A high-entropy alloy oxide / nanosilicon composite anode material for lithium-ion batteries and its preparation method

Abstract

The present invention belongs to the technical field of anode materials for lithium-ion batteries, and specifically relates to a high-entropy alloy oxide / nanosilicon composite anode material for lithium-ion batteries and a preparation method thereof. The preparation process of the present invention is as follows: 1. Preparation of modified nanosilicon; 2. Preparation of electrospinning solution; 3. Weigh appropriate amounts of iron salt, nickel salt, cobalt salt, chromium salt, manganese salt and modified nanosilicon, add them to a certain amount of electrospinning precursor solution, stir evenly by ultrasonic wave and then perform electrospinning, and then dry. Finally, calcine in a muffle furnace under air atmosphere to obtain the product. The product of the present invention has high lithium-ion conductivity (>10 ‑3 S cm ‑1 ), and the high-entropy characteristics can effectively improve the electrochemical performance and cycle stability of the silicon-based electrode material. The preparation method of the present invention is simple to operate and has a low cost, providing a new idea for the preparation of silicon-based composite electrodes.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative electrode materials for lithium-ion batteries, and particularly relates to a high-entropy alloy oxide / nanosilicon composite negative electrode material for lithium-ion batteries and a preparation method thereof. Background Art

[0002] Lithium-ion batteries (LIBs) play a crucial role in the fields of electronic communication products, energy storage power stations, and electric vehicles (EVs). As a core component, electrode materials are proposed as a key factor in the design of LIB products, and great consideration has been given to the improvement of their performance. However, there are still huge challenges in developing electrode materials with excellent performance, especially negative electrode materials. Traditional graphite negative electrode materials have characteristics such as a low lithium intercalation voltage platform and good cycle stability. Its theoretical specific capacity is 372 mAh / g. However, its relatively low specific capacity can no longer meet the current market demand. Compared with traditional graphite negative electrodes, silicon (Si), as an alloy-type negative electrode material, has a specific capacity of 3579 mAh / g, which is significantly higher than that of commercial graphite. In addition, silicon negative electrode materials have a relatively low voltage platform (≈0.4 V vs Li / Li + ), abundant reserves, and low costs, making them suitable for meeting the requirements of next-generation high-energy-density lithium-ion batteries in electric vehicle applications. Therefore, developing silicon-based negative electrode materials with excellent performance is the key.

[0003] High-entropy alloy oxides (HEOs) refer to single-phase oxides obtained by dissolving five or more elements in the same sublattice in a molar ratio of 5%-35%. The increase in the mixing configurational entropy caused by the increase in the number of constituent elements is sufficient to overcome the formation enthalpy of single-phase compounds, thereby preventing the formation of harmful intermetallic compounds. The lithium-ion conductivity of HEOs is greater than 10 -3 S cm -1 . In addition, the high-entropy characteristics can effectively improve the cycle stability of electrode materials. At the same time, most transition metal high-entropy oxides have a high theoretical specific capacity (>1000 mAh g -1 ). Based on these advantages, HEOs are expected to become electrode materials with good lithium storage performance.

[0004] The combination of Si and transition metal (TM) elements can significantly improve their mechanical properties, which is crucial for manufacturing crack-free silicon-based negative electrodes. For example, by alloying Si and Mn in a molar ratio of 1:1, the Young's modulus can be increased from 150 GPa of Si to 340 GPa of MnSi. Other Si-based alloy negative electrodes such as Fe-Si, Cu-Si, and Ni-Si systems also show improved cycle stability. To further improve the performance, it is necessary to improve the overall mechanical properties during cycling, and importantly, to avoid a decrease in mechanical properties during cycling. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a high-entropy alloy oxide / nanosilicon composite negative electrode material for a lithium-ion battery and a preparation method thereof. The high-entropy alloy oxide / nanosilicon composite negative electrode material for a lithium-ion battery has a spinel structure, excellent electrochemical performance and cycle stability, and a simple preparation method.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A high-entropy alloy oxide / nanosilicon composite negative electrode material for a lithium-ion battery, the chemical formula of the negative electrode material for a lithium-ion battery is (FeCoNiCrMn) 3 O 4 / Si, which has a spinel structure; it is prepared from iron salt, nickel salt, cobalt salt, chromium salt, manganese salt and modified nanosilicon. The iron salt, nickel salt, cobalt salt, chromium salt and manganese salt are one or more of nitrates, acetates, acetylacetonates, carbonates, bicarbonates, hydrochlorides, and sulfates of metal elements. The modified nanosilicon is prepared by soaking nanosilicon particles in a citric acid solution or a PVP solution or a hydrogen peroxide solution for modification.

