A sea urchin-shaped metal oxide coated silicon-based composite material and a preparation method thereof

Abstract

This invention provides a sea urchin-shaped metal oxide-coated silicon-based composite material and its preparation method, relating to the field of lithium-ion batteries. The method includes the following steps: S1, preparation of hard carbon-coated nano-silicon / carbon nanotube materials; S2, hollow sea urchin-shaped iron oxide coating; S3, surface soft carbon deposition. The sea urchin-shaped metal oxide-coated silicon-based composite material prepared by this invention exhibits excellent electrochemical stability, excellent rate performance and cycle performance, and has promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, and more specifically to a sea urchin-shaped metal oxide-coated silicon-based composite material and its preparation method. Background Technology

[0002] Currently, lithium-ion batteries remain the primary energy storage device for clean and sustainable energy needs. Commercially available lithium-ion battery anode materials are still mainly graphite, with a theoretical capacity of 372 mAh / g. However, graphite's capacity cannot meet the market demand for high energy / power density. Therefore, developing novel anode materials with high capacity, low charge / discharge potential, and low production costs is crucial.

[0003] In terms of specific capacity, silicon (Si) is perhaps the most promising anode material for lithium-ion batteries, as its theoretical specific capacity is >4000 mAh / g. Furthermore, silicon is non-toxic, the second most abundant element in the Earth's crust, and exhibits a relatively low average discharge potential (vs. Li). + / Li). However, due to the huge volume expansion (>300%) that occurs when silicon is fully intercalated with lithium, and the low intrinsic electronic conductivity of silicon leading to severe polarization of the anode material, the rate performance and cycle performance of silicon anode materials are affected. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a silicon-based composite material coated with urchin-like metal oxide and its preparation method, which solves the technical problems of huge volume expansion of pure silicon after full lithium insertion and low intrinsic electronic conductivity of silicon.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide includes the following steps:

[0009] S1. Preparation of hard carbon-coated nano-silicon / carbon nanotube material: Nano-silicon is etched with NaOH solution, and the etched nano-silicon, solid resin and first carbon nanotube are uniformly mixed and subjected to high temperature heating under nitrogen protection to obtain hard carbon-coated nano-silicon / carbon nanotube material.

[0010] S2. Hollow sea urchin-shaped iron oxide coating: The hard carbon-coated nano-silicon / carbon nanotube material is uniformly dispersed in a mixed solution of deionized water and glycerol, then ferric sulfate heptahydrate and a second carbon nanotube are added. After thorough stirring, the mixture is poured into a stainless steel reactor and heated to synthesize a powder material. The powder material is then subjected to high-temperature heat treatment under a nitrogen protective atmosphere to obtain a hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material.

[0011] S3. Surface soft carbon deposition: Under a nitrogen protective atmosphere, gaseous acetylene or methane is introduced into the hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material and heated to obtain a sea urchin-shaped metal oxide-coated silicon-based composite material.

[0012] Preferably, in S1, the particle size of the nano-silicon is 5-20 nm, the concentration of the NaOH solution is 3-5 mol / L, and the mass ratio of nano-silicon to solid resin and carbon nanotubes is 100:(1-5):(1-3).

[0013] Preferably, in S1, the solid resin is selected from one or more of phenolic resin, epoxy resin, and styrene resin.

[0014] Preferably, in step S1, the high-temperature heating treatment temperature is 500–1000°C, and the holding time is 1–2 hours.

[0015] Preferably, in S2, the mass ratio of deionized water to glycerol is (3-5):1.

[0016] Preferably, in S2, the mass ratio of ferric sulfate heptahydrate, carbon nanotubes, and nano-silicon is (2-5):(0.01-0.05):1.

[0017] Preferably, in step S2, the temperature for heating and synthesis is 100–300°C, and the heating and synthesis time is 20–60 h.

[0018] Preferably, in step S2, the high-temperature heating treatment temperature is 500–800°C, and the high-temperature heating treatment time is 3–10 hours.

[0019] Preferably, in step S3, the heating temperature is 500–1000°C, and the heating time is 5–8 hours.

[0020] On the other hand, a sea urchin-shaped metal oxide-coated silicon-based composite material prepared by a preparation method is provided. The sea urchin-shaped metal oxide-coated silicon-based composite material includes, from the inside out, a core layer, a shell layer and a soft carbon layer. The core layer includes hard carbon-coated nano-silicon / carbon nanotube material. The shell layer includes hollow sea urchin-shaped iron oxide and a second carbon nanotube. The first carbon nanotube penetrates the core layer and the shell layer, and the second carbon nanotube penetrates the core layer and the shell layer.

