Method for preparing silicon-carbon composite anode material and use thereof

1. A preparation method for a silicon/carbon composite anode material, comprising the following steps:

S1: heating a hypercrosslinked polymer in an inert atmosphere for carbonization to obtain a porous carbide;

S2: mixing the porous carbide with a silicon-containing solution to obtain a silicon-containing porous carbide suspension; and

S3: adding a complexing agent, a metal salt, and a reducing agent to the silicon-containing porous carbide suspension to allow a reaction, and after the reaction is completed, conducting solid-liquid separation to obtain a solid, and heating the solid in an inert atmosphere to obtain the silicon/carbon composite anode material.

2. The preparation method according to claim 1 , wherein the step S1 further comprises preparation of the hypercrosslinked polymer which comprises: in an inert atmosphere, mixing a benzenediol compound, a solvent, and a crosslinking agent, after cooling, adding a catalyst and mixing, and heating a resulting mixture to allow a reaction to obtain the hypercrosslinked polymer.

3. Use of the preparation method according to claim 2 in preparation of a lithium-ion battery.

4. The preparation method according to claim 1 , wherein in step S1, the heating for carbonization is conducted as follows: heating at a temperature from 100° C. to 320° C. for 0.1 h to 3 h, and then heating at a temperature from 600° C. to 1,000° C. for 8 h to 24 h, during the heating for carbonization, an inert gas is introduced to allow pore-expansion treatment under an action of gas flow.

5. Use of the preparation method according to claim 4 in preparation of a lithium-ion battery.

6. The preparation method according to claim 1 , wherein in step S1, the porous carbide has a particle size D50 of 2 μm to 26 μm and a specific surface area of 200 m 2 /g to 350 m 2 /g.

7. Use of the preparation method according to claim 6 in preparation of a lithium-ion battery.

8. The preparation method according to claim 1 , wherein in step S2, the silicon-containing solution is a nano-silicon oxide suspension or a nano-silicon suspension, and a mass percentage of silicon in the silicon-containing solution is in a range from 0.001 to 0.75.

9. Use of the preparation method according to claim 8 in preparation of a lithium-ion battery.

10. The preparation method according to claim 1 , wherein in step S3, the complexing agent is at least one selected from the group consisting of potassium sodium tartrate, ethylene diamine tetraacetic acid, and tartaric acid.

11. Use of the preparation method according to claim 10 in preparation of a lithium-ion battery.

12. The preparation method according to claim 1 , wherein in step S3, the metal salt is at least one selected from the group consisting of a soluble sulfate, a soluble chloride, a soluble nitrate, a soluble bromide, and a soluble phosphate of copper or silver; and the reducing agent is at least one selected from the group consisting of hypophosphorous acid and sodium hypophosphite.

13. Use of the preparation method according to claim 12 in preparation of a lithium-ion battery.

14. The preparation method according to claim 1 , wherein in step S3, the heating is conducted at a temperature from 550° C. to 1,100° C. for 1 h to 5 h.

15. Use of the preparation method according to claim 14 in preparation of a lithium-ion battery.

16. The preparation method according to claim 1 , wherein in step S3, the silicon/carbon composite anode material has a particle size D50 of 0.5 μm to 23 μm.

17. Use of the preparation method according to claim 16 in preparation of a lithium-ion battery.

18. Use of the preparation method according to claim 1 in preparation of a lithium-ion battery.