[0008] The preparation method of the above-mentioned high-entropy alloy oxide / nanosilicon composite negative electrode material for a lithium-ion battery, the preparation method includes the following steps:

[0009] (1) Mix nanosilicon particles, a modifying substance and water, stir and then perform centrifugal drying treatment to obtain modified nanosilicon. Dissolve the electrospinning polymer in a solvent, mix well to form an electrospinning solution. Then, sequentially add appropriate amounts of iron salt, nickel salt, cobalt salt, chromium salt, manganese salt and modified nanosilicon thereto, ultrasonically treat for 10 - 60 min, and then stir for 12 - 36 h to obtain a first precursor product;

[0010] (2) Draw the first precursor product with a syringe, and then place the syringe in an electrospinning machine for electrospinning. After collecting the electrospinning product, dry it at 80 - 120 °C for 8 - 12 h to obtain a second precursor product.

[0011] (3) Place the second precursor product in a muffle furnace. Under an air atmosphere condition, first heat it to 100 - 500 °C for pre-calcination for 0.5 - 3 h, then calcine it at 700 - 950 °C for 1 - 12 h, and then naturally cool it to room temperature to obtain the product (FeCoNiCrMn) 3 O 4 / Si.

[0012] Furthermore, in step (1), the electrospinning solution is prepared from a polymer and a solvent, the polymer is one or more of polyacrylonitrile (PAN) with an average molecular weight of 150,000, polyvinylpyrrolidone (PVP) with an average molecular weight of 1,300,000, and polyvinylidene fluoride (PVDF) with an average molecular weight of 400,000, and the solvent is one or more of deionized water, ethanol, and N,N-dimethylformamide (DMF).

[0013] Furthermore, in step (1), the electrospinning solution is prepared by mixing the polymer and the solvent in a mass ratio of 0.08-0.1:1. The specific process is as follows: first weigh 10 g of the solvent and spin at 200-400 r min -1 Slowly add 0.8-1g polymer under magnetic stirring, stir for 10-30min, then increase the speed to 800-1000r min -1 The mixture was stirred for 12-24 hours to obtain an electrospinning solution.

[0014] Furthermore, in step (1), the iron salt, nickel salt, cobalt salt, chromium salt, or manganese salt is one or more of nitrate, acetate, acetylacetonate, carbonate, bicarbonate, hydrochloride, and sulfate of the corresponding metal element.

[0015] Furthermore, in step (1), the molar ratio of the added iron salt, nickel salt, cobalt salt, chromium salt and manganese salt is 1:1:1:1:1, and the molar ratio of the total molar amount of the iron salt, nickel salt, cobalt salt, chromium salt and manganese salt to the added amount of modified nano-silicon is 1:(0.1-5), wherein the molar amount of modified nano-silicon is calculated based on the molar amount of nano-silicon particles, that is, the weighed amount of modified nano-silicon / molar mass of silicon.

[0016] Furthermore, in step (1), the modified nano-silicon is obtained by modifying nano-silicon particles with citric acid, PVP or hydrogen peroxide. The specific process is: dissolving the modified substance in deionized water, weighing nano-silicon particles (10-100 nm) and dispersing them in the solution, stirring for 12-24 hours, and rotating at 8000 r min. -1 The mixture is centrifuged for 3-10 min, and the precipitate obtained by centrifugation is taken and vacuum dried at 80-100° C. for 12-24 h to obtain modified nano-silicon, wherein the modified substance: deionized water: nano-silicon particles = 1-2 g: 100 mL: 0.1-0.2 g.

