Self-healing flexible high specific capacity silicon-carbon negative electrode binder and preparation method thereof

Abstract

In order to overcome the problem that the existing negative electrode binder is difficult to adapt to the volume expansion and contraction of the silicon-based negative electrode material, the present application provides a self-healing type flexible high specific capacity silicon-carbon negative electrode binder and a preparation method thereof.The self-healing type flexible high specific capacity silicon-carbon negative electrode binder comprises a polyacrylic acid main chain and a side chain connected to the polyacrylic acid main chain, the side chain comprises a polyether chain segment and a multiple hydrogen bond unit, and the polyether chain segment is connected to the multiple hydrogen bond unit and the polyacrylic acid main chain respectively.The self-healing type flexible high specific capacity silicon-carbon negative electrode binder provided by the present application can significantly improve the problems of silicon particle crushing, repeated rupture of SEI film and electrode delamination, effectively maintain the integrity of the electrode structure and the smoothness of the conductive path, and greatly improve the cycle stability of the silicon-based negative electrode lithium ion battery.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a self-healing flexible high specific capacity silicon-carbon anode binder and its preparation method. Background Technology

[0002] Against the backdrop of the rapid development of the new energy industry, high-energy-density lithium-ion batteries (LIBs) have become the core power source for electric vehicles, portable electronic devices, and other fields. Optimizing the performance of electrode materials is one of the key directions for improving the energy density of lithium-ion batteries. Among them, silicon materials are widely recognized as one of the most promising anode materials for next-generation high-energy-density lithium-ion batteries due to their significant advantages such as extremely high theoretical specific capacity (3579 mAh / g), low lithiation reaction potential, and abundant natural resource reserves. They have attracted much attention in related research and applications.

[0003] However, silicon anodes face a core technological bottleneck that is difficult to avoid in practical applications: silicon materials undergo drastic volume changes (volume expansion rate can reach 300%-400%) during lithium-ion insertion / extraction cycling. This repeated volume expansion and contraction behavior will trigger a series of chain problems, including the crushing and breaking of silicon particles, the repeated rupture and regeneration of the solid electrolyte interphase (SEI) film, and the peeling and delamination between the electrode layer and the current collector. Ultimately, this leads to a sharp decline in the cycle performance of lithium-ion batteries, which seriously restricts the commercial application of silicon anodes.

[0004] In the structure of silicon anode electrodes, the binder, as a key component, plays a crucial role in connecting the active material (silicon particles), conductive agent, and current collector, maintaining the integrity of the electrode structure. Its performance directly affects the cycle stability of the silicon anode. Currently, traditional lithium-ion battery anode binders are difficult to adapt to the volume expansion characteristics of silicon anodes. Among them, polyvinylidene fluoride (PVDF) is a commonly used binder in traditional lithium-ion batteries, but this type of binder relies only on weak van der Waals forces to bond with the various electrode components and lacks self-healing ability. It cannot withstand the huge stress generated during the repeated expansion and contraction of the silicon anode, making it difficult to meet the usage requirements of silicon anodes. Other commonly used binder materials often have high brittleness due to the entanglement and interaction forces between molecular chains, which also cannot adapt to the dynamic volume change requirements of silicon anodes.

[0005] Furthermore, commonly used binders generally lack good stretchability and dynamic self-healing ability. During the cycling process of repeated expansion and contraction of the silicon anode, they cannot buffer stress through self-deformation or structural repair, which easily leads to the destruction of the integrity of the silicon anode electrode structure. It is worth noting that polyacrylic acid (PAA) based binders, as a widely studied modified binder, have relatively good structural strength due to the strong hydrogen bonding between the numerous carboxyl groups on their molecular chains and the hydroxyl groups on the surface of silicon particles, which can improve the initial structural stability of the electrode to a certain extent. However, these PAA-based binders have significant mechanical brittleness defects. After the silicon anode undergoes volume expansion, they cannot achieve structural repair. With the increase of cycling cycles, the electrode structure will eventually break and the internal conductive pathways will be destroyed, leading to rapid capacity decay of lithium-ion batteries. This cannot fundamentally solve the problem of volume expansion of silicon anodes. Summary of the Invention

[0006] To address the problem that existing anode binders are difficult to adapt to the volume expansion and contraction of silicon-based anode materials, this invention provides a self-healing flexible high-specific-capacity silicon-carbon anode binder and its preparation method.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: On one hand, the present invention provides a self-healing flexible high specific capacitance silicon-carbon anode binder, comprising a polyacrylic acid main chain and side chains connected to the polyacrylic acid main chain, wherein the side chains comprise polyether segments and multiple hydrogen bond units, and the polyether segments are respectively connected to the multiple hydrogen bond units and the polyacrylic acid main chain.

