Two-component acrylate waterborne adhesive for hard carbon negative electrode of sodium-ion battery as well as preparation method and application of two-component acrylate waterborne adhesive

Abstract

The invention relates to the field of sodium-ion battery adhesives, in particular to a sodium-ion battery hard carbon negative electrode two-component acrylate water-based adhesive and a preparation method and application of the sodium-ion battery hard carbon negative electrode two-component acrylate water-based adhesive. The invention relates to a sodium ion battery hard carbon negative electrode two-component acrylate aqueous adhesive, which is prepared from the following raw materials in parts by mass: 40 to 70 parts of first acrylic polymer and 30 to 60 parts of second acrylic polymer. According to the preparation method of the sodium-ion battery hard carbon negative electrode two-component acrylate waterborne adhesive, through the specific combination of the first acrylic polymer and the second acrylic polymer and the specific preparation process, the obtained adhesive has excellent dispersing capacity, high cohesive strength and excellent flexibility. The adhesive can effectively solve the problem of single performance of the existing adhesive, improves the bonding strength and softness of a hard carbon negative electrode material and an electrode plate, improves the first coulombic efficiency, reduces the impedance, and further improves the performance and stability of the electrode. Meanwhile, the preparation method is simple and easy to implement and suitable for large-scale production.

Description

Technical Field

[0001] The present application relates to the field of sodium ion battery adhesives, and in particular to a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, and a preparation method and application thereof. Background Art

[0002] As a new type of energy storage device, the research on negative electrode materials of sodium ion batteries has attracted increasing attention. Hard carbon materials are widely used as negative electrodes of sodium ion batteries due to their high capacity and good rate performance. However, hard carbon materials have small particle size and many pores, resulting in large specific surface area and low compaction density, which brings challenges to electrode preparation. At present, although commonly used hard carbon negative electrode binders such as CMC+SBR combination have good flexibility, they have limited adsorption and dispersion effects on hard carbon materials, and the point connection method of SBR makes it difficult to form a strong bond between hard carbon particles, which easily leads to the phenomenon of "powder falling" of the pole piece. Although acrylic water-based binders have good dispersibility, high cohesive strength, and are not easy to "powder fall", their hardness is relatively high, which can easily cause the pole piece to crack during processing, making it difficult to achieve a high compaction density.

[0003] Therefore, it is necessary to develop a new type of adhesive to solve the problems of poor dispersibility, insufficient cohesive strength and poor flexibility of existing adhesives in the application of hard carbon negative electrode materials for sodium ion batteries, so as to meet the comprehensive requirements of hard carbon negative electrode materials for sodium ion batteries for high dispersibility, high cohesive strength and good flexibility. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present application provides a sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive and its preparation method and application. The sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive prepared in the present application combines excellent dispersion ability, high cohesive strength and excellent flexibility, solving the problem of single performance of existing adhesives; the second hydrophobic monomer has a relatively low glass transition temperature, and the prepared second acrylic polymer has relatively more flexible mechanical properties while ensuring that the adhesive maintains a high bonding force. The second acrylic polymer significantly improves the affinity and compatibility of the aqueous adhesive with the hard carbon negative electrode material, improves the bonding strength and softness of the hard carbon negative electrode material and the electrode sheet, and improves the first coulomb efficiency and reduces impedance, thereby improving the performance and stability of the electrode. At the same time, the preparation method of the present application is simple and easy, and is suitable for large-scale production.

