Silicon-based material with self-adaptive coating layer, preparation method of silicon-based material and lithium battery

Abstract

The invention provides a silicon-based material with a self-adaptive coating layer, a preparation method of the silicon-based material and a lithium battery, and relates to the field of lithium ion battery preparation. According to the preparation method of the silicon-based material with the self-adaptive coating layer, the material is successfully applied to a sulfide-based all-solid-state battery, the PEGDGE-based coating layer is constructed on the surface of the silicon-based material through a liquid phase method, a reversible disulfide bond is introduced into the PEGDGE-based coating layer, the volume fluctuation of a silicon-based negative electrode in the circulation process is adapted, and the self-adaptive coating layer can be applied to the sulfide-based all-solid-state battery. The volume expansion and shrinkage of the silicon-based material in the circulation process are adapted to maintain the completeness of the coating layer, and the interface side reaction with the sulfide solid electrolyte is avoided; disulfide bonds are introduced through chain extension, so that the mechanical strength of the coating layer is enhanced; furthermore, the polymer chain is cross-linked and cured through an amino curing agent, so that the mechanical strength of the coating layer is enhanced, the cracking of the coating layer is inhibited, and the cycle life is prolonged.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing, and more particularly to a silicon-based material with an adaptive coating layer, its preparation method, and a lithium battery thereof. Background Technology

[0002] Lithium-ion batteries (LIBs), as the current mainstream electrochemical energy storage technology, have been widely used in 3C electronics, electric vehicles, and grid energy storage. However, existing commercial liquid lithium-ion batteries are limited by the flammability of the liquid electrolyte and the limited theoretical specific capacity of the graphite anode (372 mAh g⁻¹). Problems such as ¹) make it difficult for its energy density and safety to meet the needs of the continuously growing market.

[0003] In recent years, solid-state batteries based on solid electrolytes (such as oxides, sulfides, and polymers) have become an important development direction for overcoming the energy density and safety bottlenecks of existing liquid lithium-ion batteries due to their inherent safety and better compatibility with high-energy-density anode materials (such as lithium metal and silicon-based materials). They have attracted widespread attention from academia and industry. Among various solid-state electrolyte technologies, sulfide solid electrolytes stand out due to their extremely high room-temperature lithium-ion conductivity (reaching [missing information - likely a percentage]). With its high electrical conductivity (on the order of magnitude), extremely low electronic conductivity, and good mechanical ductility, it is considered one of the most promising material systems for realizing high-performance all-solid-state batteries.

[0004] Compared to lithium metal anodes, silicon-based anode materials have significant advantages in raw material cost, interface stability, and compatibility with processing technologies (such as the ability to be compounded with graphite). Furthermore, silicon materials have a lower lithiation potential (approximately 0.4 V vs. 10 V). The potential is higher than that of lithium metal deposition potential, which helps to suppress lithium dendrite growth and may alleviate interfacial side reactions between lithium and sulfide solid electrolyte.

[0005] Despite this, the practical application of silicon-based anode materials in solid-state battery systems still faces significant challenges. These challenges mainly manifest as limited actual capacity utilization, low initial coulombic efficiency, and short cycle life. The root cause of these problems lies in the inherently low electronic conductivity and lithium-ion diffusion coefficient of silicon materials. During charge and discharge, silicon undergoes drastic and repeated volume expansion / contraction (>300%), leading to pulverization and cracking of the active material, failure of contact with the conductive network and solid electrolyte particles, deterioration of interface stability, and ultimately poor cycle reversibility. Therefore, improving the structural stability, interfacial compatibility, and ion / electron transport efficiency of silicon-based anode materials in solid-state battery environments is a crucial technical issue that urgently needs to be addressed to promote the practical application of high-energy-density solid-state batteries.

[0006] Patent CN107240688B discloses a one-step method for coating silicon-based anode materials with sulfide solid electrolytes. The coating layer alleviates the volume expansion of the silicon anode during charging and discharging, effectively improves Li ion diffusion, reduces battery internal resistance, and enhances the mechanical and electrochemical performance stability of silicon. Patent CN115172669B discloses a method for preparing silicon-based anode materials using segmented sintering. The silicon-based anode material with a uniform and dense coating exhibits high lithium-ion conductivity and a wide voltage window. This effectively improves the rate performance and long-cycle stability of silicon-based anodes in sulfide all-solid-state batteries.