[0008] Optionally, the multiple hydrogen-bonded unit includes one or more of ureidopyrimidinone and glycineamide.

[0009] Optionally, the number-average molecular weight of the self-healing flexible high-capacity silicon-carbon anode binder is 100,000 to 2,000,000.

[0010] Optionally, the self-healing flexible high-specific-capacity silicon-carbon anode binder has the following structure: Where R is the side chain, x+y=100~10000; y:x=0.01~0.8.

[0011] Optionally, R is selected from the following structural formula 1 or structural formula 2: Structural Formula 1 Structural Formula 2 Where n is an integer from 2 to 1000.

[0012] Furthermore, the present invention provides a method for preparing the self-healing flexible high-capacity silicon-carbon anode binder as described above, comprising the following steps: Polyacrylic acid and hydroxyl-terminated polyether-multi-hydrogen bonded units are dissolved in a solvent, and a catalyst is added. The hydroxyl-terminated polyether-multi-hydrogen bonded units undergo dehydration condensation with the carboxyl groups on the polyacrylic acid, resulting in a self-healing flexible high-specific-capacity silicon-carbon anode binder.

[0013] Optionally, the hydroxyl-terminated polyether-multi-hydrogen-bonded unit is prepared by the following method: Polyethylene glycol is mixed and reacted with ureidopyrimidinone containing isocyanate or glycine amide containing isocyanate to obtain the polyether-multi-hydrogen bonded unit with terminal hydroxyl groups.

[0014] Optionally, the mass ratio of the polyacrylic acid, the hydroxyl-terminated polyether-multi-hydrogen-bonded unit, and the catalyst is (100~1000):(5~20):(1~10); and / or, The catalyst comprises carbodiimide and N-hydroxysuccinimide, wherein the mass ratio of carbodiimide to N-hydroxysuccinimide is (1~10):(5~20).

[0015] The self-healing flexible high-capacitance silicon-carbon anode binder provided by this invention introduces side chains containing polyether segments and multiple hydrogen bonding units onto the polyacrylic acid backbone. The polyacrylic acid backbone can form strong hydrogen bonds with the hydroxyl groups on the silicon particle surface through carboxyl groups, ensuring the initial structural strength of the electrode and continuing the structural advantages of traditional PAA-based binders. The polyether segments possess excellent flexibility and extensibility, effectively buffering the volume expansion stress generated during lithium insertion / extraction of the silicon anode, preventing the binder from breaking due to stress concentration. The multiple hydrogen bonding units can form dynamically reversible hydrogen bonds, endowing the binder with self-healing capabilities, enabling structural repair through hydrogen bond reconstruction when microcracks appear in the binder. The synergistic effect of these three components significantly improves the problems of silicon particle pulverization, repeated SEI film rupture, and electrode delamination, effectively maintaining the integrity of the electrode structure and the smooth flow of conductive pathways, greatly improving the cycle stability of silicon-based lithium-ion batteries, overcoming the technical bottleneck of poor compatibility of traditional binders, and promoting the commercial application of silicon anodes. Detailed Implementation

[0016] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] This invention provides a self-healing flexible high-capacitance silicon-carbon anode binder, comprising a polyacrylic acid backbone and side chains connected to the polyacrylic acid backbone. The side chains include polyether segments and multiple hydrogen bond units, and the polyether segments are connected to the multiple hydrogen bond units and the polyacrylic acid backbone, respectively.

[0018] The self-healing flexible high-capacitance silicon-carbon anode binder introduces side chains containing polyether segments and multiple hydrogen bonding units onto the polyacrylic acid backbone. The polyacrylic acid backbone can form strong hydrogen bonds with the hydroxyl groups on the silicon particle surface through carboxyl groups, ensuring the initial structural strength of the electrode and continuing the structural advantages of traditional PAA-based binders. The polyether segments possess excellent flexibility and extensibility, effectively buffering the volume expansion stress generated during lithium insertion / extraction of the silicon anode, preventing the binder from breaking due to stress concentration. The multiple hydrogen bonding units can form dynamically reversible hydrogen bonds, endowing the binder with self-healing capabilities, enabling structural repair through hydrogen bond reconstruction when microcracks appear in the binder. The synergistic effect of these three components significantly improves the problems of silicon particle pulverization, repeated SEI film rupture, and electrode delamination, effectively maintaining the integrity of the electrode structure and the smooth flow of conductive pathways, greatly improving the cycle stability of silicon-based lithium-ion batteries, overcoming the technical bottleneck of poor compatibility of traditional binders, and promoting the commercial application of silicon anodes.

