] FIG6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0148] Explanation of the accompanying figures: 1 is a battery pack; 2 is an upper box; 3 is a lower box; 4 is a battery module; 5 is a battery cell; 51 is a shell; 52 is an electrode assembly; 53 is a cover plate; 6 is an electrical device. DETAILED DESCRIPTION

[0149] Below, some embodiments and some examples of the multi-molecules of polymer alkali metal salts provided in this application and their applications in the preparation of secondary batteries (including but not limited to multi-molecules of polymer alkali metal salts, polymer alkali metal salt materials, electrode slurries, electrode pole pieces, secondary batteries, electrical devices, preparation methods and applications) are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0150] " scope " disclosed in the present application can be 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 any end value can be included or not included independently, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3,4 and 5 are also listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, 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, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to listing the parameter as, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on. For example, when a parameter is expressed as an integer selected from "2-10", this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0151] In this application, if "a plurality of", "a variety of", "several", etc. are involved, unless otherwise specified, it means that the number is greater than or equal to 2. For example, "one or more" means one or greater than or equal to (≥, greater than or equal to) two.

[0152] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0153] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of such phrases in various locations in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive with other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments. References to "implementations" herein have a similar understanding.

[0154] Those skilled in the art will appreciate that, in the methods of each embodiment or embodiment, the order in which each step is written does not mean a strict order of execution and constitutes any limitation to the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present application can be performed in sequence, or can be performed randomly, or can preferably be performed in sequence. For example, method M includes steps (a) and (b), indicating that method M may include steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For another example, method M may also include step (c), indicating that step (c) can be added to method M in any order, for example, method M may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0155] In this application, in open technical features or technical solutions described with words such as "contain," "include," and "include," unless otherwise specified, additional members other than the listed members are not excluded, and it can be regarded as providing both closed features or solutions consisting of the listed members and open features or solutions including additional members in addition to the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or not. It can be regarded as providing both the feature or solution of "A consists of a1, a2, and a3" or "A is selected from a1, a2, and a3", and the feature or solution of "A includes not only a1, a2, and a3, but also other members."

[0156] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0157] In this application, "optionally" and "optional" mean optional, that is, they refer to either option selected from the two parallel options of "with" or "without". If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" is independent. Unless otherwise specified, the descriptions "optionally include" and "optionally include" in this application, such as "optionally include", mean "may include or not include", taking "optionally include" as an example.

[0158] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more relevant listed items, and also include any and all combinations of the relevant listed items, wherein the arbitrary and all combinations include any two relevant listed items, any more relevant listed items, or a combination of all relevant listed items. For example, "A and / or B" means a group consisting of A, B, and "a combination of A and B." Among them, "including A and / or B" can mean "including A, including B, and including A and B", and can also mean "including A, including B, or including A and B", which can be appropriately understood according to the sentence in which it is located.

[0159] In this application, the term "suitable" refers to the technical solution that can implement this application.

[0160] In the present application, "preferred" and "better" are merely used to describe implementation methods or examples with better effects. It should be understood that they do not constitute limitations on the scope of protection of the present application.

[0161] In this application, “further,” “further,” “particularly,” “for example,” “such as,” “example,” etc. are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0162] In this application, the terms "first," "second," "third," "fourth," etc., in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc., are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, "first," "second," "third," "fourth," etc., are only used for non-exhaustive enumeration and description purposes and should be understood not to constitute a closed-ended limitation on quantity.

[0163] In this application, the term "room temperature" generally refers to 4°C to 35°C, and may refer to 20°C ± 5°C. In some embodiments of this application, room temperature refers to 20°C to 30°C.

[0164] In this application, when a data range is described with a unit after only the right endpoint, it means that the units of the left and right endpoints are the same. For example, "3-5h" or "3-5h" both mean that the units of the left endpoint "3" and the right endpoint "5" are both hours, and both have the same meaning as "3h-5h". Furthermore, the units of other parameters such as temperature and molecular weight are understood in the same way.

[0165] The weight or mass of the relevant components mentioned in the embodiments or examples of the present application can not only refer to the content of each component, It can also represent the proportional relationship of weight or mass between each component. Therefore, as long as the content of the relevant components in accordance with the embodiments or examples of the present application is proportionally enlarged or reduced, it is within the scope described in the present application. Further, the mass involved in the embodiments or examples of the present application can be mass units known to the chemical industry such as micrograms (μg), milligrams (mg), grams (g), kilograms (kg). Unless otherwise specified, the mass ratio is equal to the corresponding weight ratio, such as the mass of substance A is m1, and the weight is W1, the mass of substance B is m2, and the weight is W2, then the mass ratio m1 / m2 of the two is numerically equal to the corresponding weight ratio W1 / W2.

[0166] In this application, unless otherwise specified, wt% represents weight percentage by weight, which is numerically equal to the corresponding mass percentage by mass.

[0167] In this application, if there is no other explanation, the unit of parameter is ℃, which means "degrees Celsius", the unit of mass is g, which means "gram", the unit of time is h, which means "hour", min, which means "minute", and s, which means "second", the unit of length is mm, which means "millimeter", and μm, which means "micrometer", the unit of volume is mL, which means "milliliter", the unit of molecular weight is Da, which means "Dalton", and the unit of kDa means "kilodalton", the unit of viscosity is mPa·S, which means "milliPascal·second", and the unit of area is mm. 2 Indicates square millimeter, surface density unit is mg / cm 2 Indicates "milligrams per square centimeter", volume density units g / cc and g / cm 3 All mean "grams per cubic centimeter", the molar concentration unit mol / L means "mole per liter", the speed unit rpm means "revolutions per minute", the amount of substance unit mol means "mole", the voltage unit V means "volt", and the battery capacity unit Ah means "ampere-hour".

[0168] In this application, "greater than or equal to", "greater than or equal to", and "≥" have the same meaning and can be used interchangeably; "less than or equal to", "less than or equal to", and "≤" have the same meaning and can be used interchangeably; "greater than" can be equivalently expressed as ">", and "less than" can be equivalently expressed as "<". In this application, unless otherwise specified, "greater than or equal to" and "≥" can be regarded as providing two solutions of "greater than" and "equal to". In this application, unless otherwise specified, "less than or equal to" and "≤" can be regarded as providing two solutions of "less than" and "equal to".

[0169] In this application, unless otherwise specified, "about" means within a certain range above or below the number, and the fluctuation range may vary depending on the type and value of the number.

[0170] In this application, exemplary descriptions such as "in some embodiments (or examples)" and "in one embodiment (or example)" may include but are not limited to the following meanings: these solutions can be combined with other solutions in a reasonable manner to form new technical solutions.

[0171] In this application, the phrase "based on any suitable implementation in this application, further" or similar exemplary descriptions may include but not be limited to the following meanings: these solutions can be combined with each other in a reasonable manner to form new technical solutions.

[0172] In the present application, any electrode plate includes an electrode active material layer, and the electrode active material layer is disposed on at least one side of the electrode plate, that is, the electrode active material layer in the electrode plate can be disposed on one side or both sides of the electrode plate. When the electrode active material layer is disposed on both sides of the electrode plate: a current collector is usually disposed between the electrode active material layers on both sides; the composition of the electrode active material layers on both sides can be the same or different; the thickness of the electrode active material layers on both sides can also be the same or different; the number of structural layers of the electrode active material layers on both sides can be the same or different; when both sides have the same number of structural layers, the multilayer structures on both sides can be the same or different in terms of parameters such as composition and thickness.

[0173] In the present application, unless otherwise specified, the "electrode active material layer" includes at least one of the positive electrode active material layer of the positive electrode sheet and the negative electrode active material layer of the negative electrode sheet, and may refer to the positive electrode active material layer or the negative electrode active material layer, depending on the detailed circumstances. It is understood that the positive electrode active material layer contains positive electrode active substances, and the negative electrode active material layer contains negative electrode active substances. It is understood that when the electrode active material layer has a multilayer structure, in this case, the electrode active material layer includes multiple electrode active layers, and any electrode active layer independently contains the corresponding electrode active substances. In the present application, the "electrode active material layer" may also be simply referred to as the "active material layer".

[0174] In this application, unless otherwise specified, the electrode plate can be a positive electrode plate or a negative electrode plate, and the "active material" in the electrode plate refers to a substance that can reversibly embed and release active ions. Unless otherwise specified, "negative electrode active material" refers to a substance used for the negative electrode plate that can reversibly embed and release active ions; "positive electrode active material" refers to a substance used for the positive electrode plate that can reversibly release and embed active ions. When the secondary battery is charged, the active ions are released from the positive electrode and embedded in the negative electrode through the electrolyte; when the secondary battery is discharged, the active ions are released from the negative electrode and embedded in the positive electrode. The active ions are not particularly limited and can be selected from the group including lithium ions, sodium ions and potassium ions; without limitation, the active ions can be lithium ions, in which case it corresponds to a lithium-ion secondary battery.

[0175] In this application, "electrode active material", "electrode active substance", "active material" and "active substance" have the same meaning and can be used interchangeably; "positive electrode active substance" and "positive electrode active material" have the same meaning and can be used interchangeably; "negative electrode active substance" and "negative electrode active material" have the same meaning and can be used interchangeably. "Positive electrode active substance" and "positive electrode active material" have the same meaning and can be used interchangeably; "negative electrode active substance" and "negative electrode active material" have the same meaning and can be used interchangeably.

[0176] Traditionally, polyacrylic acid (PA) has been used as a binder in the negative electrode active material layer. However, the long polymer chains are prone to agglomeration, resulting in poor dispersion uniformity. While lithiating the carboxyl groups in PA may improve dispersion, it remains suboptimal.

[0177] In response to the above-mentioned common technical problems, in a first aspect, the present application provides a multi-molecule of a polymer alkali metal salt, comprising a plurality of polymer alkali metal salt molecules, wherein the polymer alkali metal salt molecules have a linear structure, the polymer alkali metal salt molecules comprising a linear main chain and a plurality of side groups Q branched along the linear main chain, any side group Q independently being a carboxyl group (-COOH) or an alkali metal carboxyl group (-COOM, M is an alkali metal element), and at least a portion of the side groups Q comprising an alkali metal carboxyl group (-COOM);

[0178] The mass percentage of the M element in the polymer alkali metal salt multimolecule is ≥3wt%; the number average molecular weight of the polymer alkali metal salt multimolecule is selected from 3kDa to 1000kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecule is selected from 1 to 1.5.

[0179] In this application, a "polymer" is referred to as a polymer having multiple repeating unit structures. The number of repeating unit structures in each polymer molecule is referred to as the "degree of polymerization," and the average number of repeating unit structures per polymer molecule in a polymer multimolecule is referred to as the "average degree of polymerization." Non-limiting examples of polymers referred to in this application include one or more of polymer alkali metal salts, polymer lithium salts, polymer carboxylic acids, polyacrylic acid, lithium polyacrylate, polymethacrylic acid, and lithium polymethacrylate.

[0180] In this application, unless otherwise specified, "polymer alkali metal salt" refers to the alkali metal compound of polymer carboxylic acid, "polymer carboxylic acid" is a polymer containing a carboxyl group (-COOH), and the polymer alkali metal salt is a polymer salt formed by alkali metallization of one or more carboxyl groups in the polymer carboxylic acid, and the carboxyl group is converted into an alkali metal carboxyl group (-COOM) after alkali metallization.

[0181] In this application, unless otherwise specified, "polymer lithium salt" refers to the lithiate of polymer carboxylic acid, which is a polymer salt formed by the lithiation of one or more carboxyl groups in the polymer carboxylic acid, and the carboxyl groups are converted into carboxyl lithium (-COOLi) after lithiation.

[0182] In the present application, unless otherwise specified, the polymer alkali metal salt molecules in the polymer alkali metal salt multimolecule have a linear main chain and multiple side groups grafted to the linear main chain, these side groups are selected from carboxyl groups and alkali metal carboxyl groups, and these side groups are selected to include at least alkali metal carboxyl groups. Therefore, the "polymer alkali metal salt" in the polymer alkali metal salt multimolecule can also be recorded as "polymer carboxylic acid alkali metal salt".

[0183] In this application, unless otherwise specified, the polymer alkali metal salt molecules in the polymer alkali metal salt multimer have suitable endcaps at each end of the linear backbone chain. The suitable endcaps are derived from the type of chain termination at the end of the polymerization reaction used to prepare the polymer chain. The term "endcap" is understood by those skilled in the art. As a non-limiting example, the "endcap" may be H.

[0184] In this application, unless otherwise specified, a "polymer alkali metal salt multimolecule" refers to a combination of multiple molecules of a polymer alkali metal salt compound, or an aggregate of multiple polymer alkali metal salt molecules. Because the molecular weight distribution of polymers has a certain degree of polydispersity, this term is referred to as a "polymer alkali metal salt multimolecule." Unless otherwise specified, a "polymer alkali metal salt multimolecule" can be a reagent or material, or a portion of a reagent or material.

[0185] In the present application, when the M element is lithium (Li) element, the polymer alkali metal salt is a polymer lithium salt, the multi-molecule substance of the polymer alkali metal salt corresponds to the multi-molecule substance of the polymer lithium salt, the polymer alkali metal salt molecule corresponds to the polymer lithium salt molecule, the polymer alkali metal salt material corresponds to the polymer lithium salt material, the alkali metal carboxyl group corresponds to the carboxyl lithium, the alkali metal salt corresponds to the lithium salt, and the alkali metal salt of the polymer carboxylic acid corresponds to the polymer lithium carboxylate or the polymer lithium carboxylate.

[0186] In this application, when describing a "polymer alkali metal salt" alone, unless otherwise specified, it can refer to a "compound molecule" or a multi-molecular aggregate of "compound molecules," which can be reasonably understood by those skilled in the art. For example, parameters such as "average molecular weight," "average degree of polymerization," "polydispersity coefficient," "molecular weight distribution," and "mean" correspond to "multi-molecules of a polymer alkali metal salt." When describing a single molecule or compound, it is usually described as "molecular weight," "degree of polymerization," or discrete numerical values.

[0187] In this application, the "molecular weight", "average molecular weight", "relative atomic mass" or "relative molecular mass" of a polymer, unless otherwise specified, refers to the molecular mass measured in Daltons (Da), where 1 Dalton is equal to 12 One-twelfth of the atomic mass of C. Unless otherwise specified, the average molecular weight of a polymer is greater than or equal to (≥) 1000 Da. 1 kDa = 1000 Da.

[0188] In this application, the "average molecular weight" of a polymer, such as a polymer alkali metal salt, a polymer lithium salt, a polymer carboxylic acid, an alkali metal salt of a polymer carboxylic acid, polyacrylic acid, lithium polyacrylate, polymethacrylic acid, lithium polymethacrylate, etc., may be any suitable type of average molecular weight, such as number average molecular weight, weight average molecular weight, etc., and the corresponding average degree of polymerization may be number average degree of polymerization, weight average degree of polymerization, etc. In this application, references to "average molecular weight" refer to number average molecular weight unless otherwise specified; references to "average degree of polymerization" refer to number average degree of polymerization unless otherwise specified.

[0189] In this application, unless otherwise specified, the polydispersity index (PDI) of a polymer refers to a polymer with a molecular weight distribution characteristic, which is numerically equal to the weight average molecular weight (M w ) and number average molecular weight (M n ), PDI=M w / M n The smaller the PDI, the narrower the molecular weight distribution and the more uniform the molecular weights of different molecules. The larger the PDI, the wider the molecular weight distribution. When PDI = 1, the molecular weight of the polymer is monodisperse, meaning that the molecular weights of all molecules in the polymer are numerically equal.

[0190] In this application, unless otherwise specified, the chemical structure characteristics of polymer alkali metal salts (such as polymer lithium salts) or polymer carboxylic acids can be characterized and analyzed using test methods including but not limited to the following: electrochemical analysis method, 1 H NMR (nuclear magnetic hydrogen spectroscopy) method, 13 C NMR (nuclear magnetic carbon spectroscopy), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, inductively coupled plasma emission spectroscopy (ICP), etc.

[0191] In this application, unless otherwise specified, the molecular weight characteristics of polymer alkali metal salts (such as polymer lithium salts) or polymer carboxylic acids, such as average molecular weight and molecular weight distribution, may be characterized and analyzed using, but not limited to, the following test methods: gel permeation chromatography (GPC), high performance liquid chromatography (HPLC), mass spectrometry, etc. Furthermore, specific values ​​involving number average molecular weight, weight average molecular weight, and PDI, unless otherwise specified, may be obtained using gel permeation chromatography (GPC) testing and analysis.

[0192] In this application, if there is no other explanation, the following method can be used to test the mass percentage of M element (alkali metal element) in the multi-molecule of polymer alkali metal salt (which can be recorded as F M Or n wt%, n is a suitable positive number, wt% means weight percentage, then n and F M The numerical relationship is as follows: n = 100 × F M )”: Take a certain mass m0 of polymer alkali metal salt sample and use inductively coupled plasma emission spectroscopy (ICP) to measure the mass m1 of M element (such as lithium element). Then, the mass percentage of M element in the multi-molecule of polymer alkali metal salt (F M ) = m1 / m0 × 100%. The sample to be tested can be prepared by the following method: weigh 0.2 g of sample in a beaker, add 10 mL of concentrated nitric acid (HNO3) solution, place on a 180°C hot plate and digest for 30 min. After the sample is digested for 30 min, cool to room temperature and transfer the digestion solution to a 50 mL volumetric flask using a funnel to make up the volume.

[0193] In this application, unless otherwise specified, the following method can be used to test and analyze the number average molecular weight (M) of the polymer alkali metal salt multi-molecule or polymer alkali metal salt material. n ), weight average molecular weight (M w ) and PDI: Gel permeation chromatography (GPC) can be used to obtain the molecular weight distribution curve of the sample to be tested based on the signal intensity of different retention times and the selection of appropriate standard samples. The weight average molecular weight (M w ), number average molecular weight (M n ) and PDI values. Without limitation, polystyrene can be used as a standard sample for the oil phase test system, and starch can be used as a standard sample for the aqueous phase test system. For example, the following model of GPC instrument can be used: Waters 2695 HPLC. When testing the average molecular weight and PDI of a polymer carboxylic acid alkali metal salt (such as polymer carboxyl lithium), an organic solvent (such as N-methylpyrrolidone (NMP)) can be used as a solvent. When testing the average molecular weight and PDI of a polymer carboxylic acid, water or NMP can be used as a solvent.

[0194] In some embodiments, the aforementioned linear main chain is a polyolefin main chain, that is, a linear chain composed of carbon atoms.

[0195] In some embodiments, a multimolecular compound of a polymer alkali metal salt is provided, comprising a plurality of polymer alkali metal salt molecules, wherein the polymer alkali metal salt molecules have a linear structure, the polymer alkali metal salt molecules comprising a carbon backbone and a plurality of side groups Q branched along the carbon backbone, any side group Q independently being -COOH or -COOM, and at least a portion of the side groups Q being -COOM, and M being an alkali metal element;

[0196] The mass percentage of the M element in the polymer alkali metal salt multimolecule is greater than or equal to 3wt%, i.e. ≥3wt%; the number average molecular weight of the polymer alkali metal salt multimolecule is selected from 3kDa to 1000kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecule is selected from 1 to 1.5.

