Preparation method of sodium ion battery negative electrode slurry and vehicle

Abstract

The invention discloses a preparation method of sodium-ion battery negative electrode slurry and a vehicle, belongs to the technical field of sodium-ion batteries, and particularly relates to the preparation method of the sodium-ion battery negative electrode slurry. The preparation method specifically comprises the following steps: adding conductive carbon black and hard carbon into a glue solution, adding a binder at a constant speed of 10-15g / min at the temperature of 50-80 DEG C, stirring for 30 minutes, and carrying out vacuum defoaming treatment to obtain sodium-ion battery negative electrode slurry; the binder comprises styrene butadiene rubber; in the preparation of the glue solution, sodium carboxymethyl cellulose and deionized water are mixed, N-methyl pyrrolidone is added, and stirring is performed to obtain the glue solution. The sodium-ion battery negative electrode slurry prepared by the invention has good dispersibility, and effectively inhibits caking and lumping phenomena; meanwhile, the electrochemical performance of the sodium-ion battery is improved, the first coulombic efficiency reaches 82.6% or above, and the capacity retention rate reaches 70% or above when the sodium-ion battery is circulated for 1500 circles.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a method for preparing a negative electrode slurry for a sodium ion battery. Background Art

[0002] With the rapid development of the clean energy and electric vehicle markets, sodium-ion batteries have become a promising new energy storage technology due to their abundant resources and low cost. However, their large-scale commercial application is still limited by the stability and reliability of material properties. At present, the performance testing of sodium battery materials mainly relies on physical and chemical characterization methods. Physical performance testing mainly includes three aspects: (1) Solid content test: by measuring the content of solid components in styrene-butadiene rubber (SBR), its concentration and stability are evaluated; (2) Viscosity determination: by measuring the viscosity of SBR or other related materials, its fluidity and processing performance are understood; (3) D50 particle size test: by measuring the D50 particle size distribution of material particles, it is used to evaluate the uniformity and dispersion of the material. Chemical performance tests mainly include: (1) pH test: by measuring the acidity and alkalinity of the material to evaluate its chemical stability and adaptability to the environment; (2) thermogravimetric (TG) test: heating at a constant heating rate, by analyzing the relationship between mass and temperature, to determine the thermal stability and thermal properties of the material; (3) differential scanning calorimetry (DSC) test: by measuring the heat change of the material during heating or cooling to evaluate the thermal stability and phase change characteristics of the material. Although these methods can evaluate the basic properties of the material, they still have obvious limitations. The existing technology lacks a systematic evaluation of the temperature resistance of key binders (such as SBR) after mixing with slurry.

[0003] In practical applications, high temperatures can lead to decreased slurry stability, manifesting as poor compatibility between SBR and the slurry and easy agglomeration, which in turn affects electrode processing performance and battery cycle life. Therefore, by comprehensively evaluating the temperature resistance, dispersion stability, and electrochemical properties of styrene-butadiene rubber mixed with sodium-ion battery anode slurry, and developing a new preparation method for sodium-ion battery anode materials, this is of great significance for optimizing sodium battery performance and promoting their industrial application. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a negative electrode slurry for a sodium ion battery and a vehicle. By optimizing the preparation method of the negative electrode slurry for a sodium ion battery, the prepared sodium ion battery exhibits good dispersibility and effectively suppresses the agglomeration phenomenon, thereby greatly improving the first coulombic efficiency and cycle stability of the sodium ion battery, so that the sodium ion battery has good electrochemical performance.

[0005] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are: A method for preparing a negative electrode slurry for a sodium ion battery comprises adding conductive carbon black and hard carbon to a slurry, uniformly adding a binder at a rate of 10-15 g / min and stirring at 50-80°C for 20-40 minutes, and vacuum degassing to obtain the negative electrode slurry for the sodium ion battery. The binder comprises styrene-butadiene rubber (SBR). During the preparation of the slurry, sodium carboxymethyl cellulose is mixed with deionized water, and then N-methyl pyrrolidone is added and stirred to obtain the slurry. The mass ratio of conductive carbon black to sodium carboxymethyl cellulose is 1:1.2-1.5. By optimizing the preparation conditions of the sodium ion battery negative electrode slurry and adjusting the amounts of SBR and SCR, the prepared sodium ion battery exhibits good dispersibility and effectively suppresses clumping, thereby significantly improving the electrochemical performance of the sodium ion battery.

[0006] Preferably, the mass ratio of the conductive carbon black to the hard carbon is 1:94-96.

[0007] Preferably, the mass ratio of conductive carbon black to deionized water is 1 g:50-100 mL.

[0008] Preferably, the mass ratio of the conductive carbon black to the binder is 1:2.5-3.5.

