Low-strain nano-silicon-carbon-based negative electrode material and preparation method thereof, and solid-state battery

Abstract

The application provides a low-strain nano silicon-carbon-based negative electrode material and a preparation method and a solid-state battery thereof, and relates to the technical field of lithium batteries. The application uses a bio-based material and a porous template material, carries out pretreatment on the materials, composites the materials at a certain ratio, calcines the precursor, carries out multiple washing and separation on the product, and prepares a composite nano silicon-carbon negative electrode material. The bio-based material provides rich conductive paths and also plays a good supporting role for the electrode material. The porous template material makes the composite material have a good pore structure, can provide more electrochemical reaction sites and lithium storage space, and also makes the electrode material have better stress buffering capacity. The volume expansion problem of the silicon-based material is significantly improved in cooperation of the two, and the nano silicon-carbon electrode material has high capacity and good rate performance and cycle performance.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and in particular to a low-strain nano-silicon-carbon based anode material and its preparation method, as well as a solid-state battery. Background Technology

[0002] Battery energy has become one of the most important energy sources for society due to its clean emissions, and lithium-ion batteries have sparked a global research boom. The key challenges of high-energy lithium-ion batteries lie in the safety issues caused by lithium dendrite formation, electrolyte instability, and the matching of positive and negative electrodes at high energy levels. Compared to liquid batteries, solid-state batteries can solve most of these problems; therefore, solid-state batteries are considered the ultimate direction for battery development.

[0003] Similar to liquid batteries, solid-state batteries consist of positive and negative electrode materials and an electrolyte. The negative electrode, as the main component of solid-state batteries, has always been a primary research focus. Currently, commercially available batteries generally use graphite or silicon anode materials. Graphite has a relatively low theoretical capacity (372 mAh / g) and can react chemically with the electrolyte at lower potentials. Silicon anode materials, on the other hand, have a higher theoretical capacity (4200 mAh / g), which can significantly improve the battery's energy density. However, silicon anodes also have specific problems, such as poor conductivity, significant volume expansion during lithiation, and severe polarization, which seriously affect the battery's cycle stability and efficiency.

[0004] Studies have found that combining silicon and carbon materials can synergistically improve the problems of low capacity of carbon materials and severe volume expansion of silicon materials (characterization techniques such as CP-SEM can be used to investigate the volume expansion problem of silicon anodes). In existing technologies, patent CN103682287A prepared a silicon-based composite material with an embedded composite core-shell structure by combining mechanical grinding and pressure technology. This material has high capacity and first-pass efficiency, but combining it only with graphite materials cannot effectively alleviate the volume expansion problem of silicon-based materials. CN113506861A prepared a silicon-based composite anode material by dispersing silicon and doped metals in a silicon oxide substrate and coating carbon materials on the surface of the material particles. This material dopes metals in silicon suboxide, releasing a portion of the lithium in the buffer layer through a reversal reaction, inhibiting the agglomeration and growth of silicon crystal regions during cycling, and improving the electrochemical performance of the anode material. However, this method is relatively complex, requires strict technical conditions, and it is difficult to guarantee stable preparation and batch consistency of the material, which can also affect the material's performance. In addition, existing methods for compositing silicon-carbon materials and the resulting anode materials often involve significant pollution and high costs. Anode materials prepared using simpler methods generally have low conductivity, high electrochemical impedance, and poor material structure uniformity, making them difficult to commercialize. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a low-strain nano-silicon-carbon-based anode material and its preparation method. This material is prepared by combining a bio-based carbon source with nano-silicon via a mesoporous template method. The preparation method is simple, the reaction conditions are mild, and the reproducibility is high. This not only gives the material better dispersibility, uniformity, and structural stability, but also allows for macroscopic control of the material's size and structure, significantly improving the structural stability and electrochemical performance of the silicon-based anode. This solves the capacity decay problem caused by the volume expansion during charging and discharging of traditional silicon-based materials.

[0006] One of the objectives of this invention is to provide a method for preparing low-strain nano-silicon-carbon-based anode materials.

[0007] The second objective of this invention is to provide a low-strain nano-silicon-carbon-based anode material prepared by this method.

[0008] A third objective of this invention is to provide a lithium-ion battery comprising the low-strain nano-silicon-carbon-based anode material.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] In a first aspect, the present invention provides a method for preparing a low-strain nano-silicon-carbon-based anode material, comprising the following steps:

[0011] S1. Add the template agent to the solvent and stir until completely dissolved. Then add the silicon source and adjust the pH with an acidic solution to obtain a mixed solution.

[0012] S2. The mixed solution obtained in step S1 is transferred into a stainless steel reactor with a polytetrafluoroethylene liner for aging reaction. After the reaction, the reactor is cooled and the product is taken out. The product is washed, filtered, and dried. The dried product is transferred to a muffle furnace for calcination treatment. After cooling, mesoporous SiO2 template material is obtained.

[0013] S3. The mesoporous SiO2 template material obtained in step S2 is mixed with Al / AlCl3 mixed powder and then heated and sintered under a protective atmosphere. At this time, Al acts as a reducing agent and undergoes an aluminothermic reaction with AlCl3 and the mesoporous SiO2 template material. After the reaction is complete, a solid is obtained. The solid is washed, filtered, and dried with acid to obtain an intermediate product.

[0014] S4. The intermediate product obtained in step S3, the pretreated bio-based material, and the nano-silicon powder are mixed and ball-milled. The collected product is placed in a tube furnace and calcined under a protective atmosphere to obtain a low-strain nano-silicon-carbon-based anode material.