[0197] In this application, unless otherwise specified, "carbon backbone" refers to a linear chain consisting of carbon atoms.

[0198] In this application, unless otherwise specified, “the mass percentage of the M element in the multi-molecule compound of the polymer alkali metal salt” may also be referred to as “alkali metal content” or “M element content”, and may also be understood as: the average content of the M element in one molecule of the multi-molecule compound of the polymer alkali metal salt, expressed as a mass percentage; the alkali metal content may be recorded as F M Or n wt%, n is a suitable positive number, wt% means weight percentage. When M element includes lithium, "mass percentage of lithium element in the multi-molecule of polymer alkali metal salt" can also be called "lithium content", which can be recorded as F Li .

[0199] The aforementioned polymer alkali metal salt multi-molecule is an aggregate of multiple polymer alkali metal salt molecules, wherein the polymer alkali metal salt is an alkali metal salt of a polymer carboxylic acid, and at least a portion of the carboxyl groups (-COOH) grafted on the linear carbon backbone are alkali metal salted, that is, at least a portion of the carboxyl groups are converted into alkali metal carboxyl groups (-COOM), so that the side chains of the multi-molecule are grafted with alkali metal carboxyl groups. By simultaneously controlling the average molecular weight, molecular weight distribution and alkali metal content (F) of the polymer alkali metal salt multi-molecule, the polymer alkali metal salt is obtained. M), when a polymer alkali metal salt multi-molecule compound or a polymer alkali metal salt material containing the same is used in an electrode plate of a secondary battery, and functions as at least one of a binder and a dispersant, during the electrode slurry stirring stage, the polymer alkali metal salt achieves chain segment stretching under the dispersion effect. Due to the mutual electrostatic repulsion between lithium ions, the segments carrying alkali metal carboxyl groups in the polymer alkali metal salt molecules repel each other under the electrostatic effect, becoming more dispersed. By controlling the polymer alkali metal salt to have a relatively narrow molecular weight distribution and a certain average molecular weight, and further combining it with a certain alkali metal content control, the polymer alkali metal salt can be uniformly distributed around the electrode active material in the electrode active material layer, which is beneficial for providing uniformly distributed alkali metal carboxyl groups at the molecular level and in the electrode active material layer, improving the uniformity and stability of active ion conduction, and thus improving the battery's cycle performance and rate performance.

[0200] Based on any suitable embodiment of the present application, further, in some embodiments, in any -COOM, M is independently Li, Na or K. In some of these embodiments, the M element includes lithium (Li) element. In some of these embodiments, M is Li, and accordingly, the M element is lithium element.

[0201] In some embodiments, in any -COOM, M is independently Li or Na.

[0202] When the M element is Li, Na or K, it can improve the uniform stability of active ion conduction at the molecular level and in the electrode active material layer, thereby improving the cycle performance and rate performance of the battery. In addition, when the active ions in the secondary battery include the M element, the M element in the polymer alkali metal salt can also play a role in supplementing the active ions. When the polymer alkali metal salt includes a polymer lithium salt, for a secondary battery whose active ions include lithium ions, the lithium element in the polymer lithium salt can play a role in supplementing the active ions. Similarly, when the polymer alkali metal salt includes a polymer sodium salt, for a secondary battery whose active ions include sodium ions, the sodium element in the polymer sodium salt can play a role in supplementing the active ions. When the polymer alkali metal salt includes a polymer potassium salt, for a secondary battery whose active ions include potassium ions, the potassium element in the polymer potassium salt can play a role in supplementing the active ions.

[0203] Based on any suitable embodiment of the present application, further, in some embodiments, the carbon backbone of the polymer alkali metal salt is formed by sequentially linking the units represented by formula (I);

[0204] In the units represented by formula (I) in the multi-molecule compound of the polymer alkali metal salt, any Q is independently -COOH or -COOM, and at least a portion of Q is -COOM; any R1 is independently H or alkyl, optionally, any R1 is independently H or C 1-3 In some embodiments, any R1 is independently H or methyl.

[0205] It is understood that in any unit represented by formula (I), Q is independently -COOH or -COOM.

[0206] In some embodiments, in the units of formula (I) in the multi-molecules of the polymer alkali metal salt, any Q is independently -COOH or -COOLi, and at least a portion of Q is -COOLi; any R1 is independently H or alkyl, optionally, any R1 is independently H or C 1-3 Alkyl; in some embodiments, any R1 is independently H or methyl.

[0207] In some embodiments, in the unit represented by formula (I) in the multi-molecule compound of the polymeric alkali metal salt, R1 is H.

[0208] In other embodiments, in the unit represented by formula (I) in the multi-molecule of the polymeric alkali metal salt, R1 is a methyl group. When the carbon backbone of the polymeric alkali metal salt is formed by sequentially linking the units represented by formula (I), the polymeric alkali metal salt has the general structural formula represented by formula (I-1):

[0209] Wherein, k is the degree of polymerization of the repeating unit shown in formula (I), and the “*” at both ends are independently The polymer alkali metal salt may include a polymer lithium salt, and may further include a polymer lithium salt. The k value may be determined based on the molecular weight of the polymer alkali metal salt and the type of the corresponding structural unit. Without limitation, k can be an integer selected from 100 to 7500, and further can be an integer selected from 1000 to 6000; k can also be any of the following values, or an interval consisting of any two of the following values: 120, 125, 150, 200, 300, 400, 500, 600, 800, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, 2500, 2600, 2800, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6400, 6500, 7000, 7500, etc. Non-limiting examples of k include 100-7700, 100-7600, 100-7500, 100-7000, 100-6500, 100-6400, 125-7700, 125-7600, 125-7500, 125-7000, 125-6500, 125-6400, 110-5400, 125-5400, 1000-7700, 1000-7600, 1000-7500, 1000-7000, 1000-6500, 1000-6400, etc.

[0210] In this application, unless otherwise specified, “C 1-3 The "alkyl" group is selected from C1 alkyl (ie methyl), C2 alkyl (ie ethyl) and C3 alkyl (ie propyl). The "propyl" group can be n-propyl (-CH2CH2CH3) or isopropyl (-CH(CH3)CH3).

[0211] When the carbon backbone of the polymer alkali metal salt molecule is composed of units represented by formula (I) linked sequentially, the polymer alkali metal salt may include one or both of polyacrylic acid alkali metal salts and poly(α-alkyl acrylate alkali metal salts). In this case, the side groups Q are evenly spaced on the carbon backbone, which helps to further improve the uniformity of the distribution of alkali metal carboxyl groups around the electrode active material, thereby improving the uniformity and stability of active ion conduction and the cycle performance and rate performance of the battery.

[0212] When the M element is lithium, and the carbon backbone of the polymer lithium salt molecule is formed by sequentially linking the units shown in formula (I), the polymer lithium salt may include one or both of lithium polyacrylate and poly(α-alkyl acrylate lithium), and the α-alkyl in the poly(α-alkyl acrylate lithium) may be C 1-3At this time, the side groups Q are evenly spaced on the carbon main chain, which is beneficial to further improve the uniformity of the distribution of carboxyl lithium around the electrode active material, and is beneficial to better improve the uniform stability of active ion conduction, and better improve the cycle performance and rate performance of the battery.

[0213] In some embodiments, in the polymer alkali metal salt, any R1 is independently H, methyl, ethyl or propyl, further independently H, methyl or ethyl, and further independently H or methyl. The polymer alkali metal salt here can include a polymer lithium salt, further a polymer lithium salt.

[0214] In some embodiments, in the polymeric alkali metal salt, any R1 is independently H; in this case, the polymeric alkali metal salt is a polyacrylic acid alkali metal salt. The polymeric alkali metal salt here can include lithium polyacrylate, and further can be lithium polyacrylate.

[0215] In some embodiments, in the polymeric alkali metal salt, any one R1 is independently C 1-3 The alkyl group may be independently methyl or ethyl, and further independently methyl. The polymer alkali metal salt may include a polymer lithium salt, and further may be a polymer lithium salt.

[0216] In some embodiments, in the polymer alkali metal salt, any R1 is independently methyl. The polymer alkali metal salt here is a polymethacrylate alkali metal salt, and further can be polymethacrylate lithium.

[0217] In some embodiments, the polymer alkali metal salt is a polymer lithium salt, and may further be lithium polymethacrylate.

[0218] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer alkali metal salt includes at least one of an alkali metal polyacrylate and an alkali metal polymethacrylate, and further includes at least one of lithium polyacrylate and lithium polymethacrylate. In this case, R1 in the polymer alkali metal salt includes at least one of H and methyl.

[0219] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer alkali metal salt is any one of an alkali metal polyacrylate and an alkali metal polymethacrylate. In this case, R1 in the polymer alkali metal salt is any one of H and methyl. Without limitation, the polymer alkali metal salt can be a polymer lithium salt, and further can be any one of lithium polyacrylate and lithium polymethacrylate.

[0220] When R1 in formula (I) is one or both of H and methyl, the polymer alkali metal salt may include one or both of polyacrylic acid alkali metal salt and polymethacrylic acid alkali metal salt. In this case, the main chain carbon to which the side group Q is bonded is less affected by the steric hindrance of R1, and the overall flexibility of the polymer alkali metal salt is better. In addition, the side group Q is evenly spaced on the carbon main chain. When the multi-molecule of the polymer alkali metal salt or the polymer alkali metal salt material containing it is used in the electrode active material layer, it is more conducive to improving the uniformity of the distribution of the alkali metal carboxyl group around the electrode active material, and is more conducive to improving the uniform stability of the active ion conduction, and thus is more conducive to improving the cycle performance and rate performance of the battery. When the polymer alkali metal salt includes at least one of lithium polyacrylate and lithium polymethacrylate, it can be used in a secondary battery whose active ions include lithium ions to supplement the active ions.

[0221] Based on any suitable embodiment of the present application, further, in some embodiments, the number average molecular weight of the multimolecular substance of the polymer alkali metal salt is 3kDa to 1000kDa, and can further be 100kDa to 500kDa. The number average molecular weight of the multimolecular substance of the polymer alkali metal salt can also be any of the following molecular weights or an interval consisting of any two of the following molecular weights: 3kDa, 5kDa, 10kDa, 20kDa, 40kDa, 50kDa, 60kDa, 80kDa, 100kDa, 120kDa, 140kDa, 150kDa, 160kDa, 180kDa, 200kDa, 250kDa, 300kDa, 350kDa, 400kDa, 450kDa, 500kDa, 600kDa, 700kDa, 800kDa, etc. Without limitation, the number average molecular weight of the multimolecular substance of the polymer alkali metal salt can also be selected from the following ranges: 200kDa to 500kDa, etc. The polymer alkali metal salt may include a polymer lithium salt, and further may be a polymer lithium salt.

[0222] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer alkali metal salt has formula (I) as a repeating unit, and the value of the number average degree of polymerization can refer to the aforementioned k value. Non-limitingly, the number average degree of polymerization can be a value selected from 100 to 7500, and further can be a value selected from 1000 to 6000. The number average degree of polymerization of the polymer alkali metal salt with formula (I) as repeating units can also be any of the following values, or an interval consisting of any two of the following values: 120, 125, 150, 200, 300, 400, 500, 600, 800, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, 2500, 2600, 2800, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6400, 6500, 7000, 7500, etc. Non-limiting examples of the number average degree of polymerization of the polymer lithium salt with formula (I) as a repeating unit include 100-7700, 100-7600, 100-7500, 100-7000, 100-6500, 100-6400, 125-7700, 125-7600, 125-7500, 125-7000, 125-6500, 125-6400, 110-5400, 125-5400, 1000-7700, 1000-7600, 1000-7500, 1000-7000, 1000-6500, 1000-6400, etc. The polymer alkali metal salt may include a polymer lithium salt, and may further be a polymer lithium salt.

[0223] By adjusting the average molecular weight or average degree of polymerization of the polymer alkali metal salt, the polymer alkali metal salt is more fully dispersed in the electrode active material layer of the electrode plate, and the alkali metal carboxyl groups carried by the polymer alkali metal salt are more evenly distributed around the electrode active material, which is more conducive to improving the cycle performance and rate performance of the battery.

[0224] Based on any suitable embodiment of the present application, further, in some embodiments, the mass percentage of the M element in the multi-molecule of the polymer alkali metal salt (F M or n wt%) is greater than or equal to 3%, and accordingly, n≥3. It can be understood that F M or n wt% with 100% of all carboxyl groups in the corresponding polymer carboxylic acid being alkali metalized as the upper limit. MIt can also be any of the following percentages, or be selected from the interval consisting of any two of the following percentages: 3%, 3.2%, 3.4%, 3.5%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.5%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.5%, 5.6%, 5.8%, 6%, 6.2%, 6.4%, 6.5%, 6.6%, 6.8%, 7%, 7.2%, 7.25%, 7.29%, 7.3%, 7.4%, 7.5%, 7.6%, 7.8%, 8%, 8.1%, 8.14%, 8.15%, 8.2%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 8.974%, etc., and the above percentages correspond to wt%. F M Non-limiting examples include any of the following ranges (which may include or exclude the two endpoint values): 3wt% to 8.974wt%, 4.67wt% to 7.5wt%, 4.67wt% to 7wt%, 4.67wt% to 6.86wt%, 4.67wt% to 6.8wt%, 5wt% to 7.5wt%, 5.5wt% to 7wt%, 5wt% to 7wt%, 5wt% to 6.86wt%, 5wt% to 6.8wt%, 6wt% to 8.974wt%, 6wt% to 8.9wt%, 6wt% to 8.8wt%, 6wt% to 8.5wt%, 6wt% to 8.15wt%, 6wt% to 7.3wt%, etc., and the corresponding percentage unit is wt%. Correspondingly, n can also be any of the following values, or an interval selected from any two of the following values: 3, 3.2, 3.4, 3.5, 3.6, 3.8, 3.88, 3.886, 3.89, 4, 4.2, 4.4, 4.5, 4.6, 4.67, 4.7, 4.8, 5, 5.2, 5.4, 5.5, 5.6, 5.8, 6, 6.2, 6.4, 6.5, 6.6, 6.8, 6.85, 6.86, 7, 7.2, 7.4, 7.5, 7.6, 7.8, 8, 8.2, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 8.974, etc. Non-limiting examples of n include any of the following ranges (which may include or exclude both endpoints): 3-8.974, 4.67-7.5, 4.67-7, 4.67-6.86, 4.67-6.8, 5-7.5 (e.g., 5≤n≤7.5), 5.5-7 (e.g., 5.5≤n≤7), 5-7, 5-6.86, 5-6.8, 3.886-8.974, 6-8.974, 6-8.9, 6-8.8, 6-8.5, etc. In some embodiments, the mass percentage of the M element in the multi-molecule of the polymer alkali metal salt is greater than or equal to 5 wt%. M The definition of the value of F can also be applied to Li(mass percentage of lithium element in the polymer alkali metal salt multi-molecule); when the polymer alkali metal salt is a polymer lithium salt, F M The corresponding mass percentage of lithium element in the polymer lithium salt multi-molecule.

[0225] By adjusting the mass percentage of M element in the polymer alkali metal salt multi-molecule (F M or n wt%) within the aforementioned range, more carboxyl groups of the carbon backbone side groups can be converted into alkali metal carboxyl groups, which is beneficial for the alkali metal carboxyl groups to disperse the molecular chains better at the slurry level through electrostatic repulsion, which is more beneficial to the cycle performance of the battery. On the other hand, it is beneficial to better improve the active ion conduction and more beneficial to improve the battery rate performance. When the M element includes lithium, the mass percentage of lithium in the multi-molecule of the polymer alkali metal salt (F Li ) to better optimize battery cycle performance and rate performance.

[0226] Based on any suitable embodiment of the present application, further, in some embodiments, the polydispersity index (PDI) of the polymer alkali metal salt is selected from 1 to 1.5. The polydispersity index of the polymer alkali metal salt can also be any of the following values, or an interval consisting of any two of the following values: 1, 1.05, 1.06, 1.08, 1.1, 1.12, 1.14, 1.15, 1.16, 1.18, 1.2, 1.24, 1.25, 1.26, 1.28, 1.3, 1.32, 1.34, 1.35, 1.36, 1.38, 1.4, 1.42, 1.44, 1.45, 1.46, 1.48, 1.5, etc. The polymer alkali metal salt can include a polymer lithium salt, and can further be a polymer lithium salt.

[0227] By adjusting the polydispersity coefficient of the polymer alkali metal salt or polymer lithium salt, the molecular weight uniformity of the polymer alkali metal salt can be adjusted, which is beneficial for improving the uniformity of the dispersion of the alkali metal carboxyl groups in the polymer alkali metal salt in the electrode plate, and further beneficial for improving the cycle performance and rate performance of the battery. The polymer alkali metal salt can be a polymer lithium salt.

[0228] Based on any suitable embodiment of the present application, further, in some embodiments, the multi-molecule compound of the polymer alkali metal salt (which may include a multi-molecule compound of a polymer lithium salt, and further may be a multi-molecule compound of a polymer lithium salt) satisfies one or more of the following characteristics (any numerical parameter in the following characteristics may also be selected from any suitable numerical value or range in the context):

[0229] The number average molecular weight of the polymeric alkali metal salt is selected from 100 kDa to 500 kDa, and can also be selected from the values ​​or ranges in any suitable embodiment of the present application;

[0230] The M element includes lithium, and the mass percentage of lithium in the multi-molecule polymer alkali metal salt is selected from 5wt% to 7.5wt%, optionally 5.5wt% to 7wt%, and can also be selected from the values ​​or ranges in any suitable embodiment of the present application;

[0231] The polydispersity coefficient of the polymeric alkali metal salt is selected from 1 to 1.3, and can also be selected from the values ​​or ranges in any appropriate embodiment of the present application.

[0232] By adjusting the average molecular weight, molecular weight distribution and the mass percentage of the "M element in the polymer alkali metal salt multi-molecule (F M When one or more parameters in "(1%)" are within the aforementioned range, it is beneficial to a more uniform distribution of the alkali metal carboxyl groups in the electrode plate, which is more beneficial to improving the uniform stability of active ion conduction, and further more beneficial to improving the cycle performance and rate performance of the battery.

[0233] The percentage of -COOM relative to the side group Q in the multi-molecule of the polymer alkali metal salt can be recorded as S0, which also represents the average percentage of -COOM relative to all Q in one molecule of the polymer alkali metal salt in the multi-molecule; the average number of alkali metal atoms carried in one molecule of the polymer alkali metal salt can be recorded as N0.

[0234] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer alkali metal salt is a polymer lithium salt, and the polymer lithium salt satisfies one or two of the following characteristics:

[0235] S0 is selected from 31.6% to 100%;

[0236] N0 is selected from 12.8 to 4250.

