Photo-crosslinked polyacrylic acid-based water-based binder as well as preparation method and application of photo-crosslinked polyacrylic acid-based water-based binder

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a photo-crosslinked polyacrylic acid-based water-based binder and a preparation method and application thereof.The polyacrylic acid-based water-based binder is abbreviated as AA-MEA-CMCS / DES, choline chloride and urea are dissolved in deionized water and stirred in a water bath at the temperature of 80-90 DEG C to form a deep eutectic solvent, and then the deep eutectic solvent is added into a water bath at the temperature of 80-90 DEG C to be stirred to form the photo-crosslinked polyacrylic acid-based water-based binder. The preparation method comprises the following steps: adding an acrylic monomer and an ethanolamine monomer, stirring, adding a photoinitiator and carboxymethyl chitosan, stirring until complete dissolution, and irradiating the mixed solution with a mixed light source of 395 nm and 365 nm. The binder has excellent water solubility, ionic conductivity and flexibility, can effectively restrain the problem of volume expansion of a silicon-based negative electrode in the cycle process, remarkably improves the cycle stability of a battery, and can be applied to the field of lithium ion batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and more specifically, relates to a photocrosslinked polyacrylic acid-based aqueous binder, a preparation method thereof, and an application thereof. Background Art

[0002] Constructing a new energy storage system with high energy density, environmental friendliness and economy is the core requirement to promote the innovation of the portable electronic device and electric vehicle industries. As the most competitive energy storage carrier at present, the continuous breakthrough of the energy density of lithium-ion batteries directly determines the improvement of the battery life of terminal devices. However, the commercial graphite negative electrode significantly restricts the iterative upgrade of battery performance due to its lithium storage capacity (372 mAhg -1 ), which has approached the theoretical limit. Developing a new energy storage system with low cost, environmental friendliness and high energy density is of great significance for promoting the industrialization of portable electronic devices and electric vehicles. In this context, silicon-based negative electrode materials have become a very promising alternative due to their extremely high theoretical specific capacity (~4200 mAhg -1 ). However, the severe volume expansion (~300%) of micron-sized silicon during charge and discharge easily leads to the destruction of the electrode structure and the decline of cycle performance. Therefore, micron-sized SiO -1 with a relatively high theoretical specific capacity (~2600 mAhg x and smaller volume expansion has become one of the most promising candidate materials. However, the inherent volume expansion of the SiO x negative electrode is still an important challenge hindering its large-scale commercial application. In previous studies, researchers have used various strategies such as nanoengineering design, coating, and efficient binder design to buffer volume expansion and improve the electrochemical performance of silicon-based negative electrodes. However, the complex manufacturing process in nanoengineering and the capacity sacrifice caused by coating have raised concerns about cost increase and capacity reduction. In this context, developing an efficient binder system with multiple functional characteristics is regarded as a feasible solution to solve the problem of structural instability of silicon-based negative electrodes.

[0003] As the bond that tightly connects the electrode material and the current collector, the binder determines the mechanical structural stability of the entire electrode. An ideal silicon-based anode binder not only has strong mechanical properties, but more importantly, it has compatibility with the active material. The specific requirements are as follows: (1) It should have an excellent ion conduction network to make up for the intrinsic conductivity defect of silicon materials; (2) It should form a strong interfacial adhesion with the active particles to ensure the anti-deformation ability of the electrode structure; (3) It should establish an efficient stress dissipation mechanism to buffer the volume change during the cycling process; (4) It should maintain a stable binding interface with the current collector. Existing studies have constructed coordination bonds through functional group design (such as ether oxygen groups in PEO and amino groups in PEI) to accelerate lithium ion transport, or introduced polar groups such as hydroxyl groups and carboxyl groups to enhance covalent bonds or van der Waals force interfacial binding, and even used novel concepts such as self-healing and dynamic crosslinking to improve the binder stability. However, these systems are generally limited to the optimization of single performance and are difficult to meet the balance between multiple requirements. Summary of the Invention

[0004] In order to solve the deficiencies and disadvantages of the above-mentioned existing technologies, the object of the present invention is to provide a photo-crosslinked polyacrylic acid-based aqueous binder, which is a novel binder system based on photo-crosslinking and molecular co-assembly strategies, and constructs a three-dimensional adaptive network structure in the SiO x anode. This binder not only realizes the optimization of the ion conduction path and the dissipation of mechanical stress, but also dynamically repairs the electrode interface damage through multiple intermolecular forces.