[0005] In the first aspect, the present application provides a sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, using the following technical solution: A sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, based on a total mass of 100 parts, the preparation raw materials include: 40-70 parts of a first acrylic polymer, 30-60 parts of a second acrylic polymer, wherein the preparation method of the first acrylic polymer is: 1 The first hydrophilic monomer of COOM has the chemical formula R 2 CH=CHR 3 The first hydrophobic monomer of CN and deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, and when the water bath is heated to 70-80°C, the first water-soluble initiator solution is added dropwise, and the constant temperature reaction is continued for 4-10 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature drops below 40°C to obtain a first acrylic polymer; the preparation method of the second acrylic polymer is: a surfactant, a protective gel and deionized water are added to a reaction kettle and mixed evenly, and then a chemical formula of CH2=CR 1 The second hydrophilic monomer of COOM, the chemical formula is CH2=CHCOOR 4 The second hydrophobic monomer is added into the reaction kettle, stirred and nitrogen is passed to remove oxygen, and when the water bath temperature is raised to 60-70°C, the second water-soluble initiator solution is added dropwise, and the constant temperature reaction is continued for 2-8 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature drops below 40°C to obtain a second acrylic polymer; the mass concentration of the first water-soluble initiator solution and the second water-soluble initiator solution is uniformly 5%; R 1 is independently selected from one of H or C1-C4 alkyl, or one of amides; M is selected from at least one of H, Li, Na, and K; R 2 independently selected from H or methyl; R 3 is absent or selected from one of C1-C4 alkyl groups; R 4 One selected from C2-C22 alkyl groups, or one selected from C2-C22 substituted alkyl groups.

[0006] By adopting the above technical scheme, the first acrylic polymer and the second acrylic polymer: these two polymers are the main components of the adhesive, and they together provide excellent dispersibility, high cohesive strength and excellent flexibility. The first acrylic polymer has a high bonding force, while the second acrylic polymer has a relatively low glass transition temperature, so that the prepared adhesive has relatively more flexible mechanical properties while maintaining a high bonding force. Hydrophilic monomer and hydrophobic monomer: these monomers are used to prepare the first acrylic polymer and the second acrylic polymer respectively. The hydrophilic monomer helps to improve the affinity and compatibility of the adhesive with the hard carbon negative electrode material, while the hydrophobic monomer helps to improve the flexibility of the adhesive. Surfactant: The addition of a special component surfactant can improve the compatibility and dispersibility of the second acrylic polymer, and ultimately improve the bonding strength and softness of the hard carbon negative electrode material and the electrode sheet. Protective glue: The protective glue helps to stabilize the performance of the adhesive and prevent it from unstable changes during the preparation process. Deionized water: As a solvent, deionized water helps to fully mix the components to form a uniform adhesive. Water-soluble initiator solution: During the preparation process, the water-soluble initiator solution plays a role in initiating the polymerization reaction, prompting each monomer to polymerize into a polymer. In summary, the two-component acrylic acid ester aqueous adhesive for the hard carbon negative electrode of the sodium ion battery in this application achieves excellent dispersion ability, high cohesive strength and excellent flexibility through the synergistic effect of each component, solving the problem of the single performance of the existing adhesive. At the same time, the adhesive is suitable for large-scale production and has high practical value.

[0007] Preferably, the mass ratio of the first hydrophilic monomer, the first hydrophobic monomer, the first water-soluble initiator solution and deionized water is (10-14):(24-30):(10-18):(150-200).

[0008] Preferably, the mass ratio of the second hydrophilic monomer, the second hydrophobic monomer, the second water-soluble initiator solution, the surfactant, the protective colloid and the deionized water is (8-12):(35-40):(9-16):(0.8-1.2):(1-1.5):(150-200).

[0009] Preferably, the first hydrophilic monomer and the second hydrophilic monomer are both selected from at least one of acrylic acid (AA), methacrylic acid (MAA), sodium acrylate (AANa), sodium methacrylate (MAANa) and acrylamide.

[0010] Preferably, the first hydrophobic monomer is selected from at least one of acrylonitrile, methacrylonitrile and 3-butenenitrile.

[0011] Preferably, the second hydrophobic monomer is selected from soft monomers with a Tg lower than -10°C, specifically at least one selected from butyl acrylate, octyl acrylate, isooctyl acrylate, hexyl acrylate, lauryl acrylate, and hydroxyethyl acrylate.

[0012] Preferably, the second hydrophobic monomer is composed of butyl acrylate, isooctyl acrylate and lauryl acrylate in a mass ratio of 5:3:4.