[0017] Furthermore, in step (2), the syringe draws 10 mL of the precursor product 1; the process parameters of the electrospinning are: voltage 1-20 kV, ejection speed 0.5-2 mL / h, distance between the syringe needle and the collector 10-20 cm, and inner diameter of the syringe needle 0.61-1.2 mm.

[0018] Further, in step (3), the heating rate of the pre-burning and calcination is 1-20 °C / min.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0020] 1. In the preparation method of the present invention, a large number of HEO / Si composite fiber wires with a micro-nano fiber structure are first prepared by electrospinning. Since the synthesis is completed in air in a muffle furnace, the organic matter in the precursor product is oxidized and exhausted, resulting in the formation of a large number of pores in the final product, which alleviates the volume strain of the electrode material during the cycling process to a certain extent.

[0021] 2. The introduction of high-entropy alloy oxides can not only utilize their excellent high-entropy stability to improve the mechanical properties of the composite material and alleviate the cycling stability of the electrode material, but also have excellent lithium-ion conductivity and theoretical specific capacity. The combination of HEO and nano-Si effectively improves the performance of the electrode material.

[0022] 3. In the present invention, by modifying the nano-silicon particles, the negative charge density on the surface of the nano-silicon can be increased. Under the action of electrostatic force, a large number of metal ions are wrapped on the nano-silicon particles, and an oxide alloy shell-wrapped nano-silicon core-shell structure (FeCoNiCrMn) can be formed after calcination 3 O 4 / Si (as shown in the enlarged view of the red dotted box area in the left figure of the right figure below, where the particles show a black outer ring as the HEO shell and a light-colored inner area as Si), preventing direct contact between silicon and the electrolyte and improving the cycling stability of the electrode material. Figure 3 Description of the drawings

[0023] Figure 1 SEM morphology diagrams of the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode materials prepared in Comparative Example 1 (a) and Example 1 (b);

[0024] Figure 2 SEM morphology diagram of the second precursor product in Example 1;

[0025] Figure 3 TEM morphology diagram of the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material prepared in Example 1;

[0026] Figure 4 XRD diagrams of the products prepared in Example 1, Example 2, and Comparative Example 1; it can be seen that Comparative Example 1 shows peaks of a single-phase cubic spinel (PDF#22-1084) with the Fd-3m space group, and (FeCoNiCrMn) with a spinel structure is synthesized 3 O 4 ​; In Examples 1 and 2, the peaks of single-phase cubic spinel (PDF#22-1084) and Si (PDF#97-004-1979) can be seen, indicating the presence of (FeCoNiCrMn) 3 O 4 and Si;

[0027] Figure 5 The cycling performance comparison diagram of the half-cell made of the high-entropy alloy oxide / nanosilicon composite lithium-ion battery anode material prepared in Example 1 as the raw material and the product of Comparative Example 1 as the raw material at 0.1 A g -1 below;

[0028] Figure 6 The cycling performance comparison diagram of the half-cell made of the high-entropy alloy oxide / nanosilicon composite lithium-ion battery anode material prepared in Example 1 as the raw material and the product of Comparative Example 1 as the raw material at 1.0 A g -1 below. Detailed Embodiments

[0029] The technical solutions of the present invention will be described in detail below through specific examples and drawings, but the implementation manners of the present invention are not limited thereto.

[0030] Silicon nanoparticles (particle size range: 60-90 nm), iron(III) nitrate nonahydrate (Fe(NO 3 ) 3 ·9H 2 O, purity 99%), cobalt(II) nitrate hexahydrate (Co(NO 3 ) 2 ·6H 2 O, purity 99%), nickel(II) nitrate hexahydrate (Ni(NO 3 ) 2 ·6H 2 O, purity 99%), chromium(III) nitrate nonahydrate (Cr(NO 3 ) 3 ·9H 2 O, purity 99%), manganese(II) nitrate hexahydrate (Mn(NO 3 ) 2 ·6H 2 O, purity 99%), N,N-dimethylformamide (DMF), and polyacrylonitrile (PAN, molecular weight ≥ 150000). All of the above reagents are of analytical purity grade and are directly purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. and used directly in this experiment without any further purification.