[0007] Existing technologies use sulfide solid electrolytes to directly coat the silicon anode. This cannot prevent the reduction and decomposition of the sulfide solid electrolyte at the interface during cycling, forming an inert lithium sulfide layer that hinders electron / ion transfer and leads to rapid performance degradation. Simultaneously, the silicon anode material experiences significant volume fluctuations during lithium insertion / extraction. With repeated cycling, this expansion and contraction causes the coating layer to crack and pulverize, exposing the internal active material and resulting in a continuous thickening of the SEI layer and increased interfacial impedance. Summary of the Invention

[0008] In view of the problems in the prior art, such as the easy reduction and decomposition of sulfide solid electrolytes, which hinders electron / ion transfer, leads to rapid battery performance degradation, and the easy expansion and contraction of silicon anode materials causing the coating layer to crack and pulverize, this application provides a silicon-based material with an adaptive coating layer, its preparation method, and a lithium battery.

[0009] Technical solution:

[0010] In a first aspect, this application provides a silicon-based material with an adaptive coating layer, which has a core-shell structure and includes a silicon-based material and an adaptive coating layer covering the surface of the silicon-based material;

[0011] The silicon-based material is one of vapor-deposited silicon-carbon, milled silicon-carbon, silicon-oxygen, porous silicon, micron-sized silicon, and nano-sized silicon;

[0012] The adaptive coating layer includes a polyethylene glycol diglycidyl ether structure. Structure, curing agent structure and lithium salt, wherein the lithium salt is distributed in the polyethylene glycol diglycidyl ether structure, Within the network of polymers formed by the structure and curing agent structure;

[0013] The curing agent structure is derived from a curing agent, which is an organic compound with at least two primary amino groups and a relative molecular weight of less than 800; The structure originates from disulfide bond extenders;

[0014] The structure of the polyethylene glycol diglycidyl ether is derived from polyethylene glycol diglycidyl ether;

[0015] in, It is an organic group containing an amino group.

[0016] This application proposes a preparation technology for silicon-based materials with adaptive coating. First, a network-like three-dimensional polymer coating is constructed on the surface of a silicon anode by polymerizing a flexible linear polymer, a disulfide bond grafting agent and a curing agent. Then, a corresponding lithium salt is introduced into the coating to improve the ionic conductivity of the coating.

[0017] After curing, the polymer completely and uniformly encapsulates the silicon material particles, forming a rigid coating layer. This prevents the silicon anode from directly contacting the sulfide solid electrolyte, slows down the reduction and decomposition of the sulfide solid electrolyte, and the addition of lithium salt effectively improves the lithium-ion conductivity of the coating layer.

[0018] As lithium insertion deepens, the silicon anode gradually expands. Simultaneously, the disulfide bonds in contact with the silicon anode material are reduced and opened. Disulfide bonds not directly in contact with the silicon anode undergo disulfide bond exchange, transforming the rigid coating layer into a flexible one, achieving dynamic coating, buffering volume expansion, and preventing coating layer damage and cracking. During delithiation, the silicon particles shrink in volume, the broken disulfide bonds recover, and a long-chain network is reformed. The coating layer once again tightly encapsulates the silicon particles, preventing interface separation, the formation of pores, and the continuous growth of the SEI, thus improving interfacial ion transport. This adaptive coating layer, through the association-deassociation reaction of dynamic disulfide bonds in the reversible network under redox conditions, dynamically changes between "rigidity" and "elasticity" in sync with the volume fluctuations during the silicon anode's lithium insertion / deintercalation process, preventing coating layer cracking, reducing interfacial side reactions, and improving cycle stability. Furthermore, by extending the disulfide bond chain with low-molecular-weight PEGDGE, the crystallinity of PEGDGE is reduced. Combined with the added lithium salt, this effectively improves the lithium-ion conductivity of the coating layer.

[0019] Furthermore, the aforementioned The molar ratio of the structure to the polyethylene glycol diglycidyl ether structure is: The molar ratio of the curing agent structure to the polyethylene glycol diglycidyl ether structure is: The mass of the lithium salt is 20-50 wt% of the mass of polyethylene glycol diglycidyl ether.

[0020] Furthermore, the lithium salt includes any one or a combination of several of LiTFSI, LiFSI, LiPF6, and LiBOB; the curing agent includes any one or a combination of several of hexamethylenediamine, diethylenetriamine, triethylenetetramine, m-phenylenediamine, and diaminodiphenylmethane.