[0009] Preferably, during the preparation of the negative electrode slurry for a sodium ion battery, a binder and a functional agent are uniformly added at a rate of 10-15 g / min and stirred for 20-40 minutes at 50-80°C; the binder is styrene-butadiene rubber; and the functional agent comprises at least ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate. The present invention introduces ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate into the negative electrode slurry for a sodium ion battery, potentially improving the initial coulombic efficiency of the sodium ion battery and effectively suppressing capacity fade by optimizing the chemical stability and interfacial uniformity of the sodium ion battery.

[0010] More preferably, the mass ratio of styrene-butadiene rubber to ethylene glycol bis(4-carboxyphenyl) ether is 1:0.2-0.7.

[0011] More preferably, the mass ratio of styrene-butadiene rubber to 5-hydroxybenzyl valerate is 1:0.1-0.3.

[0012] Preferably, the method for preparing the negative electrode slurry for sodium ion batteries is specifically as follows: Sodium carboxymethyl cellulose is mixed with deionized water, N-methyl pyrrolidone is added, and the mixture is stirred at a revolution rate of 20-40 rpm and a rotation rate of 2000-2400 rpm for 200-280 min. Conductive carbon black and hard carbon are added, and the mixture is stirred at a revolution rate of 20-40 rpm and a rotation rate of 0-10 rpm for 50-90 min. Pure water is then added, and the mixture is stirred at a revolution rate of 20-40 rpm and a rotation rate of 2000-2400 rpm for 40-80 min. The mixture is stirred at a revolution rate of 0-10 rpm and a rotation rate of 0-10 rpm for 10-30 min, and the mixture is cooled to 20-30° C. Under the condition of 50-80° C., a binder is uniformly added at a rate of 10-15 g / min and stirred for 20-40 min. The mixture is subjected to vacuum degassing treatment to obtain a negative electrode slurry for a sodium ion battery.

[0013] More preferably, the ratio of conductive carbon black to sodium carboxymethyl cellulose is 1:1.2-1.5.

[0014] More preferably, sodium carboxymethyl cellulose is purchased from Changshu Weiyi Technology Co., Ltd. with a model number of BH2000 or purchased from Nippon Paper Manufacturing Co., Ltd. with a model number of 500LC.

[0015] More preferably, the ratio of conductive carbon black to deionized water is 1 g: 50-100 mL.

[0016] More preferably, the mass ratio of the conductive carbon black to N-methylpyrrolidone is 1:0.94-0.96.

[0017] More preferably, the mass ratio of the conductive carbon black to the hard carbon is 1:94-96.

[0018] More preferably, the usage ratio of the conductive carbon black to pure water is 1 g:5-20 mL.

[0019] More preferably, the mass ratio of the conductive carbon black to the binder is 1:2.5-3.5.

[0020] More preferably, the binder comprises styrene-butadiene rubber.

[0021] Further preferably, the styrene-butadiene rubber is purchased from Fujian Blue Ocean Black Stone New Material Technology Co., Ltd., model BA-149, or purchased from Japan Synthetic Rubber Company, model TDR104A, or purchased from Shanghai Sixin Industrial Co., Ltd., model LB420, or purchased from Shanghai Daoying Industrial Co., Ltd., model GD1331, or purchased from Shanghai Daoying Industrial Co., Ltd., model GD1346.

[0022] Preferably, the method for preparing the negative electrode slurry for sodium ion batteries is specifically as follows: Sodium carboxymethyl cellulose is mixed with deionized water, N-methyl pyrrolidone is added, and the mixture is stirred at a revolution rate of 20-40 rpm and a rotation rate of 2000-2400 rpm for 200-280 min. Conductive carbon black and hard carbon are added, and the mixture is stirred at a revolution rate of 20-40 rpm and a rotation rate of 0-10 rpm for 50-90 min. Pure water is then added, and the mixture is stirred at a revolution rate of 20-40 rpm and a rotation rate of 2000-2400 rpm for 40-80 min. The mixture is stirred at a revolution rate of 0-10 rpm and a rotation rate of 0-10 rpm for 10-30 min, and the mixture is cooled to 20-30° C. At 50-80° C., a binder and a functional agent are uniformly added at a rate of 10-15 g / min and stirred for 20-40 min. The mixture is subjected to vacuum degassing treatment to obtain a sodium ion battery negative electrode slurry.

[0023] More preferably, the ratio of conductive carbon black to sodium carboxymethyl cellulose is 1:1.2-1.5.

[0024] More preferably, sodium carboxymethyl cellulose is purchased from Changshu Weiyi Technology Co., Ltd. with a model number of BH2000 or purchased from Nippon Paper Manufacturing Co., Ltd. with a model number of 500LC.

[0025] More preferably, the ratio of conductive carbon black to deionized water is 1 g: 50-100 mL.

[0026] More preferably, the mass ratio of the conductive carbon black to N-methylpyrrolidone is 1:0.94-0.96.