[0237] In the present application, the "percentage of -COOM relative to the side group Q in the polymer alkali metal salt multimolecule" is recorded as S0. This parameter reflects the average ratio of hydrogen atoms in the carboxyl groups on the main chain of the polymer alkali metal salt to be replaced by alkali metal atoms, which can indirectly regulate the alkali metal content in the polymer alkali metal salt multimolecule.

[0238] In this application, the S0 value can be calculated based on the mass percentage of the M element in the polymer alkali metal salt multimolecule (F M or n wt%).

[0239] Taking the polymer alkali metal salt as polymer lithium salt as an example, at this time, F M Numerically equal to F Li , S0 can be converted using the following formula:

[0240] S0=(M n ×n% / M Li ) / (M P ×n% / M Li +(M P -M P ×n% / M Li ×M Q ) / M C )×100%

[0241] =(1×n% / M Li ) / (1×n% / M Li +(1-1×n% / M Li ×M Q ) / M C )×100%; where n% is the mass percentage of F M , M P is the number average molecular weight of the polymer lithium salt, M Li is the relative atomic mass of lithium atoms, which is the mass of lithium atoms and 12 The ratio of one twelfth of the mass of a carbon atom; M Q is the relative molecular mass of the repeating unit of the polymer lithium salt in the form of carboxyl lithium, M C It is the relative molecular mass when the repeating unit of the polymer lithium salt is in the form of carboxyl group.

[0242] In the multi-molecule of lithium polyacrylate, n is 3 (F Li 3wt%) as an example, taking M Li =7,M Q =78,M C =72 into the calculation, we can get S0=31.67%.

[0243] In the multi-molecule of lithium polyacrylate, n is 6 (F Li 6wt%) as an example, taking M Li =7,M Q =78,M C =72 into the calculation, we can get S0=65.06%.

[0244] Based on the above formula, the n value can also be converted according to S0. n% = S0 × M Li / (S0×M Q +(1-S0)×M C )×100%.

[0245] Based on any appropriate embodiment of the present application, further, in some embodiments, S0 can be 31.6% to 100%. S0 can also be any of the following percentages, or an interval consisting of any two of the following percentages: 31.6%, 32%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 65.06%, 70%, 75%, 77%, 77.5%, 77.7%, 80%, 85%, 90%, 95%, 100%, etc. S0 can also be selected from any of the following ranges: 50% to 75%, 50% to 70%, 55% to 75%, 60% to 75%, 65% to 100%, 65% to 90%, 65% to 80%, 77% to 100%, 77% to 90%, 77% to 80%, etc. In some embodiments, the polymer alkali metal salt includes a polymer lithium salt, and further can be a polymer lithium salt.

[0246] In this application, the "average number of M atoms carried in a molecule of the polymer alkali metal salt" is denoted as N0. This parameter can reflect the number of alkali-metallated carboxyl groups carried on a polymer chain. By regulating N0 in conjunction with the average molecular weight of the polymer alkali metal salt, the alkali metal content in the polymer alkali metal salt multimolecule can also be indirectly adjusted.

[0247] In this application, N0 refers to the number average molecular weight (M P ) and the mass percentage of M element in the polymer alkali metal salt multi-molecule (F M or n wt%).

[0248] Taking the polymer alkali metal salt as polymer lithium salt as an example, in this case, N0 can be converted using the following formula:

[0249] N0=M P ×n% / M Li ; Where n% is the mass percentage of F M , M P is the number average molecular weight of the polymer lithium salt, M Li is the relative atomic mass of lithium atoms, which is the mass of lithium atoms and 12 The ratio of the mass of carbon atoms to one-twelfth of the mass of carbon atoms. The number average molecular weight of the multi-molecule of lithium polyacrylate is 30kDa, and n is 3 (F Li =3wt%), we can get N0≈1286. Assuming the number average molecular weight of the multi-molecule of lithium polyacrylate is 50kDa, n is 3 (F Li (3wt%) into the calculation, we can get N0≈2142.

[0250] Based on any appropriate embodiment of the present application, further, in some embodiments, N0 can also be any of the following values, or an interval consisting of any two of the following values: 20, 25, 30, 35, 40, 45, 50, 55, 60, 64, 65, 70, 80, 90, 95, 100, 120, 125, 150, 200, 300, 400, 500, 600, 800, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, 2500, 2600, 2800, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6400, 6500, etc. N0 can also be selected from any of the following ranges (which may include or exclude both endpoints): 20-5700, 20-5000, 20-4900, 20-4840, 20-4800, 20-4000, 20-3800, 20-3200, 50-5700, 50-5000, 50-4900, 50-4840, 50-4800, 50-4000, 50-3800, 50-3200, 50-3000, 50-2700, 60-5700, 60-5000, 60-4900, 60-6400 0-4840, 60-4800, 60-4000, 60-3800, 60-3200, 60-3000, 80-5700, 80-5000, 80-4900, 80-4840, 80-4800, 80-4000, 80-3800, 80-3200, 80-2700, 95-5700, 95-5000, 95-4900, 95-4840, 95-4800, 95-4000, 95-3800, 95-3200, 100-4000, 100-5000, etc. In some embodiments, the polymer alkali metal salt includes a polymer lithium salt, and can further be a polymer lithium salt.

[0251] By regulating one or both of SO and NO within the above range, it is beneficial to further improve the uniformity of the distribution of alkali metal carboxyl groups in the electrode active material layer, which is beneficial to better improve the uniform stability of active ion conduction and better improve the cycle performance and rate performance of the battery. The alkali metal carboxyl group can include lithium carboxyl, and can further be lithium carboxyl.

[0252] In a second aspect of the present application, a polymer alkali metal salt material is provided, which comprises multiple molecules of the polymer alkali metal salt described in the first aspect of the present application.

[0253] The polymer alkali metal salt material may contain multiple molecules of the polymer alkali metal salt described in the first aspect of the present application and inevitable impurities.

[0254] In this application, unless otherwise specified, "unavoidable impurities" come from impurities passively introduced during the material preparation process, residues of preparation raw materials, reaction by-products, etc. Among them, passively introduced impurities do not come from actively input raw materials, residues of preparation raw materials refer to residual raw materials remaining in the product after the preparation process is completed, and reaction by-products refer to reaction by-products remaining in the product after the preparation process is completed.

[0255] The polymer alkali metal salt material may be composed of multiple molecules of the polymer alkali metal salt and inevitable impurities. In addition, it may also contain intentionally added additives, such as additives used to improve the storage stability of the material.

[0256] In this application, unless otherwise specified, the "purity of the polymeric alkali metal salt material" refers to the mass percentage of the polymeric alkali metal salt compound in the polymeric alkali metal salt material. Generally, the purity of the polymeric alkali metal salt material can be ≥90%, or ≥95%, or greater than or equal to (≥) any of the following percentages: 96%, 97%, 98%, 99%, 99.5%, 99.6%, 99.8%, 99.9%, etc.

[0257] The multi-molecules of the polymer alkali metal salt described in the first aspect of the present application and the polymer alkali metal salt material described in the second aspect of the present application can be prepared using the preparation method provided in the seventh aspect of the present application.

[0258] In some embodiments, the polymer alkali metal salt material may be a polymer lithium salt material.

[0259] In some embodiments, a polymer lithium salt material is provided, comprising a polymer lithium salt multi-molecule compound described in the first aspect of the present application. The polymer lithium salt material may comprise the polymer lithium salt multi-molecule compound described in the first aspect of the present application and unavoidable impurities. The polymer lithium salt material may be composed of the polymer lithium salt multi-molecule compound and unavoidable impurities, and may further comprise intentionally added additives, such as additives used to improve the storage stability of the material.

[0260] In a third aspect of the present application, an electrode slurry is provided.

[0261] In some embodiments, an electrode slurry is provided, which contains an electrode active substance and a multi-molecular substance of the polymer alkali metal salt described in the first aspect of the present application, or the electrode slurry contains an electrode active substance and the polymer alkali metal salt material described in the second aspect of the present application; the electrode slurry is a positive electrode slurry or a negative electrode slurry.

[0262] The multi-molecule polymer alkali metal salt provided in the first aspect of the present application or the polymer alkali metal salt material provided in the second aspect of the present application can be used to prepare an electrode slurry, which can be used to prepare a positive electrode slurry or a negative electrode slurry. The multi-molecule polymer alkali metal salt can be used as at least one of a binder and a dispersant, which can improve the dispersion uniformity and stability of the electrode slurry system and prevent the electrode slurry from settling for a long time. The multi-molecule polymer alkali metal salt and the polymer alkali metal salt in the polymer alkali metal salt material have a certain average molecular weight and a certain molecular weight distribution, and have a certain content of alkali metal carboxyl groups, so that they can be more uniformly and stably dispersed in the electrode slurry. In the electrode active material layer prepared using the electrode slurry, the polymer alkali metal salt is uniformly coated around the electrode active material and has a uniform distribution in the electrode active material layer. A good connection can be formed between the electrode active material and the current collector, providing good adhesion performance, reducing the polarization impedance between the electrodes, and helping to better improve the uniform stability of active ion conduction, and better improve the cycle performance and rate performance of the battery.

[0263] Based on any suitable embodiment of the present application, further, in some embodiments, in the electrode slurry, the mass percentage of the M element (e.g., lithium) in the multi-molecule polymer alkali metal salt can refer to the definition in the first aspect of the present application. Taking lithium as an example, non-limiting examples include 3 wt% to 8.974 wt%, 5 wt% to 7.5 wt%, 5.5 wt% to 7 wt%, etc.

[0264] In the positive electrode slurry used to prepare the positive electrode plate, when the mass percentage of lithium element in the multi-molecule polymer alkali metal salt or the polymer alkali metal salt material is within the above range, it is more conducive to forming a coating layer on the surface of the positive electrode plate, inhibiting the dissolution and migration of metal ions, stabilizing the lattice structure of the positive electrode material, and improving the cycle performance of the battery.

[0265] In the negative electrode slurry used to prepare the negative electrode plate, when the mass percentage of lithium element in the multi-molecule compound of polymer alkali metal salt or polymer alkali metal salt material is within the above range, it is more conducive to the uniform dispersion of the negative electrode active material in the negative electrode plate, reducing the polarization impedance between the negative electrode active material and the negative electrode active material and between the negative electrode active material and the negative electrode current collector, and improving the battery charging rate performance.

[0266] In any suitable embodiment of the polymer alkali metal salt involved in the third aspect of the present application, the polymer alkali metal salt may include a polymer lithium salt, and may further be a polymer lithium salt; accordingly, the multi-molecule substance of the polymer alkali metal salt may include a polymer lithium salt, and may further be a multi-molecule substance of the polymer lithium salt; the polymer alkali metal salt material may include a polymer lithium salt, and may further be a polymer lithium salt material.

[0267] In some embodiments, in any suitable embodiment of the polymer alkali metal salt in the third aspect of the present application, the polymer alkali metal salt exists in the form of multiple molecules of the polymer alkali metal salt.

[0268] Without limitation, the mass proportion of the polymer alkali metal salt or the polymer alkali metal salt's multi-molecules in the dry weight of the electrode slurry can be 0.1% to 5%, or any of the following percentages, or an interval consisting of any two of the following percentages: 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.25%, 1.4%, 1.5%, 1.6%, 1.75%, 1.8%, 2%, 2.25%, 2.5%, 2.75%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5%, etc. Without limitation, the mass proportion of the polymer alkali metal salt in the dry weight of the electrode slurry can also be selected from any of the following ranges: 0.1% to 5%, 0.2% to 5%, 0.5% to 5%, 1% to 5%, 0.1% to 2%, 0.2% to 2%, 0.5% to 2%, 0.1% to 1.5%, 0.2% to 1.5%, 0.5% to 1.5%, 0.1% to 1%, 0.2% to 1%, 0.5% to 1%, 1% to 2%, etc. The above percentages correspond to wt%. The electrode slurry can be a positive electrode slurry or a negative electrode slurry.

[0269] In this application, unless otherwise specified, the reference to “dry weight of electrode slurry” refers to the weight corresponding to the substance that can be present in the electrode active material layer formed after drying. Generally, after the electrode slurry is coated on the surface of a substrate (such as a current collector), it is dried, the volatile components (solvent) are removed, and the non-volatile components including the multi-molecules of the polymer alkali metal salt form a film on the surface of the substrate, thereby forming an electrode active material layer containing electrode active substances. Therefore, the numerical range of “the mass proportion of the multi-molecules of the polymer alkali metal salt in the electrode active material layer of the electrode pole piece” can refer to the “mass proportion of the multi-molecules of the polymer alkali metal salt in the dry weight of the electrode slurry”.

[0270] Without limitation, the mass proportion of the polymer alkali metal salt or the polymer alkali metal salt multi-molecules in the electrode slurry may be 0.1 wt % to 5 wt %, and may be optionally 0.1 wt % to 2 wt %.

[0271] The polymer alkali metal salt provided in this application may be used alone as a binder in the electrode slurry.

[0272] Non - restrictively, the electrode paste may not include or may further include a second binder. The mass percentage of the second binder in the dry weight of the electrode paste may be 0 to 3 wt%, further may be 0 to 1.5 wt%, and still further may be 0 to 1 wt%. The second binder may be selected from common binders applicable to electrode pastes in the art.

[0273] The electrode paste includes a solvent, which may be an aqueous solvent (such as water) or an organic solvent. The solvent in the positive electrode paste may be an organic solvent. Non - restrictively, the solvent in the positive electrode paste may be one or more of N - methylpyrrolidone (NMP), dimethylformamide (DMF), ethylene glycol dimethyl ether (EGDME), etc. Non - restrictively, the solvent in the negative electrode paste may be water.

[0274] In some embodiments, the distribution of the alkali - metal carboxyl groups in the multimolecular substance of the polymeric alkali metal salt along the linear main chain (such as a carbon main chain) enables the electrode paste not to settle within 24 hours at 20°C to 30°C. This electrode paste may be a positive electrode paste or a negative electrode paste, and the corresponding solvent can be referred to in the context. The distribution of the alkali - metal carboxyl groups in the polymeric alkali metal salt along the linear main chain (such as a carbon main chain) can be achieved by adjusting the feeding parameters of the reaction raw materials. For example, it can be achieved by controlling the value of m (such as 0.27 ≤ m ≤ 1.3), and further controlling 0.3 ≤ m ≤ 1.253 is beneficial to further improving the stability of the electrode paste; further, by controlling n - 5.965m within a certain range (such as 0.977 ≤ n - 5.965m ≤ 1.583, or 1 < n - 5.965m < 1.5, etc.), a distribution mode of the alkali - metal carboxyl groups along the linear main chain (such as a carbon main chain) that is more beneficial to improving the stability of the electrode paste can be obtained, which can not settle within 36 hours at 20°C to 30°C, and can also not settle within 48 hours. In some of these embodiments, the polymeric alkali metal salt may include a polymeric lithium salt, and further may be a polymeric lithium salt.

[0275] [ In some embodiments, the distribution of the alkali - metal carboxyl groups in the multimolecular substance of the polymeric alkali metal salt along the carbon main chain enables the electrode paste not to settle within 36 hours at 20°C to 30°C.

[0276] In some embodiments, the distribution of the alkali - metal carboxyl groups in the multimolecular substance of the polymeric alkali metal salt along the carbon main chain enables the electrode paste not to settle within 48 hours at 20°C to 30°C.

[0277] Non - restrictively, the electrode paste optionally includes a conductive agent, that is, it may include or may not include a conductive agent. A suitable conductive agent can be selected according to the needs of the positive electrode paste or the negative electrode paste.

[0278] In some embodiments, the electrode slurry is a positive electrode slurry, which includes a positive electrode active material and multiple molecules of the polymer alkali metal salt described in the first aspect of the present application.

[0279] In some embodiments, the electrode slurry is a positive electrode slurry, which includes a positive electrode active material and the polymer alkali metal salt material described in the second aspect of the present application.

[0280] Without limitation, the positive electrode slurry may include a second binder. Further, the second binder in the positive electrode slurry may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin. Without limitation, the mass proportion of the second binder in the dry weight of the positive electrode slurry may be 0-3wt%, further 0-1.5wt%, and further 0-1wt%.

[0281] In some embodiments, the positive electrode active material includes a lithium ion active material. In a non-limiting manner, the lithium ion active material may account for 100 wt % of the positive electrode active material.

[0282] In a non-limiting manner, the mass proportion of the polymer alkali metal salt or the polymer alkali metal salt multi-molecules in the dry weight of the positive electrode slurry can be 0.1 wt % to 5 wt %, and reference can also be made to the above definition.

[0283] In a non-limiting manner, the mass proportion of the polymer alkali metal salt or the polymer alkali metal salt multi-molecules in the positive electrode slurry may be 0.1 wt % to 2 wt %.

[0284] Without limitation, the positive electrode active material may be a positive electrode active material for batteries known in the art.

[0285] Taking the positive electrode active material that can provide active lithium ions as an example, as a non-limiting example, the positive electrode active material may include one or more of the following materials or substances: lithium transition metal oxides with an olivine structure and their respective modified compounds. However, the present application is not limited to these materials or substances, and other traditional materials or substances that can be used as battery positive electrode active materials may also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, non-limiting examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and their modified compounds. Non-limiting examples of lithium phosphates containing olivine structures may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include 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 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.80 Co 0.15 Al 0.05 O2. An example of lithium iron phosphate is LiFePO4 (also referred to as LFP). An example of lithium manganese phosphate is LiMnPO4.

[0286] In some embodiments, the positive electrode active material includes the following active material (the mass percentage of the following active material in the positive electrode active material can be 80 wt% to 100 wt%, further can be 90 wt% to 100 wt%, still further can be 100 wt%, but not limited thereto): The chemical formula is Li x (Ni a Co b M c M’ d )O 2-e (This is a nickel-containing lithium oxide), where 0.6 ≤ x ≤ 1.2, 0 < a < 1, 0 < b < 1, 0 < c < 1, 0 < d < 1, a + b + c + d = 1, -0.1 ≤ e ≤ 0.1, M can include at least one of Mn and Al, and M’ can include one or more of Na, K, Ca, Ba, Sb, Ti, Zr, W, Sr, Nb, Mo, Si, Mg, B, Cr, and Ta; further optionally, a ≥ 0.8; still further optionally, 0.8 ≤ a < 1; still further optionally, 0.9 ≤ a < 1. a can also be any of the following values, or greater than or equal to any of the following values and less than 1, or selected from the intervals formed by any two of the following values: 0.8, 0.83, 0.85, 0.86, 0.88, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, etc. Non-limitingly, x can also be any of the following values, or greater than or equal to any of the following values and less than 1, or selected from the intervals formed by any two of the following values: 0.6, 0.64, 0.65, 0.67, 2 / 3, 0.7, 0.75, 0.8, 0.83, 0.84, 0.85, 0.86, 0.88, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 1, 1.05, 1.1, 1.15, 1.2, etc. <000073@1>

[0287] For a secondary battery whose active ions include lithium ions, the above limitation on x includes the molar content of lithium (Li) under different charge and discharge states of the battery (usually the battery voltage is between 2V and 5V).