[0021] Furthermore, the aforementioned In the structure, R is any one or a combination of 2-aminoethyl, 4-aminophenyl and 2-aminophenyl.

[0022] Furthermore, the relative molecular mass of the polyethylene glycol diglycidyl ether is 3000-30000.

[0023] Furthermore, the relative molecular mass of the polyethylene glycol diglycidyl ether is 4000-20000.

[0024] The optimal effect of PEGDGE is achieved when the molecular weight is 4000~20000 (PEGDGE4000~20000). Excessive ethoxy chains in the polymer can lead to local crystallization. The use of short-chain ethoxy chain network construction and the synergistic effect of lithium salt significantly improve the lithium-ion diffusion coefficient of the coating layer and enhance the rate performance of the material.

[0025] Furthermore, the silicon-based material is any one of silicon-carbon, silicon-oxygen, pre-lithium silicon-oxygen, porous silicon, micron-sized silicon, and nano-sized silicon; the D50 of the silicon-based material is 20 nm-20 μm.

[0026] Furthermore, the thickness of the adaptive coating layer is 2-50 nm.

[0027] Preferably, the thickness of the adaptive coating layer is 5-10 nm.

[0028] Secondly, this application provides a method for preparing the silicon-based material with an adaptive coating layer as described in this application, comprising the following steps:

[0029] S1: In an inert atmosphere, linear polyethylene glycol diglycidyl ether is dissolved in an organic solvent, heated and stirred, and then a disulfide chain extender is added dropwise to carry out a grafting chain extension reaction to obtain solution A;

[0030] S2: Add silicon-based material and lithium salt to solution A, stir and slowly add curing agent, heat to react and obtain suspension B;

[0031] S3: The powder product after the suspension is dried is transferred to a tube furnace and heated and cured under an inert atmosphere to obtain a silicon-based material with an adaptive coating layer.

[0032] Optionally, the organic dispersant includes one or more of tetrahydrofuran, dimethyl sulfoxide, and dimethylformamide.

[0033] Optionally, the grafting and chain extension reaction temperature in step S1 is 60-100℃.

[0034] Optionally, the thermosetting temperature in step S2 is 90-130℃.

[0035] Thirdly, this application provides a lithium battery comprising the silicon-based material with an adaptive coating layer as described in this application.

[0036] Beneficial effects:

[0037] 1. This invention proposes a method for preparing silicon-based materials with an adaptive coating layer and successfully applies the material to sulfide-based all-solid-state batteries. This application constructs a PEGDGE-based coating layer on the surface of a silicon-based material using a liquid-phase method. Reversible disulfide bonds are introduced into the PEGDGE-based coating layer to adapt to volume fluctuations in the silicon-based anode during cycling, and to accommodate the volume expansion and contraction of the silicon-based material during cycling, maintaining the integrity of the coating layer and avoiding interfacial side reactions with the sulfide solid electrolyte. The introduction of disulfide bonds through chain extension enhances the mechanical strength of the coating layer. Furthermore, crosslinking and curing of the polymer chains using an amino curing agent further enhances the mechanical strength of the coating layer, inhibits cracking, and improves cycle life.

[0038] 2. Furthermore, PEGDGE is preferred. While ensuring the mechanical strength of the coating layer, it avoids excessively long ethoxy chains in the polymer, which can lead to local crystallization. By constructing a short-chain ethoxy chain network and adding lithium salt, the lithium-ion diffusion coefficient of the coating layer is significantly improved, thereby enhancing the rate performance of the material. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the adaptive breaking and repair of disulfide bonds in the coating layer of the silicon-based material obtained by Example 1 of the present invention. Detailed Implementation

[0040] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] The raw materials used in this application include PEGDGE (polyethylene glycol diglycidyl ether), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiFSI (lithium bis(fluorosulfonyl)imide), LiPF6 (lithium hexafluorophosphate), and LiBOB (lithium bis(oxalato)borate).

[0042] Example 1: A method for preparing a silicon-based material with an adaptive coating layer, comprising the following preparation steps:

[0043] (1) Disulfide bond chain extension: Under an inert atmosphere, 10g of PEGDGE4000 was added to 50g of DMSO (dimethyl sulfoxide), heated to 60℃, and stirred for 60min before adding 1.0g of bis( Disulfides (also known as) Maintain the reaction temperature at 60℃ for 5 hours.