[0013] By adopting the above technical solution, the second hydrophobic monomer is selected from soft monomers with a Tg lower than -10°C, and is composed of butyl acrylate, isooctyl acrylate and lauryl acrylate in a mass ratio of 5:3:4. This combination is selected to achieve the following effects: Lowering the glass transition temperature (Tg): By selecting a soft monomer with a Tg lower than -10°C, the glass transition temperature of the entire adhesive can be lowered, so that it still has good flexibility at low temperatures. This is crucial for the performance of the battery in low temperature environments. Improve flexibility: Butyl acrylate, isooctyl acrylate and lauryl acrylate all have a lower glass transition temperature, and the synergistic effect between them can make the adhesive have more flexible mechanical properties while maintaining a high bonding force. This helps to improve the bonding strength and softness of the electrode sheet and the hard carbon negative electrode material, thereby improving the performance and stability of the electrode. Improve the first coulomb efficiency and reduce impedance: By adding a special component surfactant, the compatibility and dispersibility of the second acrylic polymer are improved, which ultimately improves the bonding strength and softness between the hard carbon negative electrode material and the electrode sheet, and improves the first coulomb efficiency and reduces impedance, thereby improving the performance and stability of the electrode. In short, by selecting a suitable second hydrophobic monomer combination (butyl acrylate, isooctyl acrylate and lauryl acrylate), the performance of the binder is optimized, the performance and stability of the electrode are improved, and the needs of large-scale production are met.

[0014] Preferably, the protective colloid is one or a mixture of two of sodium polyacrylate, sodium carboxymethyl cellulose, hydroxyethyl cellulose and polyvinyl alcohol, and the initiator is one of ammonium persulfate, potassium persulfate and sodium persulfate.

[0015] Preferably, the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octylphenol polyoxyethylene (10) ether in a mass ratio of 3:5:6.

[0016] By adopting the above technical scheme, sodium dodecylbenzene sulfonate is an anionic surfactant with good cleaning, emulsification, wetting and other properties, which can improve the dispersibility of the second acrylic polymer and form a uniform coating on the electrode sheet. Polyvinyl pyrrolidone K30 is a nonionic surfactant with good stability, wetting, adhesion and other properties, which can improve the compatibility of the second acrylic polymer and make it better combined with the hard carbon negative electrode material. Octylphenol polyoxyethylene (10) ether is a nonionic surfactant with good wetting, penetration, emulsification and other properties, which can improve the fluidity of the second acrylic polymer and form a uniform coating on the electrode sheet. Sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octylphenol polyoxyethylene (10) ether, through their respective complementary properties and synergistic effects, jointly improve the compatibility and dispersibility of the second acrylic polymer, thereby improving the bonding strength and softness between the hard carbon negative electrode material and the electrode sheet, and improving the first coulomb efficiency and reducing impedance, thereby improving the performance and stability of the electrode.

[0017] In a second aspect, the present application provides a method for preparing a two-component acrylic acid ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery, using the following technical solution: As a general technical concept, the present application also provides a method for preparing the above-mentioned sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, comprising the following steps: The pH of the first acrylic polymer and the second acrylic polymer were pre-adjusted to 7-9 by weight, and then the two were mixed and stirred for 20-30 minutes to prepare a two-component acrylic ester aqueous adhesive for the hard carbon negative electrode of a sodium ion battery.

[0018] In a third aspect, the present application provides an application of a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, using the following technical solution: As a general technical concept, the present application also provides the use of the above-mentioned two-component acrylic ester aqueous adhesive for the hard carbon negative electrode of a sodium ion battery in the hard carbon negative electrode of a sodium ion battery.

[0019] By adopting the above-mentioned technical scheme and the two-component acrylic aqueous adhesive for the hard carbon negative electrode of the sodium ion battery provided in this application, the bonding strength and softness between the hard carbon negative electrode material and the electrode sheet are improved, and the first coulombic efficiency is improved and the impedance is reduced, thereby improving the performance and stability of the electrode.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. By preparing a first acrylic polymer and a second acrylic polymer, the performance of a two-component acrylic ester water-based binder for a hard carbon negative electrode of a sodium ion battery is optimized. This optimization is mainly reflected in the dispersion ability, cohesive strength and flexibility of the binder, so that the binder has better performance in practical applications.