[0021] (III) Beneficial Effects

[0022] This invention provides a method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide. Compared with the prior art, it has the following advantages:

[0023] 1. The method of this invention involves uniformly mixing nano-silicon, solid-phase resin, and first carbon nanotubes, followed by high-temperature heating under nitrogen protection to obtain a hard carbon-coated nano-silicon / carbon nanotube material. The solid-phase resin carbonizes the coated silicon nanoparticles to form a highly disordered hard carbon layer. This hard carbon layer possesses high strength, a well-developed pore structure, and excellent electrical conductivity, which helps improve the conductivity of the nano-silicon particles and buffers the expansion of the sea urchin-shaped metal oxide-coated silicon-based composite material after lithium intercalation. The well-developed pore structure also facilitates rapid lithium ion intercalation / deintercalation, thereby improving the rate performance of the sea urchin-shaped metal oxide-coated silicon-based composite material. The first carbon nanotubes are dispersed in the hard carbon-coated nano-silicon / carbon nanotube material, forming a good conductive network for the nano-silicon and penetrating both the core and shell layers. This promotes the transfer of electrons and lithium ions from the silicon material to ferric oxide, increasing their transport speed and thus enhancing the electronic and ionic conductivity of the sea urchin-shaped metal oxide-coated silicon-based composite material.

[0024] 2. Hard carbon-coated silicon / carbon nanotube material was uniformly dispersed in a mixed solution of deionized water and glycerol. Then, ferric sulfate heptahydrate and a second carbon nanotube were added to prepare a hollow, sea urchin-shaped iron oxide-coated hard carbon-coated silicon / carbon nanotube material. The sea urchin-shaped iron oxide possesses well-developed lithium intercalation sites, which can significantly improve the rate performance of the sea urchin-shaped metal oxide-coated silicon-based composite material. The second carbon nanotubes intercalating between the core and shell layers can enhance the electronic and ionic conductivity of the sea urchin-shaped metal oxide-coated silicon-based composite material. Furthermore, the iron oxide shell has strong rigidity, which can suppress the expansion and subsequent cracking of the core layer after lithium intercalation.

[0025] 3. Gas-phase acetylene or methane is introduced into the hollow sea urchin iron oxide-coated hard carbon-coated silicon / carbon nanotube material, and the mixture is heated. A soft, dense carbon layer is deposited on the outer layer of the hollow sea urchin iron oxide-coated hard carbon-coated silicon / carbon nanotube material, resulting in a sea urchin-shaped metal oxide-coated silicon-based composite material. The deposition of a soft carbon layer on the outer layer improves the conductivity of the ferric oxide shell, prevents the well-developed active sites of the ferric oxide from directly contacting the electrolyte, and thus avoids the reaction between the ferric oxide and the electrolyte, preventing the consumption of lithium ions. This is beneficial for improving the capacitance and cycle stability of the sea urchin-shaped metal oxide-coated silicon-based composite material.

[0026] Therefore, the urchin-like metal oxide-coated silicon-based composite material prepared by this invention has excellent electrochemical stability, good rate performance and good cycle performance, and has good application prospects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a structural diagram of the urchin-shaped metal oxide-coated silicon-based composite material prepared according to the present invention.

[0029] Among them, 1 is hard carbon-coated nano-silicon, 2 is hard carbon coated on the surface of nano-silicon particles, 3 is carbon nanotubes located inside the core and shell layers and penetrating the core and shell layers, 4 is hollow sea urchin-shaped iron oxide shell layer, and 5 is outer dense soft carbon layer.

[0030] Figure 2 This is a SEM image of the urchin-shaped metal oxide-coated silicon-based composite material prepared in Example 1 of this invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This application provides a silicon-based composite material coated with a sea urchin-like metal oxide and its preparation method, which solves the technical problems of huge volume expansion of pure silicon after full lithium insertion and low intrinsic electronic conductivity of silicon, thereby improving the rate performance and cycle performance of silicon anode materials.

[0033] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0034] Iron oxide (Fe₂O₃) is a binary compound composed of oxygen and iron. It boasts abundant raw material sources, low cost, and a theoretical capacity as high as 1007 mAh / g, making it a promising anode material for lithium-ion batteries. Furthermore, iron oxide exhibits high rigidity, which effectively suppresses silicon expansion. However, its poor electronic and ionic conductivity significantly limits its application in anode material preparation.