[0044] (2) Pre-curing coating: Continue to add 1950g DMSO, 1000g silicon carbide powder (Si / C, carbon content 50 wt%; D50: 8μm) and 5g LiFSI. After stirring and mixing for 60min, add 0.5g triethylenetetramine and heat to 80℃ to react and cure for 10h to obtain a suspension.

[0045] (3) Spray drying: After filtration and drying of the suspension, a powder product is obtained. Under an inert atmosphere, the powder is heated to 110℃ and held at that temperature for 2 hours for thermosetting to obtain a silicon-based material with an adaptive coating layer. A schematic diagram of the adaptive breaking and repair of disulfide bonds in the coating layer of the silicon-based material with the adaptive coating layer is shown below. Figure 1 .

[0046] Example 2: A method for preparing a silicon-based material with an adaptive coating layer, comprising the following preparation steps:

[0047] (1) Disulfide bond chain extension: Under an inert atmosphere, 20g of PEGDGE8000 was added to 50g of DMF, the temperature was raised to 70℃, and after stirring and mixing for 60min, 1.6g of 2,2'-dithiodiethylamine was added, and the reaction was maintained at 70℃ for 3h.

[0048] (2) Pre-curing coating: Add 1950g DMF, 1000g pre-lithium silicate (Li2SiO3 / Si; D50: 8μm) and 5g LiTFSI, stir and mix for 60min, then add 0.8g hexamethylenediamine, heat to 100℃ and react and cure for 10h to obtain a suspension.

[0049] (3) Drying and curing: After the suspension is filtered and dried, a powder product is obtained. Under an inert atmosphere, it is heated to 100°C and kept at a constant temperature for 2 hours to perform thermal curing, thereby obtaining a silicon-based material with an adaptive coating layer.

[0050] Example 3: A method for preparing a silicon-based material with an adaptive coating layer, comprising the following preparation steps:

[0051] (1) Disulfide chain extension: Under an inert atmosphere, 15g of PEGDGE20000 was added to 50g of DMSO, stirred and heated to 60℃, and after stirring and mixing for 60min, 0.5g of bis(2-aminophenyl) disulfide was added, and the reaction was maintained at 60℃ for 10h.

[0052] (2) Pre-curing coating: Continue to add 1950g DMSO, 1000g nano-silicon (D50: 80nm) and 7g LiBOB, stir and mix for 60min, then add 2.5g diaminodiphenylmethane, heat to 100℃ and react and cure for 6h to obtain a suspension;

[0053] (3) Spray drying: After the suspension is filtered and dried, a powder product is obtained. Under an inert atmosphere, it is heated to 120°C and kept at a constant temperature for 2 hours for thermal curing to obtain a silicon-based material with an adaptive coating layer.

[0054] Example 4, a method for preparing a silicon-based material with an adaptive coating layer, differs from Example 1 in that PEGDGE25000 is used to replace PEGDGE4000 in an equal amount.

[0055] Example 5, a method for preparing a silicon-based material with an adaptive coating layer, differs from Example 1 in that PEGDGE30000 is used to replace PEGDGE4000 in an equal amount.

[0056] Example 6, a method for preparing a silicon-based material with an adaptive coating layer, differs from Example 1 in that PEGDGE3000 is used to replace PEGDGE4000 in an equal amount.

[0057] Comparative Example 1, a method for preparing a silicon-based material with an adaptive coating layer, differs from Example 1 in that: PEG4000 is used in equal amounts to replace PEGDGE4000, a larger amount of DMSO and triethylenetetramine is used, and di( Disulfides, comprising the following preparation steps:

[0058] Pre-curing coating: Under an inert atmosphere, 10g of PEGDGE4000 was added to 2000g of DMSO, stirred and heated to 60℃, and kept at the temperature for 30min until completely dissolved. Then, 1000g of vapor-deposited silicon carbide (D50: 5μm) and 5g of LiFSI were added, stirred and mixed for 60min, and then 1.0g of triethylenetetramine was added. The mixture was heated to 80℃ and cured for 10h to obtain a suspension.

[0059] (2) Spray drying and high temperature curing: After the suspension is filtered and dried, a powder product is obtained. Under an inert atmosphere, it is heated to 110°C and kept at a constant temperature for 2 hours to perform thermal curing, thereby obtaining a silicon-based material with an adaptive coating layer.