[0005] Another object of the present invention is to provide a preparation method of the above-mentioned photo-crosslinked polyacrylic acid-based aqueous binder. This method uses choline chloride and urea as raw materials to prepare a deep eutectic solvent, then adds acrylic acid monomer (AA) and ethanolamine monomer (MEA) and a photoinitiator and carboxymethyl chitosan, and initiates crosslinking through ultraviolet light irradiation to form a stable polymer network structure.

[0006] Another object of the present invention is to provide the application of the above-mentioned photo-crosslinked polyacrylic acid-based aqueous binder.

[0007] The object of the present invention is achieved by the following technical solutions: A photo-crosslinked polyacrylic acid-based aqueous binder, abbreviated as AA-MEA-CMCS / DES, is prepared by dissolving choline chloride and urea in deionized water, heating in a water bath at 80-90 °C and stirring to form a deep eutectic solvent (DES), adding acrylic acid monomer (AA) and ethanolamine monomer (MEA) and stirring, then adding a photoinitiator and carboxymethyl chitosan (CMCS) and stirring until completely dissolved, and irradiating the above mixed solution with a mixed light source of 395 nm and 365 nm.

[0008] Preferably, the molar ratio of choline chloride to urea is 2:1; the mass ratio of the total mass of choline chloride and urea to the mass of deionized water is 1:(4 - 8); the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator I2959); the photoinitiator is 0.1 - 0.5 wt% of the total mass of acrylic acid monomer and monoethanolamine monomer; the carboxymethyl chitosan is 0.3 - 0.5 wt% of the total mass of acrylic acid monomer and monoethanolamine monomer, and the mass ratio of the deep eutectic solvent, acrylic acid monomer and ethanolamine monomer is 8.37:(3 - 4):1.

[0009] Preferably, the irradiation time is 1 - 2 h.

[0010] The preparation method of the photo-crosslinked polyacrylic acid-based waterborne binder includes the following steps: S1. Dissolve choline chloride and urea in deionized water, and water bath and stir at 80 - 90 °C to form a uniform deep eutectic solvent; S2. Add acrylic acid monomer and ethanolamine monomer to the deep eutectic solvent and stir, then add photoinitiator and carboxymethyl chitosan and stir until completely dissolved to obtain a mixed solution; S3. Transfer the mixed solution under an ultraviolet lamp and irradiate it with a mixed light source of 395 nm and 365 nm to obtain a polyacrylic acid-based waterborne binder.

[0011] Preferably, the stirring time in step S1 is 90 - 120 min.

[0012] The application of the photo-crosslinked polyacrylic acid-based waterborne binder in a lithium-ion battery.

[0013] Preferably, the negative electrode material of the lithium-ion battery is SiO x , 0 < x < 2.

[0014] In the present invention, through a photo-crosslinking and electrostatic / hydrogen bond self-assembly strategy, a waterborne conductive binder (AA-MEA-CMCS / DES) with an innovative structure is constructed in a deep eutectic solvent (DES) environment. During the construction of the molecular network of the binder, acrylic acid monomer (AA) forms a three-dimensional skeleton structure through UV photoinitiated polymerization. This crosslinked network endows the material with necessary mechanical strength and can effectively resist the volume change stress generated by the SiO x negative electrode during charge and discharge. At the same time, the introduction of monoethanolamine monomer (MEA) not only provides elastic segments, but its hydroxyl group (–OH) also forms a wide range of hydrogen bond networks with the carboxyl group of carboxymethyl chitosan (CMCS) and the DES components. This dynamically reversible secondary bonding endows the material with significant flexibility and energy dissipation ability. The rich polar groups on the AA-MEA-CMCS / DES molecular chain can also interact with SiOx Si–OH bonds on the surface of the anode material form supramolecular interactions, and this chemical bonding mechanism significantly enhances the interfacial bonding strength between the binder and the silicon suboxide particles. In addition, DES plays multiple key roles in this system. Its inherent ionic conductivity characteristics cooperate with charged groups such as carboxylate groups (–COO - ), and protonated amino groups (–NH 3+ ), etc., to construct an efficient lithium-ion transport channel, increasing the ionic conductivity (σ) by three orders of magnitude. Moreover, AA-MEA CMCS / DES forms a protective layer on the SiO x anode surface through supramolecular interactions, which can effectively inhibit the decomposition reaction of the electrolyte.