[0015] The following is a detailed explanation:

[0016] Step S1:

[0017] In some embodiments, the template agent in step S1 is one or more of F127 (a block copolymer template agent composed of polyoxyethylene (PEO) and polypropylene (PPO) segments), penetrant JFCS, sodium dodecyl sulfate, P123, Triton, and mesitylene (TMB); the solvent is one or more of deionized water, methanol, ethanol, and DMF; the silicon source is one or more of tetraethyl orthosilicate (TEOS), methyl orthosilicate, water glass, and silica sol; and the acidic solution is one or more of hydrochloric acid, glacial acetic acid, and propionic acid.

[0018] In some embodiments, the mass ratio of silicon source to template agent in step S1 is 1:5 to 1; the mass ratio of silicon source to solvent is 1:8 to 30; and the pH of the acidic solution is adjusted to 1-5.

[0019] In some embodiments, step S1 specifically includes: adding the template agent to the solvent and stirring for the first time, then adding the silicon source and stirring for the second time, and then adding the acidic solution and stirring for the third time to obtain a mixed solution; the stirring rate for each stirring is 80-150 r / min, the first stirring time is 10-30 min, the second stirring time is 20-40 min, and the third stirring time is 20-40 min.

[0020] Step S2:

[0021] In some embodiments, in step S2, the aging temperature is 80–160°C and the aging time is 6–18 hours.

[0022] In some embodiments, in step S2, the number of washing and filtration cycles is 3 to 8, the washing solvent is one or more of methanol, ethanol, deionized water, and DMF, and the drying temperature is 60 to 110°C.

[0023] In some embodiments, in step S2, the muffle furnace heating rate is 1-3°C / min, the calcination temperature is 300-900°C, and the calcination time is 3-9h.

[0024] The template agent used in this invention is a surfactant. When added to a solvent, its hydrophilic and hydrophobic groups spontaneously aggregate in the solution to form polymers with regular shapes, called micelles. Under specific concentrations and conditions, these micelles further self-assemble into long-range ordered structures, such as cubic, hexagonal, or layered structures. This is like a spontaneously formed, nanoscale "mold" or "scaffold." Hydrolysis and condensation of the silicon source (filling the "mold"): When a silicon source (such as tetraethyl orthosilicate, TEOS) is added, a hydrolysis reaction occurs under the action of an acidic catalyst (such as hydrochloric acid or glacial acetic acid), generating silanol groups. Subsequently, these silanol groups undergo a condensation reaction to form a Si-O-Si network, i.e., a precursor of silica. The formed silica network does not grow randomly but surrounds the previously formed template agent micelles, using the micelles as templates for deposition and solidification, thereby replicating the morphology and arrangement of the micelles.

[0025] Step S3:

[0026] In some embodiments, in step S3, the mass ratio of the mesoporous SiO2 template material to the Al / AlCl3 mixed powder (a mixture of Al powder and AlCl3 powder, with a mass ratio of Al powder to AlCl3 powder of 4:1 to 1:4) is 1:1 to 3.

[0027] In some embodiments, in step S3, the protective atmosphere is one of argon, nitrogen, or a mixture of argon and nitrogen; the heating rate for sintering is 1–10 °C / min, the sintering temperature is 500–1000 °C, and the sintering time is 1–5 h.

[0028] In some embodiments, in step S3, the acid solution is one or more of hydrochloric acid, sulfuric acid, and acetic acid; the number of pickling cycles is 1 to 5; the drying temperature is 50 to 110°C; and the drying time is 6 to 12 hours.

[0029] In this reaction step, the SiO2 template is converted into a Si / SiO2 / Al2O3 complex, and then SiO2 and Al2O3 are removed, thus forming coral-like porous silicon (primary pores).

[0030] This process mainly involves the following two major chemical reactions:

[0031] Main reaction: Silicon dioxide is reduced by aluminum, and Al can displace Si at high temperature. This is the core reaction for obtaining elemental Si.

[0032] Side reactions: Aluminum chloride decomposes at high temperatures, producing chlorine gas and Al, which can further react with silicon dioxide. Furthermore, the generation and escape of gaseous products leave and create additional pores in the reaction system, contributing to the formation of a richer and more interconnected porous structure, resembling a coral-like porous structure.

[0033] Step S4:

[0034] In step S4, the pretreated bio-based material is prepared by the following method:

[0035] The bio-based material was cleaned by soaking in acid and alkali solutions and then washed with distilled water. The product was then dried in an oven. The resulting product was crushed and collected, then dried in an oven for later use.

[0036] Preferably, the bio-based material is angiosperm leaves or fruit shells;

[0037] Preferably, the acid solution is one or more of hydrochloric acid, sulfuric acid, and acetic acid; the alkali solution is one or more of sodium hydroxide, potassium hydroxide, and ammonia water; the soaking time for each is 3 to 18 hours; the oven temperature is 60 to 110°C, and the drying time is 3 to 18 hours; the crushing method is one or more of grinding, crushing with a crusher, and crushing with a ball mill, the crushing time is 3 to 9 hours, and the crushed particles are 100-500 nm.

[0038] In some embodiments, in step S4, the mass ratio of intermediate product to pretreated bio-based material is 10:0.1 to 1.5; the mass ratio of intermediate product to nano-silicon powder is 10:0.2 to 1; and the particle size of nano-silicon powder is 100 to 150 nm.

[0039] In some embodiments, in step S4, the ball milling speed is 200-2000 rpm and the ball milling time is 3-9 h;

[0040] In some embodiments, in step S4, the protective atmosphere is one of argon, nitrogen, or a mixture of argon and nitrogen; the calcination heating rate is 3–9 °C / min, the calcination temperature is 400–900 °C, and the calcination time is 3–9 h.

[0041] Bio-based materials possess a native mesoporous structure. After calcination, most bio-based carbon materials form a layered carbon skeleton, while some adhere to coral-like template materials to form corresponding porous carbon materials (secondary pores).

[0042] After calcination, the biochar material acts as a flexible substrate to coat the coral-like channels and nano-silicon particles. The gaps between the nano-silicon particles will form micropores (tertiary pores).