[0019] In some embodiments, the multiple hydrogen-bonded unit comprises one or more of ureidopyrimidinone and glycineamide.

[0020] Both ureidinone and glycineamide possess strong hydrogen bond donor and acceptor sites, enabling the formation of a high-strength and reversible multi-hydrogen bond network. Ureidinone can form quadruple hydrogen bonds, exhibiting strong hydrogen bond strength and significantly improving the mechanical strength and self-healing efficiency of the binder. Glycineamide units possess triple hydrogen bonds, exhibiting good hydrophilicity and compatibility, which can enhance the interaction between the binder and silicon particles and electrolyte, improving interfacial compatibility. The use of these two multi-hydrogen bond units, individually or in combination, allows for precise control of the strength and dynamics of the hydrogen bond network according to actual performance requirements. This enables the binder to maintain high mechanical strength while possessing superior stress buffering and self-healing capabilities, further enhancing the cycle stability and structural durability of silicon-based anodes.

[0021] In some embodiments, the number-average molecular weight of the self-healing flexible high-capacity silicon-carbon anode binder is 100,000 to 2,000,000.

[0022] If the molecular weight is too low, the self-healing flexible high-capacitance silicon-carbon anode binder will lack sufficient bonding strength, making it difficult to effectively connect the anode active material, anode conductive agent, and anode current collector, thus failing to maintain the integrity of the electrode structure. If the molecular weight is too high, the viscosity of the self-healing flexible high-capacitance silicon-carbon anode binder will increase significantly, leading to increased difficulty in the preparation and coating processes of the electrode slurry, and decreased flexibility after film formation, making it unable to adapt to the volume expansion of the silicon-based anode. A specific range of number-average molecular weights ensures that the binder possesses good solubility, film-forming properties, and machinability, while guaranteeing sufficient bonding strength and extensibility, providing convenience for electrode preparation, and stably performing its core performance of buffering volume expansion and self-healing, ensuring the stable operation of the silicon-based anode.

[0023] In some embodiments, the self-healing flexible high-specific-capacity silicon-carbon anode binder has the following structure: Where R is the side chain, x+y=100~10000; y:x=0.01~0.8.

[0024] By limiting the molar ratio of y and x, the ratio of acrylic units providing carboxyl groups to side chains providing polyether and multiple hydrogen bond units in the self-healing flexible high-specific-capacity silicon-carbon anode binder can be adjusted. This achieves an optimal synergistic effect between the structural strength of the main chain and the flexibility and self-healing ability of the side chains, maximizing the binder's compatibility with the silicon anode and ensuring the electrode maintains structural integrity and conductivity throughout long-term cycling. If the side chain content is too low (y:x too small), the flexibility and self-healing ability cannot be fully utilized, making it difficult to buffer the volume expansion of the silicon anode; if the side chain content is too high (y:x too large), it weakens the structural strength of the polyacrylic acid main chain and the hydrogen bond strength with the silicon-based anode, leading to decreased bonding stability.

[0025] In some embodiments, R is selected from the following structural formula 1 or structural formula 2: Structural Formula 1 Structural Formula 2 Where n is an integer from 2 to 1000.

[0026] The integer range of n=2~1000 limits the length of the polyether segments. If the polyether segments are too short, they cannot provide enough flexibility to buffer volume expansion, while if they are too long, they will cause side chain entanglement, reducing the mechanical strength and processing performance of the binder.

[0027] Another embodiment of the present invention provides a method for preparing the self-healing flexible high-capacity silicon-carbon anode binder as described above, comprising the following steps: Polyacrylic acid and hydroxyl-terminated polyether-multi-hydrogen bonded units are dissolved in a solvent, and a catalyst is added. The hydroxyl-terminated polyether-multi-hydrogen bonded units undergo dehydration condensation with the carboxyl groups on the polyacrylic acid, resulting in a self-healing flexible high-specific-capacity silicon-carbon anode binder.