[0015] The preparation process of the electrode and the battery assembly process of the binder of the present invention are as follows: Using silicon-oxygen material (SiO x ), as the active material, it is mixed with conductive carbon black (Super P) and the above-mentioned binder according to a mass ratio of (7~8):(1~2):1, and after adding deionized water, it is defoamed and stirred to form a uniform slurry. The slurry is uniformly coated on a copper foil current collector, and after vacuum drying at 80 °C for 12 h, it is punched into a circular electrode with a diameter of 14 mm. The battery assembly is completed in an argon-protected glove box. A metal lithium sheet is used as the counter electrode, and the electrolyte system is: 1 M LiPF6 dissolved in a mixed solvent of EC / DEC (1:1 v / v), and 10% FEC and 1% VC are added as film-forming additives. Finally, a CR2032 type button battery is selected for encapsulation testing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The binder of the present invention has excellent water solubility, ionic conductivity and flexibility, can effectively inhibit the volume expansion problem of the silicon-based anode during the cycling process, and significantly improves the cycling stability of the battery.

[0017] In the ultraviolet light cross-linking process of the SiO x anode binder of the present invention, polyacrylic acid (PAA) formed by the photopolymerization of acrylic acid provides a stable three-dimensional skeleton structure for the entire binder system through its rigid molecular main chain. At the same time, the introduction of the hydroxyethyl flexible chain segment (–CH2–CH2–OH) in the ethanolamine molecule significantly improves the flexibility and anti-deformation ability of the molecular network. In addition, the rich polar functional groups such as hydroxyl groups and carboxyl groups in carboxymethyl chitosan not only form multiple hydrogen bond interactions with the silicon-based active material, but also produce synergistic cross-linking with the PAA network, thereby greatly improving the interfacial adhesion performance of the binder.

[0018] The SiO xThe unique advantages of the anode binder in terms of ion transport, which are mainly due to the structural features such as high free ion concentration and continuous ion migration paths in the DES. Secondly, the abundant polar functional groups (such as –NH2, –OH, and –COOH) in the CMCS molecule can form multiple hydrogen bond networks with the DES components, providing an ordered channel for ion transport, resulting in efficient transport of ions and electrons in the polymer network, and ultimately achieving a significant increase in the ionic conductivity of the binder system.

[0019] The SiO of the present invention x The anode binder is prepared by photocrosslinking, and the synthesis process is simple and easy. The three-dimensional crosslinked network endows it with excellent mechanical adaptability to buffer the volume expansion effect of the SiO x material. The abundant polar groups ensure strong adhesion to the current collector and active materials, and the introduction of the deep eutectic solvent provides an efficient channel for lithium ion conduction. These characteristics can better withstand the volume change of SiO x during the charge and discharge process of the electrode, which helps to maintain the structural integrity of the SiO x electrode during cycling, thereby improving the cycle stability of the SiO x anode. Brief Description of the Drawings

[0020] Figure 1 It is the Fourier infrared spectrum of choline chloride, urea, and the deep eutectic solvent (DES) formed by the two in Example 1; Figure 2 It is the Fourier infrared spectrum of acrylic acid monomer (AA), monoethanolamine monomer (MEA), carboxymethyl chitosan (CMCS), deep eutectic solvent (DES), and the AA-MEA-CMCS / DES polymer binder in Application Example 1; Figure 3 It is the rate performance graph of the coin cells prepared in Application Example 1 and Comparative Examples 1-2; Figure 4 It is the comparison graph of the cycle performance of the coin cells prepared in Application Example 1 at a current density of 500 mA g -1 and Comparative Examples 1-2. Detailed Description of the Invention