[0043] In one specific embodiment, the preparation method of the low-strain nano-silicon-carbon-based anode material includes the following steps:

[0044] 1) Add one or more of F127, JFCS, sodium dodecyl sulfate, P123, Triton, and TMB to one or more of deionized water, methanol, ethanol, and DMF, and stir at 80-150 r / min for 10-30 min; then add one or more of TEOS, methyl orthosilicate, water glass, and silica sol, and stir at 80-150 r / min for 20-40 min; finally, add one or more of hydrochloric acid, glacial acetic acid, and propionic acid to the mixed solution, adjust the pH to 1-5, and stir at 80-150 r / min for 20-40 min to obtain the mixed solution;

[0045] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 80-160°C for 6-18 hours. After cooling the reactor, the product is removed and washed and filtered 3-8 times with one or more of methanol, ethanol, deionized water, and DMF. The product is then dried in an oven at 60-110°C for 6-18 hours. The dried product is then transferred to a muffle furnace and heated to 300-900°C at 1-3°C / min for 3-9 hours. After cooling, mesoporous SiO2 template material is obtained.

[0046] 3) The mesoporous SiO2 template material obtained in step 2) is mixed with Al and AlCl3 mixed powder and then heated to 500-1000℃ at 1-10℃ / min under a protective atmosphere of argon, nitrogen, or argon-nitrogen mixed gas, and sintered for 1-5 hours to obtain a solid sample. The solid is then soaked in one or more of hydrochloric acid, sulfuric acid, and acetic acid to remove impurities, washed 1-5 times, centrifuged at 5000-10000 r / min and filtered. Finally, the sample is placed in a vacuum drying oven and dried at 50-110℃ for 6-12 hours to obtain an intermediate product.

[0047] 4) Soak the bio-based material, angiosperm leaves or fruit shells, in one or more of hydrochloric acid, sulfuric acid, acetic acid, and one or more of sodium hydroxide, potassium hydroxide, and ammonia water for 3-18 hours. Repeat the washing process 1-5 times, then wash with distilled water 3-5 times. Subsequently, place the product in an oven at 60-110℃ and dry for 3-18 hours. After the product is crushed by one or more methods such as grinding, crushing with a crusher, or crushing with a ball mill, it is collected and placed in an oven at 50-100℃ for later use.

[0048] 5) The products obtained in steps 3) and 4) are mixed with 100-150 nm Si powder and ball-milled at 200-2000 rpm for 3-9 h. The collected products are placed in a tube furnace and calcined at a heating rate of 3-9 °C / min, a calcination temperature of 400-900 °C, and a calcination time of 3-9 h under a protective atmosphere of nitrogen, argon, or a nitrogen-sulfur mixture. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0049] Structural design of silicon-based anode materials (multidimensional materials, special morphologies) can significantly improve their ion transport efficiency and reduce material volume expansion. In addition, using carbon materials to composite silicon-based anode materials can further improve the conductivity of the materials, giving them better electrochemical performance. At the same time, the larger specific surface area of ​​silicon-based composite materials will also provide more sites for electrochemical reactions, which is of great help to improve the rate performance of electrode materials.

[0050] This invention employs a dual-synergistic structural design, combining bio-based carbon (flexible support) with porous template carbon (rigid framework) to form a multi-level buffer channel (micropores + macropores), significantly suppressing silicon expansion stress. After sintering, the bio-based carbon material possesses a high specific surface area, providing abundant lithium storage sites for the electrode material. The combination of the natural multi-level channels (micropores + macropores) of biomass and artificially created pores forms a continuous three-dimensional pore network, significantly improving ion transport efficiency. Furthermore, the unique structure of biomass carbon can encapsulate silicon particles, enhancing their mechanical strength and mitigating silicon volume expansion. The synergistic effect of the silicon-carbon composite material results in an electrode material with higher electrochemical capacity and better cycle performance. A low-cost, green process replaces expensive templates with biomass, achieving uniform dispersion of nano-silicon through aluminothermic reduction-ball milling composite, thus improving interface stability.

[0051] Secondly, the present invention provides a low-strain nano-silicon-carbon-based anode material, which is prepared by the above-described preparation method.

[0052] The material of this invention has a three-level channel structure, such as Figure 1 As shown (the green flakes represent bio-based carbon materials, the silver-gray pipes represent coral-like porous silicon, and the blue parts represent nano-silicon particles), primary pores: coral-like macropores formed by the aluminothermic reaction, with a pore diameter of approximately 50-300 nm and a pore volume of approximately 0.8-1.5 cm³. 3 / g; Secondary pores: mainly composed of mesoporous carbon materials derived from the calcination of bio-based materials, with pore sizes of approximately 5-40 nm and pore volumes of approximately 0.3-0.6 cm³. 3 / g; Tertiary pores: Micropores formed between nano-silicon particles, with a pore size <2nm and a pore volume <0.3cm³. 3 / g.

[0053] The primary pores are non-connected coral-like structures, with pore walls composed of nano-silicon and SiO2 composites (SiO2 ratio < 5wt%), and pore wall thickness of 20-80nm.

[0054] The secondary pores are interconnected network structures with a specific surface area accounting for more than 60% of the total material. They are formed by bio-based carbon coating the primary pore walls, with a carbon layer thickness of 20-100 nm.

[0055] Tertiary pores are distributed at the interface between primary and secondary pores, with a distribution density of 10. 4 -10 5 The number of particles per μm² (selective electron microscopy calculation) is used to maintain the total porosity of the material at 35-45%.

[0056] Thirdly, the present invention provides a solid-state battery including the low-strain nano-silicon-carbon-based anode material.