[0060] Comparative Example 2, a method for preparing a silicon-based material with an adaptive coating layer, differs from Example 1 in that it does not use LiFSI, and includes the following preparation steps:

[0061] (1) Disulfide bond chain extension: Under an inert atmosphere, 10g of PEGDGE4000 was added to 50g of DMSO (dimethyl sulfoxide), the temperature was raised to 60℃, and after stirring and mixing for 60min, 1.0g of bis(4-aminophenyl) disulfide was added, and the reaction was maintained at 60℃ for 5h.

[0062] (2) Pre-curing coating: Continue to add 1950g DMSO and 1000g vapor-deposited silicon carbon (D50: 5μm), stir and mix for 60min, then add 0.5g triethylenetetramine, heat to 80℃ and react and cure for 10h to obtain a suspension;

[0063] (3) Drying and curing: After the suspension is filtered and dried, a powder product is obtained. Under an inert atmosphere, it is heated to 110°C and kept at a constant temperature for 2 hours to perform thermal curing, thereby obtaining a silicon-based material with an adaptive coating layer.

[0064] Comparative Example 3, a method for preparing a silicon-based material with an adaptive coating layer, differs from Example 1 in that functional polyurethane is used to replace PEGDGE8000 in equal amounts.

[0065] The preparation of functional polyurethane is as follows:

[0066] 1 mmol of polyethylene glycol (PEG2000) was heated at 110°C under vacuum for 2 hours, followed by stirring with a magnetic stirrer. A sample containing...

[0067] It contains 2 mmol of isophorone diisocyanate and 1 mmol of dibutyltin dilaurate. The solution (10 mL) was added dropwise to polyethylene glycol, and the reaction was continued at 75 °C for 2 h. Then, a solution containing 1 mmol of bis(oxo) was added. disulfide Add 5 mL of solution dropwise, incubate at 40°C, and observe under infrared light. The functional groups disappear, resulting in functional polyurethane.

[0068] The silicon anode materials described in Examples 1-6 and Comparative Examples 1-3 were homogenized and coated into modular half-cells for electrochemical performance testing. The specific scheme is as follows:

[0069] Solid-state half-cell assembly and electrochemical testing: 100 mg of Li6PS5Cl solid electrolyte powder was pre-pressed at 1 t. Then, 8 mg of composite negative electrode powder and 2 mg of Li6PS5Cl solid electrolyte powder were uniformly dispersed on one side and held at 7 t for 3 min. On the other side, In foil and Li foil were attached sequentially, and then held at 3 t for about 1 min. Finally, the screws of the battery mold were tightened to obtain the solid-state half-cell. All cells were tested at room temperature, and the cycle test rate was 0.1 C.

[0070] Table 1. List of lithium battery performance obtained using the methods of Examples 1-3 and Comparative Examples 1-2:

[0071] Material Initial delithiation capacity (mAh / g) First-time efficiency (%) 100-week capacity retention rate (%) 1C delithiation capacity utilization (mAh / g) 2C delithiation capacity utilization (mAh / g) Example 1 1858.2 93.6 92.5 1641.5 1333.8 Example 2 1358.9 92.5 88.1 1006.1 817.1 Example 3 2709.4 90.9 85.4 2177.3 1706.6 Example 4 1776.8 92.2 82.3 1479.0 927.4 Example 5 1701.5 91.4 83.9 1305.9 871.1 Example 6 1823.1 92.8 72.0 1600.3 1186.7 Comparative Example 1 1806.6 92.7 70.3 1208.7 992.5 Comparative Example 2 1468.1 88.3 61.9 1048.3 437.1 Comparative Example 3 1786.7 90.2 66.1 1346.8 1008.5

[0072] Electrochemical test results show that: Experiment 1, which uses vapor-deposited silicon-carbon as the core, is superior to vapor-deposited silicon-carbon with lithium intercalation because it has lower expansion and better internal conductivity. Therefore, silicon-based materials with silicon-carbon as the core have better cycle stability and rate performance than those with pre-lithiated silicon-oxygen (Experiment 2) and nano-silicon (Experiment 3).

[0073] In Comparative Example 1, no disulfide bonds were introduced into the polymer coating layer. During cycling, the expansion of the silicon-based material due to lithium intercalation caused irreversible rupture of the coating layer, exposing the silicon-based material. This led to continuous growth of the SEI and rapid capacity decay.

[0074] In Comparative Example 2, no lithium salt was added to the coating layer, resulting in a low lithium-ion diffusion coefficient in the coating layer, which significantly reduced the material's first efficiency, rate performance, and cycle life.