[0288] It is understandable that lithium-ion secondary batteries are accompanied by the deintercalation and consumption of lithium (Li) during the charge and discharge process, and the content of lithium (Li) in the positive electrode plate is different when the battery is discharged to different states. In the exemplary description of the positive active material in this application, unless otherwise specified, the Li content can be the initial state of the material or the non-initial state after the charge and discharge cycle. The positive active material is applied to the positive electrode plate in the battery system. After the charge and discharge cycle, the Li content in the positive active material contained in the positive electrode plate usually changes. Among them, the Li content can be measured using the atomic molar content, but is not limited to this. Regarding "the Li content is the initial state of the material", the initial state of the material refers to the state before the material is added to the positive electrode slurry. It is understandable that new materials or new substances obtained by appropriate modification on the basis of the listed positive active materials are also within the scope of positive active materials. The aforementioned appropriate modification refers to an acceptable modification method for the positive active material, and a non-limiting example is coating modification.

[0289] In the exemplary descriptions of the positive electrode active material in this application, the oxygen (O) content is only a theoretical value. Lattice oxygen release will cause the atomic molar content of oxygen to change, and the actual O content will fluctuate. The O content can be measured by atomic molar content, but is not limited to this.

[0290] In some embodiments, the positive electrode active material includes the following active material (the mass percentage of the following active material in the positive electrode active material may be 80 wt% to 100 wt%, further may be 90 wt% to 100 wt%, and further may be 100 wt%, but is not limited thereto): nickel-containing lithium oxide, wherein the total atomic number of non-lithium and non-oxygen elements is 1, and the atomic number of nickel is denoted as n. In some embodiments, n ≥ 0.5; alternatively, n ≥ 0.8; further alternatively, 0.8 ≤ n < 1; further alternatively, 0.9 ≤ n < 1. n can also be any of the following values, or greater than or equal to any of the following values ​​and less than 1, or selected from an interval consisting of any two of the following values: 0.5, 0.6, 0.7, 0.75, 0.8, 0.83, 0.833, 0.85, 0.86, 0.88, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, etc. n can also be expressed as a percentage, for example, 80%, 90%, 95%, etc.

[0291] In some embodiments, the positive electrode active material may include one or more of a lithium-containing phosphate, a lithium transition metal oxide, and modified forms of any of the foregoing, wherein the modified forms include one or more of doping modification and coating modification. Both the doping modification and the coating modification may adopt or refer to existing modification methods in the art, including but not limited to the selection of element type and doping amount.

[0292] In some embodiments, the positive electrode active material may include lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium nickel phosphate, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt manganese aluminum oxide, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, and one or more modified forms of any of the foregoing substances, wherein the modified form includes one or more of doping modification and coating modification.

[0293] In some embodiments, the positive electrode slurry optionally includes a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. Without limitation, the conductive agent may comprise 0 to 10 wt %, further 0 to 5 wt %, and even further 0 to 3 wt % of the dry weight of the positive electrode slurry.

[0294] In some embodiments, the solid content of the positive electrode slurry may be 40 wt % to 70 wt %. The viscosity of the positive electrode slurry at room temperature may be adjusted to 5000 mPa·s to 25000 mPa·s.

[0295] In some embodiments, the positive electrode sheet can be prepared by dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent to form a positive electrode slurry.

[0296] In some embodiments, the positive electrode slurry can be kept from settling at 20°C to 30°C for 24 hours, further can be kept from settling at 20°C to 30°C for 36 hours, and further can be kept from settling at 20°C to 30°C for 48 hours. Optionally, the solvent in the positive electrode slurry includes one or more of N-methylpyrrolidone, dimethylformamide, and ethylene glycol dimethyl ether; further optionally, the solvent in the positive electrode slurry is N-methylpyrrolidone, dimethylformamide, or ethylene glycol dimethyl ether; further optionally, the solvent in the positive electrode slurry is N-methylpyrrolidone.

[0297] In some embodiments, the electrode slurry is a negative electrode slurry, which includes a negative electrode active material and multiple molecules of the polymer alkali metal salt described in the first aspect of the present application.

[0298] In some embodiments, the electrode slurry is a negative electrode slurry, which includes a negative electrode active material and the polymer alkali metal salt material described in the second aspect of the present application.

[0299] Without limitation, the negative electrode slurry may include a second binder. Furthermore, the second binder in the negative electrode slurry may include one or more of styrene-butadiene rubber (SBR), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). Without limitation, the mass proportion of the second binder in the dry weight of the negative electrode slurry may be 0-3 wt%, further 0-1.5 wt%, and even further 0-1 wt%.

[0300] In a non-limiting manner, the mass proportion of the polymer alkali metal salt or the polymer alkali metal salt multi-molecules in the dry weight of the negative electrode slurry can be 0.1 wt % to 5 wt %, and reference can also be made to the above definition.

[0301] In a non-limiting manner, the mass proportion of the polymer alkali metal salt or the polymer alkali metal salt multi-molecules in the negative electrode slurry may be 0.1 wt % to 2 wt %.

[0302] Without limitation, the negative electrode active material can adopt the negative electrode active material for batteries known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following substances or materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds and tin alloys. However, the present application is not limited to these substances or materials, and other traditional materials or substances 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.

[0303] In some embodiments, the negative electrode active material includes one or more of a carbon-based material, a silicon-based material, a tin-based material, and lithium titanate, as well as modified forms of any of the foregoing materials, wherein the modified form includes one or more of a doping modification and a coating modification. Both the doping modification method and the coating modification method can adopt or refer to existing modification methods in the art, including but not limited to the selection of element types and doping amounts. Carbon-based materials may include but are not limited to one or more of graphite materials, soft carbon, hard carbon, etc. Graphite materials may include one or more of artificial graphite and natural graphite.

[0304] In some embodiments, the negative electrode active material may include one or more of the following substances or materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like.

[0305] In some embodiments, the negative electrode active material includes a carbon-based material. Without limitation, the mass percentage of the carbon-based material in the negative electrode active material can be ≥80wt%, optionally ≥90wt%, further optionally ≥95wt%, further optionally ≥96wt%, etc., further optionally 100wt%, etc. The mass percentage of the carbon-based material in the negative electrode active material can also be any of the following percentages, or greater than or equal to any of the following percentages and less than or equal to 100%, or selected from the interval consisting of any two of the following percentages: 80%, 82%, 83%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 98%, etc. The above percentages correspond to wt%. The definition of carbon-based materials can be found above. For example, the carbon-based material can be a graphite material.

[0306] In some embodiments, the negative electrode slurry optionally includes a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The mass percentage of the conductive agent in the dry weight of the negative electrode slurry may independently be 0 to 10 wt%, further 0 to 5 wt%, further 0 to 3 wt%, and further optionally 0.5 to 3 wt%.

[0307] In some embodiments, the negative electrode slurry may optionally include other additives, such as a thickener (eg, sodium carboxymethylcellulose (CMC-Na)).

[0308] In some embodiments, the solid content of the negative electrode slurry may be 40 wt % to 70 wt %. The viscosity of the negative electrode slurry at room temperature may be adjusted to 2000 mPa·s to 15000 mPa·s.

[0309] In some embodiments, the negative electrode sheet can be prepared by dispersing the above components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry.

[0310] In some embodiments, the negative electrode slurry can be kept from settling at 20° C. to 30° C. for 24 hours, further kept from settling at 20° C. to 30° C. for 36 hours, and further kept from settling at 20° C. to 30° C. for 48 hours. Optionally, the solvent in the negative electrode slurry includes water, and further optionally, the solvent in the negative electrode slurry is water.

[0311] In a third aspect of the present application, an electrode slurry is further provided, wherein the electrode slurry contains an electrode active material and a multi-molecule substance of a polymer alkali metal salt; the electrode slurry is a positive electrode slurry or a negative electrode slurry;

[0312] The multi-molecule substance of the polymer alkali metal salt can be prepared by the preparation method described in the seventh aspect of the present application.

[0313] In some embodiments, the multi-molecule compound of the polymeric alkali metal salt can be prepared by a method comprising the following steps:

[0314] A polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution are provided respectively; wherein the polymer carboxylic acid solution is an aqueous solution containing polymer carboxylic acid, the polymer carboxylic acid has a linear structure, and the polymer carboxylic acid includes a carbon backbone and a plurality of carboxyl groups branched along the carbon backbone; the alkali metal hydroxide aqueous solution is an aqueous solution containing alkali metal hydroxide, and the alkali metal element in the alkali metal hydroxide is denoted as M element;

[0315] A polymer carboxylic acid solution is mixed with an alkali metal hydroxide aqueous solution, and an alkali metalization reaction is performed to replace the hydrogen atoms of at least a portion of the multiple carboxyl groups included in the polymer carboxylic acid with an M element, thereby preparing a polymer alkali metal salt multimolecular compound containing n wt% of the M element; wherein n is greater than or equal to 3; the number average molecular weight of the polymer alkali metal salt multimolecular compound is 3 kDa to 1000 kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecular compound is 1 to 1.5.

[0316] Based on any suitable embodiment of the present application, further, in some embodiments, the ratio of the molar amount of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution to the molar amount of the carboxyl group in the polymer carboxylic acid solution is denoted as m, then 0.27≤m≤1.3;

[0317] Optionally, 0.3≤m≤1.253;

[0318] Further optionally, 0.4≤m≤1.1;

[0319] Further optionally, 0.4≤m≤1.0.

[0320] The value of the aforementioned m can also be found in the seventh aspect of this application.

[0321] Based on any suitable embodiment of the present application, further, in some embodiments, 3.886≤n≤8.974;

[0322] Optionally, 5≤n≤7.5;

[0323] Further optionally, 5.5≤n≤7.

[0324] The value of the aforementioned n can also be found in the first aspect of this application.

[0325] Based on any suitable embodiment of the present application, further, in some embodiments, 0.977≤n-5.965m≤1.583;

[0326] Optionally, 1≤n-5.965m≤1.5;

[0327] Further optionally, 1 <n-5.965m<1.5。

[0328] The value of the aforementioned n-5.965m can also be found in the seventh aspect of this application.

[0329] Based on any suitable embodiment of the present application, further, in some embodiments, the alkali metal hydroxide includes one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide;

[0330] Optionally, the alkali metal hydroxide comprises lithium hydroxide;

[0331] Optionally, the alkali metal hydroxide is lithium hydroxide.

[0332] Based on any suitable embodiment of the present application, further, in some embodiments, the carbon backbone of the polymer carboxylic acid is formed by sequentially linking the units represented by formula (II);

[0333] In the unit represented by formula (II) of the polymer carboxylic acid, any one R1 is independently H or C 1-3 alkyl.

[0334] The definition of R1 can also be found in the seventh aspect of this application.

[0335] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid satisfies at least one of the following characteristics:

[0336] In the polymer carboxylic acid, any R1 is independently H or methyl;

[0337] The polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid. Optionally, the polymer carboxylic acid is at least one of polyacrylic acid and polymethacrylic acid.

[0338] Based on any suitable embodiment of the present application, further, in some embodiments, the method for preparing a multimolecular compound of a polymer alkali metal salt satisfies one or more of the following characteristics (see also the seventh aspect of the present application):

[0339] In the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution;

[0340] The number average molecular weight of the polymer carboxylic acid is selected from 97 kDa to 485 kDa;

[0341] The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10 wt% to 40 wt%;

[0342] The solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture, and the alcohol-water mixture is C 1-3 Alkyl alcohol and water mixture, C in alcohol-water mixture 1-3 The volume ratio of alkyl alcohol to water is selected from 5% to 30%;

[0343] The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5wt% to 11.5wt%;

[0344] After the alkali metalization reaction is completed, the process further includes drying and dispersing the liquid phase reaction system, wherein the dispersion is carried out by ball milling.

[0345] Based on any appropriate embodiment of the present application, further, in some embodiments, the prepared multi-molecule compound of the polymer alkali metal salt is the multi-molecule compound of the polymer alkali metal salt of the first aspect of the present application.

[0346] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode slurry meets the following characteristics:

[0347] The alkali metal carboxyl groups in the polymer alkali metal salt multimolecule are distributed along the carbon backbone in a manner such that the electrode slurry does not settle within 24 hours at 20° C. to 30° C.; wherein the alkali metal carboxyl groups refer to -COOM;

[0348] Optionally, the alkali metallated carboxyl groups in the polymeric alkali metal salt multimolecule are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 36 hours at 20° C. to 30° C.;

[0349] Further optionally, the alkali metallated carboxyl groups in the polymer alkali metal salt multimolecules are distributed along the carbon backbone in a manner such that the electrode slurry does not settle within 48 hours at 20° C. to 30° C.

[0350] In a fourth aspect of the present application, an electrode plate is provided, comprising an electrode active material layer, wherein the electrode plate is a positive electrode plate or a negative electrode plate;

[0351] The electrode active material layer satisfies any one of the following characteristics:

[0352] The electrode active material layer comprises an electrode active substance and a multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application, or the electrode active material layer comprises an electrode active substance and the polymer alkali metal salt material described in the second aspect of the present application;

[0353] The electrode active material layer is a film layer made using the electrode slurry described in the third aspect of the present application.

[0354] In any suitable embodiment of the polymer alkali metal salt involved in the fourth aspect of the present application, the polymer alkali metal salt may include a polymer lithium salt, and may further be a polymer lithium salt; accordingly, the multi-molecule substance of the polymer alkali metal salt may include a polymer lithium salt, and may further be a multi-molecule substance of the polymer lithium salt; the polymer alkali metal salt material may include a polymer lithium salt, and may further be a polymer lithium salt material.

[0355] The electrode active material layer can be made from raw materials including the electrode slurry described in the third aspect of the present application. The aforementioned electrode slurry alone can be used, and other suitable substances (such as other additives) can also be introduced.

[0356] In some embodiments, the electrode active material layer can be prepared by coating and drying the electrode slurry described in the third aspect of the present application.

[0357] In some embodiments, when the electrode sheet is a positive electrode sheet, the electrode active material layer is a positive electrode active material layer, and the positive electrode active material layer satisfies any one of the following characteristics:

[0358] The positive electrode active material layer includes a positive electrode active material and a multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application, or the positive electrode active material layer includes a positive electrode active material and the polymer alkali metal salt material described in the second aspect of the present application;

[0359] The positive electrode active material layer is a film layer made using the positive electrode slurry described in the third aspect of the present application.

[0360] The positive electrode active material layer may be made using raw materials including the positive electrode slurry described in the third aspect of the present application.

[0361] In some embodiments, the positive electrode active material layer can be prepared by coating and drying the positive electrode slurry described in the third aspect of the present application.

[0362] The definitions of positive electrode active material and positive electrode slurry can refer to the definitions above and below.

[0363] In some embodiments, when the electrode plate is a negative electrode plate, the electrode active material layer is a negative electrode active material layer, and the negative electrode active material layer satisfies any one of the following characteristics:

[0364] The negative electrode active material layer includes a negative electrode active material and a multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application, or the negative electrode active material layer includes a negative electrode active material and the polymer alkali metal salt material described in the second aspect of the present application;

[0365] The negative electrode active material layer is a film layer made using the negative electrode slurry described in the third aspect of the present application.

[0366] The negative electrode active material layer may be made using raw materials including the negative electrode slurry described in the third aspect of the present application.

[0367] In some embodiments, the negative electrode active material layer may be prepared by coating and drying the negative electrode slurry described in the third aspect of the present application.

[0368] The definitions of negative electrode active material and negative electrode slurry can refer to the definitions above and below.

[0369] When the aforementioned polymer alkali metal salt multi-molecule or polymer alkali metal salt material is provided in the electrode active material layer, by controlling the polymer alkali metal salt to have a relatively narrow molecular weight distribution and a certain average molecular weight, and further combining a certain alkali metal content control, the polymer alkali metal salt can be uniformly distributed around the electrode active substance in the electrode active material layer, which is beneficial to provide uniformly distributed alkali metal carboxyl groups at the molecular level and in the electrode active material layer, improving the uniform stability of active ion conduction, thereby improving the cycle performance and rate performance of the battery.

[0370] In the positive electrode sheet, the multi-molecule compound of polymer alkali metal salt or polymer alkali metal salt material can play the role of coating the positive electrode electrolyte interface film (CEI film), which can alleviate the dissolution of metal ions in the positive electrode, inhibit the decomposition of the electrolyte at high voltage, and improve the battery cycle performance.

[0371] In the negative electrode plate, the multi-molecule substance of the polymer alkali metal salt or the polymer alkali metal salt material can play the role of coating the negative electrode plate and participating in the formation of the negative electrode electrolyte interface film (SEI film), which can accelerate the conduction of active ions, reduce polarization, and be beneficial to reduce the cumulative polarization, thereby improving the rate performance of the battery.

[0372] When the electrode slurry is used to prepare the electrode active material layer, the dispersion uniformity and stability of the electrode slurry system can be improved, thereby making the polymer alkali metal salt and the alkali metal carboxyl groups contained therein uniformly distributed in the electrode active material layer, which is beneficial to better improve the uniform stability of active ion conduction and better improve the cycle performance and rate performance of the battery.

[0373] Based on any suitable embodiment of the present application, further, in some embodiments, the mass proportion of the polymer alkali metal salt multimolecule or polymer alkali metal salt material in the electrode active material layer can be 0.1% to 5%, or can be any of the following percentages, or an interval consisting of any two of the following percentages: 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.25%, 1.4%, 1.5%, 1.6%, 1.75%, 1.8%, 2%, 2.25%, 2.5%, 2.75%, 2.8%, 3%, 3.5%, 4%, 4.5%, 5%, etc. Without limitation, the mass percentage of the polymeric alkali metal salt multi-molecule or polymeric alkali metal salt material in the electrode active material layer can also be selected from any of the following ranges: 0.1% to 5%, 0.2% to 5%, 0.5% to 5%, 1% to 5%, 0.1% to 2%, 0.2% to 2%, 0.5% to 2%, 1% to 2%, etc. The above percentages correspond to wt%. The electrode active material layer can be a positive electrode active material layer or a negative electrode active material layer.

[0374] Based on any suitable embodiment of the present application, further, in some embodiments, the mass proportion of the polymer alkali metal salt multimolecule or polymer alkali metal salt material in the electrode active material layer is 0.1 wt% to 5 wt%, optionally 0.5 wt% to 2 wt%.

[0375] By adjusting the mass ratio of the polymeric alkali metal salt multi-molecule or polymeric alkali metal salt material in the electrode active material layer, the binder effect and active ion conductivity can be adjusted. By regulating the mass ratio of the polymeric alkali metal salt multi-molecule or polymeric alkali metal salt material in the electrode active material layer within the aforementioned range, the binder effect is effectively exerted while also improving the kinetic performance of the battery cell, helping to accelerate the conduction rate of active ions in the electrode during the charge and discharge process, and facilitating a balanced balance between the battery's cycle performance and rate capability.