[0027] More preferably, the mass ratio of the conductive carbon black to the hard carbon is 1:94-96.

[0028] More preferably, the usage ratio of the conductive carbon black to pure water is 1 g:5-20 mL.

[0029] More preferably, the mass ratio of the conductive carbon black to the binder is 1:2.5-3.5.

[0030] More preferably, the binder comprises styrene-butadiene rubber, and the functional agent comprises at least one of ethylene glycol bis(4-carboxyphenyl) ether, benzyl 5-hydroxyvalerate, and benzylaminoacetaldehyde diethanol acetal. The present invention further introduces benzylaminoacetaldehyde diethanol acetal into the sodium-ion negative electrode slurry, potentially improving the cycling stability of the sodium-ion battery by reducing interfacial impedance, minimizing irreversible capacity loss during the first cycle, and maintaining interfacial stability.

[0031] Further preferably, the styrene-butadiene rubber is purchased from Fujian Blue Ocean Black Stone New Material Technology Co., Ltd., model BA-149, or purchased from Japan Synthetic Rubber Company, model TDR104A, or purchased from Shanghai Sixin Industrial Co., Ltd., model LB420, or purchased from Shanghai Daoying Industrial Co., Ltd., model GD1331, or purchased from Shanghai Daoying Industrial Co., Ltd., model GD1346.

[0032] More preferably, the mass ratio of styrene-butadiene rubber to ethylene glycol bis(4-carboxyphenyl) ether is 1:0.2-0.7.

[0033] More preferably, the mass ratio of styrene-butadiene rubber to 5-hydroxybenzyl valerate is 1:0.1-0.3.

[0034] More preferably, the mass ratio of styrene-butadiene rubber to benzylaminoacetaldehyde diethyl acetal is 1:0.02-0.1.

[0035] The invention also discloses the sodium ion battery negative electrode slurry prepared by the preparation method.

[0036] The present invention also discloses a sodium ion battery, comprising a reference electrode, an electrode sheet, a glass fiber membrane and a high-voltage electrolyte; the reference electrode is metallic sodium, and the electrode sheet is formed by coating the above-mentioned sodium ion battery negative electrode slurry on copper foil.

[0037] The present invention also discloses a vehicle, comprising the above-mentioned sodium ion battery.

[0038] Since the present invention optimizes the preparation process of the sodium ion battery negative electrode slurry and adjusts the usage of styrene-butadiene rubber and sodium carboxymethyl cellulose, it has the following beneficial effects: the sodium ion battery negative electrode slurry prepared by the present invention exhibits good dispersibility and effectively suppresses the agglomeration phenomenon; at the same time, the cycle stability of the sodium ion battery is improved. When the sodium ion battery negative electrode slurry prepared by the present invention is cycled 1500 times, the capacity retention rate reaches 70%, which effectively improves the cycle stability of the sodium ion battery.

[0039] The present invention utilizes at least one of ethylene glycol bis(4-carboxyphenyl) ether, benzyl 5-hydroxyvalerate, and benzylaminoacetaldehyde diethyl acetal as a functional agent for preparing a negative electrode slurry for a sodium ion battery. This advantageous effect is achieved by: the sodium ion battery negative electrode slurry prepared by the present invention exhibits excellent electrochemical performance, with an initial coulombic efficiency of 78.4-90.3% and a capacity retention rate of 70-96% at the 1500th cycle. Therefore, the present invention provides a method for preparing a sodium ion battery negative electrode slurry with high initial coulombic efficiency and high capacity retention. The prepared sodium ion battery negative electrode slurry exhibits excellent electrochemical performance and has important application value in the field of new energy vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the SEM image of the electrode sheet. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0042] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are commercially available unless otherwise specified.

[0043] Example 1: A method for preparing a negative electrode slurry for a sodium ion battery comprises: Sodium carboxymethyl cellulose was mixed with deionized water, and N-methyl pyrrolidone was added. The mixture was stirred at 30 rpm and 2200 rpm for 240 min. Conductive carbon black and hard carbon were added and stirred at 30 rpm and 0 rpm for 70 min. Pure water was then added and stirred at 30 rpm and 2200 rpm for 60 min. The mixture was then stirred at 5 rpm and 0 rpm for 15 min and cooled to 30°C. Styrene-butadiene rubber was added at a constant rate of 10 g / min and stirred at 50°C for 30 min. The mixture was then vacuum degassed to obtain a negative electrode slurry for sodium ion batteries. Sodium carboxymethyl cellulose was purchased from Changshu Weiyi Technology Co., Ltd., model BH2000; styrene-butadiene rubber was purchased from Fujian Blue Ocean Black Stone New Materials Technology Co., Ltd., model BA-149. The mass ratio of conductive carbon black and sodium carboxymethyl cellulose is 1:1.2; the usage ratio of sodium carboxymethyl cellulose and deionized water is 1g:100mL; the mass ratio of conductive carbon black and N-methylpyrrolidone is 1:0.95; the mass ratio of conductive carbon black and hard carbon is 1:95; the usage ratio of conductive carbon black and pure water is 1g:10mL; the mass ratio of conductive carbon black and styrene-butadiene rubber is 1:2.5.