[0021] The following further illustrates the content of the present invention with specific examples, but it should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise stated, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0022] In the embodiments of the present invention, the purity of the acrylic monomer used > 99%; the purity of the ethanolamine monomer > 99%; the degree of substitution of carboxymethyl chitosan > 80%; (ACS, analytical reagent conforming to the American Chemical Society). The photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator I2959) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Example

[0023] Dissolve 5.58 g of choline chloride and 4.8 g of urea in 50 g of deionized water, and continuously stir in a water bath at 80 °C for 90 min to fully dissolve, forming a uniform deep eutectic solvent (DES).

[0024] Add 3.73 g of acrylic monomer (AA) and 1.24 g of ethanolamine monomer (MEA) to the above deep eutectic solvent, and continue to stir evenly to fully disperse the monomers in the solvent, obtaining a mixed solution; Add 0.01 g of the photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator I2959) and 0.311 g of carboxymethyl chitosan to the mixed solution obtained in step 1, and stir until completely dissolved to ensure the uniformity and high efficiency of the subsequent photocrosslinking reaction. Transfer the above mixed solution under an ultraviolet lamp and irradiate it with a mixed light source of 395 nm and 365 nm for 1 h to prepare an aqueous binder based on polyacrylic acid.

[0025] Figure 1 It is the Fourier transform infrared spectrum of choline chloride (Choline Chloride), urea (Urea) and the deep eutectic solvent (DES) formed by the two in Example 1. From Figure 1 it can be seen that the C=O stretching vibration peak at 1676 cm -1 in the urea molecule redshifts to 1610 cm -1 in the DES, and at the same time, the intensity of the C-N -1 vibration peak of the choline chloride quaternary ammonium salt group at 960 cm + weakens, revealing the formation of the DES solution. Figure 2 It is the Fourier transform infrared spectrum of the acrylic monomer (AA), ethanolamine monomer (MEA), carboxymethyl chitosan (CMCS), deep eutectic solvent (DES) and the AA-MEA-CMCS / DES polymer binder in Example 1. As Figure 2 shown, in terms of the photopolymerization reaction system, it shows that the C=C stretching vibration peak at 1630 cm -1 and the =C–H bending vibration peak at 810 cm -1 in the acrylic monomer (AA) completely disappear after the reaction. At the same time, at 1452 cm -1The characteristic CH2 bending vibration peak of the polyacrylic acid (PAA) main chain appears here. This series of changes provides conclusive evidence for the ultraviolet light-induced double bond cleavage and polymerization reaction of acrylic acid. At the same time, the systematic displacement of the characteristic peaks of each component functional group further confirms the existence of various supramolecular interactions between components.

[0026] Application Example 1 Mix the active substance SiO with a mass ratio of 7:2:1 x (0 < x < 2), the conductive agent Super P and the polyacrylic acid-based binder AA-MEA-CMCS / DES of Example 1, add 600 - 800 mL of deionized water, and then put it into a degassing machine and stir for 20 - 30 min to obtain a uniformly dispersed slurry. Coat the obtained slurry on a copper foil, vacuum dry it at 80 °C for 12 h, and then cut it into circular electrode sheets with a diameter of 14 mm, denoted as AA-MEA-CMCS / DES@SiO x electrode sheet. Transfer this electrode sheet into a glove box filled with argon for battery assembly. In the battery, a lithium sheet is used as the counter electrode, the electrolyte uses 1 mol / L LiPF6 as the solute, and ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 as the solvent. Among them, 10 wt% fluoroethylene carbonate (FEC) and 1 wt% vinylene carbonate (VC) are used as additives, and a CR2032 coin cell is used for assembly.

[0027] Comparative Example 1 Dissolve 5.58 g of choline chloride and 4.8 g of urea in 50 g of deionized water, and continuously stir in a water bath at 80 °C for 90 min to ensure complete dissolution and form a uniform deep eutectic solvent (DES).