[0376] The structural and component analysis of the "electrode pole piece" provided in the fourth aspect of the present application can be tested and analyzed by focused electron beam (FIB) technology, scanning electron microscope (SEM) and elemental analysis technology, for example, it can be obtained by combining continuous sectioning of frozen focused electron beam (FIB), cross-section SEM morphology observation, energy dispersive spectroscopy (EDS) element spectrum and three-dimensional reconstruction analysis software analysis. For example, a frozen focused ion beam (FIB) is used to finely slice the sample layer by layer in the transverse direction at different thickness positions (the minimum scale can reach nanometer-level thin slices), and separate different layers of samples at different thickness positions. The morphology, structure and element distribution of each layer of the cross section can also be analyzed by scanning electron microscope (SEM) under FIB continuous sectioning. The three-dimensional structure of the sample can be reconstructed by combining with three-dimensional structure reconstruction software, and the mass and / or volume of different areas of the sample to be tested can be estimated. By disassembling the battery, samples of the electrode active material layer of the electrode plate can be obtained. The electrode active material layer can then be analyzed using the following method: Utilizing the nanometer spatial dynamic resolution and layer-by-layer cutting technology of FIB-SEM, the three-dimensional structure of the sample can be reconstructed. EDS elemental spectroscopy analysis can then be used to determine the distribution and proportion of each element. Finally, software-based quantitative analysis can be used to determine parameters such as the composition and thickness of each structural layer of the electrode active material layer. As a non-limiting example, the aforementioned parameters can be tested and analyzed using a FEI Scios 2HiVac instrument.

[0377] In this application, unless otherwise specified, "transverse" refers to a direction perpendicular to the thickness direction of the electrode sheet. When the thickness of each position of the electrode sheet is uniform, the transverse direction is parallel to the surface of the electrode sheet.

[0378] The following is some description about the positive electrode.

[0379] Without limitation, the positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material. The definition of the positive electrode active material can be found in the above text.

[0380] In a non-limiting manner, the mass percentage of the positive electrode active material in the positive electrode active material layer may be ≥80 wt %, and further may be ≥90 wt %.

[0381] As a non-limiting example, the positive electrode current collector has two surfaces facing away from each other in its thickness direction, and the positive electrode active material layer is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0382] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. In the positive electrode current collector, the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. In the positive electrode current collector, the composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, the metal material may include but is not limited to at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, the polymer material substrate may include but is not limited to one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0383] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent to form a positive electrode slurry. Further, the positive electrode slurry is coated on at least one side of the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained. Cold pressing can be performed using a cold rolling mill. The type of solvent in the positive electrode slurry can include but is not limited to any of the aforementioned embodiments, for example, it can include N-methylpyrrolidone (NMP), and further can be NMP. The surface of the positive electrode current collector coated with the positive electrode slurry can be on a single surface of the positive electrode current collector or on both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40wt% to 70wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000mPa·s to 25000mPa·s. When applying the positive electrode slurry, the coating unit surface density based on dry weight (excluding solvent) can be 15mg / cm 2 ~35mg / cm 2 The compaction density of the positive electrode can be 2.0g / cm 3 ~3.6g / cm 3 , optional 2.3g / cm 3 ~3.5g / cm 3 .

[0384] The following is some description about the negative electrode.

[0385] Without limitation, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material. The definition of the negative electrode active material can be found in the above text.

[0386] In a non-limiting manner, the mass percentage of the negative electrode active material in the negative electrode active material layer may be ≥80 wt %, and further may be ≥90 wt %.

[0387] 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. In the negative electrode current collector, the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. In the negative electrode current collector, the composite current collector may be formed by forming a metal material on a polymer material substrate. In the negative electrode current collector, the metal material may include but is not limited to at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, the polymer material substrate may include but is not limited to one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0388] In some embodiments, the negative electrode sheet can be prepared in the following manner: 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 (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry. Further, the negative electrode slurry is coated on at least one side of the surface of the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode collector coated with the negative electrode slurry can be on a single surface of the negative electrode collector or on both surfaces of the negative electrode collector. The solid content of the negative electrode slurry can be 40wt% to 70wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s to 15000mPa·s. When coating the negative electrode slurry, the coating unit surface density on a dry weight basis (excluding the solvent) can be 75g / m 2 ~220g / m 2 The compaction density of the negative electrode can be 1.2g / cm 3 ~1.8g / cm 3 .

[0389] In a fifth aspect of the present application, a secondary battery is provided, comprising a positive electrode sheet and a negative electrode sheet, wherein one or more of the positive electrode sheet and the negative electrode sheet is the electrode sheet described in the fourth aspect of the present application.

[0390] Based on any appropriate embodiment of the present application, further, in some embodiments, the secondary battery is a lithium-ion secondary battery.

[0391] For lithium-ion secondary batteries whose active ions include lithium ions, the multi-molecule substance of the aforementioned polymer alkali metal salt or the polymer alkali metal salt material can also play a role in compensating for lithium loss.

[0392] In some embodiments, the secondary battery satisfies either or both of the following characteristics:

[0393] The positive electrode sheet is the positive electrode sheet described in the fourth aspect of this application;

[0394] The negative electrode plate is the negative electrode plate described in the fourth aspect of this application.

[0395] Based on any appropriate embodiment of the present application, further, in some embodiments, the positive electrode sheet in the secondary battery is the positive electrode sheet described in the fourth aspect of the present application.

[0396] Based on any appropriate embodiment of the present application, further, in some embodiments, the negative electrode plate in the secondary battery is the negative electrode plate described in the fourth aspect of the present application.

[0397] In some embodiments, the alkali metallated carboxyl groups in the polymer alkali metal salt multimolecules are distributed along the linear main chain (such as the carbon main chain) in such a manner that the resuspended slurry of the electrode active material layer in the electrode plate does not settle within 24 hours at 20°C to 30°C.

[0398] The distribution of the alkali metallized carboxyl groups along the linear main chain (such as the carbon main chain) is relatively uniform, and the uniformity of the distribution can be characterized by the stability of the resuspended slurry of the electrode active material layer in the electrode plate. Since the distribution of the alkali metallized carboxyl groups along the linear main chain (such as the carbon main chain) is relatively uniform, the resuspended slurry of the electrode active material layer in the electrode plate has good stability and can avoid sedimentation for a long time. Non-limiting examples of the resuspended slurry include the following positive electrode dispersion or negative electrode dispersion.

[0399] The prepared electrode sheets can be resuspended in a suitable solvent to form a slurry with an appropriate solid content and viscosity. The sedimentation performance of the resuspended slurry can then be tested. The time it takes for sedimentation to occur can be observed; the later the sedimentation occurs, the better the slurry stability. Typically, sedimentation can be determined by the appearance of sediment at the bottom of the container.

[0400] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode active material layer in the positive electrode plate is dispersed in a first solvent according to a solid content of 40 wt% to 70 wt%, and the obtained positive electrode dispersion (a resuspended slurry) can not settle within 24 hours at 20°C to 30°C; optionally, the first solvent includes one or more of N-methylpyrrolidone, dimethylformamide and ethylene glycol dimethyl ether; further optionally, the first solvent is N-methylpyrrolidone, dimethylformamide or ethylene glycol dimethyl ether; further optionally, the first solvent is N-methylpyrrolidone.

[0401] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode active material layer in the positive electrode plate is dispersed in a first solvent according to a solid content of 40 wt% to 70 wt%, and the obtained positive electrode dispersion (a resuspended slurry) can not settle within 36 hours at 20°C to 30°C; optionally, the first solvent includes one or more of N-methylpyrrolidone, dimethylformamide and ethylene glycol dimethyl ether; further optionally, the first solvent is N-methylpyrrolidone, dimethylformamide or ethylene glycol dimethyl ether; further optionally, the first solvent is N-methylpyrrolidone.

[0402] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode active material layer in the positive electrode plate is dispersed in a first solvent according to a solid content of 40 wt% to 70 wt%, and the obtained positive electrode dispersion (a resuspended slurry) can not settle within 48 hours at 20°C to 30°C; optionally, the first solvent includes one or more of N-methylpyrrolidone, dimethylformamide and ethylene glycol dimethyl ether; further optionally, the first solvent is N-methylpyrrolidone, dimethylformamide or ethylene glycol dimethyl ether; further optionally, the first solvent is N-methylpyrrolidone.

[0403] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode active material layer in the negative electrode sheet is dispersed in a second solvent at a solid content of 40 wt% to 70 wt%, and the resulting negative electrode dispersion (a resuspended slurry) is capable of not settling within 24 hours at 20°C to 30°C. Optionally, the second solvent includes water; further optionally, the second solvent is water.

[0404] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode active material layer in the negative electrode sheet is dispersed in a second solvent at a solid content of 40 wt% to 70 wt%, and the resulting negative electrode dispersion (a resuspended slurry) is capable of not settling within 36 hours at 20°C to 30°C. Optionally, the second solvent includes water; further optionally, the second solvent is water.

[0405] Based on any suitable embodiment of the present application, further, in some embodiments, the electrode active material layer in the negative electrode sheet is dispersed in a second solvent at a solid content of 40 wt% to 70 wt%, and the resulting negative electrode dispersion (a resuspended slurry) is capable of not settling within 48 hours at 20°C to 30°C. Optionally, the second solvent includes water; further optionally, the second solvent is water.

[0406] The electrode plate containing the multi-molecule compound or polymer alkali metal salt material of the aforementioned polymer alkali metal salt can be a positive electrode plate or a negative electrode plate. By adjusting the distribution of the alkali metal carboxyl groups along the linear main chain (such as the carbon main chain) of the polymer alkali metal salt, the system dispersion of the corresponding positive electrode slurry and the negative electrode slurry can be made uniform and stable, and can avoid sedimentation for a long time. The components in the prepared electrode plate have good dispersion, and the polymer alkali metal salt and the alkali metal carboxyl groups contained therein have a uniform distribution in the electrode active material layer. In addition, it is also beneficial to the uniformity and stability of the active ion transmission channel in the electrode plate, which is conducive to better utilization of the battery capacity. Accordingly, when the electrode active material layer in the electrode plate is resuspended in a solvent, the obtained dispersion also has good dispersibility and can remain stable for a long time.

[0407] Typically, a secondary battery 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.

[0408] The electrolyte is exemplarily described below.

[0409] The electrolyte conducts ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0410] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0411] In some embodiments, the electrolyte is a non-aqueous electrolyte. The non-aqueous electrolyte may include an electrolyte salt and a solvent.

[0412] The concentration of the electrolyte salt in the electrolyte solution may generally be 0.5 mol / L to 5 mol / L.

[0413] In some embodiments, the secondary battery is a lithium ion secondary battery, and the electrolyte salt may include an electrolyte lithium salt.

[0414] In some embodiments, the electrolyte lithium salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0415] In some embodiments, the solvent in the non-aqueous electrolyte may include fluoroethylene carbonate (FEC), ethylene carbonate (EC, ), propylene carbonate (PC, ), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC, ), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0416] In some embodiments, the electrolyte may optionally 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.

[0417] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethylethylene carbonate (TFPC), and the like.

[0418] The separator is exemplarily described below.

[0419] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0420] In some embodiments, the material of the separator can include one or more 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.

[0421] In some embodiments, the thickness of the isolation film is 3 μm to 40 μm, and optionally 5 μm to 20 μm.

[0422] 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.

[0423] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0424] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery can also be a soft shell, such as a pouch-type soft shell. The material of the soft shell can be plastic. Further, non-limiting examples of plastic can include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0425] A secondary battery includes at least one battery cell. A secondary battery may include one or more battery cells.

[0426] In this application, unless otherwise specified, a "battery cell" refers to a basic unit that can achieve the mutual conversion of chemical energy and electrical energy. Further, generally speaking, it includes at least a positive electrode plate, a negative electrode plate, and an electrolyte. During the battery's charge and discharge process, active ions are embedded in and out of the positive and negative electrode plates. The electrolyte plays the role of conducting active ions between the positive and negative electrode plates.

[0427] The present application has no particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 5 with a square structure as an example.

[0428] In some embodiments, referring to Figure 2, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.

[0429] The secondary battery may be a battery module 4 or a battery pack 1 .

[0430] A battery module includes at least one battery cell. The number of battery cells contained in a battery module can be one or more, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module.

[0431] FIG3 shows an example battery module 4. Referring to FIG3 , within the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0432] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0433] In some embodiments, the battery modules may be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select an appropriate number based on the application and capacity of the battery pack.

[0434] Figures 4 and 5 illustrate an example battery pack 1. Referring to Figures 4 and 5 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0435] In a sixth aspect of the present application, an electrical device is provided, which includes the secondary battery described in the fifth aspect of the present application.

[0436] In some embodiments, the present application further provides an electrical device, which includes a secondary battery of any embodiment provided in the present application. The secondary 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, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto. Among them, mobile devices may be, for example, mobile phones, laptops, etc.; electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, electric motorcycles, electric tools, etc., but are not limited thereto. The electrical device can also be used in military equipment, aerospace and other fields, and can also be used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations.

[0437] As an electrical device, a secondary battery can be selected according to its usage requirements.

[0438] Figure 6 shows an example of an electric device 6. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module may be used.

[0439] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0440] In the seventh aspect of the present application, a method for preparing a multimolecular compound of a polymer alkali metal salt or a polymer alkali metal salt material is provided, which can be used to prepare the multimolecular compound of the polymer alkali metal salt described in the first aspect of the present application or the polymer alkali metal salt material described in the second aspect of the present application.

[0441] In any suitable embodiment of the polymer alkali metal salt involved in the seventh aspect of the present application, the polymer alkali metal salt may include a polymer lithium salt, and may further be a polymer lithium salt; accordingly, the alkali metal hydroxide may include lithium hydroxide, and may further be lithium hydroxide; the multi-molecule compound of the polymer alkali metal salt may include a polymer lithium salt, and may further be a multi-molecule compound of the polymer lithium salt; the polymer alkali metal salt material may include a polymer lithium salt, and may further be a polymer lithium salt material.

[0442] In some embodiments, a method for preparing a multimolecular compound of a polymer alkali metal salt is provided, comprising the steps of mixing a polymer carboxylic acid solution with an aqueous alkali metal hydroxide solution, performing an alkali metalization reaction, and preparing a multimolecular compound of a polymer alkali metal salt.

[0443] In some embodiments, a method for preparing a polymer alkali metal salt material is provided, comprising the steps of mixing a polymer carboxylic acid solution with an alkali metal hydroxide aqueous solution, and performing an alkali metalization reaction to prepare a polymer alkali metal salt material.

[0444] In some embodiments, a method for preparing a polymer alkali metal salt material is provided, comprising the following steps:

[0445] A polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution are provided respectively; wherein the polymer carboxylic acid solution is an aqueous solution containing polymer carboxylic acid, the polymer carboxylic acid has a linear structure, and the polymer carboxylic acid includes a carbon backbone and a plurality of carboxyl groups branched along the carbon backbone; the alkali metal hydroxide aqueous solution is an aqueous solution containing alkali metal hydroxide, and the alkali metal element in the alkali metal hydroxide corresponds to the aforementioned M element;

[0446] A polymer carboxylic acid solution is mixed with an alkali metal hydroxide aqueous solution, and an alkali metalization reaction is performed to replace the hydrogen atoms of at least a portion of the multiple carboxyl groups included in the polymer carboxylic acid with an M element, thereby preparing a polymer alkali metal salt multimolecular compound containing n wt% of the M element; wherein n is greater than or equal to 3, the number average molecular weight of the polymer alkali metal salt multimolecular compound is 3 kDa to 1000 kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecular compound is 1 to 1.5.

[0447] In this application, unless otherwise specified, "polymer carboxylic acid" refers to a polymer containing a carboxyl group (-COOH). The polymer carboxylic acid involved in the seventh aspect of the present application has a linear structure. Without limitation, the polymer carboxylic acid may include a carbon backbone and a plurality of carboxyl groups (-COOH) grafted along the carbon backbone.

[0448] In the present application, unless otherwise specified, "alkali metalization reaction" refers to the salt-forming reaction between the polymer carboxylic acid in the polymer carboxylic acid solution and the alkali metal hydroxide in the alkali metal hydroxide aqueous solution, so that at least a portion of the carboxyl groups in the polymer carboxylic acid are converted into alkali metal carboxyl groups (-COOM), thereby converting at least a portion of the polymer carboxylic acid molecules into polymer alkali metal salt molecules. Without limitation, the temperature for carrying out the alkali metalization reaction can be 20°C to 50°C, and the time for carrying out the alkali metalization reaction can be 1h to 3h. As a non-limiting example, when the alkali metal hydroxide is lithium hydroxide, the alkali metalization reaction corresponds to a lithiation reaction. It should be noted that the ratio of carboxyl groups to alkali metal carboxyl groups is mainly controlled by the raw material feed ratio, and the control of the alkali metalization reaction time is mainly to fully mix the reaction raw materials. As long as the reaction raw materials can be fully mixed, the alkali metalization reaction time does not need to be limited to the above-mentioned exemplary 1h to 3h.

[0449] In this application, the "ratio of the molar amount of alkali metal hydroxide in the aqueous alkali metal hydroxide solution to the molar amount of carboxyl groups in the polymer carboxylic acid solution" is recorded as the m value, which reflects the feed molar ratio of the alkali metal hydroxide and the carboxyl groups in the polymer carboxylic acid and can be used to adjust the degree of alkali metalization of the carboxyl groups in the polymer carboxylic acid. Therefore, the feed ratio parameter m can be used to accurately control the n value. The higher the m value, the higher the degree of alkali metalization. However, it is understood that the degree of alkali metalization is limited to 100%. Without limitation, m can be selected from 0.27 to 1.3 (e.g., 0.27 ≤ m ≤ 1.3). m can also be any of the following values, or can be selected from an interval consisting of any two of the following values: 0.27, 0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.839, 0.84, 0.85, 0.9, 1.0, 1.1, 1.2, 1.25, 1.253, 1.255, 1.3, etc. m may also be selected from any of the following ranges (which may or may not include both endpoints): 0.27 to 1, 0.3 to 1, 0.3 to 1.253 (e.g., 0.3 ≤ m ≤ 1.253), 0.839 to 1.253, 0.4 to 1.1 (e.g., 0.4 ≤ m ≤ 1.1), 0.4 to 1.0 (e.g., 0.4 ≤ m ≤ 1.0), etc. As a non-limiting example, when the alkali metal is lithium, the degree of alkali metalization corresponds to the degree of lithiation.

[0450] The definition of "the mass percentage of the element M in the polymer alkali metal salt multimolecule (which may be expressed as n wt%)" is consistent with the above. The value of n may also refer to the above text. For example, the value of n may also refer to the description of the first aspect of this application.

[0451] The mass percentage of the M element in the polymeric alkali metal salt material can be expressed as n'wt%. Numerically, n'≤n. In some embodiments, n' can be calculated by multiplying the value of n by the purity of the polymeric alkali metal salt material.