[0044] Example 2: A method for preparing a negative electrode slurry for a sodium ion battery comprises: Sodium carboxymethyl cellulose was mixed with deionized water, and N-methyl pyrrolidone was added. The mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 240 min. Conductive carbon black and hard carbon were added and stirred at a revolution rate of 30 rpm and a rotation rate of 0 rpm for 70 min. Pure water was then added and stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 60 min. The mixture was then stirred at a revolution rate of 5 rpm and a rotation rate of 0 rpm for 15 min and cooled to 30°C. Styrene-butadiene rubber was added at a constant rate of 10 g / min at 60°C and stirred for 30 min. The mixture was then vacuum degassed to obtain a negative electrode slurry for a sodium ion battery. Sodium carboxymethyl cellulose was purchased from Changshu Weiyi Technology Co., Ltd. under the model number BH2000; styrene-butadiene rubber was purchased from Fujian Blue Ocean Blackstone New Materials Technology Co., Ltd. under the model number BA-149. The mass ratio of conductive carbon black and sodium carboxymethyl cellulose is 1:1.2; the usage ratio of sodium carboxymethyl cellulose and deionized water is 1g:100mL; the mass ratio of conductive carbon black and N-methylpyrrolidone is 1:0.95; the mass ratio of conductive carbon black and hard carbon is 1:95; the usage ratio of conductive carbon black and pure water is 1g:10mL; the mass ratio of conductive carbon black and styrene-butadiene rubber is 1:2.5.

[0045] Example 3: A method for preparing a negative electrode slurry for a sodium ion battery comprises: Sodium carboxymethyl cellulose was mixed with deionized water, and N-methyl pyrrolidone was added. The mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 240 min. Conductive carbon black and hard carbon were added, and the mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 0 rpm for 70 min. Pure water was then added, and the mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 60 min. The mixture was then stirred at a revolution rate of 5 rpm and a rotation rate of 0 rpm for 15 min, and then cooled to 30°C. Styrene-butadiene rubber was added at a constant rate of 10 g / min at 70°C and stirred for 30 min. The mixture was then vacuum degassed to obtain a negative electrode slurry for a sodium ion battery. Sodium carboxymethyl cellulose was purchased from Changshu Weiyi Technology Co., Ltd., model BH2000; styrene-butadiene rubber was purchased from Fujian Blue Ocean Blackstone New Materials Technology Co., Ltd., model BA-149. The mass ratio of conductive carbon black and sodium carboxymethyl cellulose is 1:1.2; the usage ratio of sodium carboxymethyl cellulose and deionized water is 1g:100mL; the mass ratio of conductive carbon black and N-methylpyrrolidone is 1:0.95; the mass ratio of conductive carbon black and hard carbon is 1:95; the usage ratio of conductive carbon black and pure water is 1g:10mL; the mass ratio of conductive carbon black and styrene-butadiene rubber is 1:2.5.

[0046] Example 4: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd. with model number TDR104A. Other conditions are the same as those in Example 1.

[0047] Example 5: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as those in Example 2.

[0048] Example 6: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as those in Example 3.

[0049] Example 7: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber of model LB420 purchased from Shanghai Sixin Industrial Co., Ltd., and other conditions are the same as those in Example 1.

[0050] Example 8: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber of model LB420 purchased from Shanghai Sixin Industrial Co., Ltd., and other conditions are the same as those in Example 2.

[0051] Example 9: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber of model LB420 purchased from Shanghai Sixin Industrial Co., Ltd., and other conditions are the same as those in Example 3.

[0052] Example 10: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1331. Other conditions are the same as those in Example 1.

[0053] Example 11: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1331. Other conditions are the same as those in Example 2.

[0054] Example 12: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1331. Other conditions are the same as those in Example 3.

[0055] Example 13: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1346. Other conditions are the same as those in Example 1.

[0056] Example 14: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1346. Other conditions are the same as those in Example 2.

[0057] Example 15: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the styrene-butadiene rubber is replaced with styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1346. Other conditions are the same as those in Example 3.

[0058] Example 16: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced with 1:1.5. Other conditions are the same as those in Example 1.

[0059] Example 17: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced with 1:1.5. Other conditions are the same as those in Example 2.

[0060] Example 18: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced with 1:1.5. Other conditions are the same as those in Example 3.

[0061] Example 19: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd. with model TDR104A. Other conditions are the same as those in Example 1.

[0062] Example 20: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd. with model number TDR104A. Other conditions are the same as those in Example 2.