[0035] Silicon has a theoretical specific capacity >4000mAh / g and exhibits a lower average discharge potential (vs. Li). + / Li). However, silicon exhibits poor cycle performance as an anode material. This poor cycle stability is mainly due to two reasons: first, silicon experiences significant volume expansion (>300%) after full lithium insertion; second, silicon's low intrinsic electronic conductivity leads to sluggish electrochemical kinetics and severe polarization. Especially under high-rate current conditions, rapid lithium insertion / extraction results in even faster expansion and contraction, and polarization doubles. These two issues severely limit the large-scale application of silicon anode materials in lithium-ion batteries. To address these application problems, many attempts have been made to modify silicon anode materials. For example, nano-scale modification is used, primarily to improve lithium insertion / extraction channels and reduce expansion by adjusting the material's size and morphology; or silicon is combined with conductive materials or stress buffers to enhance its conductivity and suppress or buffer its expansion.

[0036] This application combines the advantages of iron oxide and silicon to provide a method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide, comprising the following steps:

[0037] S1. Preparation of hard carbon-coated nano-silicon / carbon nanotube material: Nano-silicon is etched with NaOH solution, and the etched nano-silicon, solid resin and first carbon nanotube are uniformly mixed and subjected to high temperature heating under nitrogen protection to obtain hard carbon-coated nano-silicon / carbon nanotube material.

[0038] S2. Hollow sea urchin-shaped iron oxide coating: The hard carbon-coated nano-silicon / carbon nanotube material is uniformly dispersed in a mixed solution of deionized water and glycerol, then ferric sulfate heptahydrate and a second carbon nanotube are added. After thorough stirring, the mixture is poured into a stainless steel reactor and heated to synthesize a powder material. The powder material is then subjected to high-temperature heat treatment under a nitrogen protective atmosphere to obtain a hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material.

[0039] S3. Surface soft carbon deposition: Under a nitrogen protective atmosphere, gaseous acetylene or methane is introduced into the hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material and heated to obtain a sea urchin-shaped metal oxide-coated silicon-based composite material.

[0040] like Figure 1 As shown, the structure of the sea urchin-shaped metal oxide-coated silicon-based composite material includes hard carbon-coated nano-silicon 1, hard carbon 2 coated on the surface of the nano-silicon particles, carbon nanotubes 3 located inside the core and shell layers and penetrating the core and shell layers, hollow sea urchin-shaped iron oxide shell layer 4, and outer dense soft carbon layer 5.

[0041] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0042] Example 1

[0043] This embodiment provides a method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide, comprising the following steps:

[0044] S1. Preparation of hard carbon-coated silicon nanoparticles / carbon nanotubes: 100g of 5-20 nanometer silicon particles were etched with 4mol / L NaOH solution, and then thoroughly mixed with 2g of phenolic resin and 1g of carbon nanotubes. The mixture was heated at 600℃ for 1h under nitrogen protection to obtain hard carbon-coated silicon nanoparticles / carbon nanotubes.

[0045] S2. Hollow sea urchin-shaped iron oxide coating: Take 50g of hard carbon-coated nano-silicon / carbon nanotube material, add 200g of deionized water and 60g of glycerol, then add 100g of ferric sulfate heptahydrate and 0.1g of carbon nanotubes and stir thoroughly. Place in a polytetrafluoroethylene stainless steel reactor for heating and synthesis reaction at 200℃ for 48h to obtain powder material. Then heat the powder material at 600℃ for 5h under a nitrogen protective atmosphere to obtain hollow sea urchin-shaped iron oxide hard carbon-coated nano-silicon / carbon nanotube material.

[0046] S3. Surface soft carbon dense deposition: Gas-phase acetylene is selected as the coating agent. Under a nitrogen protective atmosphere, acetylene is introduced into the hard carbon-coated nano-silicon / carbon nanotube material coated with hollow sea urchin iron oxide, and heated to 550℃ and held for 5h to obtain sea urchin-shaped metal oxide-coated silicon-based composite material.

[0047] The prepared urchin-like metal oxide-coated silicon-based composite material was imaged using scanning electron microscopy (SEM). The images were obtained from the SEM (see...). Figure 2 It can be seen that the nanoparticle silicon was successfully coated with hollow sea urchin iron oxide, and the surface was uniformly coated with a carbon layer, which avoided direct contact between the iron oxide and the electrolyte.