[0028] The dehydration condensation reaction is used to connect the main chain and side chains of polyacrylic acid. The reaction conditions are mild under the action of a catalyst, without the need for harsh high temperature and high pressure environments, which reduces production energy consumption and equipment requirements. Solvent dissolution of the reactants ensures uniform mixing of polyacrylic acid and hydroxyl-terminated polyether-multiple hydrogen bond units, resulting in a complete reaction and avoiding uneven product performance caused by incomplete local reactions. This preparation method can stably prepare self-healing flexible high specific capacity silicon-carbon anode binders that meet design requirements. The product performance is reproducible and easy to scale up for industrial production.

[0029] In some embodiments, the solvent is water.

[0030] In some embodiments, after the dehydration condensation reaction, unreacted small molecules are removed by dialysis, and the final self-healing flexible high specific capacity silicon-carbon anode binder is obtained by freeze drying.

[0031] In some embodiments, the hydroxyl-terminated polyether-multi-hydrogen bond unit is selected from hydroxyl-terminated polyethylene glycol-ureidopyrimidinone or hydroxyl-terminated polyethylene glycol-glycineamide.

[0032] In some embodiments, the hydroxyl-terminated polyether-multi-hydrogen-bonded unit is prepared by the following method: Polyethylene glycol is mixed and reacted with ureidopyrimidinone containing isocyanate or glycine amide containing isocyanate to obtain the polyether-multi-hydrogen bonded unit with terminal hydroxyl groups.

[0033] In some embodiments, the isocyanate-containing ureidopyrimidinone is obtained by reacting ureidopyrimidinone with a polyisocyanate.

[0034] In some embodiments, the mass ratio of the polyacrylic acid, the hydroxyl-terminated polyether-multi-hydrogen bonded unit and the catalyst is (100~1000):(5~20):(1~10).

[0035] In some embodiments, the catalyst comprises carbodiimide and N-hydroxysuccinimide, wherein the mass ratio of carbodiimide to N-hydroxysuccinimide is (1~10):(5~20).

[0036] Another embodiment of the present invention provides a negative electrode sheet, including a negative electrode current collector and a negative electrode material layer located on the negative electrode current collector. The negative electrode material layer includes a negative electrode active material, a negative electrode conductive agent, and a self-healing flexible high specific capacitance silicon-carbon negative electrode binder as described above. The negative electrode active material includes a silicon-based material.

[0037] The self-healing flexible high-capacity silicon-carbon anode binder can firmly connect the silicon-based material, conductive agent, and current collector. When the silicon particles repeatedly expand and contract, the binder buffers stress through its own extensibility and repairs microcracks through its self-healing ability, preventing silicon-based material from shattering, electrode delamination, and disruption of the conductive pathway. Simultaneously, the excellent interaction between the self-healing flexible high-capacity silicon-carbon anode binder and the silicon-based material stabilizes the SEI film, reducing its repeated rupture and regeneration, and minimizing battery capacity decay. Therefore, this anode sheet possesses excellent cycle stability, structural integrity, and conductivity, fully leveraging the high-capacity advantage of silicon-based materials and laying the foundation for the fabrication of high-energy-density lithium-ion batteries.

[0038] Another embodiment of the present invention provides a secondary battery, including the negative electrode sheet as described above.

[0039] In some embodiments, the secondary battery further includes a positive electrode sheet, which includes a positive current collector and a positive electrode material layer disposed on the positive current collector. The positive electrode material layer includes a positive electrode active material, which includes one or more of the following: lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium nickel oxide (e.g., lithium nickel oxide), lithium manganese oxide (e.g., spinel-type lithium manganese oxide, layered lithium manganese oxide, etc.), lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, and doped / coated modified compounds. Preferably, the positive electrode active material includes LiFe... 1-x’ M' x’ PO4, LiMn 2-y’ M y’ O4 and LiNi x Co y Mn z M 1-x-y-z At least one of O2, wherein M' is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, Zr, W, V or Ti, and M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, Zr, W, V or Ti, and 0≤x'<1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1.

[0040] In some embodiments, the positive electrode material layer further includes a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder and the positive electrode conductive agent are blended to obtain the positive electrode material layer.

[0041] The positive electrode binder includes at least one of the following: polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-fluorinated vinylidene, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene; acrylic resins; and styrene-butadiene rubber.

[0042] The positive electrode conductive agent includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fiber, carbon nanotubes, graphene, or reduced graphene oxide.