[0063] Example 21: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd. with model number TDR104A. Other conditions are the same as those in Example 3.

[0064] Example 22: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber model LB420 purchased from Shanghai Sixin Industrial Co., Ltd. Other conditions are the same as those in Example 1.

[0065] Example 23: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber model LB420 purchased from Shanghai Sixin Industrial Co., Ltd., and the other conditions are the same as those in Example 2.

[0066] Example 24: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber model LB420 purchased from Shanghai Sixin Industrial Co., Ltd., and the other conditions are the same as those in Example 3.

[0067] Example 25: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1331. Other conditions are the same as those in Example 1.

[0068] Example 26: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1331. Other conditions are the same as those in Example 2.

[0069] Example 27: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1331. Other conditions are the same as those in Example 3.

[0070] Example 28: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1346. Other conditions are the same as those in Example 1.

[0071] Example 29: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1346. Other conditions are the same as those in Example 2.

[0072] Example 30: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with model number GD1346. Other conditions are the same as those in Example 3.

[0073] Example 31: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that sodium carboxymethyl cellulose is replaced with sodium carboxymethyl cellulose of model 500LC purchased from Nippon Paper Industries, Ltd., and other conditions are the same as those in Example 1.

[0074] Example 32: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that sodium carboxymethyl cellulose is replaced with sodium carboxymethyl cellulose of model 500LC purchased from Nippon Paper Industries, Ltd., and other conditions are the same as those in Example 2.

[0075] Example 33: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that sodium carboxymethyl cellulose is replaced with sodium carboxymethyl cellulose of model 500LC purchased from Nippon Paper Industries, Ltd., and other conditions are the same as those in Example 3.

[0076] Example 34: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as those in Example 1.

[0077] Example 35: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Company, model TDR104A. Other conditions are the same as those in Example 2.

[0078] Example 36: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as those in Example 3.

[0079] Example 37: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Sixin Industrial Co., Ltd., model LB420, and other conditions are the same as Example 1.

[0080] Example 38: The preparation method of the negative electrode slurry of the sodium ion battery is compared with Example 2, except that the sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Sixin Industrial Co., Ltd., model LB420. Other conditions are the same as Example 2.

[0081] Example 39: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Sixin Industrial Co., Ltd., model LB420. Other conditions are the same as those in Example 3.

[0082] Example 40: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd., model GD1331. Other conditions are the same as those in Example 1.

[0083] Example 41: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd., model GD1331. Other conditions are the same as those in Example 2.

[0084] Example 42: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd., model GD1331. Other conditions are the same as those in Example 3.

[0085] Example 43: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd., model GD1346. Other conditions are the same as those in Example 1.

[0086] Example 44: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd., model GD1346. Other conditions are the same as those in Example 2.

[0087] Example 45: The preparation method of the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd., model GD1346. Other conditions are the same as those in Example 3.

[0088] Example 46: The preparation method of the negative electrode slurry for a sodium ion battery is as follows: compared with Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose model 500LC purchased from Nippon Paper Industries, Ltd., and the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced with 1:1.5, and other conditions are the same as Example 1.

[0089] Example 47: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose model 500LC purchased from Nippon Paper Industries, Ltd., and the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced with 1:1.5. Other conditions are the same as those in Example 2.

[0090] Example 48: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose model 500LC purchased from Nippon Paper Industries, Ltd., and the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced with 1:1.5. Other conditions are the same as those in Example 3.

[0091] Example 49: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 1, except that the sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as in Example 1.

[0092] Example 50: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 2, except that the sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as in Example 2.

[0093] Example 51: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 3, except that the sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd., model 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and the styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Japan Synthetic Rubber Co., Ltd., model TDR104A. Other conditions are the same as in Example 3.

[0094] Example 52: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Sixin Industrial Co., Ltd. with a model number of LB420. Other conditions are the same as in Example 1.

[0095] Example 53: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Sixin Industrial Co., Ltd. with a model number of LB420. Other conditions are the same as in Example 2.

[0096] Example 54: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black and sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Sixin Industrial Co., Ltd. with a model number of LB420. Other conditions are the same as in Example 3.

[0097] Example 55: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with a model number of GD1331. Other conditions are the same as in Example 1.

[0098] Example 56: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with a model number of GD1331. Other conditions are the same as in Example 2.

[0099] Example 57: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with a model number of GD1331. Other conditions are the same as in Example 3.

[0100] Example 58: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 1, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with a model number of GD1346. Other conditions are the same as in Example 1.

[0101] Example 59: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 2, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with a model number of GD1346. Other conditions are the same as in Example 2.