[0048] The prepared urchin-shaped metal oxide-coated silicon-based composite material was mixed with superconducting carbon black and LA133 at a mass ratio of 8:1.5:0.5. A slurry was prepared using deionized water as a solvent and uniformly coated onto a 16 μm thick copper foil. The slurry was then dried in a vacuum oven at 100 °C for 8 hours, rolled, and punched into electrode sheets. Using lithium foil as the counter electrode and a 1 mol / L LiPF6 EC+PC+DMC solution (volume ratio 1:1:1) as the electrolyte, and employing a Celgard 2400 separator, CR2025 coin cells were assembled in an argon glove box and immediately sealed. After standing for 24 hours, electrochemical performance was tested using a Newway testing instrument. The charge / discharge cutoff voltage was 5 mV–1.5 V (vs. Li). + (Li), ambient temperature 25±2℃, charge / discharge cycle performance test: test current density 100mA / g. Rate performance test: 200mA / g, 300mA / g. Test results: initial reversible capacity 2078mAh / g, initial coulombic efficiency 82.6%, 50-week reversible capacity 1960mAh / g, reversible capacity retention 92.2%, rate performance test results 1807mAh / g (current 200mA / g, capacity ratio of 100mA / g is 87%) and 1586mAh / g (current 300mA / g, capacity ratio of 100mA / g is 76%).

[0049] Example 2

[0050] This embodiment provides a method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide, comprising the following steps:

[0051] Preparation of hard carbon-coated silicon nanoparticles / carbon nanotubes: 100g of 5-20 nm silicon particles were etched with 3 mol / L NaOH solution, and then thoroughly mixed with 2g of phenolic resin and 2g of carbon nanotubes. The mixture was heated at 500℃ for 1 h under nitrogen protection to obtain hard carbon-coated silicon nanoparticles / carbon nanotube materials.

[0052] Hollow sea urchin-shaped iron oxide coating: Take 50g of hard carbon-coated nano-silicon / carbon nanotube material, add 200g of deionized water and 50g of glycerol, then add 150g of ferric sulfate heptahydrate and 0.2g of carbon nanotubes and stir thoroughly. Place in a polytetrafluoroethylene stainless steel reactor for heating and synthesis reaction at 100℃ for 20h to obtain powder material. Then heat the powder material at 500℃ for 3h under a nitrogen protective atmosphere to obtain hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material.

[0053] S3. Surface soft carbon dense deposition: Gas-phase acetylene is selected as the coating agent. Under a nitrogen protective atmosphere, acetylene is introduced into the hollow sea urchin-shaped iron oxide coated hard carbon coated nano-silicon / carbon nanotube material, and heated to 500℃ and kept at that temperature for 5h to obtain sea urchin-shaped metal oxide coated silicon-based composite material.

[0054] Coin cells were prepared according to the method in Example 1 and their charge-discharge performance was tested. The test results were as follows: initial reversible capacity of 1898 mAh / g, initial coulombic efficiency of 81.3%, reversible capacity of 1769 mAh / g at week 50, reversible capacity retention of 93.2%, and rate performance of 1746 mAh / g (current of 200 mA / g, with a capacity ratio of 92% to 100 mA / g) and 1651 mAh / g (current of 300 mA / g, with a capacity ratio of 87% to 100 mA / g).

[0055] Example 3

[0056] This embodiment provides a method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide, comprising the following steps:

[0057] S1. Preparation of hard carbon-coated silicon nanoparticles / carbon nanotubes: 100g of 5-20 nanometer silicon particles were etched with 4mol / L NaOH solution, and then thoroughly mixed with 2g of epoxy resin and 1g of carbon nanotubes. The mixture was heated at 600℃ for 1h under nitrogen protection to obtain hard carbon-coated silicon nanoparticles / carbon nanotubes.

[0058] S2. Hollow sea urchin-shaped iron oxide coating: Take 50g of hard carbon-coated nano-silicon / carbon nanotube material, add 200g of deionized water and 60g of glycerol, then add 100g of ferric sulfate heptahydrate and 0.1g of carbon nanotubes and stir thoroughly. Place in a polytetrafluoroethylene stainless steel reactor for heating and synthesis reaction at 250℃ for 60h to obtain powder material. Then heat the powder material at 800℃ for 10h under a nitrogen protective atmosphere to obtain hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material.

[0059] S3. Surface soft carbon dense deposition: Gas-phase methane is selected as the coating agent. Under a nitrogen protective atmosphere, acetylene is introduced into the hard carbon-coated nano-silicon / carbon nanotube material coated with hollow sea urchin iron oxide, and the mixture is heated to 1000℃ and kept at that temperature for 8 hours to obtain sea urchin-shaped metal oxide-coated silicon-based composite material.

[0060] Coin cells were prepared according to the method in Example 1 and their charge-discharge performance was tested. The test results were as follows: initial reversible capacity of 1978 mAh / g, initial coulombic efficiency of 82.3%, reversible capacity of 1804 mAh / g at week 50, reversible capacity retention of 91.2%, and rate performance of 1741 mAh / g (current of 200 mA / g, with a capacity ratio of 88% to 100 mA / g) and 1622 mAh / g (current of 300 mA / g, with a capacity ratio of 82% to 100 mA / g).