[0021] 2. The introduction of the second hydrophobic monomer makes the second acrylic polymer have a relatively low glass transition temperature, thereby ensuring that the binder has a high bonding force while also having more flexible mechanical properties. This helps to improve the affinity and compatibility of the aqueous binder with the hard carbon negative electrode material, thereby improving the bonding strength and softness of the hard carbon negative electrode material and the electrode sheet.

[0022] 3. The preparation method of the present application is simple and easy to implement, and is suitable for large-scale production. This makes the technical solution of the present application have high practical value and is conducive to promoting the development and application of hard carbon negative electrode materials for sodium ion batteries.

[0023] 4. Adding a special component surfactant further improves the compatibility and dispersibility of the second acrylic polymer. This helps to ultimately improve the bonding strength and softness between the hard carbon negative electrode material and the electrode sheet, and improve the first coulomb efficiency and reduce impedance, thereby improving the performance and stability of the electrode. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0025] Example 1 A sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, the preparation raw materials include: a first acrylic polymer 40g, a second acrylic polymer 60g, wherein the first acrylic polymer is prepared by: 10g acrylic acid (AA), 24g acrylonitrile and 150g deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, when the water bath is heated to 70°C, 10g of a 5% ammonium persulfate aqueous solution is added dropwise, and the reaction is continued at a constant temperature for 4 hours after the addition, and then the reaction is stopped by cooling, and the material is discharged when the temperature drops to 35°C to obtain the first acrylic polymer; the second acrylic polymer is prepared by: The preparation method is as follows: 0.8 g of a surfactant (the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octylphenol polyoxyethylene (10) ether in a mass ratio of 3:5:6), 1 g of sodium polyacrylate and 150 g of deionized water are added to a reaction kettle and mixed evenly, then 8 g of acrylic acid (AA) and 35 g of butyl acrylate are added to the reaction kettle, stirred and nitrogen is passed through to remove oxygen, and when the water bath is heated to 60° C., 9 g of an aqueous solution of ammonium persulfate with a mass concentration of 5% is added dropwise, and after the addition is completed, the reaction is continued at a constant temperature for 2 hours, and then the reaction is stopped by cooling, and when the temperature is reduced to 40° C., the material is discharged to obtain a second acrylic polymer; The above-mentioned method for preparing a two-component acrylic ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery comprises the following steps: pre-adjusting the pH of a first acrylic polymer and a second acrylic polymer to 7 in parts by mass, respectively, and then mixing and stirring the two for 20 minutes to obtain a two-component acrylic ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery.

[0026] Example 2 A sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, the preparation raw materials include: a first acrylic polymer 70g, a second acrylic polymer 30g, wherein the first acrylic polymer is prepared by: 14g methacrylic acid (MAA), 30g methacrylonitrile and 200g deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, when the water bath is heated to 80°C, 18g of a 5% potassium persulfate aqueous solution is added dropwise, the constant temperature reaction is continued for 10 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature drops to 40°C to obtain the first acrylic polymer; the preparation of the second acrylic polymer The method comprises the following steps: adding 1.2 g of a surfactant (the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octylphenol polyoxyethylene (10) ether in a mass ratio of 3:5:6), 1.5 g of sodium carboxymethyl cellulose and 200 g of deionized water into a reaction kettle and mixing them evenly, then adding 12 g of methacrylic acid (MAA) and 40 g of octyl acrylate into the reaction kettle, stirring and passing nitrogen to remove oxygen, and then dripping 16 g of a 5% potassium persulfate aqueous solution when the water bath is heated to 70° C., continuing the constant temperature reaction for 8 hours after the dripping, then cooling to stop the reaction, and discharging the material when the temperature drops to 40° C. to obtain a second acrylic polymer; The above-mentioned method for preparing a two-component acrylic ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery comprises the following steps: pre-adjusting the pH of a first acrylic polymer to 9 and a second acrylic polymer to 9 according to their mass fractions, respectively, and then mixing and stirring the two for 30 minutes to obtain a two-component acrylic ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery.