[0102] Example 60: The preparation method of the negative electrode slurry of the sodium ion battery is as follows: compared with Example 3, except that sodium carboxymethyl cellulose is replaced by sodium carboxymethyl cellulose purchased from Nippon Paper Industries, Ltd. with a model number of 500LC, the mass ratio of conductive carbon black to sodium carboxymethyl cellulose is replaced by 1:1.5, and styrene-butadiene rubber is replaced by styrene-butadiene rubber purchased from Shanghai Daoying Industrial Co., Ltd. with a model number of GD1346. Other conditions are the same as in Example 3.

[0103] Example 61: A method for preparing a negative electrode slurry for a sodium ion battery comprises: Sodium carboxymethyl cellulose was mixed with deionized water, N-methyl pyrrolidone was added, and the mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 240 min. Conductive carbon black and hard carbon were added, and the mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 0 rpm for 70 min. Pure water was then added, and the mixture was stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 60 min. The mixture was stirred at a revolution rate of 5 rpm and a rotation rate of 0 rpm for 15 min, and then cooled to 30° C. At 50° C., styrene-butadiene rubber, ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxyvaleric acid benzyl ester were uniformly added at a rate of 10 g / min. The styrene-butadiene rubber and ethylene glycol bis(4-carboxyphenyl) ether were stirred for 30 min, and vacuum degassing was performed to obtain a negative electrode slurry for a sodium ion battery. Sodium carboxymethyl cellulose was purchased from Nippon Paper Industries, Ltd., model 500LC; styrene-butadiene rubber was purchased from Shanghai Sixin Industrial Co., Ltd., model LB420; the mass ratio of conductive carbon black to sodium carboxymethyl cellulose was 1:1.2; the dosage ratio of sodium carboxymethyl cellulose to deionized water was 1 g:100 mL; the mass ratio of conductive carbon black to N-methylpyrrolidone was 1:0.95; the mass ratio of conductive carbon black to hard carbon was 1:95; the dosage ratio of conductive carbon black to pure water was 1 g:10 mL; the mass ratio of conductive carbon black to styrene-butadiene rubber was 1:2.5; the mass ratio of styrene-butadiene rubber to ethylene glycol bis(4-carboxyphenyl) ether was 1:0.7, and the mass ratio of styrene-butadiene rubber to 5-hydroxybenzyl valerate was 1:0.3.

[0104] Example 62: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 61, except that the mass ratio of styrene-butadiene rubber and ethylene glycol bis(4-carboxyphenyl) ether is replaced with 1:0.2. Other conditions are the same as those in Example 61.

[0105] Example 63: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 61, except that the mass ratio of styrene-butadiene rubber and 5-hydroxybenzyl valerate is replaced with 1:0.1. Other conditions are the same as those in Example 61.

[0106] Example 64: A method for preparing a negative electrode slurry for a sodium ion battery comprises: Sodium carboxymethyl cellulose is mixed with deionized water, N-methyl pyrrolidone is added, and the mixture is stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 240 minutes. Conductive carbon black and hard carbon are added, and the mixture is stirred at a revolution rate of 30 rpm and a rotation rate of 0 rpm for 70 minutes. Pure water is then added, and the mixture is stirred at a revolution rate of 30 rpm and a rotation rate of 2200 rpm for 60 minutes. The mixture is stirred at a revolution rate of 5 rpm and a rotation rate of 0 rpm for 15 minutes, and then cooled to 30° C. At 50° C., styrene-butadiene rubber, ethylene glycol bis(4-carboxyphenyl) ether, 5-hydroxyvaleric acid benzyl ester and benzylaminoacetaldehyde diethyl acetal are uniformly added at a rate of 10 g / min. The styrene-butadiene rubber and ethylene glycol bis(4-carboxyphenyl) ether are stirred for 30 minutes, and vacuum degassing is performed to obtain a negative electrode slurry for a sodium ion battery. Sodium carboxymethyl cellulose was purchased from Nippon Paper Industries, Ltd., model 500LC; styrene-butadiene rubber was purchased from Shanghai Sixin Industrial Co., Ltd., model LB420; the mass ratio of conductive carbon black to sodium carboxymethyl cellulose was 1:1.2; the dosage ratio of sodium carboxymethyl cellulose to deionized water was 1 g:100 mL; the mass ratio of conductive carbon black to N-methylpyrrolidone was 1:0.95; the mass ratio of conductive carbon black to hard carbon was 1:95; the dosage ratio of conductive carbon black to pure water was 1 g:10 mL; the mass ratio of conductive carbon black to styrene-butadiene rubber was 1:2.5; the mass ratio of styrene-butadiene rubber to ethylene glycol bis(4-carboxyphenyl) ether was 1:0.7, the mass ratio of styrene-butadiene rubber to benzyl 5-hydroxyvalerate was 1:0.3, and the mass ratio of styrene-butadiene rubber to benzylaminoacetaldehyde diethyl acetal was 1:0.1.

[0107] Example 65: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 64, except that the mass ratio of styrene-butadiene rubber and benzylaminoacetaldehyde diethyl acetal is changed to 1:0.02. Other conditions are the same as those in Example 64.