[0452] In some embodiments, a method for preparing a polymer alkali metal salt multimolecule or a polymer alkali metal salt material comprises the following steps: mixing a polymer carboxylic acid solution with an alkali metal hydroxide aqueous solution, performing an alkali metalization reaction, drying, and optionally dispersing to prepare a polymer alkali metal salt multimolecule or a polymer alkali metal salt material.

[0453] In some embodiments, the method for preparing a polymer alkali metal salt material may further include a step of post-treating the reaction system after the alkali metalization reaction. Post-treatment methods may include, but are not limited to, one or more of the following: concentration, solid-liquid separation, drying, purification, and dispersion. Concentration can remove some of the solvent, thereby increasing the concentration of the polymer alkali metal salt in the system; solid-liquid separation can remove most of the solvent; drying can produce a solid product; purification can control the impurity content; and dispersion of the dried product can reduce the agglomeration of solid particles in the product.

[0454] The reaction system after the alkali metalization reaction is a liquid phase system. This liquid phase system has a certain viscosity and can therefore also be called a glue. This glue can be directly used as a polymer alkali metal salt material. When a multi-molecule substance of a polymer alkali metal salt is used as at least one of a binder and a dispersant, it can be used directly in the form of a glue or a concentrated glue, or it can be dried and optionally dispersed and then used in the form of solid particles. Accordingly, the polymer alkali metal salt material can be in the form of a glue or a concentrated glue, or it can be solid particles (such as a solid powder).

[0455] Without limitation, the solid particles may be in powder form. The dried glue may also be dispersed to reduce agglomeration between particles.

[0456] Without limitation, when the polymer alkali metal salt multi-molecule substance or polymer alkali metal salt material is used to prepare the positive electrode slurry, it can be added in the form of solid particles.

[0457] Without limitation, when a polymeric alkali metal salt multi-molecule or polymeric alkali metal salt material is used to prepare the negative electrode slurry, it can be added in the form of a colloid or a concentrated colloid, or in the form of solid particles. The solid particles can be obtained by drying the colloid and optionally dispersing it.

[0458] Without limitation, the dispersion can be performed by ball milling. Furthermore, the ball milling can be dry ball milling. For the dispersion method, please refer to the relevant definition in the context.

[0459] Without limitation, the prepared polymer alkali metal salt multi-molecule compound or polymer alkali metal salt material can be a glue.

[0460] Without limitation, the prepared polymer alkali metal salt multi-molecule compound or polymer alkali metal salt material may also be in powder form after drying.

[0461] Using a polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution as raw materials, by controlling the average molecular weight and polydispersity coefficient of the polymer carboxylic acid raw materials and further controlling the proportion of carboxyl groups in the polymer carboxylic acid that are alkali metalized, a multimolecular compound of a polymer alkali metal salt having a certain alkali metal content or a polymer alkali metal salt material containing the multimolecular compound can be obtained.

[0462] In some embodiments, a method for preparing a polymer alkali metal salt multi-molecule compound or a polymer alkali metal salt material is provided, comprising the following steps: mixing a polymer carboxylic acid solution with an alkali metal hydroxide aqueous solution, performing an alkali metalization reaction so that the hydrogen atoms of at least a portion of the carboxyl groups included in the polymer carboxylic acid are replaced by an M element, thereby preparing a polymer alkali metal salt multi-molecule compound containing n wt % of the M element or a polymer alkali metal salt material containing n wt % of the M element;

[0463] Wherein, n≥3, in the polymer carboxylic acid solution, the number average molecular weight of the polymer carboxylic acid is selected from 2.91 kDa to 970 kDa, and the polydispersity coefficient of the polymer carboxylic acid is selected from 1 to 1.5.

[0464] Based on any suitable embodiment of the present application, further, in some embodiments, the ratio of the molar amount of alkali metal hydroxide in the alkali metal hydroxide aqueous solution to the molar amount of carboxyl groups in the polymer carboxylic acid solution is recorded as m, then 0.27≤m≤1.3, that is, m is selected from 0.27 to 1.3.

[0465] In some embodiments, 0.3≤m≤1.253, that is, m is selected from 0.3 to 1.253.

[0466] By controlling the ratio (m) of the molar amount of alkali metal hydroxide in the aqueous alkali metal hydroxide solution to the molar amount of carboxyl groups in the polymer carboxylic acid solution, the mass percentage (n wt%) of the M element in the polymer alkali metal salt multimolecule can be controlled within a certain range, which is beneficial to the uniform distribution of the alkali metal carboxyl groups in the polymer alkali metal salt multimolecule or polymer alkali metal salt material, and further beneficial to the uniform distribution of the alkali metal carboxyl groups in the electrode active material layer.

[0467] Based on any appropriate embodiment of the present application, further, in some embodiments, 0.977≤n-5.965m≤1.583; optionally, 1≤n-5.965m≤1.5.

[0468] In some embodiments, the value of n-5.965m can be any of the following values ​​or an interval consisting of any two of the following values: 0.977, 0.98, 0.99, 1.00, 1.005, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.063, 1.07, 1.08, 1.09, 1.10, 1.104, 1.105, 1.11, 1.12, 1.14, 1.15, 1.16, 1.18, 1.20, 1.22, 1.24, 1.244, 1 .245, 1.247, 1.25, 1.26, 1.27, 1.274, 1.28, 1.30, 1.32, 1.33, 1.334, 1.34, 1.35, 1.36, 1.38, 1.383, 1.385, 1.40, 1.42, 1.424, 1.43, 1.44, 1.45, 1.46, 1.469, 1.47, 1.476, 1.48, 1.49, 1.492, 1.494, 1.495, 1.50, 1.55, 1.58, 1.583, etc. For example, the value of n-5.965m may be selected from any appropriate range as follows: 1.005≤n-5.965m≤1.495, 1.00≤n-5.965m≤1.50, 1≤n-5.965m≤1.5, etc.

[0469] Based on any suitable embodiment of the present application, further, in some embodiments, 1 <n-5.965m<1.5。

[0470] The n-5.965m value range can be used to coordinately control the n value and the m value. By controlling n-5.965m within the above range, it is beneficial to balance the battery performance and cost at different alkali metal contents.

[0471] Based on any suitable embodiment of the present application, further, in some embodiments, the alkali metal hydroxide may include one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide. In some embodiments, the alkali metal hydroxide may be one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide. In some of these embodiments, the alkali metal hydroxide may include one or both of lithium hydroxide and sodium hydroxide. In some embodiments, the alkali metal hydroxide may be one or both of lithium hydroxide and sodium hydroxide. In some embodiments, the alkali metal hydroxide includes lithium hydroxide. In some embodiments, the alkali metal hydroxide is lithium hydroxide.

[0472] By selecting different kinds of alkali metal hydroxides, it is possible to prepare polymer alkali metal salts containing different alkali metalated carboxyl groups.

[0473] Based on any suitable embodiment of the present application, further, in some embodiments, the carbon backbone of the polymer carboxylic acid is formed by sequentially linking the units represented by formula (II);

[0474] In the unit represented by formula (II) of the polymer carboxylic acid, any one R1 is independently H or C 1-3 alkyl.

[0475] By controlling the structure of the polymer carboxylic acid, the structure of the polymer alkali metal salt in a multi-molecule or polymer alkali metal salt material can be controlled. When the carbon backbone of the polymer carboxylic acid is composed of units represented by formula (II) linked sequentially, it can react to form the alkali metal structural unit represented by formula (I) above, thereby obtaining the corresponding polymer alkali metal salt.

[0476] When the carbon backbone of the polymer carboxylic acid is formed by sequentially linking the units represented by formula (II), the polymer carboxylic acid has the general structural formula represented by formula (II-1):

[0477] Wherein, j is the degree of polymerization of the repeating unit shown in formula (II), and the “*” at both ends are independently An acceptable endcapping for the polymerization reaction is exemplified by "*" as H. j may be an integer selected from 100 to 7500, and may further be an integer selected from 1000 to 6000. j may also be any of the following values, or an interval consisting of any two of the following values: 120, 125, 150, 200, 300, 400, 500, 600, 800, 1000, 1200, 1400, 1500, 1600, 1800, 2000, 2200, 2400, 2500, 2600, 2800, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6400, 6500, 7000, 7500, and the like. Non-limiting examples of j are also selected from any of the following ranges (which may or may not include both endpoints): 100-7700, 100-7600, 100-7500, 100-7000, 100-6500, 100-6400, 125-7700, 125-7600, 125-7500, 125-7000, 125-6500, 125-6400, 110-5400, 125-5400, 1000-7700, 1000-7600, 1000-7500, 1000-7000, 1000-6500, 1000-6400, etc.

[0478] Without limitation, the number average degree of polymerization of the polymer carboxylic acid in the polymer carboxylic acid solution can be referred to as the j value. The number average degree of polymerization of the polymer carboxylic acid having repeating units represented by formula (II) can be any of the aforementioned exemplary values ​​of j, or can be selected from an interval consisting of any two exemplary values ​​of j, for example, a value selected from any of the following ranges (which may include or exclude the two endpoints): 1000-6000, 100-7700, 100-7600, 100-7500, 100-7000, 100 ~6500, 100~6400, 125~7700, 125~7600, 125~7500, 125~7000, 125~6500, 125~6400, 110~5400, 125~5400, 1000~7700, 1000~7600, 1000~7500, 1000~7000, 1000~6500, 1000~6400, etc.

[0479] In some embodiments, in the polymer carboxylic acid, any R1 is independently H, methyl, ethyl, or propyl, further independently H, methyl, or ethyl, and further independently H or methyl.

[0480] In some embodiments, in the polymeric carboxylic acid, any R1 is independently H; in this case, the polymeric carboxylic acid is polyacrylic acid.

[0481] In some embodiments, in the polymer carboxylic acid, any R1 is independently C 1-3 The alkyl group may independently be a methyl group or an ethyl group, and may independently be a methyl group.

[0482] In some embodiments, in the polymeric carboxylic acid, any R1 is independently methyl; in this case, the polymeric carboxylic acid is polymethacrylic acid.

[0483] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid. In this case, R1 in the polymer carboxylic acid includes at least one of H and methyl.

[0484] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid is any one of polyacrylic acid and polymethacrylic acid. In this case, R1 in the polymer carboxylic acid is any one of H and methyl.

[0485] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid satisfies at least one of the following characteristics:

[0486] In the polymer carboxylic acid, any R1 is independently H or methyl;

[0487] The polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid.

[0488] Based on any suitable embodiment of the present application, further, in some embodiments, the polymer carboxylic acid is any one of polyacrylic acid and polymethacrylic acid.

[0489] By controlling any one of R1 to be independently H or methyl, or by controlling the polymer carboxylic acid to include at least one of polyacrylic acid and polymethacrylic acid, the polymer alkali metal salt can be made to include at least one of polyacrylic acid alkali metal salt and polymethacrylic acid alkali metal salt. By controlling the polymer carboxylic acid to be either polyacrylic acid or polymethacrylic acid, the polymer alkali metal salt can be made to be either polyacrylic acid alkali metal salt and polymethacrylic acid alkali metal salt. As a non-limiting example, when the alkali metal hydroxide is lithium hydroxide, the product is a polymer lithium salt. By controlling any one of R1 to be independently H or methyl, or by controlling the polymer carboxylic acid to include at least one of polyacrylic acid and polymethacrylic acid, the polymer lithium salt can be made to include at least one of lithium polyacrylate and lithium polymethacrylate; by controlling the polymer carboxylic acid to be either polyacrylic acid or polymethacrylic acid, the polymer lithium salt can be made to be either lithium polyacrylate and lithium polymethacrylate.

[0490] Based on any suitable embodiment of the present application, further, in some embodiments, in the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution, which is more conducive to achieving uniform and effective alkali metal saltization of the carboxyl group. The polymer carboxylic acid solution can be added by dropwise addition, but is not limited thereto. Adding the polymer carboxylic acid solution at a slow rate is conducive to improving the uniformity of the alkali metalization of the carboxyl groups in the polymer carboxylic acid. For example, every 50 mL of polymer carboxylic acid solution can be gradually added within 30 seconds. Non-limitingly, in the step of adding the polymer carboxylic acid solution to the alkali metal hydroxide aqueous solution, the addition rate of the polymer carboxylic acid solution can be 1.5 mL / s to 2.5 mL / s, that is, 1.5 to 2.5 milliliters can be added per second on average. Alternatively, the addition rate of the polymer carboxylic acid solution can also be 1.5 mL / s to 2 mL / s.

[0491] Based on any suitable embodiment of the present application, further, in some embodiments, the number average molecular weight of the polymer carboxylic acid is 2.91kDa to 970kDa, 3kDa to 970kDa, further 100kDa to 500kDa, further 100kDa to 485kDa. The number average molecular weight of the polymer carboxylic acid can also be any of the following molecular weights or an interval consisting of any two of the following molecular weights: 2.91kDa, 3kDa, 5kDa, 9.7kDa, 10kDa, 19.4kDa, 20kDa, 38.8kDa, 40kDa, 48.5kDa, 50kDa, 58.2kDa, 60kDa, 77.6kDa, 80kDa, 97kDa, 100kDa, 116.4kDa, 120kDa, 135.8kDa, 14 kDa, 194 kDa, 200 kDa, 242.5 kDa, 250 kDa, 291 kDa, 300 kDa, 350 kDa, 388 kDa, 400 kDa, 450 kDa, 485 kDa, 500 kDa, 582 kDa, 600 kDa, 679 kDa, 700 kDa, 776 kDa, 800 kDa, etc. Without limitation, the number average molecular weight of the polymer carboxylic acid can also be selected from the following ranges: 200 kDa to 500 kDa, 200 kDa to 485 kDa, 194 kDa to 500 kDa, 194 kDa to 485 kDa, etc.

[0492] Based on any suitable embodiment of the present application, further, in some embodiments, the mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10% to 40%. The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution can also be any of the following percentages, and can also be selected from the interval consisting of any two of the following percentages: 10%, 12%, 14%, 15%, 16%, 18%, 20%, 24%, 25%, 26%, 28%, 30%, 32%, 35%, 36%, 40%, etc. The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution can also be selected from any of the following ranges: 20% to 30%, etc. The above percentages correspond to wt%.

[0493] Based on any suitable embodiment of the present application, further, in some embodiments, the solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture. In a non-limiting manner, the alcohol-water mixture can be C 1-3 A mixture of alkyl alcohol and water. 1-3 The alkyl alcohol may be selected from one or more of methanol, ethanol and propanol. Without limitation, in an alcohol-water mixture, C 1-3The volume ratio of the alkyl alcohol to water may be 5% to 30%.

[0494] Based on any suitable embodiment of the present application, further, in some embodiments, the mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5% to 11.5%. The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution can also be any of the following percentages, and can also be selected from the interval consisting of any two of the following percentages: 5%, 6%, 8%, 9%, 10%, 11%, 11.5%, etc. The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution can also be selected from any of the following ranges: 5% to 10%, etc. The above percentages correspond to wt%. As a non-limiting example, the alkali metal hydroxide can be lithium hydroxide.

[0495] Based on any suitable embodiment of the present application, further, in some embodiments, after the alkali metalization reaction is completed, the liquid phase reaction system is further dried and dispersed; optionally, the dispersion can be performed by ball milling. Furthermore, the ball milling dispersion method can be dry ball milling. One or more of the following materials can be used for the milling balls: agate balls, zirconium oxide, and corundum. Without limitation, the ball milling speed can be 300 rpm to 600 rpm, optionally 400 rpm to 500 rpm, and the ball milling time can be 2 hours to 4 hours.

[0496] Based on any suitable embodiment of the present application, further, in some embodiments, the preparation method of the polymer alkali metal salt multimolecule or polymer alkali metal salt material satisfies one or more of the following characteristics (any numerical parameter in the following characteristics can also be selected from any suitable numerical value or range in the context):

[0497] In the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution by dropwise addition, but is not limited to this method;

[0498] The number average molecular weight of the polymer carboxylic acid is selected from 2.91 kDa to 970 kDa, and can be optionally 97 kDa to 485 kDa, and can also refer to the values ​​or ranges defined below;

[0499] The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10 wt% to 40 wt%, optionally 20 wt% to 30 wt%, and may also refer to the values ​​or ranges defined above and below;

[0500] The solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture, and the alcohol-water mixture is C 1-3 The mixture of alkyl alcohol and water, alcohol-water mixture can also refer to the definition in the above context, for example, C1-3 The volume ratio of alkyl alcohol to water can be selected from 5% to 30%;

[0501] The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5 wt% to 11.5 wt%, optionally 5 wt% to 10 wt%, and may also refer to the values ​​or ranges defined above and below;

[0502] After the alkali metalation reaction is completed, the process further includes drying and dispersing the liquid phase reaction system. Optionally, the dispersion is performed by ball milling, and the definition in the context can also be referred to. For example, the ball milling dispersion can be dry ball milling.

[0503] By controlling the average molecular weight of the polymer carboxylic acid, the average molecular weight of the polymer alkali metal salt multimer and the polymer alkali metal salt material can be better controlled. By using a low concentration of the polymer carboxylic acid solution and / or a low concentration of the alkali metal hydroxide aqueous solution, the alkali metallated carboxyl groups are more evenly dispersed in the polymer alkali metal salt.

[0504] Based on any suitable embodiment of the present application, further, in some embodiments, the multi-molecule compound of the polymer alkali metal salt is as defined in the first aspect of the present application; that is, the multi-molecule compound of the polymer alkali metal salt prepared in the seventh aspect of the present application can be the multi-molecule compound of the polymer alkali metal salt described in the first aspect of the present application.

[0505] In the eighth aspect of the present application, there is provided the use of the multi-molecule polymer alkali metal salt described in the first aspect of the present application, or the polymer alkali metal salt material described in the second aspect of the present application, or the electrode slurry described in the third aspect of the present application, or the electrode pole piece described in the fourth aspect of the present application, or the multi-molecule polymer alkali metal salt prepared by the preparation method described in the seventh aspect of the present application in the preparation of secondary batteries, wherein the multi-molecule polymer alkali metal salt is used as at least one of a binder and a dispersant in the electrode pole piece.

[0506] When the aforementioned polymer alkali metal salt multi-molecule compound or polymer alkali metal salt material is used in the electrode plate of a secondary battery as at least one of a binder and a dispersant, the alkali metal ions in the alkali metal carboxyl groups in the electrode slurry generate electrostatic repulsion, which can further disperse the different chain segments of the polymer alkali metal salt molecules. By controlling the polymer alkali metal salt to have a relatively narrow molecular weight distribution and a certain average molecular weight, and further combining it with a certain alkali metal content, the polymer alkali metal salt can be uniformly distributed around the electrode active material in the electrode active material layer, which is beneficial for providing uniform distribution of alkali metal carboxyl groups at the molecular level and in the electrode active material layer, improving the uniformity and stability of active ion conduction, and thus improving the battery's cycling performance.