[0027] Example 3 A sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, the preparation raw materials include: a first acrylic polymer 50g, a second acrylic polymer 50g, wherein the first acrylic polymer is prepared by: 13g sodium acrylate, 27g 3-butenenitrile and 180g deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, when the water bath is heated to 75°C, 15g of a 5% sodium persulfate aqueous solution is added dropwise, and the constant temperature reaction is continued for 6 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature is lowered to 38°C to obtain the first acrylic polymer; the second acrylic polymer is prepared by: 1g of a surfactant (the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octane) is added to a reaction kettle; 1.2g of hydroxyethyl cellulose and 180g of deionized water are mixed evenly, and then 10g of sodium acrylate (AANa) and 37g of isooctyl acrylate are added into the reaction kettle, stirred and nitrogen is passed through to remove oxygen, and when the water bath is heated to 65°C, 13g of a 5% sodium persulfate aqueous solution is added dropwise, and the reaction is continued at a constant temperature for 5 hours after the addition is completed, and then the reaction is stopped by cooling. When the temperature drops to 37°C, the material is discharged to obtain a second acrylic polymer; The above-mentioned method for preparing a two-component acrylic ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery comprises the following steps: pre-adjusting the pH of a first acrylic polymer to 8 and a second acrylic polymer to 8 according to their mass fractions, respectively, and then mixing and stirring the two for 25 minutes to obtain a two-component acrylic ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery.

[0028] Example 4 A sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, the preparation raw materials include: a first acrylic polymer 50g, a second acrylic polymer 50g, wherein the first acrylic polymer is prepared by: 3g acrylic acid (AA), 7g sodium methacrylate (MAANa), 4g acrylamide, 26g acrylonitrile and 190g deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, when the water bath is heated to 75°C, 16g of 5% mass concentration of ammonium persulfate, potassium persulfate and sodium persulfate aqueous solution is added dropwise, and after the addition is completed, the constant temperature reaction is continued for 7 hours, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature drops to 36°C to obtain the first acrylic polymer; the second acrylic polymer is discharged when the temperature drops to 36°C to obtain the first acrylic polymer; The preparation method is as follows: 1.1g of a surfactant (the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octylphenol polyoxyethylene (10) ether in a mass ratio of 3:5:6), 1.3g of polyvinyl alcohol and 180g of deionized water are added to a reactor and mixed evenly, and then 4g of acrylic acid (AA), 5g of sodium acrylate (AANa), 4g of sodium methacrylate (MAANa) and 36g of hexyl acrylate are added to the reactor, stirred and nitrogen is passed through to remove oxygen, and when the water bath is heated to 65°C, 12g of a 5% ammonium persulfate aqueous solution is added dropwise, and the reaction is continued at a constant temperature for 5 hours after the addition is completed, and then the reaction is stopped by cooling, and the material is discharged when the temperature drops to 38°C to obtain a second acrylic polymer; The above-mentioned method for preparing a two-component acrylic acid ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery comprises the following steps: pre-adjusting the pH of a first acrylic acid polymer and a second acrylic acid polymer to 8.3 in parts by mass, respectively, and then mixing and stirring the two for 25 minutes to obtain a two-component acrylic acid ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery.