[0108] Comparative Example 1: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 61, except that 5-hydroxybenzyl valerate is not added. Other conditions are the same as those in Example 61.

[0109] Comparative Example 2: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 61, except that ethylene glycol bis(4-carboxyphenyl) ether is not added. Other conditions are the same as those in Example 61.

[0110] Comparative Example 3: The method for preparing the negative electrode slurry for a sodium ion battery is the same as that in Example 64, except that ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate are not added. Other conditions are the same as those in Example 64.

[0111] Comparative Example 4: The method for preparing the negative electrode slurry for a sodium ion battery is compared with Example 7, except that no styrene-butadiene rubber is added, and other conditions are the same as Example 7.

[0112] Experimental example: 1. Material characterization The sodium ion battery negative electrode slurry prepared in Example 64 was evenly coated on the surface of a copper foil and dried at 100° C. for 18 hours to obtain an electrode sheet. The surface morphology of the electrode sheet was observed using a scanning electron microscope.

[0113] Figure 1 is the SEM picture of the electrode sheet. Figure 1 It can be seen that in the sodium ion battery negative electrode slurry of the present invention, the hard carbon particles are uniformly attached to the surface of the electrode sheet, which shows that the sodium ion battery negative electrode slurry prepared by the present invention has good dispersibility.

[0114] 2. Agglomeration of negative electrode slurry The sodium ion battery negative electrode slurry prepared in Example 1-60 was collected to observe whether agglomeration occurred.

[0115] The sodium ion battery negative electrode slurries prepared in Examples 7, 10, 13, 19, 22-30, 37-45, 46, 49, and 52-60 of the present invention all exhibited good dispersibility and showed no agglomeration. This property helps ensure the stability of the sodium ion battery negative electrode slurry, not only maintaining its electrochemical performance and performance, but also helping to extend the battery's cycle life.

[0116] 3. Electrochemical performance test The sodium ion battery negative electrode slurries prepared in Example 7, Examples 61-65, and Comparative Examples 1-4 were collected and prepared into negative electrode sheets. The method for preparing the negative electrode sheets was as follows: the sodium ion battery negative electrode slurry was evenly coated on the surface of a copper foil and dried at 100°C for 18 hours to obtain an electrode sheet. A button cell was assembled using a metallic sodium reference electrode, the electrode sheet as a counter electrode, a glass fiber separator as a separator, and a high-voltage electrolyte as an electrolyte. The high-voltage electrolyte was purchased from Zhejiang Sodium Innovation Energy Co., Ltd. After the button cell was allowed to stand at room temperature for 12 hours, the cycle stability and first coulombic efficiency of the button cell were measured using a Xinwei multi-channel battery testing system.

[0117] Under 0.2C conditions, the button cell of Example 7 of the present invention maintained a capacity of 70% at the 1500th cycle, while the button cell of Comparative Example 4 maintained a capacity of 68% at the 200th cycle. This demonstrates that Example 7 of the present invention effectively improved the cycling stability of the button cell by optimizing the preparation conditions of the sodium-ion battery negative electrode slurry.

[0118] Table 1 Capacity retention rate (%)

[0119] Table 1 shows the capacity retention rate (%). As can be seen from Table 1, the capacity retention rates of Examples 61-63 of the present invention are higher than those of Example 7 because Examples 61-63 introduce ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate in the preparation of the negative electrode slurry for the sodium ion battery. The capacity retention rate of Example 61 is higher than that of Examples 62 and 63 because the amounts of ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate used in the preparation of the negative electrode slurry for the sodium ion battery are different. The capacity retention rate of Example 61 is higher than that of Comparative Examples 1 and 2 because Example 61 uses ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate in combination in the preparation of the negative electrode slurry for the sodium ion battery, while Comparative Example 1 uses ethylene glycol bis(4-carboxyphenyl) ether alone, and Comparative Example 2 uses 5-hydroxybenzyl valerate alone. This shows that compared with the use of ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate alone, the coordinated use of ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate as functional agents can effectively improve the capacity retention rate of the prepared sodium ion battery negative electrode slurry.

[0120] The capacity retention rate of Examples 64-65 of the present invention is higher than that of Example 61, because in the preparation of the negative electrode slurry of the sodium ion battery, Examples 64-65 further introduce benzylaminoacetaldehyde diethanol acetal into the functional agent; the capacity retention rate of Example 64 is higher than that of Example 65, because in the preparation of the negative electrode slurry of the sodium ion battery, the amount of benzylaminoacetaldehyde diethanol acetal used is different; the capacity retention rate of Example 64 is higher than that of Comparative Example 3, because in the preparation of the negative electrode slurry of the sodium ion battery, Comparative Example 3 uses benzylaminoacetaldehyde diethanol acetal alone, without using ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxyvaleric acid benzyl ester. This shows that in the preparation of the negative electrode slurry of the sodium ion battery, further introducing benzylaminoacetaldehyde diethanol acetal into the functional agent can further improve the capacity retention rate of the prepared sodium ion battery negative electrode slurry.