[0507] In an eighth aspect of the present application, there is further provided an application of a polymer alkali metal salt multi-molecule substance or a polymer alkali metal salt material in the preparation of a secondary battery, wherein the polymer alkali metal salt multi-molecule substance is the polymer alkali metal salt multi-molecule substance in the electrode slurry described in the second aspect of the present application, and the polymer alkali metal salt material contains the polymer alkali metal salt multi-molecule substance; the polymer alkali metal salt multi-molecule substance is used as at least one of a binder and a dispersant in an electrode plate;

[0508] The electrode plate includes an electrode active material layer, and the electrode plate is a positive electrode plate or a negative electrode plate;

[0509] The electrode active material layer is a film layer made using the electrode slurry described in the second aspect of the present application; wherein, the electrode active material layer is prepared by coating and drying the electrode slurry.

[0510] Below, some embodiments of the present application are described. The embodiment described below is exemplary, is only used to explain the present application, and cannot be construed as limiting the present application. In the embodiment, if no technology or conditions are indicated, it is carried out according to the description above, or according to the technology or conditions described in the document in this area or according to the product specification. Reagents used or instruments that are not indicated by the manufacturer are conventional products that can be obtained commercially, or can be synthesized in a conventional manner by commercially available products.

[0511] In the following examples, room temperature refers to 20°C to 30°C.

[0512] In the following examples, the average molecular weight is the number average molecular weight (M n ).

[0513] The term "compacted density" as used in this application has a well-known meaning in the art and is one of the reference indicators for material energy density. In this application, unless otherwise specified, the compacted density of an electrode sheet refers to the ratio of the mass of the electrode active material layer to its volume. The compacted density of a positive electrode sheet refers to the ratio of the mass of the positive electrode active material layer to its volume, and the compacted density of a negative electrode sheet refers to the ratio of the mass of the negative electrode active material layer to its volume. This can be determined using conventional methods in the art.

[0514] In this application, unless otherwise specified, for the positive and negative electrode sheets, the change in the sheet area before and after cold pressing is not significant, usually not exceeding 3%. The corresponding compaction density is calculated as follows:

[0515] Compaction density = coating surface density / (thickness of the electrode after cold pressing - thickness of the current collector).

[0516] Coating area density = slurry dry weight / area of ​​the electrode before cold pressing. Wherein, area of ​​the electrode before cold pressing ≈ area of ​​the electrode before cold pressing. "≈" means "approximately equal to."

[0517] In this application, the unit of compacted density is g / cc, which can also be expressed as g / cm 3 .

[0518] 1. Preparation of Polymer Alkali Metal Salt Polymers and Polymer Alkali Metal Salt Materials

[0519] The preparation is carried out using polymer lithium salt multi-molecules and polymer lithium salt materials as examples.

[0520] Preparation Example 1: Preparation of lithium polyacrylate PAALi-1

[0521] The polymer lithium salt (PolyLi) is selected as lithium polyacrylate, and the polymer carboxylic acid raw material used is polyacrylic acid.

[0522] 0.4 mol of lithium hydroxide is prepared into a uniform solution with a mass percentage concentration of 10 wt%. 1 mol of polyacrylic acid (polymer carboxylic acid) with a number average molecular weight of approximately 300 kDa is prepared into a polyacrylic acid solution with a mass percentage concentration of 30 wt%. The polyacrylic acid solution is slowly added (by dropwise addition) to the lithium hydroxide solution, with an average of approximately 40 mL to 50 mL added every 30 seconds (s). The mixture is stirred at 1200 rpm to mix uniformly, and the lithiation reaction is carried out at 25°C for 3 hours to obtain a viscous polymer lithium salt gel. The mixed solution is dried at 80°C and ball milled with agate balls at a ball milling speed of 450 rpm for 4 hours to obtain lithium polyacrylate powder (polymer lithium salt powder). The solvents of the lithium hydroxide solution and the polyacrylic acid solution are both water.

[0523] The prepared lithium polyacrylate powder is a lithium polyacrylate material belonging to the aforementioned polymer lithium salt material. The lithium polyacrylate material is basically composed of multiple molecules of lithium acrylate and has a purity of nearly 100%.

[0524] Preparation Example 2-13, Preparation of lithium polyacrylates PAALi-2 to PAALi-13: A method substantially identical to that used for preparing PAALi-1 was employed, with the exception of at least one of the following parameters: the number average molecular weight of the polyacrylic acid raw material, the ratio of the molar amount of lithium hydroxide in the lithium hydroxide solution to the molar amount of carboxyl groups in the polyacrylic acid solution (m), the mass percentage of lithium in the prepared lithium polyacrylate (n wt %), n-5.965m, the concentration of the lithium hydroxide solution, and the concentration of the polyacrylic acid solution; see Tables 1 and 2.

[0525] Preparation Example 14. Preparation of lithium polymethacrylate PMALi-1: The same method as that for preparing PAALi-1 was used, with the polymer lithium salt being lithium polymethacrylate and the polymer carboxylic acid being polymethacrylic acid. The remaining parameters were similar, as shown in Tables 1 and 2.

[0526] Reference Examples 1-4

[0527] PAA-1 (Reference Example 1), PAALi-D2 (Reference Example 2), PAALi-D3 (Reference Example 3), PMA-1 (Reference Example 4):

[0528] PAA-1 in Reference Example 1 is the polyacrylic acid raw material in Example 1P, which has not been lithiated.

[0529] The lithium polyacrylate PAALi-D2 in Reference Example 2 and the lithium polyacrylate PAALi-D3 in Reference Example 3 were prepared using essentially the same method as PAALi-1, with the difference being at least one of the following parameters: the number average molecular weight of the polyacrylic acid raw material, the ratio of the molar amount of lithium hydroxide in the lithium hydroxide solution to the molar amount of carboxyl groups in the polyacrylic acid solution (m), the mass percentage of lithium element in the prepared lithium polyacrylate (n wt%), and n-5.965m; see Tables 1 and 2.

[0530] PMA-1 in Reference Example 4 is the polymethacrylic acid raw material in Example 14P, which has not been lithiated.

[0531] In the above examples, the PDI of the polymer carboxylic acid raw material is selected to have a PDI value close to the target PDI range of the polymer lithium salt.

[0532] The preparation parameters and product parameters for each preparation example and reference example can be found in Tables 1 and 2. Here, the ratio of the molar amount of lithium hydroxide in the lithium hydroxide solution to the molar amount of carboxyl groups in the polymer carboxylic acid solution corresponds to m; the mass percentage of lithium in the polymer lithium salt (PolyLi) product corresponds to n wt%.

[0533] Table 1.

[0534] Table 2.

[0535] In Table 2, "%" in the mass percentage concentration corresponds to wt%.

[0536] 2. Use of the polymer alkali metal salt (further polymer lithium salt) provided in this application in the positive electrode

[0537] Example 1P

[0538] (1) Preparation of positive electrode sheet

[0539] With a solid content of 62 wt%, lithium iron phosphate (LFP): lithium polyacrylate (PAALi-1) and conductive carbon SP were stirred at a mass ratio of 98:1:1 in N-methylpyrrolidone (NMP) at a high speed of 1200 rpm to prepare a positive electrode slurry. The obtained positive electrode slurry was evenly coated on both sides of a 15 μm thick aluminum foil with a coating density of 0.45 g / 1540.25 mm 2 After the positive electrode slurry on the aluminum foil is fully dried in an environment of 50℃ to 140℃, it is cold pressed with a compaction density of 2.6g / cc to obtain a positive electrode sheet with a thickness of 0.2384mm. It is then cut into pieces with a width of 100mm for later use.

[0540] (2) Preparation of negative electrode sheet

[0541] A negative electrode slurry was prepared by mixing graphite (artificial graphite), sodium carboxymethyl cellulose (CMC-Na), conductive carbon SP, binder (SBR, styrene-butadiene rubber), and polyacrylic acid (PAA raw material for PAALi-1) in a mass ratio of 96:1:0.5:1.5:1 in water at a high speed of 1800 rpm with a solid content of 53 wt%. The resulting negative electrode slurry was evenly coated on both sides of a 10 μm thick copper foil at a coating density of 0.209 g / 1540.25 mm 2 , and dried in an environment of 50℃~140℃. After the negative electrode slurry on the copper foil is fully dried, cold pressing is performed, and the compaction density is controlled to be 1.7g / cc. Cold pressing is performed to obtain a negative electrode sheet with a thickness of 0.1694mm, which is then cut into pieces with a width of 97mm for standby use.

[0542] (3) Preparation of electrolyte

[0543] The electrolyte solution is prepared by dissolving an electrolyte salt in a solvent. The electrolyte lithium salt is 1 mol / L lithium hexafluorophosphate (LiPF6) and the solvent is a composite solvent of ethylene carbonate / dimethyl carbonate / propylene carbonate (EC / DMC / PC) in a volume ratio of 1:1:1.

[0544] (4) Selection of isolation membrane

[0545] Conventional polyethylene (PE) separator, 7μm thick.

[0546] (5) Battery assembly:

[0547] The separator is cut into 106mm widths. Using a 322mm circumference winding needle, the positive electrode sheet, separator, and negative electrode sheet are arranged in sequence, with the separator positioned between the positive and negative electrodes to provide insulation. The resulting dry cell is wound. Electrolyte is injected, and the cells are packaged, formed, and vented. The resulting secondary battery is a lithium-ion secondary battery.

[0548] 2. Examples 2P to 14P use methods substantially the same as those of Example 1P, with the difference being that the composition of the polymer lithium salt gel is different, and the dry weight percentage of the polymer lithium salt in the positive electrode slurry of some examples is also different, as shown in Table 3.

[0549] 3. Comparative Examples 1P to 4P adopt the same method as Example 1P, except that the composition of the polymer lithium salt glue is different, as shown in Table 3.

[0550] 3. Use of the polymer alkali metal salt (further polymer lithium salt) provided in the negative electrode

[0551] Example 1N

[0552] (1) Preparation of negative electrode sheet

[0553] A negative electrode slurry was prepared by mixing graphite (artificial graphite): sodium carboxymethyl cellulose (CMC-Na): conductive carbon SP: binder (SBR, styrene-butadiene rubber): lithium polyacrylate (PAALi-1) in water at a mass ratio of 96:1:0.5:1.5:1 with a solid content of 53 wt%. The mixture was stirred at a speed of 1800 rpm in water to obtain a uniform mixture. The resulting negative electrode slurry was evenly coated on both sides of a 10 μm thick copper foil at a coating density of 0.209 g / 1540.25 mm 2 , and dried in an environment of 50℃~140℃. After the negative electrode slurry on the copper foil is fully dried, cold pressing is performed, and the compaction density is controlled to be 1.7g / cc. Cold pressing is performed to obtain a negative electrode sheet with a thickness of 0.1694mm, which is then cut into pieces with a width of 97mm for standby use.

[0554] (2) Preparation of positive electrode sheet

[0555] Lithium iron phosphate (LFP), polyvinylidene fluoride (PVDF), and conductive carbon (SP) were stirred in N-methylpyrrolidone (NMP) at a mass ratio of 98:1:1 at a speed of 1200 rpm to prepare a positive electrode slurry with a solid content of 62 wt%. The resulting positive electrode slurry was evenly coated on both sides of a 15 μm thick aluminum foil at a coating density of 0.45 g / 1540.25 mm 2 After the positive electrode slurry on the aluminum foil is fully dried in an environment of 50℃ to 140℃, the density is controlled to 2.6g / cc and cold pressed to obtain a positive electrode sheet with a thickness of 0.2384mm. The sheet is then cut into pieces with a width of 100mm for later use.

[0556] (3) Preparation of electrolyte

[0557] The electrolyte solution is prepared by dissolving an electrolyte salt in a solvent. The electrolyte lithium salt is 1 mol / L lithium hexafluorophosphate (LiPF6) and the solvent is a composite solvent of ethylene carbonate / dimethyl carbonate / propylene carbonate (EC / DMC / PC) in a volume ratio of 1:1:1.

[0558] (4) Selection of isolation membrane

[0559] Conventional polyethylene (PE) separator, 7μm thick.

[0560] (5) Battery assembly:

[0561] The separator is cut into 106mm widths. Using a 322mm circumference winding needle, the positive electrode sheet, separator, and negative electrode sheet are arranged in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The cells are then wound to form a dry cell. Electrolyte is then injected, and the cells are packaged, formed, and vented to create a lithium-ion secondary battery.

[0562] 2. Examples 2N to 14N adopt the same method as Example 1N, except that the composition of the polymer lithium salt gel is different. In some examples, the dry weight percentage of the polymer lithium salt in the negative electrode slurry is also different. Please refer to Table 4.

[0563] 3. Comparative Examples 1N to 4N adopt the same method as Example 1N, except that the composition of the polymer lithium salt glue is different, as shown in Table 4.

[0564] 4. Both the positive and negative electrodes use the polymer alkali metal salt (further polymer lithium salt) provided in this application.

[0565] Example 1F: The positive electrode sheet of Example 1P and the negative electrode sheet of Example 1N are selected. The electrolyte preparation step (3), the separator selection step (4), and the battery assembly step (5) are the same as those used to prepare the secondary battery in Example 1P.

[0566] Example 2F: The positive electrode sheet of Example 14P and the negative electrode sheet of Example 14N were selected. The electrolyte preparation step (3), the separator selection step (4), and the battery assembly step (5) were the same as those used to prepare the secondary battery in Example 14P.

[0567] 5. Test Analysis

[0568] 1. Sedimentation performance of electrode slurry

[0569] After stirring and adjusting the viscosity to within a certain range, the electrode slurry was allowed to stand at 20°C to 30°C for various periods of time (0h, 4h, 8h, 12h, 16h, 20h, 24h, 36h, and 48h). Observe the bottom of the slurry for any sedimentation at various times. The viscosity of the positive electrode slurry was adjusted to 5000mPa·s to 25000mPa·s. The viscosity of the negative electrode slurry was adjusted to 2000mPa·s to 15000mPa·s.

[0570] The basis for judging whether "sedimentation" has occurred is the appearance of sediment at the bottom of the container.

[0571] If settlement occurs within 48 hours of the observation period, the time when settlement begins will be recorded; if there is still no settlement after 48 hours of the observation period, it will be recorded as "no settlement in 48 hours".

[0572] “No sedimentation after 36 hours” means that the sedimentation time is greater than 36 hours and less than or equal to 48 hours.

[0573] “No sedimentation in 24 hours” means that the sedimentation time is greater than 24 hours and less than or equal to 36 hours.

[0574] “No sedimentation within 16 hours” means that the sedimentation time is greater than 16 hours and less than or equal to 24 hours.

[0575] The later the sedimentation occurs, that is, the longer the electrode slurry can be allowed to stand stably without sedimentation, the better the stability of the electrode slurry. The better the stability of the electrode slurry, the more uniform the distribution of the polymer alkali metal salt and the alkali metal carboxyl groups it contains in the electrode active material layer, the more uniform the stability of the active ion conduction, and the better the battery's cycle performance and rate performance. Moreover, the active ion transport channels within the electrode sheet are more uniform and stable, which is conducive to better utilization of the battery capacity. In addition, the electrode active material layer in the prepared electrode sheet can be sampled and resuspended into a slurry with a corresponding solid content using a corresponding solvent. The test results of the sedimentation performance of the resuspended slurry are basically consistent with the test results of the electrode slurry used to prepare the electrode sheet.

[0576] Taking Example 1P as an example, the positive electrode active material layer can be extracted from the positive electrode plate, and the sample of the positive electrode active material layer can be resuspended into a slurry using N-methylpyrrolidone (NMP) at a solid content of 62 wt%, and the sedimentation performance can be tested using the above method.

[0577] Taking Example 1N as an example, the negative electrode active material layer can be extracted from the negative electrode plate, and the sample of the negative electrode active material layer can be resuspended into a slurry with deionized water at a solid content of 53 wt %, and the sedimentation performance can be tested using the above method.

[0578] 2. Battery capacity

[0579] At 25°C, the battery was charged at a constant current of 1 / 3C to a voltage of 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C. After standing for 5 minutes, the battery was discharged at a constant current of 1 / 3C to a voltage of 2.0V. The discharge capacity this time is the battery capacity.

[0580] 3. Cycle performance

[0581] Test 80% SOH cycle number.

[0582] At 25°C, the secondary battery under test is charged at a constant current of 1 / 3C to a voltage of 3.65V. Then, it is charged at a constant voltage of 3.65V to a current of 0.05C. After standing for 5 minutes, the battery is discharged at a constant current of 1 / 3C to a voltage of 2.0V. This is a charge cycle, and the discharge capacity of this cycle is the discharge capacity C1 of the first cycle. The cyclic charge test is repeated as described above until the discharge capacity decays to 80% of the initial value C1. The cycle is completed. The number of cycles when the capacity decays to 80% is recorded as the "80% SOH Cycles."

[0583] The greater the number of 80% SOH cycles, the better the cycle performance of the battery cell and the longer the cycle life.

[0584] 4. Rate performance

[0585] At 25°C, 10% to 80% SOC equivalent charging window test: At 25°C, charge the secondary battery at a constant current of 1 / 3C to a charge cut-off voltage of 3.65V, then charge at a constant voltage to a current of 0.05C, let it stand for 5 minutes, and then discharge at a constant current of 1 / 3C to a discharge cut-off voltage of 2V, and record its actual capacity as C0. Then charge the secondary battery at a constant current of 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, 4.5C0 in sequence to a full battery charge cut-off voltage of 3.65V or a negative electrode cut-off potential of 0V (whichever is reached first). After each charge is completed, discharge at 1C0 to a full battery discharge cut-off voltage of 2V, and record the SOC (State of The negative electrode potential corresponding to the state of charge (SOC) is plotted, and the rate-negative electrode potential curves under different SOC states are drawn. After linear fitting, the charge rate corresponding to the negative electrode potential of 0V under different SOC states is obtained. The charge rate is the charging window under the SOC state, which is recorded as C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC and C80% SOC respectively. The 10% to 80% SOC equivalent charging window is the average value of the charging window of 10% to 80% SOC. The larger the equivalent charging window value, the greater the rate of charge and discharge can be carried out under a certain set temperature and SOC conditions, and it is more difficult for the anode (negative electrode) to reach the 0V lithium plating potential, that is, the rate performance of the battery is improved.

[0586] The larger the equivalent charging window of the battery cell, that is, the equivalent rate value, the better the rate performance.

[0587] 6. Test Results Analysis

[0588] For Examples 1P to 14P using the polymer alkali metal salt material provided in this application in the positive electrode sheets, the prepared positive electrode slurries all have good stability. All of them can not sediment within 24 hours at 20℃~30℃, most of them can not sediment within 36 hours at 20℃~30℃, and some can not sediment within 48 hours at 20℃~30℃. The resuspended slurry of the positive electrode active material layer was prepared using the positive electrode sheet, and the sedimentation performance test results were basically consistent. The secondary batteries prepared in Examples 1P to 14P all have good cycle performance and rate performance.