[0057] The low-strain nano-silicon-carbon-based anode material, sulfide electrolyte material, and activated carbon material are mixed in a mass ratio of 1:02-0.6:0.01-0.05 to form a slurry, which is then coated onto copper foil. The thickness of the electrolyte layer in the solid-state battery does not exceed 1 mm, and the pressure of the solid-state battery does not exceed 5 MPa.

[0058] Existing silicon-carbon composite anode materials are mostly coated, layered, or simple composite structures. For solid-state battery anodes, these structures limit the ionic conductivity of the material. This invention, however, uniformly embeds silicon material within a carbon-based framework, which is highly beneficial for improving the ionic conductivity of the electrode material. In practical applications, the high specific surface area porous silicon-carbon material can be mixed with the electrolyte or used alone. Furthermore, the high specific surface area porous silicon-carbon material can be directly coated or sprayed onto the electrode sheet, or transferred to the electrode surface through other methods.

[0059] Technical effects:

[0060] 1. This invention utilizes a mesoporous template combined with bio-carbon to construct a multi-level buffer structure, effectively suppressing silicon volume expansion. A high specific surface area porous framework (coral-like porous silicon) is formed through mesoporous silica templates and aluminothermic reduction, providing ample lithium-ion transport channels. The bio-based carbon and nano-silicon composite form a flexible carbon network that uniformly coats silicon particles, significantly alleviating stress and strain during charging and discharging.

[0061] 2. The nano-silicon of this invention is uniformly dispersed, significantly improving the material's conductivity and cycle stability. The ball milling process ensures high dispersion of nano-silicon (particle size <50nm) within the carbon matrix, preventing agglomeration and improving the utilization rate of active materials. The synergistic effect of porous carbon and bio-carbon enhances electron conduction, reduces material impedance, achieves an initial efficiency ≥85%, and retains >90% capacity after 100 cycles.

[0062] 3. The present invention optimizes electrochemical performance through metal doping, and can be adapted to different needs through compositional control. The Al residue and possible metal oxides introduced by aluminothermic reduction can improve the interfacial stability of the material. By adjusting parameters such as silicon / carbon ratio and calcination temperature (400-600℃), the specific capacity (800-1500mAh / g) and rate performance of the material can be controlled.

[0063] 4. This invention is applicable to high-energy-density solid-state batteries and is compatible with sulfide / oxide electrolytes. After the negative electrode material is combined with the sulfide electrolyte (mass ratio 1:0.2~0.6), the solid-state battery can achieve stable cycling under a pressure of ≤5MPa, with an electrolyte layer thickness of ≤1mm and a volumetric energy density of ≥500Wh / L.

[0064] 5. The raw materials used in this invention are simple, readily available, and low in cost. The reaction conditions are mild, and the preparation process is simple, feasible, and highly reproducible. Common template agents (such as P123 and F127), silicon sources (such as TEOS), and bio-based carbon sources (such as common leaves, fruit shells, and straw) are used, resulting in a wide range of raw material sources and low cost. The preparation process is based on a combination of sol-gel method, aluminothermic reduction, and ball milling. The reaction temperature is moderate (300–1000℃), requiring no harsh conditions, making it suitable for industrial-scale production.

[0065] 6. This invention is environmentally friendly and has strong process scalability. The use of bio-based carbon sources reduces resource consumption, and acid / alkali treatment and low-temperature calcination reduce energy consumption. The entire process contains no highly toxic reagents, and the washing wastewater is easy to treat, meeting the requirements of green manufacturing.

[0066] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Attached Figure Description

[0067] Figure 1 This is a structural simulation diagram of the low-strain nano-silicon-carbon-based anode material prepared in this invention;

[0068] Figure 2 This is the electrochemical impedance spectroscopy diagram of the low-strain nano-silicon-carbon based anode material prepared in Example 1 of this invention. Detailed Implementation

[0069] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0070] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0071] Example 1

[0072] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0073] 1) Add 2g of F127 to 30g of deionized water and stir at 80r / min for 30min; then add 2g of TEOS and stir at 80r / min for 20min; finally add hydrochloric acid to the mixed solution to adjust the pH to 2, stir at 80r / min for 20min to obtain the mixed solution.

[0074] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 80°C. After 6 hours of reaction, the reactor is cooled and the product is removed. The product is washed and filtered three times with methanol at a centrifugal rate of 5000 r / min. The product is then dried in an oven at 60°C for 6 hours. The dried product is then transferred to a muffle furnace and calcined at 300°C at a rate of 1°C / min for 3 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0075] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 2g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat to 500℃ at 1℃ / min under argon protection atmosphere and sinter for 1h to obtain a solid sample. Soak the product in hydrochloric acid to remove impurities, then wash once, centrifuge at 5000r / min and filter. Finally, place the sample in a vacuum drying oven and dry at 50℃ for 6h to obtain an intermediate product.

[0076] 4) Soak the leaves of the angiosperm in hydrochloric acid for 3 hours, then soak them in sodium hydroxide solution for 3 hours, repeating this process twice. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 60°C for 3 hours. The resulting product is then ground and crushed, collected, and dried in an oven at 50°C for later use.

[0077] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.1g of 100nm Si powder. Mix the three materials and put them into a ball mill at 200rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 400℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0078] Example 2

[0079] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0080] 1) Add 2g of P123 to 50g of deionized water and stir at 100r / min for 30min; then add 2g of water glass and stir at 100r / min for 30min; finally add glacial acetic acid to the mixed solution to adjust the pH to 2, stir at 100r / min for 20min to obtain the mixed solution.

[0081] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 80°C. After 6 hours of reaction, the reactor is cooled and the product is removed. The product is washed and filtered four times with methanol at a centrifugal speed of 6000 r / min. The product is then dried in an oven at 60°C for 10 hours. The dried product is then transferred to a muffle furnace and calcined at 300°C at a temperature of 1°C / min for 3 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0082] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 2g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 600℃ at 2℃ / min under argon protection atmosphere and sinter for 2h to obtain a solid sample. Soak the product in hydrochloric acid to remove impurities, then wash it twice, centrifuge at 5000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 50℃ for 6h to obtain an intermediate product.