[0043] In some embodiments, the positive current collector comprises a metallic material capable of conducting electrons. Preferably, the positive current collector comprises at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive current collector is selected from aluminum foil.

[0044] In some embodiments, the secondary battery further includes a separator located between the positive electrode and the negative electrode.

[0045] The diaphragm can be a conventional diaphragm, such as a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, or an inorganic-organic composite diaphragm, including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and triple-layer PP / PE / PP diaphragms.

[0046] In some embodiments, the secondary battery further includes a non-aqueous electrolyte, which includes lithium salts, non-aqueous organic solvents, and additives.

[0047] The present invention will be further illustrated by the following examples.

[0048] Table 1 Example 1 This embodiment illustrates the secondary battery and its preparation method disclosed in this invention, and includes the following steps: 1) The positive electrode preparation steps are as follows: Ternary positive electrode active material NCM811, conductive carbon black, and binder polyvinylidene fluoride are mixed at a mass ratio of 96:2.5:1.5 and dispersed in N-methyl-2-pyrrolidone to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated on both sides of an aluminum foil with a loading of 20 mg / cm². 2 After drying, rolling and vacuum drying, and then welding aluminum leads onto them with an ultrasonic welding machine, a positive electrode plate is obtained. 2) 100g of PAA (polyacrylic acid) with a molecular weight of 400,000 and 5g of HO-PEO (n=22)-UPy (hydroxyl-terminated polyethylene glycol-ureidopyrimidinone) were dissolved in water. 1g of carbodiimide (EDC) and 1g of N-hydroxysuccinimide (NHS) were added as catalysts, and the reaction was carried out at room temperature for 48 hours to obtain the target polymer. Unreacted small molecules were removed by dialysis, and the final self-healing flexible high-specific-capacity silicon-carbon anode binder (PAA-PEO-UPy, yield: 86%) was obtained by freeze-drying. A 10wt% polymer solution was prepared by dissolving a self-healing flexible high-capacity silicon-carbon anode binder in water. Silicon-carbon 600 (SiC600) and conductive carbon black were added to the polymer solution and mixed and dispersed to obtain an anode slurry. The mass ratio of SiC600: conductive carbon black: self-healing flexible high-capacity silicon-carbon anode binder was 8:1:1. The anode slurry was coated on both sides of a copper foil, vacuum dried at 60 degrees Celsius, and then the temperature was raised to 120 degrees Celsius for in-situ crosslinking reaction for 12 hours. Nickel leads were then welded on using an ultrasonic welding machine to obtain the anode plate. 3) The preparation steps of the non-aqueous electrolyte are as follows: 1 M LiPF6 is dissolved in EC / DMC (EC / DMC mass ratio 3:7), and 10 wt% FEC is added to obtain the non-aqueous electrolyte.

[0049] 4) The battery assembly steps are as follows: assemble the positive electrode, negative electrode and separator and inject liquid to obtain a coin cell, and then perform the first charge formation to obtain a secondary battery.

[0050] Examples 2-7 Examples 2-7 illustrate the secondary battery and its preparation method disclosed in this invention, and include most of the operations in Example 1, except that: The amounts of polyacrylic acid, hydroxyl-terminated polyether-multiple hydrogen bond units, and catalysts added, as well as the types of hydroxyl-terminated polyether-multiple hydrogen bond units, are shown in Examples 2-7 of Table 1.

[0051] Comparative Examples 1-2 Comparative Examples 1 and 2 are used to compare and illustrate the secondary battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences: The amounts of polyacrylic acid, hydroxyl-terminated polyether-multi-hydrogen bonded units, and catalyst added are shown in Comparative Examples 1-2 in Table 1.

[0052] Performance testing The secondary batteries prepared above were subjected to the following performance tests: Room temperature charge-discharge cycle performance test: At 25℃, the formed battery was charged to 80% SOC using a 1C constant current, then charged to 4.4V using a 1C constant current and constant voltage, and finally discharged to 3.0V using a constant current. After 200 charge / discharge cycles in this manner, the capacity retention rate and internal resistance growth rate were calculated for the 300th cycle. The calculation formulas are as follows: Capacity retention rate after 200 cycles (%) = (Discharge capacity after 300 cycles / Discharge capacity after 1 cycle) × 100%; The internal resistance growth rate (%) after the 200th cycle = (internal resistance after the 300th cycle - initial internal resistance of the 1st cycle) / initial internal resistance of the 1st cycle × 100%.