[0031] Example 1 A preparation method of a high-entropy alloy oxide / nanosilicon composite lithium-ion battery anode material, comprising the following steps:

[0032] Preparation of modified nano - silicon: Dissolve 1.5 g of citric acid in 100 mL of deionized water. Then weigh 0.1 g of nano - silicon particles (60 - 90 nm) and disperse them in the above - mentioned solution. Stir for 24 h and centrifuge at 8000 r min -1 for 5 min. The precipitate obtained by centrifugation is vacuum - dried at 80 °C for 12 h to obtain citric - acid - modified nano - silicon;

[0033] Preparation of electrospinning solution: Using N,N - dimethylformamide (DMF) as the solvent, at room temperature (all refer to 25 °C), weigh 10 g of DMF. Under magnetic stirring at 400 r min -1 slowly add 1 g of polymer PAN with an average molecular weight of 150000. Stir for 10 min first, and then increase the rotation speed to 1000 r min -1 and stir at high speed for 24 h to obtain the PAN electrospinning solution;

[0034] Sequentially add 0.5 mmol of ferric nitrate nonahydrate, 0.5 mmol of nickel nitrate hexahydrate, 0.5 mmol of cobalt nitrate hexahydrate, 0.5 mmol of chromium nitrate nonahydrate, 0.5 mmol of manganese nitrate hexahydrate, and 0.075 g of citric - acid - modified nano - silicon (calculated by the molar mass of silicon, i.e., 0.075 g / 28 g / mol = 2.68 mmol. The same below) to the PAN electrospinning solution. Ultrasonic for 30 min and stir for 12 h to obtain the first precursor product;

[0035] Use a syringe with a needle inner diameter of 0.84 mm to suck 10 mL of the first precursor product; then place it in an electrospinning machine. The voltage of electrospinning is 20 kV, the ejection speed is set at 1 mL / h, the distance between the syringe needle and the collector is 15 cm. Control the environmental temperature at 25 ± 2 °C and the relative humidity at 20%. Continuously electrospin for 10 h. After collecting the electrospinning product, dry it at 80 °C for 12 h to obtain the second precursor product;

[0036] Place the second precursor product in a muffle furnace. Under an air - atmosphere condition, heat it to 200 °C at a heating rate of 5 °C / min and pre - burn for 1 h, then heat it to 800 °C at a heating rate of 5 °C / min and calcine for 1 h, and then naturally cool to room temperature to obtain the high - entropy alloy oxide / nano - silicon composite lithium - ion battery anode material (FeCoNiCrMn) 3 O 4 / Si.

[0037] Example 2 A preparation method of a high - entropy alloy oxide / nano - silicon composite lithium - ion battery anode material, including the following steps:

[0038] Preparation of modified nano-silicon: Dissolve 3 g of citric acid in 200 mL of deionized water, and then weigh 0.2 g of nano-silicon particles (60 - 90 nm) and disperse them in the solution. Stir for 24 h and centrifuge at 8000 r min -1 for 5 min. The precipitate obtained by centrifugation is vacuum dried at 80 °C for 24 h to obtain citric acid-modified nano-silicon;

[0039] Preparation of electrospinning solution: Using N,N-dimethylformamide (DMF) as the solvent, at room temperature, weigh 10 g of DMF and slowly add 1 g of polymer PAN with an average molecular weight of 150000 under magnetic stirring at 400 r min -1 Stir for 10 min first, then increase the rotation speed to 1000 r min -1 and stir at high speed for 12 h to obtain the PAN electrospinning solution;

[0040] Sequentially add 0.5 mmol of ferric nitrate nonahydrate, 0.5 mmol of nickel nitrate hexahydrate, 0.5 mmol of cobalt nitrate hexahydrate, 0.5 mmol of chromium nitrate nonahydrate, 0.5 mmol of manganese nitrate hexahydrate and 0.15 g of citric acid-modified nano-silicon to the PAN electrospinning solution, ultrasonicate for 30 min and stir for 12 h to obtain the first precursor product;