[0028] Add 3.73 g of acrylic acid monomer (AA) and 1.24 g of ethanolamine monomer (MEA) to the above-mentioned deep eutectic solvent (DES), and continue to stir evenly to fully disperse the monomers in the solvent to obtain a mixed solution; Add 0.01 g of photoinitiator I2959 to the above-mentioned mixed solution and stir until completely dissolved to ensure the uniformity and high efficiency of the subsequent photocrosslinking reaction. Then transfer the mixed solution under an ultraviolet lamp and irradiate it with a mixed light source of 395 nm and 365 nm for 1 h to prepare a polymer binder without carboxymethyl chitosan, denoted as AA-MEA / DES binder.

[0029] Mix the active substance SiO with a mass ratio of 7:2:1 xWhen \(0 \lt x \lt 2\), conductive agent Super P is mixed with the AA-MEA / DES binder of Comparative Example 1. After adding 600 - 800 mL of deionized water, it is put into a degassing machine and stirred for 20 - 30 min to obtain a uniformly dispersed slurry. The obtained slurry is coated on a copper foil, vacuum dried at 80 °C for 12 h, and then cut into circular electrode sheets with a diameter of 14 mm, denoted as AA-MEA / DES@SiO x electrode sheet. This electrode sheet is transferred to a glove box filled with argon for battery assembly. In the battery, a lithium sheet is used as the counter electrode. The electrolyte uses 1 mol / L LiPF6 as the solute, and ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 as the solvent. Among them, 10 wt% fluoroethylene carbonate (FEC) and 1 wt% vinylene carbonate (VC) are used as additives, and a CR2032 coin cell is used for assembly.

[0030] Comparative Example 2 3.73 g of acrylic acid monomer (AA) and 1.24 g of ethanolamine monomer (MEA) are dissolved in 50 g of deionized water and continuously stirred evenly to fully disperse the monomers in the solvent, obtaining a mixed solution.

[0031] 0.01 g of photoinitiator (I2959) and 0.31 g of carboxymethyl chitosan are added to the mixed solution and stirred until completely dissolved to ensure the uniformity and high efficiency of the subsequent photocrosslinking reaction. Then the mixed solution is transferred under an ultraviolet lamp and irradiated with a mixed light source of 395 nm and 365 nm for 1 h to prepare a polymer binder without a deep eutectic solvent, denoted as AA-MEA-CMCS / H2O.

[0032] The active material SiO with a mass ratio of 7:2:1 x When \(0 \lt x \lt 2\), conductive agent Super P is mixed with the AA-MEA / DES binder of Comparative Example 2. After adding 600 - 800 mL of deionized water, it is put into a degassing machine and stirred for 20 - 30 min to obtain a uniformly dispersed slurry. The obtained slurry is coated on a copper foil, vacuum dried at 80 °C for 12 h, and then cut into circular electrode sheets with a diameter of 14 mm, denoted as AA-MEA-CMCS / H2O electrode sheet. This electrode sheet is transferred to a glove box filled with argon for battery assembly. In the battery, a lithium sheet is used as the counter electrode. The electrolyte uses 1 mol / L LiPF6 as the solute, and ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 as the solvent. Among them, 10 wt% fluoroethylene carbonate (FEC) and 1 wt% vinylene carbonate (VC) are used as additives, and a CR2032 coin cell is used for assembly.

[0033] The button cells assembled in Application Example 1 and Comparative Examples 1-2 were left standing at 28 °C for 12 h and then subjected to a constant current test of electrochemical performance in a Neware test system. The test conditions were: current density 500 mA g -1 ; voltage window 0.1~1.5 V. Figure 3 Figure is the rate performance diagram of the button cells prepared in Application Example 1 and Comparative Examples 1-2. It can be seen from Figure 3 that the AA-MEA-CMCS / DES@SiO x electrode sheet exhibits the most excellent rate performance. The discharge specific capacities at current densities of 0.2 C, 0.5 C, 1 C, 2 C, and 3 C are 1310.46, 1178.92, 764.81, 629.79, and 369.12 mAh g -1 respectively. It is worth noting that when the current density is restored from 3 C to 0.2 C, its discharge specific capacity can be restored to 1349.8 mAh g -1 , showing good capacity reversibility. The rate performance of the AA-MEA / DES@SiO x electrode sheet is reduced to some extent, while the performance of the AA-MEA-CMCS / H2O@SiO x electrode sheet is the least ideal. It can only provide discharge specific capacities of 742.36, 615.2, 403.87, 267.22, and 142.51 mAh g -1 under the same current density conditions, indicating the significant advantage of the AA-MEA-CMCS / DES binder in improving the rate performance of the electrode.