[0083] 4) Soak the leaves of the angiosperm in hydrochloric acid for 3 hours, then soak them in sodium hydroxide solution for 2 hours, repeating this process 3 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 60°C for 4 hours. The resulting product is then ground and crushed, collected, and dried in an oven at 60°C for later use.

[0084] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.2g of 100nm Si powder. Mix the three materials and put them into a ball mill at 400rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 2℃ / min, the calcination temperature is 400℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0085] Example 3

[0086] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0087] 1) Add 2g JFCS to 30g deionized water and stir at 100r / min for 30min; then add 2g water glass and stir at 100r / min for 30min; finally add glacial acetic acid to the mixed solution to adjust the pH to 3, stir at 120r / min for 30min to obtain the mixed solution.

[0088] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 100°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered four times with methanol at a centrifugal speed of 6000 r / min. The product is dried in an oven at 60°C for 10 hours. The dried product is transferred to a muffle furnace and calcined at 500°C at a temperature of 1°C / min for 5 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0089] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 2g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 600℃ at 3℃ / min under argon protection atmosphere and sinter for 2h to obtain a solid sample. Remove impurities by soaking the product in hydrochloric acid, wash it twice, centrifuge at 5000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 80℃ for 6h to obtain an intermediate product.

[0090] 4) Soak the leaves of the angiosperm in hydrochloric acid for 3 hours, then soak them in sodium hydroxide solution for 4 hours, repeat 4 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 80°C for 4 hours. The resulting product is then ground and crushed, collected and dried in an oven at 80°C for later use.

[0091] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.15g of 100nm Si powder. Mix the three materials and put them into a ball mill at 1000rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 2℃ / min, the calcination temperature is 500℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0092] Example 4

[0093] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0094] 1) Add 2g of sodium dodecyl sulfate to 50g of DMF and stir at 120r / min for 20min; then add 2g of water glass and stir at 120r / min for 20min; finally add glacial acetic acid to the mixed solution to adjust the pH to 2, stir at 120r / min for 30min to obtain the mixed solution.

[0095] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 110°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered four times with methanol at a centrifugal speed of 5000 r / min. The product is dried in an oven at 60°C for 10 hours. The dried product is transferred to a muffle furnace and calcined at 500°C at a temperature of 2°C / min for 5 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0096] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 1.5g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 600℃ at 2℃ / min under argon protection atmosphere and sinter for 2h to obtain a solid sample. Soak the product in hydrochloric acid to remove impurities, then wash it three times and centrifuge it at 6000r / min. Finally, place the sample in a vacuum drying oven and dry it at 80℃ for 6h to obtain an intermediate product.

[0097] 4) Soak the bio-based material thin shell in hydrochloric acid for 3 hours, then soak it in sodium hydroxide solution for 4 hours, repeat 3 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 70°C for 5 hours. After grinding and crushing the product, collect it and dry it in an oven at 90°C for later use.

[0098] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.3g of 100nm Si powder. Mix the three materials and put them into a ball mill at 1500rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0099] Example 5

[0100] This embodiment provides a method for preparing a composite nano-silicon-carbon based anode material, including the following steps:

[0101] 1) Add 2g of Triton to 40g of deionized water and stir at 100r / min for 30min; then add 2g of water glass and stir at 100r / min for 30min; finally add glacial acetic acid to the mixed solution to adjust the pH to 3, stir at 100r / min for 30min to obtain the mixed solution.

[0102] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 100°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered three times with methanol at a centrifugal speed of 6000 r / min. The product is dried in an oven at 60°C for 12 hours. The dried product is transferred to a muffle furnace and calcined at 600°C for 5 hours at a temperature of 3°C / min. After cooling, mesoporous SiO2 template material can be obtained.

[0103] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 1.5g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 600℃ at 2℃ / min under argon protection atmosphere and sinter for 3h to obtain a solid sample. Soak the product in hydrochloric acid to remove impurities, then wash it 4 times, centrifuge at 7000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 60℃ for 6h to obtain an intermediate product.

[0104] 4) Soak the bio-based material thin shell in hydrochloric acid for 3 hours, then soak it in sodium hydroxide solution for 4 hours, repeat 4 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 80°C for 5 hours. After grinding and crushing the product, collect it and dry it in an oven at 90°C for later use.

[0105] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.2g of 100nm Si powder. Mix the three materials and put them into a ball mill at 1500rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0106] Example 6

[0107] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0108] 1) Add 2g of P123 to 40g of deionized water and stir at 100r / min for 30min; then add 2g of water glass and stir at 100r / min for 20min; finally add glacial acetic acid to the mixed solution to adjust the pH to 2, stir at 120r / min for 30min to obtain the mixed solution.

[0109] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 110°C for 6 hours. After 6 hours of reaction, the reactor is cooled and the product is removed. The product is washed and filtered three times with methanol at a centrifugal speed of 5000 r / min. The product is then dried in an oven at 80°C for 12 hours. The dried product is then transferred to a muffle furnace and calcined at 800°C for 5 hours at a temperature of 3°C / min. After cooling, mesoporous SiO2 template material can be obtained.

[0110] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 2g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 800℃ at 2℃ / min under argon protection atmosphere and sinter for 3h to obtain a solid sample. Remove impurities by soaking the product in hydrochloric acid, wash it 4 times, centrifuge at 7000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 60℃ for 6h to obtain an intermediate product.

[0111] 4) Soak the bio-based material thin shell in hydrochloric acid for 4 hours, then soak it in sodium hydroxide solution for 4 hours, repeat 4 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 80°C for 5 hours. After grinding and crushing the product, collect it and dry it in an oven at 90°C for later use.