[0041] Use a syringe with a needle inner diameter of 0.84 mm to suck 10 mL of the first precursor product; then place it in an electrospinning machine. The voltage of electrospinning is 20 kV, the ejection speed is set at 1 mL / h, the distance between the syringe needle and the collector is 15 cm, control the environmental temperature at 25 ± 2 °C, and the relative humidity at 20%. Continuously electrospin for 10 h. After collecting the electrospinning product, dry it at 80 °C for 12 h to obtain the second precursor product;

[0042] Place the second precursor product in a muffle furnace, pre-calcine at 200 °C for 1 h with a heating rate of 5 °C / min under an air atmosphere condition, then calcine at 800 °C for 1 h with a heating rate of 5 °C / min, and then naturally cool to room temperature to obtain the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material.

[0043] Example 3 A preparation method of a high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material, comprising the following steps:

[0044] Preparation of modified nano-silicon: Dissolve 1.5 g of citric acid in 100 mL of deionized water, and then weigh 0.1 g of nano-silicon particles (60 - 90 nm) and disperse them in the solution. Stir for 24 h and centrifuge at 8000 r min -1 for 5 min. The precipitate obtained by centrifugation is vacuum dried at 80 °C for 18 h to obtain citric acid-modified nano-silicon;

[0045] Preparation of electrospinning solution: Using N,N-dimethylformamide (DMF) and absolute ethanol as solvents, at room temperature, weigh 6 g of DMF and 4 g of absolute ethanol and mix them. Slowly add 1 g of polyvinylpyrrolidone (PVP) with an average molecular weight of 1300000 under magnetic stirring at 400 r min -1 and stir for 10 min first, then increase the rotation speed to 1000 r min -1 and stir at high speed for 18 h to obtain the PVP electrospinning solution;

[0046] Sequentially add 0.5 mmol of ferric nitrate nonahydrate, 0.5 mmol of nickel nitrate hexahydrate, 0.5 mmol of cobalt nitrate hexahydrate, 0.5 mmol of chromium nitrate nonahydrate, 0.5 mmol of manganese nitrate hexahydrate and 0.075 g of citrate-modified nanosilicon to the PVP electrospinning solution, ultrasonicate for 30 min, and stir for 12 h to obtain the first precursor product;

[0047] Use a syringe with a needle inner diameter of 0.84 mm to suck 10 mL of the first precursor product; then place it in an electrospinning machine. The voltage of electrospinning is 20 kV, the ejection speed is set to 1 mL / h, the distance between the syringe needle and the collector is 15 cm, control the ambient temperature to be 25±2 °C, and the relative humidity to be 20%. Continuously electrospin for 10 h. After collecting the electrospinning product, dry it at 80 °C for 12 h to obtain the second precursor product;

[0048] Place the second precursor product in a muffle furnace, pre-burn it at 200 °C for 1 h with a heating rate of 5 °C / min under an air atmosphere condition, then heat it to 800 °C and calcine it for 1 h with a heating rate of 5 °C / min, and then naturally cool it to room temperature to obtain the high-entropy alloy oxide / nanosilicon composite lithium-ion battery anode material.

[0049] Comparative Example 1 A preparation method of a high-entropy alloy oxide lithium-ion battery anode material, comprising the following steps:

[0050] Using N,N-dimethylformamide (DMF) as a solvent, at room temperature, weigh 10 g of DMF solvent, and under magnetic stirring at 400 r min -1 slowly add 1 g of polymer PAN with an average molecular weight of 150000, stir for 10 min first, and then increase the rotation speed to 1000 rmin -1 and stir at high speed for 24 h to obtain the PAN electrospinning solution;

[0051] Sequentially add 0.5 mmol of ferric nitrate nonahydrate, 0.5 mmol of nickel nitrate hexahydrate, 0.5 mmol of cobalt nitrate hexahydrate, 0.5 mmol of chromium nitrate nonahydrate, 0.5 mmol of manganese nitrate hexahydrate to the PAN electrospinning solution, ultrasonicate for 30 min, and stir for 12 h to obtain the first precursor product;