[0053] The test results are entered into Table 2.

[0054] Table 2 The test results from Examples 1-6 and Comparative Examples 1-2 show that when using the self-healing flexible high-capacity silicon-carbon anode binder containing polyether segments and multiple hydrogen bond units provided by this invention, and following a reasonable raw material ratio and using the specified catalyst, the cycle performance and structural stability of the secondary battery are significantly optimized, the cycle capacity retention rate is higher, and the internal resistance growth is more gradual. This indicates that the self-healing flexible high-capacity silicon-carbon anode binder can effectively buffer the volume expansion and contraction stress of the silicon-based anode, repair microcracks, and maintain the integrity of the electrode structure and the smooth flow of conductive paths. However, without the addition of polyether-multiple hydrogen bond units or catalysts with terminal hydroxyl groups, the battery cannot resist the negative impact of volume changes in the silicon-based anode, resulting in rapid capacity decay and a significant increase in internal resistance. This fully demonstrates the core role of side chain components and catalysts in improving battery performance.

[0055] The test results from Examples 1 and 7 show that even with different types of multiple hydrogen-bonding units (ureidopyrimidinone and glycineamide, respectively), both binders can maintain excellent cycle stability and a low internal resistance growth rate in the secondary battery. This indicates that ureidopyrimidinone and glycineamide, as multiple hydrogen-bonding units, can form a good synergistic effect with the polyether segments and the polyacrylic acid backbone, endowing the binder with self-healing ability through dynamic and reversible hydrogen bonding. Combined with the flexibility of the polyether segments to buffer stress, and relying on the polyacrylic acid backbone to ensure structural strength, this demonstrates the adaptability of the binder structure to different multiple hydrogen-bonding units.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-healing, flexible, high-specific-capacity silicon-carbon anode binder, characterized in that, It includes a polyacrylic acid backbone and side chains connected to the polyacrylic acid backbone. The side chains include polyether segments and multiple hydrogen bond units, and the polyether segments are connected to the multiple hydrogen bond units and the polyacrylic acid backbone, respectively.

2. The self-healing flexible high-specific-capacity silicon-carbon anode binder according to claim 1, characterized in that, The multiple hydrogen-bonded units include one or more of ureidopyrimidinone and glycineamide.

3. The self-healing flexible high-specific-capacity silicon-carbon anode binder according to claim 1, characterized in that, The self-healing flexible high-capacity silicon-carbon anode binder has a number-average molecular weight of 100,000 to 2,000,000.

4. The self-healing flexible high-specific-capacity silicon-carbon anode binder according to claim 1, characterized in that, The self-healing flexible high-specific-capacity silicon-carbon anode binder has the following structure: Where R is the side chain, x+y=100~10000; y:x=0.01~0.

8.

5. The self-healing flexible high-specific-capacity silicon-carbon anode binder according to claim 4, characterized in that, The R is selected from either structural formula 1 or structural formula 2: Structural Formula 1 Structural Formula 2 Where n is an integer from 2 to 1000.

6. The preparation method of the self-healing flexible high-specific-capacity silicon-carbon anode binder according to any one of claims 1 to 5, characterized in that, The following steps are included: Polyacrylic acid and hydroxyl-terminated polyether-multi-hydrogen bonded units are dissolved in a solvent, and a catalyst is added. The hydroxyl-terminated polyether-multi-hydrogen bonded units undergo dehydration condensation with the carboxyl groups on the polyacrylic acid, resulting in a self-healing flexible high-specific-capacity silicon-carbon anode binder.

7. The preparation method of the self-healing flexible high-specific-capacity silicon-carbon anode binder according to claim 6, characterized in that, The hydroxyl-terminated polyether-multiple hydrogen bond units are prepared by the following method: Polyethylene glycol is mixed and reacted with ureidopyrimidinone containing isocyanate or glycine amide containing isocyanate to obtain the polyether-multi-hydrogen bonded unit with terminal hydroxyl groups.

8. The preparation method of the self-healing flexible high-specific-capacity silicon-carbon anode binder according to claim 6, characterized in that, The mass ratio of the polyacrylic acid, the hydroxyl-terminated polyether-multi-hydrogen-bonded unit, and the catalyst is (100~1000):(5~20):(1~10); and / or, The catalyst comprises carbodiimide and N-hydroxysuccinimide, wherein the mass ratio of carbodiimide to N-hydroxysuccinimide is (1~10):(5~20).

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