[0121] Table 2 First coulombic efficiency (%)

[0122] Table 2 shows the first coulombic efficiency (%). As can be seen from Table 2, the first coulombic efficiency of Examples 61-63 of the present invention is higher than that of Example 7 because Examples 61-63 introduce ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate in the preparation of the negative electrode slurry for the sodium ion battery. The first coulombic efficiency of Example 61 is higher than that of Examples 62 and 63 because the amounts of ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate used in the preparation of the negative electrode slurry for the sodium ion battery are different. The first coulombic efficiency of Example 61 is higher than that of Comparative Examples 1 and 2 because Example 61 uses ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate in combination in the preparation of the negative electrode slurry for the sodium ion battery, while Comparative Example 1 uses ethylene glycol bis(4-carboxyphenyl) ether alone, and Comparative Example 2 uses 5-hydroxybenzyl valerate alone. This shows that compared with the use of ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate alone, the synergistic use of ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate as functional agents can effectively improve the first coulombic efficiency of the prepared sodium ion battery negative electrode slurry.

[0123] The first coulombic efficiency of Examples 64-65 of the present invention is higher than that of Example 61, because in the preparation of the negative electrode slurry of the sodium ion battery, Examples 64-65 further introduce benzylaminoacetaldehyde diethanol acetal into the functional agent; the first coulombic efficiency of Example 64 is higher than that of Example 65, because in the preparation of the negative electrode slurry of the sodium ion battery, the amount of benzylaminoacetaldehyde diethanol acetal used is different; the first coulombic efficiency of Example 64 is higher than that of Comparative Example 3, because in the preparation of the negative electrode slurry of the sodium ion battery, Comparative Example 3 uses benzylaminoacetaldehyde diethanol acetal alone, without using ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxyvaleric acid benzyl ester. This shows that in the preparation of the negative electrode slurry of the sodium ion battery, further introducing benzylaminoacetaldehyde diethanol acetal into the functional agent can further improve the first coulombic efficiency of the prepared sodium ion battery negative electrode slurry.

[0124] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0125] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any changes and modifications made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a negative electrode slurry for a sodium ion battery, comprising adding conductive carbon black and hard carbon to a glue solution, uniformly adding a binder at a rate of 10-15 g / min and stirring for 20-40 minutes at 50-80°C, and vacuum degassing to obtain a negative electrode slurry for a sodium ion battery; the binder comprises styrene-butadiene rubber; in the preparation of the glue solution, sodium carboxymethyl cellulose is mixed with deionized water, and N-methyl pyrrolidone is added and stirred to obtain the glue solution; the mass ratio of the conductive carbon black to the sodium carboxymethyl cellulose is 1:1.2-1.

5.

2. The method for preparing a negative electrode slurry for a sodium ion battery according to claim 1, wherein: The mass ratio of the conductive carbon black to the hard carbon is 1:94-96.

3. The method for preparing a negative electrode slurry for a sodium ion battery according to claim 1, wherein: The mass ratio of the conductive carbon black to deionized water is 1 g:50-100 mL.

4. The method for preparing a negative electrode slurry for a sodium ion battery according to claim 1, wherein: The mass ratio of the conductive carbon black to the binder is 1:2.5-3.

5.

5. The method for preparing a negative electrode slurry for a sodium ion battery according to claim 1, wherein: In the preparation of the sodium ion battery negative electrode slurry, a binder and a functional agent are uniformly added at a rate of 10-15 g / min and stirred for 20-40 minutes at 50-80° C.; the binder is styrene-butadiene rubber; and the functional agent includes at least ethylene glycol bis(4-carboxyphenyl) ether and 5-hydroxybenzyl valerate.

6. The method for preparing a negative electrode slurry for a sodium ion battery according to claim 5, characterized in that: The mass ratio of the styrene-butadiene rubber to ethylene glycol bis(4-carboxyphenyl) ether is 1:0.2-0.

7.

7. The method for preparing a negative electrode slurry for a sodium ion battery according to claim 5, characterized in that: The mass ratio of the styrene-butadiene rubber to 5-hydroxybenzyl valerate is 1:0.1-0.

3.

8. A sodium ion battery negative electrode slurry prepared by the preparation method according to any one of claims 1 to 7.

9. A sodium ion battery comprising a reference electrode, an electrode sheet, a glass fiber membrane, and a high-voltage electrolyte; the reference electrode is metallic sodium, and the electrode sheet is formed by coating the sodium ion battery negative electrode slurry according to claim 8 on copper foil.

10. A vehicle comprising the sodium ion battery according to claim 9.

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