[0052] Use a syringe with a needle inner diameter of 0.84 mm to aspirate 10 mL of the first precursor product, and then place it in an electrospinning machine. The electrospinning voltage is 20 kV, the ejection speed is set to 1 mL / h, the distance between the syringe needle and the collector is 15 cm, control the ambient temperature at 25 ± 2 °C, and the relative humidity at 20%. Continuously electrospin for 10 h. After collecting the electrospinning product, dry it at 80 °C for 12 h to obtain the second precursor product;

[0053] Place the second precursor product in a muffle furnace and pre-calcine it at 200 °C for 1 h with a heating rate of 5 °C / min under an air atmosphere condition, then calcine it at 800 °C for 1 h with a heating rate of 5 °C / min, and then naturally cool it to room temperature to obtain the negative electrode material for high-entropy alloy oxide lithium-ion batteries.

[0054] Electrochemical performance test

[0055] Prepare half-cells from the negative electrode materials for lithium-ion batteries obtained in Examples 1-3 and Comparative Example 1 respectively for electrochemical performance determination. The assembly method of the half-cells is as follows: Mix the sample to be tested, a conductive agent (Super P), and a binder (sodium alginate) in a mass ratio of 7:2:1, and mix and grind them evenly with deionized water as the solvent. Coat the prepared electrode slurry evenly on a 3 cm × 10 cm copper foil, take it out after vacuum drying at 60 °C for 12 h, punch it into a pole piece with a diameter of 12 mm, and the loading of the active material is between 0.8 and 1.2 mg / cm 2 Between. The half-cell is assembled in a glove box (with water and oxygen contents both lower than 0.01 ppm), and a CR2032 button battery is used. The separator used is made of Celgard 2400 polypropylene separator, and the CR2032 button battery uses a commercially available circular lithium sheet with a diameter of 1.5 cm as the counter electrode. The electrolyte consists of a 1M LiPF 6 Mixed solution, and the solvent of the mixed solution includes ethylene carbonate (EC) and diethyl carbonate (DEC) (the volume ratio of EC and DEC is 1:1). Use a BlueTron CT2001A battery test system (Wuhan BlueTron Electronic Co., Ltd.) to evaluate the electrochemical charge and discharge performance.

[0056] As Figure 1 Shown, Figure 1 (a) is the SEM morphology diagram of the negative electrode material for lithium-ion batteries in Comparative Example 1, Figure 1 (b) is the SEM morphology diagram of the negative electrode material for lithium-ion batteries prepared in Example 1. It can be seen that in Comparative Example 1, there is no nano-silicon composite, the HEO fiber particles are relatively uniform, and no porous structure is shown; in Example 1, the fiber lines show an obvious porous structure, and the surface is evenly distributed with particles. As Figure 3The TEM morphology diagram of the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material prepared in Example 1 is shown. The fiber-like wires present a porous structure, and the nano-silicon particles are evenly distributed therein. Moreover, a core-shell structure formed by HEO coating the nano-silicon can be observed.

[0057] As Figure 5 , 6 shown are the cyclic performance diagrams of the half-cells made of the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material prepared in Example 1 as the raw material and the half-cells made of the high-entropy alloy oxide lithium-ion battery anode material prepared in Comparative Example 1 as the raw material at 0.1 A g -1 , 1.0 A g -1 . In Figure 5 , when comparing Example 1 with Comparative Example 1, the initial discharge capacities at a current density of 0.1 A g -1 are 1230 mAh / g and 1211 mAh / g respectively, and the remaining capacities after 150 cycles are 1237 mAh / g and 792 mAh / g respectively. In Figure 6 , a high-rate performance test was carried out. At a current density of 1.0 A g -1 , the remaining capacity of the half-cell made of the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material prepared in Example 1 as the raw material is 679 mAh / g after 500 cycles, and the remaining capacity of the half-cell made of the high-entropy alloy oxide lithium-ion battery anode material prepared in Comparative Example 1 as the raw material is 342 mAh / g after 200 cycles. It can be seen from this that the addition of the modified nano-silicon can greatly improve the electrochemical performance of HEO, and the half-cell made of the high-entropy alloy oxide / nano-silicon composite lithium-ion battery anode material prepared in Example 1 as the raw material has excellent specific capacity and cycle stability.