[0034] Figure 4 Figure is the comparison diagram of the cycle performance of the button cells prepared in Application Example 1 at a current density of 500 mA g -1 and Comparative Examples 1-2. It can be seen from Figure 4 that the electrode assembled with the AA-MEA-CMCS / DES binder of the present invention has a capacity retention rate of 87.92% after 200 cycles (after two activation cycles), and still maintains a high reversible capacity of 986.97 mAh g -1 after 320 cycles, showing excellent cycle stability. In contrast, the cycle performance of the AA-MEA / DES@SiO x electrode decreases significantly. The discharge specific capacity is only 739.9 mAh g -1 after 190 cycles, and the capacity retention rate drops to 66.48%. The AA-MEA-CMCS / H2O@SiO x electrode sheet shows the worst performance. The capacity drops sharply to 171.34 mAh g -1The results show that the electrode sheet assembled with the photo-crosslinkable polyacrylic acid-based aqueous binder (AA-MEA-CMCS / DES) of the present invention exhibits excellent cycle stability and can effectively inhibit the volume expansion of the SiO x negative electrode material (0 < x < 2) during the charge and discharge process of the electrode, enabling the SiO x negative electrode to exhibit good cycle stability.

[0035] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A photocrosslinkable polyacrylic acid-based aqueous binder, characterized in that, The polyacrylic acid-based aqueous binder, abbreviated as AA-MEA-CMCS / DES, is prepared by dissolving choline chloride and urea in deionized water, heating in a water bath at 80-90 °C with stirring to form a deep eutectic solvent; then adding acrylic acid monomer and ethanolamine monomer with stirring, followed by adding a photoinitiator and carboxymethyl chitosan and stirring until completely dissolved, and irradiating the above mixed solution with a mixed light source of 395 nm and 365 nm.

2. The photocrosslinkable polyacrylic acid-based aqueous binder according to claim 1, wherein The molar ratio of choline chloride to urea is 2:1; the mass ratio of the total mass of choline chloride and urea to the mass of deionized water is 1:(4-8); the photoinitiator is 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, and the photoinitiator accounts for 0.1-0.5 wt% of the total mass of the acrylic acid monomer and monoethanolamine monomer; the carboxymethyl chitosan accounts for 0.3-0.5 wt% of the total mass of the acrylic acid monomer and monoethanolamine monomer, and the mass ratio of the deep eutectic solvent, acrylic acid monomer and ethanolamine monomer is 8.37:(3-4):

1.

3. The photocrosslinked polyacrylic acid-based binder according to claim 1, characterized in that, The irradiation time is 1-2 h.

4. The preparation method of the photo-crosslinked polyacrylic acid-based aqueous binder according to any one of claims 1 to 3, characterized in that, It includes the following steps: S1. Dissolve choline chloride and urea in deionized water, heat the mixed solution in a water bath at 80-90 °C with stirring to form a homogeneous deep eutectic solvent; S2. Add acrylic acid monomer and ethanolamine monomer to the deep eutectic solvent with stirring, then add a photoinitiator and carboxymethyl chitosan and stir until completely dissolved to obtain a mixed solution; S3. Transfer the mixed solution to under an ultraviolet lamp and irradiate it with a mixed light source of 395 nm and 365 nm to prepare the polyacrylic acid-based aqueous binder.

5. The preparation method of the photocrosslinked polyacrylic acid-based aqueous binder according to claim 4, characterized in that, The stirring time in step S1 is 90-120 min.

6. Use of the photocrosslinked polyacrylic acid-based aqueous binder according to any one of claims 1-3 in a lithium-ion battery.

7. Use of the photocrosslinked polyacrylic acid-based aqueous binder according to claim 6 in a lithium ion battery, characterized in that, The negative electrode material of the lithium-ion battery is SiO x , where 0 < x < 2.

Images