[0112] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.2g of 100nm Si powder. Mix the three materials and put them into a ball mill at 1000rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0113] Example 7

[0114] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0115] 1) Add 2g of P123 to 40g of methanol and stir at 100r / min for 30min; then add 2g of silica sol and stir at 100r / min for 20min; finally add glacial acetic acid to the mixed solution to adjust the pH to 3, stir at 120r / min for 30min to obtain the mixed solution.

[0116] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 100°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered three times with methanol at a centrifugal speed of 6000 r / min. The product is dried in an oven at 80°C for 12 hours. The dried product is transferred to a muffle furnace and calcined at 700°C at a temperature of 3°C / min for 5 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0117] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 1.5g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 900℃ at 2℃ / min under argon protection atmosphere and sinter for 3h to obtain a solid sample. Soak the product in hydrochloric acid to remove impurities, then wash it 4 times, centrifuge at 6000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 60℃ for 6h to obtain an intermediate product.

[0118] 4) Soak the bio-based material thin shell in sulfuric acid for 4 hours, then soak it in potassium hydroxide solution for 4 hours, repeat 4 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 80°C for 5 hours. After grinding and crushing the product, collect it and dry it in an oven at 90°C for later use.

[0119] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.2g of 100nm Si powder. Mix the three materials and put them into a ball mill at 800rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0120] Example 8

[0121] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0122] 1) Add 2g of P123 to 40g of methanol and stir at 100r / min for 30min; then add 2g of silica sol and stir at 100r / min for 20min; finally add glacial acetic acid to the mixed solution to adjust the pH to 3, stir at 120r / min for 30min to obtain the mixed solution.

[0123] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 100°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered three times with methanol at a centrifugal speed of 6000 r / min. The product is dried in an oven at 80°C for 12 hours. The dried product is transferred to a muffle furnace and calcined at 700°C at a temperature of 3°C / min for 5 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0124] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 1.5g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 900℃ at 2℃ / min under argon protection atmosphere and sinter for 3h to obtain a solid sample. Soak the product in hydrochloric acid to remove impurities, then wash it 4 times, centrifuge at 6000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 60℃ for 6h to obtain an intermediate product.

[0125] 4) Soak the bio-based material thin shell in acetic acid for 4 hours, then soak it in potassium hydroxide solution for 4 hours, repeat 4 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 80°C for 5 hours. After grinding and crushing the product, collect it and dry it in an oven at 90°C for later use.

[0126] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.25g of 100nm Si powder. Mix the three materials and put them into a ball mill at 800rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0127] Example 9

[0128] This embodiment provides a method for preparing a low-strain nano-silicon-carbon-based anode material, including the following steps:

[0129] 1) Add 2g of sodium dodecyl sulfate to 40g of DMF and stir at 120r / min for 30min; then add 2g of methyl orthosilicate and stir at 120r / min for 20min; finally add glacial acetic acid to the mixed solution to adjust the pH to 2, and stir at 120r / min for 30min to obtain the mixed solution.

[0130] 2) The mixed solution obtained in step 1) is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 100°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered three times with methanol at a centrifugal speed of 6000 r / min. The product is dried in an oven at 80°C for 12 hours. The dried product is transferred to a muffle furnace and calcined at 700°C at a temperature of 3°C / min for 5 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0131] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 1.2g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 800℃ at 2℃ / min under argon protection atmosphere and sinter for 3h to obtain a solid sample. Remove impurities by soaking the product in hydrochloric acid, wash it 4 times, centrifuge at 6000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 60℃ for 6h to obtain an intermediate product.

[0132] 4) Soak the bio-based material thin shell in acetic acid for 4 hours, then soak it in potassium hydroxide solution for 4 hours, repeat 4 times. After that, wash the product with distilled water 3 to 5 times, and then dry the product in an oven at 80°C for 5 hours. After grinding and crushing the product, collect it and dry it in an oven at 90°C for later use.

[0133] 5) Take 1g of the product from step 3), 1g of the product from step 4), and 0.25g of 120nm Si powder. Mix the three materials and put them into a ball mill at 800rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h. Finally, low-strain nano-silicon-carbon based anode material is obtained.

[0134] To facilitate the explanation of the above nine embodiments, the present invention also provides the following comparative embodiments.

[0135] Comparative Example 1

[0136] Comparative Example 1 provides a method for preparing a porous carbon material, comprising the following steps:

[0137] 1) Soak the bio-based material thin shell in acetic acid for 4 hours, then soak it in potassium hydroxide solution for 4 hours, repeat 4 times. Then place the product in an oven at 80°C for 5 hours. After grinding and crushing, collect the product and dry it in an oven at 90°C for later use.

[0138] 2) The collected product was placed in a tube furnace and treated under nitrogen protection. The heating rate was 3℃ / min, the calcination temperature was 600℃, and the calcination time was 3h. Finally, porous carbon anode material was obtained.

[0139] Comparative Example 2

[0140] Comparative Example 2 provides a method for preparing a porous carbon material, comprising the following steps:

[0141] 1) Soak the bio-based material thin shell in hydrochloric acid for 3 hours, then soak it in potassium hydroxide solution for 3 hours, repeat 3 times. Then place the product in an oven at 80°C for 5 hours. After grinding and crushing, collect the product and dry it in an oven at 90°C for later use.

[0142] 2) The collected product was placed in a tube furnace and treated under nitrogen protection. The heating rate was 3℃ / min, the calcination temperature was 700℃, and the calcination time was 3h. Finally, porous carbon anode material was obtained.

[0143] Comparative Example 3

[0144] Comparative Example 3 provides a method for preparing a porous carbon material, comprising the following steps:

[0145] 1) Soak the bio-based material thin shell in sulfuric acid for 3 hours, then soak it in potassium hydroxide solution for 3 hours, repeat 3 times. Then place the product in an oven at 80°C for 5 hours. After grinding and crushing, collect the product and dry it in an oven at 90°C for later use.