[0589] Comparative Example 1P uses polyacrylic acid that has not been salted with alkali metal as a binder, the molecular weight of the alkali metal salt of polyacrylic acid (corresponding to lithium polyacrylate) in Comparative Example 2P is low and the PDI is wide, the n value and n-5.965m value in Comparative Example 3P are both low, and Comparative Example 4P uses methyl polyacrylic acid that has not been salted with alkali metal as a binder. According to the test results, the stability of the positive electrode slurry in Comparative Examples 1P to 4P has significantly deteriorated, the 80% SOH cycle number and charge rate of the prepared secondary batteries have also decreased significantly, and the comprehensive performance of the cycle performance and rate performance has significantly deteriorated.

[0590] Table 3.

[0591] For Examples 1N to 14N using the polymer alkali metal salt material provided in this application in the negative electrode plate, the prepared negative electrode slurries all have good stability. All of them can not sediment within 24 hours at 20℃~30℃, most of them can not sediment within 36 hours at 20℃~30℃, and some can not sediment within 48 hours at 20℃~30℃. The resuspended slurry of the negative electrode active material layer prepared using the negative electrode plate has basically the same sedimentation performance test results. The secondary batteries prepared in Examples 1N to 14N all have good cycle performance and rate performance.

[0592] Comparative Example 1N uses polyacrylic acid that has not been salted with alkali metal as a binder, the molecular weight of the alkali metal salt of polyacrylic acid (corresponding to lithium polyacrylate) in Comparative Example 2N is low and the PDI is wide, the n value and n-5.965m value in Comparative Example 3N are both low, and Comparative Example 4N uses methyl polyacrylic acid that has not been salted with alkali metal as a binder. According to the test results, the stability of the negative electrode slurry in Comparative Examples 1N to 4N is significantly deteriorated, the 80% SOH cycle number and charging rate of the prepared secondary batteries are also significantly reduced, and the comprehensive performance of the cycle performance and rate performance is significantly deteriorated.

[0593] Table 4.

[0594] When the polymer alkali metal salt material provided in the present application is used as a binder and / or dispersant in both the positive and negative electrode sheets, the cycle performance and rate performance of the prepared secondary battery are more significantly improved compared with comparative examples 1P to 4P and comparative examples 1N to 4N.

[0595] Table 5.

[0596] The above description of the various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced with each other and will not be repeated herein for the sake of brevity.

[0597] The technical features of the various embodiments and examples described above can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0598] It should be noted that the present application is not limited to the above-mentioned embodiments and examples. The above-mentioned embodiments and examples are only examples, and within the scope of the technical solution of the present application, embodiments that have substantially the same structure as the technical idea and exert the same effect are all included in the technical scope of the present application. The above-mentioned embodiments only express several embodiments of the present application, and their descriptions are relatively detailed, but they cannot be understood as limiting the scope of the patent. In addition, without departing from the scope of the subject matter of the present application, other methods of applying various modifications that can be thought of by those skilled in the art to the embodiments or examples, and combining some of the constituent elements in the embodiments or examples to construct the embodiments are also included in the scope of the present application.

Claims

1. A polymer alkali metal salt multi-molecule, comprising a plurality of polymer alkali metal salt molecules, wherein: The polymer alkali metal salt molecule has a linear structure, and the polymer alkali metal salt molecule includes a carbon main chain and a plurality of side groups Q branched along the carbon main chain, any of the side groups Q is independently -COOH or -COOM, and at least a portion of the side groups Q is -COOM, and M is an alkali metal element; Among them, the mass percentage of M element in the polymer alkali metal salt multimolecule is greater than or equal to 3wt%; the number average molecular weight of the polymer alkali metal salt multimolecule is selected from 3kDa to 1000kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecule is selected from 1 to 1.

5.

2. The multimolecular substance of the polymer alkali metal salt according to claim 1, wherein: In any -COOM, M is independently Li, Na or K; Optionally, in any -COOM, M is independently Li or Na.

3. The multimolecular substance of the polymer alkali metal salt according to claim 1 or 2, wherein: The carbon backbone of the polymer alkali metal salt molecule is formed by sequentially bonding the units shown in formula (I); In the units of formula (I) in the multimolecular substance of the polymer alkali metal salt, any Q is independently -COOH or -COOM, and at least a portion of Q is -COOM; any R1 is independently H or C 1-3 alkyl; Optionally, any R1 is independently H or methyl.

4. The multimolecular substance of the polymer alkali metal salt according to any one of claims 1 to 3, wherein The polymer alkali metal salt includes at least one of a polyacrylic acid alkali metal salt and a polymethacrylic acid alkali metal salt.

5. The multimolecular substance of the polymer alkali metal salt according to any one of claims 1 to 4, wherein The polymer alkali metal salt includes at least one of lithium polyacrylate and lithium polymethacrylate.

6. The multi-molecule of the polymer alkali metal salt according to any one of claims 1 to 5, which satisfies one or more of the following characteristics: The number average molecular weight of the polymer alkali metal salt is selected from 100 kDa to 500 kDa; The mass percentage of the M element in the multi-molecule of the polymer alkali metal salt is greater than or equal to 5wt%; The M element includes lithium, and the mass percentage of lithium in the multi-molecule of the polymer alkali metal salt is selected from 5wt% to 7.5wt%; The polydispersity coefficient of the polymer alkali metal salt is selected from 1 to 1.

3.

7. The multimolecular substance of the polymer alkali metal salt according to any one of claims 1 to 6, wherein The M element includes lithium element, and the mass percentage of lithium element in the multi-molecule of the polymer alkali metal salt is selected from 5.5wt% to 7wt%.

8. A polymer alkali metal salt material, comprising multi-molecules of the polymer alkali metal salt according to any one of claims 1 to 7.

9. An electrode slurry, wherein the electrode slurry contains an electrode active substance and a multi-molecular substance of the polymer alkali metal salt according to any one of claims 1 to 7, or the electrode slurry contains an electrode active substance and the polymer alkali metal salt material according to claim 8; the electrode slurry is a positive electrode slurry or a negative electrode slurry.

10. The electrode slurry according to claim 9, wherein: The mass proportion of the polymer alkali metal salt multi-molecule in the dry weight of the electrode slurry is 0.1wt% to 5wt%; Optionally, the mass proportion of the polymer alkali metal salt multi-molecules in the dry weight of the electrode slurry is 0.5wt% to 2wt%.

11. The electrode slurry according to claim 9 or 10, wherein: The alkali metal carboxyl groups in the polymer alkali metal salt multimolecules are distributed along the carbon backbone in a manner such that the electrode slurry does not settle within 24 hours at 20° C. to 30° C.; wherein the alkali metal carboxyl groups refer to -COOM; Optionally, the alkali metallated carboxyl groups in the polymer alkali metal salt multimolecules are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 36 hours at 20° C. to 30° C.; Further optionally, the alkali metallated carboxyl groups in the polymer alkali metal salt multimolecules are distributed along the carbon backbone in such a manner that the electrode slurry does not settle within 48 hours at 20° C. to 30° C.

12. An electrode slurry, wherein: The electrode slurry contains electrode active material and polymer alkali metal salt multi-molecules; the electrode slurry is positive electrode slurry or negative electrode slurry; The multi-molecule substance of the polymer alkali metal salt is prepared by a method comprising the following steps: A polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution are provided respectively; wherein the polymer carboxylic acid solution is an aqueous solution containing a polymer carboxylic acid, the polymer carboxylic acid has a linear structure, and the polymer carboxylic acid includes a carbon backbone and a plurality of carboxyl groups grafted along the carbon backbone; the alkali metal hydroxide aqueous solution is an aqueous solution containing an alkali metal hydroxide, and the alkali metal element in the alkali metal hydroxide is denoted as M element; The polymer carboxylic acid solution is mixed with the alkali metal hydroxide aqueous solution, and an alkali metalization reaction is performed so that the hydrogen atoms of at least a part of the multiple carboxyl groups included in the polymer carboxylic acid are replaced by the M element, so as to obtain a polymer alkali metal salt multimolecular substance containing n wt% of the M element; wherein n≥3; the number average molecular weight of the polymer alkali metal salt multimolecular substance is 3kDa~1000kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecular substance is 1~1.

5.

13. The electrode slurry according to claim 12, wherein: The ratio of the molar amount of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution to the molar amount of the carboxyl group in the polymer carboxylic acid solution is denoted as m, and then 0.27≤m≤1.3; Optionally, 0.3≤m≤1.253; Further optionally, 0.4≤m≤1.1; Further optionally, 0.4≤m≤1.

0.

14. The electrode slurry according to claim 12 or 13, wherein: 3.886≤n≤8.974； Optionally, 5≤n≤7.5; Further optionally, 5.5≤n≤7.

15. The electrode slurry according to any one of claims 12 to 14, wherein 0.977≤n-5.965m≤1.583; Optionally, 1≤n-5.965m≤1.5; Further optionally, 1 <n-5.965m<1.5。 16. The electrode slurry according to any one of claims 12 to 15, wherein The alkali metal hydroxide includes one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; Optionally, the alkali metal hydroxide comprises lithium hydroxide; Optionally, the alkali metal hydroxide is lithium hydroxide.

17. The electrode slurry according to any one of claims 12 to 16, wherein The carbon backbone of the polymer carboxylic acid is formed by sequentially bonding the units represented by formula (II); In the unit of formula (II) of the polymer carboxylic acid, any one R1 is independently H or C 1-3 alkyl.

18. The electrode slurry according to claim 17, wherein: The polymer carboxylic acid satisfies at least one of the following characteristics: In the polymer carboxylic acid, any R1 is independently H or methyl; The polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid. Optionally, the polymer carboxylic acid is at least one of polyacrylic acid and polymethacrylic acid.

19. The electrode slurry according to any one of claims 12 to 18, which satisfies one or more of the following characteristics: In the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution; The number average molecular weight of the polymer carboxylic acid is selected from 97 kDa to 485 kDa; The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10wt% to 40wt%; The solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture, wherein the alcohol-water mixture is C 1-3 A mixture of alkyl alcohol and water, wherein C 1-3 The volume ratio of alkyl alcohol to water is selected from 5% to 30%; The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5wt% to 11.5wt%; After the alkali metalation reaction is completed, the step of drying and dispersing the liquid phase reaction system is also included, and the dispersion is carried out by ball milling.

20. The electrode slurry according to claim 12, wherein: The multi-molecule substance of the polymer alkali metal salt is the multi-molecule substance of the polymer alkali metal salt described in any one of claims 1 to 7.

21. The electrode slurry according to claim 12, wherein: The electrode slurry is the electrode slurry according to claim 10 or 11.

22. An electrode plate, comprising an electrode active material layer, wherein the electrode plate is a positive electrode plate or a negative electrode plate; The electrode active material layer satisfies any one of the following characteristics: The electrode active material layer comprises an electrode active substance and a multi-molecule substance of the polymer alkali metal salt according to any one of claims 1 to 7, or the electrode active material layer comprises an electrode active substance and the polymer alkali metal salt material according to claim 8; The electrode active material layer is a film layer made using the electrode slurry according to any one of claims 9 to 21.

23. The electrode plate according to claim 22, wherein: The mass proportion of the polymer alkali metal salt multi-molecule or the polymer alkali metal salt material in the electrode active material layer is 0.1 wt % to 5 wt %.

24. The electrode plate according to claim 22, wherein: The mass proportion of the polymer alkali metal salt multi-molecule or the polymer alkali metal salt material in the electrode active material layer is 0.5 wt % to 2 wt %.

25. The electrode sheet according to any one of claims 22 to 24, wherein: The electrode plate meets one or two of the following characteristics: Dispersing the electrode active material layer in the positive electrode plate in a first solvent according to a solid content of 40wt% to 70wt%, and the obtained positive electrode dispersion can not precipitate within 24 hours at 20°C to 30°C; wherein the first solvent includes one or more of N-methylpyrrolidone, dimethylformamide and ethylene glycol dimethyl ether; The electrode active material layer in the negative electrode plate is dispersed in water according to a solid content of 40wt% to 70wt%, and the obtained negative electrode dispersion can be kept at 20°C to 30°C without sedimentation within 24 hours.

26. The electrode sheet according to any one of claims 22 to 24, wherein: The electrode plate meets one or two of the following characteristics: Dispersing the electrode active material layer in the positive electrode sheet in the first solvent according to a solid content of 40wt% to 70wt%, and the obtained positive electrode dispersion can not precipitate within 36 hours at 20°C to 30°C; The electrode active material layer in the negative electrode plate is dispersed in water according to a solid content of 40wt% to 70wt%, and the obtained negative electrode dispersion can be kept at 20°C to 30°C without sedimentation within 36 hours.

27. The electrode sheet according to any one of claims 22 to 24, wherein: The electrode plate meets one or two of the following characteristics: Dispersing the electrode active material layer in the positive electrode sheet in the first solvent according to a solid content of 40wt% to 70wt%, and the obtained positive electrode dispersion can not precipitate within 48 hours at 20°C to 30°C; The electrode active material layer in the negative electrode plate is dispersed in water according to a solid content of 40wt% to 70wt%, and the obtained negative electrode dispersion can be kept at 20°C to 30°C without sedimentation within 48 hours.

28. A secondary battery, wherein: The secondary battery comprises a positive electrode sheet and a negative electrode sheet, and one or more of the positive electrode sheet and the negative electrode sheet is the electrode sheet according to any one of claims 22 to 27.

29. The secondary battery according to claim 28, wherein The secondary battery is a lithium ion secondary battery.

30. An electrical device comprising the secondary battery according to claim 28 or 29.

31. A method for preparing a multimolecular compound of a polymer alkali metal salt, comprising the following steps: A polymer carboxylic acid solution and an alkali metal hydroxide aqueous solution are provided respectively; wherein, The polymer carboxylic acid solution is an aqueous solution containing polymer carboxylic acid, wherein the polymer carboxylic acid has a linear structure and comprises a carbon backbone and a plurality of carboxyl groups grafted along the carbon backbone; the alkali metal hydroxide aqueous solution is an aqueous solution containing alkali metal hydroxide, wherein the alkali metal element in the alkali metal hydroxide is denoted as M element; The polymer carboxylic acid solution is mixed with the alkali metal hydroxide aqueous solution, and an alkali metalization reaction is performed so that the hydrogen atoms of at least a part of the multiple carboxyl groups included in the polymer carboxylic acid are replaced by the M element, so as to obtain a polymer alkali metal salt multimolecular substance containing n wt% of the M element; wherein n≥3; the number average molecular weight of the polymer alkali metal salt multimolecular substance is 3kDa~1000kDa, and the polydispersity coefficient of the polymer alkali metal salt multimolecular substance is 1~1.

5.

32. The method for preparing a multimolecular compound of a polymer alkali metal salt according to claim 31, wherein: The ratio of the molar amount of the alkali metal hydroxide in the aqueous alkali metal hydroxide solution to the molar amount of the carboxyl group in the polymer carboxylic acid solution is denoted as m, and then 0.27≤m≤1.

3.

33. The method for preparing a multimolecular compound of a polymer alkali metal salt according to claim 32, wherein: 0.3≤m≤1.253； Optionally, 0.4≤m≤1.1; Optionally, 0.4≤m≤1.

0.

34. The method for preparing a multimolecular compound of a polymer alkali metal salt according to any one of claims 31 to 33, wherein: 3.886≤n≤8.974； Optionally, 5≤n≤7.5; Optionally, 5.5≤n≤7.

35. The method for preparing a multimolecular compound of a polymer alkali metal salt according to any one of claims 31 to 34, wherein: 0.977≤n-5.965m≤1.583; Optionally, 1≤n-5.965m≤1.5; Further optionally, 1 <n-5.965m<1.5。 36. The method for preparing a multimolecular compound of a polymer alkali metal salt according to any one of claims 31 to 35, wherein: The alkali metal hydroxide includes one or more of lithium hydroxide, sodium hydroxide and potassium hydroxide; Optionally, the alkali metal hydroxide includes one or more of lithium hydroxide and sodium hydroxide; Optionally, the alkali metal hydroxide is lithium hydroxide.

37. The method for preparing a multimolecular compound of a polymer alkali metal salt according to claim 22, wherein: The carbon backbone of the polymer carboxylic acid is formed by sequentially bonding the units represented by formula (II); In the unit of formula (II) of the polymer carboxylic acid, any one R1 is independently H or C 1-3 alkyl.

38. The method for preparing a multimolecular compound of a polymer alkali metal salt according to claim 37, wherein: The polymer carboxylic acid satisfies at least one of the following characteristics: In the polymer carboxylic acid, any R1 is independently H or methyl; The polymer carboxylic acid includes at least one of polyacrylic acid and polymethacrylic acid.

39. The method for preparing a multimolecular compound of a polymer alkali metal salt according to any one of claims 31 to 38, which satisfies one or more of the following characteristics: In the step of mixing the polymer carboxylic acid solution with the alkali metal hydroxide aqueous solution, the polymer carboxylic acid solution is added to the alkali metal hydroxide aqueous solution; The number average molecular weight of the polymer carboxylic acid is selected from 97 kDa to 485 kDa; The mass percentage concentration of the polymer carboxylic acid in the polymer carboxylic acid solution is 10wt% to 40wt%; The solvent in the polymer carboxylic acid solution is water or an alcohol-water mixture, wherein the alcohol-water mixture is C 1-3 A mixture of alkyl alcohol and water, wherein C 1-3 The volume ratio of alkyl alcohol to water is selected from 5% to 30%; The mass percentage concentration of the alkali metal hydroxide in the alkali metal hydroxide aqueous solution is 5wt% to 11.5wt%; After the alkali metalation reaction is completed, the step of drying and dispersing the liquid phase reaction system is also included, and the dispersion is carried out by ball milling.

40. The method for preparing a multimolecular compound of a polymer alkali metal salt according to claim 31, wherein: The multi-molecule substance of the polymer alkali metal salt is the multi-molecule substance of the polymer alkali metal salt described in any one of claims 1 to 7.

41. Use of the polymer alkali metal salt multimolecule according to any one of claims 1 to 7, or the polymer alkali metal salt material according to claim 8, or the electrode slurry according to any one of claims 9 to 21, or the electrode plate according to any one of claims 22 to 27, or the polymer alkali metal salt multimolecule prepared by the preparation method of the polymer alkali metal salt multimolecule according to any one of claims 31 to 39 in the preparation of a secondary battery, wherein: The multi-molecule substance of the polymer alkali metal salt is used as at least one of a binder and a dispersant in an electrode plate.

42. Use of a polymer alkali metal salt multi-molecule or polymer alkali metal salt material in the preparation of a secondary battery, wherein: The polymer alkali metal salt multi-molecule is a polymer alkali metal salt multi-molecule in the electrode slurry as claimed in any one of claims 9 to 21, and the polymer alkali metal salt material comprises the polymer alkali metal salt multi-molecule; the polymer alkali metal salt multi-molecule is used as at least one of a binder and a dispersant in the electrode plate; The electrode plate comprises an electrode active material layer, and the electrode plate is a positive electrode plate or a negative electrode plate; The electrode active material layer is a film layer made of the electrode slurry described in any one of claims 9 to 21; wherein the electrode active material layer is prepared by coating and drying the electrode slurry.

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