Claims

1. A method for preparing a high entropy alloy oxide / nano-silicon composite lithium-ion battery negative electrode material, the preparation method comprising the following steps: (1) mixing nano-silicon particles, a modified substance and water, stirring and then centrifugally drying to obtain modified nano-silicon, wherein the modified substance increases the surface negative charge density of the modified nano-silicon; dissolving an electrospinning polymer in a solvent, fully mixing to form an electrospinning solution, and then sequentially adding appropriate amounts of iron salt, nickel salt, cobalt salt, chromium salt, manganese salt and modified nano-silicon therein, ultrasonicating for 10-60 minutes, and stirring for 12-36 hours to obtain a precursor product 1; (2) sucking the precursor product 1 with a syringe, and then placing the syringe in an electrospinning machine for electrospinning, collecting the electrospinning product, and drying it at 80-120° C. for 8-12 hours to obtain a precursor product 2; (3) placing the precursor product 2 in a muffle furnace, first heating it to 100-500° C. for pre-calcination for 0.5-3 h in an air atmosphere, then calcining it at 700-950° C. for 1-12 h, and then naturally cooling it to room temperature to obtain the product (FeCoNiCrMn)3O4 / Si.

2. The preparation method according to claim 1, characterized in that: In step (1), the electrospinning solution is prepared from a polymer and a solvent, wherein the polymer is one or more of polyacrylonitrile (PAN) with an average molecular weight of 150,000, polyvinylpyrrolidone (PVP) with an average molecular weight of 1,300,000, and polyvinylidene fluoride (PVDF) with an average molecular weight of 400,000, and the solvent is one or more of deionized water, ethanol, and N,N-dimethylformamide (DMF).

3. The preparation method according to claim 2, characterized in that: In step (1), the electrospinning solution is prepared by polymer and solvent in a mass ratio of 0.08-0.1:

1. The specific process is: first weigh the solvent, slowly add the polymer under 200-400r / min magnetic stirring, stir for 10-30min, then increase the speed and stir at 800-1000r / min for 12-24h to obtain the electrospinning solution.

4. The preparation method according to claim 1, characterized in that: In step (1), the iron salt, nickel salt, cobalt salt, chromium salt and manganese salt are one or more of nitrates, acetates, acetylacetonates, carbonates, bicarbonates, hydrochlorides and sulfates of the corresponding metal elements.

5. The preparation method according to claim 4, characterized in that: In step (1), the molar ratio of the added iron salt, nickel salt, cobalt salt, chromium salt and manganese salt is 1:1:1:1:1, and the molar ratio of the total molar amount of the iron salt, nickel salt, cobalt salt, chromium salt and manganese salt to the added amount of modified nano-silicon is 1:(0.1-5).

6. The preparation method according to claim 1, characterized in that: In step (1), the modified nano-silicon is obtained by modifying nano-silicon particles with citric acid, PVP or hydrogen peroxide. The specific process is: dissolving the modified substance in deionized water, weighing the nano-silicon particles and dispersing them in the solution, stirring for 12-24 hours, centrifuging at 8000r / min for 3-10 minutes, taking the precipitate obtained by centrifugation, and vacuum drying it at 80-100°C for 12-24 hours to obtain the modified nano-silicon, wherein the modified substance: deionized water: nano-silicon particles = 1-2g: 100mL: 0.1-0.2g.

7. The preparation method according to claim 1, characterized in that: In step (2), the process parameters of the electrospinning are: voltage 1-20 kV, ejection speed 0.5-2 mL / h, distance between the syringe needle and the collector 10-20 cm, and inner diameter of the syringe needle 0.61-1.2 mm.

8. The preparation method according to claim 1, characterized in that: In step (3), the heating rates of the pre-sintering and calcining are both 1-20°C / min.

9. The high entropy alloy oxide / nano silicon composite lithium ion battery negative electrode material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The chemical formula of the obtained high entropy alloy oxide / nano-silicon composite lithium-ion battery negative electrode material is (FeCoNiCrMn)3O4 / Si, which is a spinel structure, forming a core-shell structure of high entropy alloy oxide encapsulating nano-silicon.

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