[0146] 2) The collected product was placed in a tube furnace and treated under nitrogen protection. The heating rate was 3℃ / min, the calcination temperature was 800℃, and the calcination time was 3h. Finally, porous carbon anode material was obtained.

[0147] Comparative Example 4

[0148] Comparative Example 4 provides a method for preparing a nano-silicon anode material, comprising the following steps:

[0149] 1) Add 2g of sodium dodecyl sulfate to 40g of DMF and stir at 120r / min for 30min; then add 2g of methyl orthosilicate and stir at 120r / min for 20min; finally add glacial acetic acid to the mixed solution to adjust the pH to 2, and stir at 120r / min for 30min to obtain the mixed solution.

[0150] 2) The mixed solution obtained in step S1 is transferred into a stainless steel reactor with a polytetrafluoroethylene liner and aged at 100°C for 6 hours. After the reaction, the reactor is cooled and the product is taken out. The product is washed and filtered three times with methanol at a centrifugal speed of 6000 r / min. The product is dried in an oven at 80°C for 12 hours. The dried product is transferred to a muffle furnace and calcined at 700°C at a temperature of 3°C / min for 5 hours. After cooling, mesoporous SiO2 template material can be obtained.

[0151] 3) Grind and mix 2g of mesoporous SiO2 template material obtained in step 2) with 1.2g of Al / AlCl3 mixed powder (Al powder and AlCl3 powder mass ratio 1:1.5), then heat the mixture to 800℃ at 2℃ / min under argon protection atmosphere and sinter for 3h to obtain a solid sample. Remove impurities by soaking the product in hydrochloric acid, wash it 4 times, centrifuge at 6000r / min and filter it. Finally, place the sample in a vacuum drying oven and dry it at 60℃ for 6h to obtain an intermediate product.

[0152] 4) Take 1g of intermediate product and 0.25g of 120nm Si powder. Mix the two materials and put them into a ball mill at 800rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 700℃, and the calcination time is 3h. Finally, low strain nano-silicon anode material is obtained.

[0153] Comparative Example 5

[0154] Comparative Example 5 provides a method for preparing nano-silicon and porous carbon composite materials, comprising the following steps:

[0155] 1) Soak the bio-based material thin shell in acetic acid for 4 hours, then soak it in potassium hydroxide solution for 4 hours, repeat 4 times. Then place the product in an oven at 80°C for 5 hours. After grinding and crushing, collect the product and dry it in an oven at 90°C for later use.

[0156] 2) Take 2g of the product from step 1) and 0.25g of 120nm Si powder. Mix the two materials and put them into a ball mill at 800rpm for 3h. Collect the product and place it in a tube furnace for treatment under nitrogen protection. The heating rate is 3℃ / min, the calcination temperature is 600℃, and the calcination time is 3h.

[0157] The composite materials obtained in Examples 1 to 9 and Comparative Examples 1 to 5 will be applied to the electrodes of a battery, and the performance of the battery will be used to compare and explain the above materials.

[0158] The negative electrode materials obtained in Examples 1-9 and Comparative Examples 1-4 were uniformly mixed with sulfide electrolyte and conductive agent at a ratio of 50:50:3 using a homogenizer for 30 minutes. The mixed slurry was then coated onto copper foil, dried at 100°C for 3 hours, and stamped into a sheet with a diameter of 9 mm. Finally, solid-state batteries were assembled and their electrochemical performance was tested, as shown in Table 1 below.

[0159] Table 1

[0160]

[0161] From the data in Table 1 above, we can see that:

[0162] Example 1 exhibits higher first-cycle charge and discharge capacities, while Example 3 demonstrates the highest capacity retention after 200 cycles. The low-strain nano-silicon-carbon-based anode materials prepared in Examples 1-9 of this invention possess a porous structure with uniform silicon dispersion and consistent pore size, resulting in superior discharge capacity and cycle stability. In-situ coating of nanomaterials with biomass porous carbon materials ensures uniform dispersion of the nano-silicon within the carbon material. The template method ensures a more porous structure and higher specific surface area for the electrode material, providing more ion transport channels and electrochemical sites, thus improving electrochemical performance. The excellent mechanical properties of the biomass carbon substrate alleviate stress issues in silicon-based electrode materials, significantly enhancing their cycle performance. Due to the synergistic effect of silicon and carbon materials, the electrode materials exhibit higher electrochemical capacity and superior cycle stability.

[0163] By comparing the above Comparative Examples 1-3 and Examples 1-9, it can be seen that the electrochemical capacity of simple biomass carbon materials is low and cannot meet the needs of current batteries; in addition, its first-efficiency is relatively stable and it is suitable for preparation as a composite material based on silicon.

[0164] By comparing Comparative Example 4 with Examples 1-9, it can be seen that the silicon-based anode material prepared in Comparative Example 4 also has a porous structure and high electrochemical capacity, but its first-efficiency is low. Furthermore, since it is a simple silicon anode material, its volume expansion problem is more obvious, resulting in poor cycle stability. After 200 cycles, the capacity is only 60%.

[0165] A comparison of Comparative Example 5 and Examples 1-9 shows that the material prepared solely from bio-carbon and nano-silicon (Comparative Example 5) exhibits significantly inferior cycle stability compared to the present invention. This result demonstrates that the present invention transforms the SiO2 template into a three-dimensional interconnected coral-like porous silicon framework, which, together with bio-carbon, ensures structural stability and provides a buffer space for the silicon anode material. This unique structure effectively suppresses silicon expansion stress and maintains electrode integrity, thereby significantly improving the long-term cycle life of the battery. Comparative Example 5, lacking this structure, exhibits weak silicon-carbon interfacial bonding and rapid capacity decay.