[0061] Comparative Example

[0062] This comparative example provides a method for preparing a silicon-based composite material coated with a sea urchin-like metal oxide, comprising the following steps:

[0063] Preparation of hard carbon-coated silicon nanoparticles / carbon nanotubes: 100g of 5-20 nm silicon particles were etched with 4 mol / L NaOH solution, and then thoroughly mixed with 2g of epoxy resin and 1g of carbon nanotubes. The mixture was heated at 600℃ for 1 h under nitrogen protection to obtain hard carbon-coated silicon nanoparticles / carbon nanotubes.

[0064] Coin cells were prepared according to the method in Example 1 and their charge-discharge performance was tested. The test results were as follows: initial reversible capacity of 2578 mAh / g, initial coulombic efficiency of 83.3%, reversible capacity of 352 mAh / g at week 50, reversible capacity retention of 14%, and rate performance of 645 mAh / g (current of 200 mA / g, with a capacity ratio of 25% to 100 mA / g) and 284 mAh / g (current of 300 mA / g, with a capacity ratio of 11% to 100 mA / g).

[0065] Comparing the test results of Examples 1-3 and the comparative examples, it can be seen that the urchin-like metal oxide-coated silicon-based composite material prepared by the present invention improves the structural stability of the material during cycling and has advantages such as good cycling performance and rate performance.

[0066] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0067] The above embodiments are only used to illustrate 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 still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any aspects of the present invention not described in detail are well-known to those skilled in the art.

Claims

1. A method for preparing a sea urchin-like metal oxide-coated silicon-based composite material, characterized by, Includes the following steps: S1. Preparation of hard carbon-coated nano-silicon / carbon nanotube material: Nano-silicon is etched with NaOH solution, and the etched nano-silicon, solid resin and first carbon nanotube are uniformly mixed and subjected to high temperature heating under nitrogen protection to obtain hard carbon-coated nano-silicon / carbon nanotube material. S2. Hollow sea urchin-shaped iron oxide coating: The hard carbon-coated nano-silicon / carbon nanotube material is uniformly dispersed in a mixed solution of deionized water and glycerol, then ferric sulfate heptahydrate and a second carbon nanotube are added. After thorough stirring, the mixture is poured into a stainless steel reactor and heated to synthesize a powder material. The powder material is then subjected to high-temperature heat treatment under a nitrogen protective atmosphere to obtain a hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material. S3. Surface soft carbon deposition: Under a nitrogen protective atmosphere, gaseous acetylene or methane is introduced into the hollow sea urchin-shaped iron oxide-coated hard carbon-coated nano-silicon / carbon nanotube material and heated to obtain a sea urchin-shaped metal oxide-coated silicon-based composite material.

2. The production method according to claim 1, wherein In S1, the particle size of nano-silicon is 5-20 nm, the concentration of NaOH solution is 3-5 mol / L, and the mass ratio of nano-silicon to solid resin and carbon nanotubes is 100:(1-5):(1-3).

3. The preparation method according to claim 1, characterized in that, In S1, the solid resin is selected from one or more of phenolic resin, epoxy resin, and styrene resin.

4. The preparation method according to claim 1, characterized in that, In step S1, the high-temperature heating treatment temperature is 500–1000℃, and the holding time is 1–2 hours.

5. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of deionized water to glycerol is (3-5):

1.

6. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of ferric sulfate heptahydrate, carbon nanotubes, and nano-silicon is (2-5):(0.01-0.05):

1.

7. The preparation method according to claim 1, characterized in that, In step S2, the temperature for heating and synthesis is 100–300°C, and the heating and synthesis time is 20–60 h.

8. The preparation method according to claim 1, characterized in that, In step S2, the high-temperature heating treatment temperature is 500–800°C, and the high-temperature heating treatment time is 3–10 hours.

9. The preparation method according to claim 1, characterized in that, In step S3, the heating temperature is 500–1000°C, and the heating time is 5–8 hours.

10. A silicon-based composite material with sea urchin-like metal oxide coating prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The urchin-shaped metal oxide-coated silicon-based composite material comprises, from the inside out, a core layer, a shell layer, and a soft carbon layer. The core layer comprises hard carbon-coated nano-silicon / carbon nanotube material, and the shell layer comprises hollow urchin-shaped iron oxide and a second carbon nanotube. The first carbon nanotube penetrates the core layer and the shell layer, and the second carbon nanotube penetrates the core layer and the shell layer.

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