[0029] Example 5 A sodium ion battery hard carbon negative electrode two-component acrylic ester aqueous adhesive, the preparation raw materials include: a first acrylic polymer 50g, a second acrylic polymer 50g, wherein the first acrylic polymer is prepared by: 4g acrylic acid (AA), 3g methacrylic acid (MAA), 5g sodium methacrylate (MAANa), 25g 3-butenenitrile and 180g deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, when the water bath is heated to 75°C, 14g of a 5% ammonium persulfate aqueous solution is added dropwise, and the constant temperature reaction is continued for 6 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature is lowered to 37°C to obtain the first acrylic polymer; the second acrylic polymer is prepared by: 1g of a surfactant (the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K3 0 and octylphenol polyoxyethylene (10) ether in a mass ratio of 3:5:6), 1.2g of sodium carboxymethyl cellulose and 180g of deionized water are mixed evenly, then 9g of acrylamide and 37g of hydroxyethyl acrylate are added into the reaction kettle, stirred and nitrogen is passed through to remove oxygen, when the water bath is heated to 65°C, 12g of a 5% sodium persulfate aqueous solution is added dropwise, and the reaction is continued at a constant temperature for 5 hours after the addition is completed, and then the reaction is stopped by cooling, and the material is discharged when the temperature drops to 38°C to obtain a second acrylic polymer; The above-mentioned method for preparing a two-component acrylic acid ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery comprises the following steps: pre-adjusting the pH of a first acrylic acid polymer and a second acrylic acid polymer to 7.3 in parts by mass, respectively, and then mixing and stirring the two for 25 minutes to obtain a two-component acrylic acid ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery.

[0030] Example 6 The same as Example 5, except that an equal amount of a second hydrophobic monomer (composed of butyl acrylate, isooctyl acrylate and lauryl acrylate in a mass ratio of 5:3:4) is used instead of hydroxyethyl acrylate.

[0031] Comparative Example 1 The same as Example 6, except that an equal amount of butyl acrylate is used to replace the second hydrophobic monomer.

[0032] Comparative Example 2 The same as Example 6, except that an equal amount of isooctyl acrylate is used to replace the second hydrophobic monomer.

[0033] Comparative Example 3 The same as Example 6, except that an equal amount of lauryl acrylate is used to replace the second hydrophobic monomer.

[0034] Comparative Example 4 The same as Example 6, except that the surfactant is sodium dodecylbenzene sulfonate.

[0035] Comparative Example 5 The same as Example 6, except that the surfactant is polyvinyl pyrrolidone K30.

[0036] Comparative Example 6 The same as Example 6, except that the surfactant is octylphenol polyoxyethylene (10) ether.

[0037] Performance testing Test Method The preparation method of hard carbon negative electrode slurry and pole piece is as follows: dry weight ratio of hard carbon formula slurry, two-component acrylic ester aqueous binder: SP: hard carbon negative electrode material (425mAh / g) = 3.5:1:95.5.

[0038] In the slurry preparation process, the amount of water added is calculated based on the solid content of the negative electrode slurry before the viscosity is adjusted, which is 45%. Take 3.5 parts of the two-component acrylic acid ester aqueous binder for the hard carbon negative electrode of the sodium ion battery prepared in Examples 1-6 and Comparative Examples 1-6 respectively, mix them with 50% of water, disperse them at 300rpm for 15 minutes, add 1 part of SP conductive carbon black, stir them at 150rpm for 10 minutes, and then stir them at 800rpm for 120 minutes; adjust the speed down to 300rpm, add 50% of the hard carbon negative electrode material, disperse them for 10 minutes, add the remaining 50% of the hard carbon negative electrode material and the remaining 50% of the water, disperse them for 10 minutes, and then stir them at 800rpm for 120 minutes. After high-speed stirring, adjust the viscosity (25℃) between 3000 and 4000mPa·s, filter the material with a 150-mesh filter to obtain the negative electrode slurry.

[0039] In the preparation process of the CMC+SRS comparative slurry, the amount of water added is calculated based on the solid content of the slurry before the viscosity of the negative electrode slurry is adjusted to 45%. 1.75 parts of CMC and 50% of water are mixed, dispersed at 300rpm for 15 minutes, and then 1 part of SP conductive carbon black is added, stirred at 150rpm for 10 minutes, and then stirred at 800rpm for 120 minutes; the speed is lowered to 300rpm, 50% of hard carbon negative electrode material is added, dispersed for 10 minutes, and then the remaining 50% of hard carbon negative electrode material and the remaining 50% of water are added and dispersed for 10 minutes, followed by high-speed stirring at 800rpm for 120 minutes. After high-speed stirring, the viscosity (25℃) is adjusted to between 3000 and 4000mPa·s, and then 1.75 parts of SBR are added, dispersed at 500rpm for 30min, and then filtered with a 150-mesh filter to complete the discharge, and the CMC+SRS comparative negative electrode slurry is obtained.