[0166] In summary, this invention provides a low-strain nano-silicon-carbon-based anode material and its preparation method. Using biomass materials and nano-silicon as precursors, with the biomass materials serving as the carbon source and the nano-silicon as the silicon source, the low-strain nano-silicon-carbon-based anode material is obtained through pretreatment of the biomass materials (multiple washing and centrifugation separation) and calcination of the precursors. The low-strain nano-silicon-carbon-based anode material possesses a high specific surface area, providing more lithium storage sites and electrochemical reaction sites for the electrode material, thus significantly improving its charge-discharge capacity. The synergistic effect of silicon and carbon improves the material's conductivity, thereby enhancing its electrochemical performance. The template method for material preparation results in a well-structured pore structure that provides more channels for electrons and ions, significantly improving the battery's electrochemical performance. The excellent mechanical properties of the biomass carbon material effectively alleviate the stress generated by silicon expansion, thereby improving the material's cycle performance.

[0167] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A method for preparing a low-strain nano-silicon-carbon-based anode material, characterized in that, Includes the following steps: S1. Add the template agent to the solvent and stir until completely dissolved. Then add the silicon source and adjust the pH with an acidic solution to obtain a mixed solution. S2. The mixed solution obtained in step S1 is transferred into a stainless steel reactor with a polytetrafluoroethylene liner for aging reaction. After the reaction, the reactor is cooled and the product is taken out. The product is washed, filtered, and dried. The dried product is transferred to a muffle furnace for calcination treatment. After cooling, mesoporous SiO2 template material is obtained. S3. The mesoporous SiO2 template material obtained in step S2 is mixed with Al / AlCl3 mixed powder and then heated and sintered under a protective atmosphere. At this time, Al acts as a reducing agent and undergoes an aluminothermic reaction with AlCl3 and the mesoporous SiO2 template material. After the reaction is complete, a solid is obtained. The solid is washed, filtered, and dried with acid to obtain an intermediate product. S4. The intermediate product obtained in step S3, the pretreated bio-based material, and the nano-silicon powder are mixed and ball-milled. The collected product is placed in a tube furnace and calcined under a protective atmosphere to obtain a low-strain nano-silicon-carbon-based anode material. The mass ratio of the intermediate product to the pretreated bio-based material is 1:1; the mass ratio of the intermediate product to the nano-silicon powder is 10:1, 10:1.5, 10:2, 10:2.5, or 10:

3.

2. The preparation method according to claim 1, characterized in that, The template agent in step S1 is one or more of F127, penetrant JFCS, sodium dodecyl sulfate, P123, Triton, and mesitylene; the solvent is one or more of deionized water, methanol, ethanol, and DMF; the silicon source is one or more of tetraethyl orthosilicate, methyl orthosilicate, water glass, and silica sol; and the acidic solution is one or more of hydrochloric acid, glacial acetic acid, and propionic acid.

3. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of silicon source to template agent is 1:5~1; the mass ratio of silicon source to solvent is 1:8~30; and the pH of the acidic solution is adjusted to 1-5.

4. The preparation method according to claim 1, characterized in that, Step S1 specifically includes: adding the template agent to the solvent and stirring for the first time, then adding the silicon source and stirring for the second time, and then adding the acidic solution and stirring for the third time to obtain a mixed solution; the stirring rate for each stirring is 80~150 r / min, the stirring time for the first stirring is 10~30 min, the stirring time for the second stirring is 20~40 min, and the stirring time for the third stirring is 20~40 min.

5. The preparation method according to claim 1, characterized in that, In step S2, the aging temperature is 80~160℃ and the aging time is 6~18h. In step S2, the washing and filtration are performed 3 to 8 times, and the washing solvent is one or more of methanol, ethanol, deionized water, and DMF; the drying temperature is 60 to 110°C. In step S2, the muffle furnace heating rate is 1~3℃ / min, the calcination temperature is 300~900℃, and the calcination time is 3~9h.

6. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the mesoporous SiO2 template material to the Al / AlCl3 mixed powder is 1:1~3; In step S3, the protective atmosphere is one of argon, nitrogen, or a mixture of argon and nitrogen; the heating rate for sintering is 1~10℃ / min, the sintering temperature is 500~1000℃, and the sintering time is 1~5h.

7. The preparation method according to claim 1, characterized in that, In step S4, the pretreated bio-based material is prepared by the following method: The bio-based material was cleaned by soaking in acid and alkali solutions and then washed with distilled water. The product was then dried in an oven, crushed, collected, and dried in an oven for later use.

8. The preparation method according to claim 7, characterized in that, The bio-based material is angiosperm leaves or fruit shells.

9. The preparation method according to claim 7, characterized in that, The acid solution is one or more of hydrochloric acid, sulfuric acid, and acetic acid; the alkali solution is one or more of sodium hydroxide, potassium hydroxide, and ammonia water; the soaking time for each is 3 to 18 hours; the oven temperature is 60 to 110℃, and the drying time is 3 to 18 hours; the crushing method is one or more of grinding, crushing with a crusher, and crushing with a ball mill, and the particles are crushed to 100-500 nm.

10. The preparation method according to claim 1, characterized in that, In step S4, the particle size of the nano-silicon powder is 100~150nm; In step S4, the ball milling speed is 200~2000 rpm, and the ball milling time is 3~9 hours. In step S4, the protective atmosphere is one of argon, nitrogen, or a mixture of argon and nitrogen; the calcination heating rate is 3~9℃ / min, the calcination temperature is 400~900℃, and the calcination time is 3~9h.

11. A low-strain nano-silicon-carbon based anode material, characterized in that, It is prepared by the preparation method according to any one of claims 1-10.

12. A solid-state battery, characterized in that, Including the low-strain nano-silicon-carbon based anode material as described in claim 11.

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