[0075] Analysis of data obtained from electrochemical tests reveals that constructing an adaptive coating layer on the surface of silicon-based materials helps to isolate the sulfide solid electrolyte from the silicon-based materials, avoiding interfacial side reactions. Simultaneously, the reversible breaking of disulfide bonds ensures the coating layer remains intact during cycling, preventing cracking and effectively extending the material's cycle life.

[0076] Example 1 exhibits higher rate capability compared to Comparative Example 3. This may be because the urethane bonds (urethane bonds) formed by the reaction of isocyanate and hydroxyl groups in Comparative Example 3 are highly polar and readily form hard segment microdomains through hydrogen bonding. These microdomains have higher crystallinity, which restricts the movement of polymer chain segments and reduces the ionic conductivity of the coating layer. Furthermore, isocyanate is highly toxic, and the resulting urethane groups are sensitive to moisture, easily decomposing slowly and disrupting the integrity of the coating layer.

[0077] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A silicon-based material with an adaptive coating layer, characterized in that, It has a core-shell structure, consisting of a silicon-based material and an adaptive coating layer covering the surface of the silicon-based material; The silicon-based material is one of vapor-deposited silicon-carbon, milled silicon-carbon, silicon-oxygen, porous silicon, micron-sized silicon, and nano-sized silicon; The adaptive coating layer includes a polyethylene glycol diglycidyl ether structure, an RSSR structure, a curing agent structure, and a lithium salt, wherein the lithium salt is distributed in the network of the polymer formed by the polyethylene glycol diglycidyl ether structure, the RSSR structure, and the curing agent structure. The curing agent structure is derived from the curing agent, which is an organic compound with at least two primary amino groups and a relative molecular weight of less than 800; the RSSR structure is derived from a disulfide chain extender. The structure of the polyethylene glycol diglycidyl ether is derived from polyethylene glycol diglycidyl ether; R- represents an organic group containing an amino group.

2. The silicon-based material with an adaptive coating layer according to claim 1, characterized in that, The molar ratio of the RSSR structure to the polyethylene glycol diglycidyl ether structure is 100:25-75; the molar ratio of the curing agent structure to the polyethylene glycol diglycidyl ether structure is 5-20:100; and the mass of the lithium salt is 20-50 wt% of the mass of the polyethylene glycol diglycidyl ether.

3. The silicon-based material with an adaptive coating layer according to claim 1 or 2, characterized in that, The lithium salt includes any one or a combination of several of LiTFSI, LiFSI, LiPF6, and LiBOB; the curing agent includes any one or a combination of several of hexamethylenediamine, diethylenetriamine, triethylenetetramine, m-phenylenediamine, and diaminodiphenylmethane.

4. The silicon-based material with an adaptive coating layer according to claim 3, characterized in that, In the RSSR structure, R is any one or a combination of 2-aminoethyl, 4-aminophenyl, and 2-aminophenyl.

5. The silicon-based material with an adaptive coating layer according to any one of claims 1-2 and 4, characterized in that, The polyethylene glycol diglycidyl ether has a relative molecular mass of 3000-30000.

6. The silicon-based material with an adaptive coating layer according to claim 5, characterized in that, The polyethylene glycol diglycidyl ether has a relative molecular mass of 4000-20000.

7. The silicon-based material with an adaptive coating layer according to any one of claims 1-2, 4, and 6, characterized in that, The silicon-based material is any one of vapor-deposited silicon-carbon, milled silicon-carbon, silicon-oxygen, porous silicon, micron-sized silicon, and nano-sized silicon; the D50 of the silicon-based material is 20 nm-20 μm.

8. The silicon-based material with an adaptive coating layer according to claim 7, characterized in that, The thickness of the adaptive coating layer is 2-50 nm.

9. A method for preparing a silicon-based material with an adaptive coating layer as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: In an inert atmosphere, linear polyethylene glycol diglycidyl ether is dissolved in an organic solvent, heated and stirred, and then a disulfide chain extender is added dropwise to carry out a grafting chain extension reaction to obtain solution A; S2: Add silicon-based material and lithium salt to solution A, stir and slowly add curing agent, heat to react and obtain suspension B; S3: The powder product after the suspension is dried is transferred to a tube furnace and heated and cured under an inert atmosphere to obtain a silicon-based material with an adaptive coating layer.

10. A lithium battery, characterized in that, A silicon-based material having an adaptive coating as described in any one of claims 1-8.

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