[0040] During the electrode preparation process, place the copper foil on the coating machine, adjust the scraper scale of the wet film preparation machine, evenly pour the filtered slurry, send it into a 100°C environment and bake it until dry, cut it into 12.5cm×5cm specifications, and the single-sided surface density is 100-110g / m 2 The pole piece.

[0041] Test method for solid content of slurry: take a container made of tin foil and weigh its weight with an electronic balance as m1, peel it and weigh the weight of the slurry as m2 (1.0000g≤m2≤1.1000g), put the container containing the slurry into a 150℃ forced air oven and dry it for 30 minutes, take out the container and weigh its weight as m3, the solid content of slurry = (m3-m1) / m2*100%.

[0042] Pole peeling force test method: Place the cut pole pieces in a 35% RH constant temperature room for 30 minutes. Place the two pole pieces together with the coating facing outward and the copper foil facing inward, and place them in an electric roller press to roll the pole pieces to a compaction density of 0.95g / cm 3 , and then place it for 30 minutes after rolling. During this period, select five 12.5cm×5cm stainless steel plates, stick double-sided tape of corresponding specifications on the stainless steel plates, and then stick the electrode on the double-sided tape with the coating facing down, and then stick a 2.5cm wide masking tape on the copper foil. The electrode steel plate is rolled back and forth by an electric rolling roller with a certain pressure (1kg) for one week, and then an electronic stripping machine is used to test the adhesion of the electrode; the same method as above, only the electrode is attached to the double-sided tape with the coating facing up to test the cohesion of the electrode.

[0043] The softness is tested using the softness tester IMT-RRD01*1. The smaller the value, the softer the electrode is.

[0044] Electrode resistivity test method: Use a BER2500 electrode resistor to test the electrode resistivity.

[0045] The assembly sequence of the button battery is from bottom to top: negative electrode shell - spring - gasket - lithium sheet - electrolyte - diaphragm - electrolyte - electrode sheet - positive electrode shell; the first coulomb efficiency and impedance test are as follows: first efficiency test 0.1C, 0.005-1.5V charge and discharge; impedance scan from 100kHz to 0.1Hz.

[0046] Table 1 Performance test Analyzing the data in Table 1, we can see that: 1) The two-component acrylic acid ester aqueous adhesives prepared in Examples 1 to 6 have excellent dispersibility, high cohesive strength and excellent flexibility, which solves the problem of single performance of existing adhesives; the two-component acrylic acid ester aqueous adhesives improve the bonding strength and softness between the hard carbon negative electrode material and the electrode sheet, and improve the first coulombic efficiency and reduce impedance, thereby improving the performance and stability of the electrode.

[0047] 2) A comparative analysis of the performance of the two-component acrylic acid ester aqueous adhesives prepared in combination with Example 6 and Comparative Examples 1 to 3 shows that the use of a second hydrophobic monomer composed of butyl acrylate, isooctyl acrylate and lauryl acrylate in a mass ratio of 5:3:4, and the synergistic effect therebetween enables the two-component acrylic acid ester aqueous adhesive to have more flexible mechanical properties while maintaining a high bonding force, thereby optimizing the performance of the two-component acrylic acid ester aqueous adhesive, improving the performance and stability of the electrode, and meeting the needs of large-scale production.

[0048] 3) A comparative analysis of the performance of the two-component acrylic acid ester aqueous adhesives prepared in combination with Example 6 and Comparative Examples 4 to 6 shows that the surfactant is composed of sodium dodecylbenzene sulfonate, polyvinyl pyrrolidone K30 and octylphenol polyoxyethylene (10) ether in a mass ratio of 3:5:6. Through the complementary and synergistic effects of their respective properties, the compatibility and dispersibility of the second acrylic acid polymer are jointly improved, thereby improving the bonding strength and softness of the hard carbon negative electrode material and the electrode sheet, and improving the first coulomb efficiency and reducing the impedance, thereby improving the performance and stability of the electrode.

[0049] The above embodiments are only used to explain the technical solutions of the present application rather than to limit them. Although the above embodiments provide a specific description of the present application, relevant technical personnel should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents, and any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the protection scope of the present application.

Claims

1. A two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The raw materials for preparation include 40-70 parts of a first acrylic polymer and 30-60 parts of a second acrylic polymer, based on 100 parts by total weight. The preparation method of the first acrylic polymer is as follows: 2 =CR 1 The first hydrophilic monomer of COOM has the chemical formula R 2 CH=CHR 3 The first hydrophobic monomer of CN and deionized water are added to a reaction bottle, stirred and nitrogen is passed to remove oxygen, and when the water bath is heated to 70-80°C, the first water-soluble initiator solution is added dropwise, and the reaction is continued at a constant temperature for 4-10 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature drops below 40°C to obtain a first acrylic polymer; the preparation method of the second acrylic polymer is: a surfactant, a protective gel and deionized water are added to a reaction kettle and mixed evenly, and then a chemical formula of CH 2 =CR 1 The second hydrophilic monomer of COOM has the chemical formula CH 2 =CHCOOR 4 The second hydrophobic monomer is added into the reaction kettle, stirred and nitrogen is passed to remove oxygen, and when the water bath temperature rises to 60-70°C, the second water-soluble initiator solution is added dropwise, and the reaction is continued at a constant temperature for 2-8 hours after the addition, and then the temperature is lowered to stop the reaction, and the material is discharged when the temperature drops below 40°C to obtain a second acrylic polymer; the mass concentration of the first water-soluble initiator solution and the second water-soluble initiator solution is uniformly 5%; R 1 is independently selected from one of H or C1-C4 alkyl, or one of amides; M is selected from at least one of H, Li, Na, and K; R 2 independently selected from H or methyl; R 3 is absent or selected from one of C1-C4 alkyl groups; R 4 One selected from C2-C22 alkyl groups, or one selected from C2-C22 substituted alkyl groups.

2. According to claim 1, a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The mass ratio of the first hydrophilic monomer, the first hydrophobic monomer, the first water-soluble initiator solution and deionized water is (10-14): (24-30): (10-18): (150-200).

3. According to claim 1, a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The mass ratio of the second hydrophilic monomer, the second hydrophobic monomer, the second water-soluble initiator solution, the surfactant, the protective colloid and the deionized water is (8-12): (35-40): (9-16): (0.8-1.2): (1-1.5): (150-200).

4. According to claim 1, a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The first hydrophilic monomer and the second hydrophilic monomer are both selected from at least one of acrylic acid, methacrylic acid, sodium acrylate, sodium methacrylate and acrylamide.

5. According to claim 1, a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The first hydrophobic monomer is selected from at least one of acrylonitrile, methacrylonitrile and 3-butenenitrile.

6. According to claim 1, a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The second hydrophobic monomer is selected from soft monomers with a Tg lower than -10°C, specifically at least one selected from butyl acrylate, octyl acrylate, isooctyl acrylate, hexyl acrylate, lauryl acrylate, and hydroxyethyl acrylate.

7. According to claim 1, a two-component acrylic acid ester aqueous adhesive for a sodium ion battery hard carbon negative electrode, It is characterized in that The initiator is one of ammonium persulfate, potassium persulfate and sodium persulfate.

8. A method for preparing a two-component acrylic acid ester aqueous adhesive for a hard carbon negative electrode of a sodium ion battery as claimed in any one of claims 1 to 7, It is characterized in that The following steps are involved: The pH of the first acrylic polymer and the second acrylic polymer were pre-adjusted to 7-9 by weight, and then the two were mixed and stirred for 20-30 minutes to prepare a two-component acrylic ester aqueous adhesive for hard carbon negative electrode of sodium ion battery.

9. Use of a two-component acrylic acid ester aqueous binder for a sodium ion battery hard carbon negative electrode as claimed in any one of claims 1 to 7 in a sodium ion battery hard carbon negative electrode.

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