Composite-coated nano-tin negative electrode material and preparation method and use thereof

1. A composite-coated nanosized-tin negative electrode material, comprising: a tin-based nanomaterial, a copper layer coated on the surface of the tin-based nanomaterial, and a conductive protective layer coated on the surface of the copper layer, wherein a carbon layer is further provided between the tin-based nanosized material and the copper layer, and wherein the copper layer is a layer of nanosized copper particles or a copper film having a nanometer thickness.

2. The nanosized-tin negative electrode material according to claim 1 , wherein the tin-based nanosized material is one or more of tin nanosized material, tin-carbon nanosized material or tin alloy nanosized material.

3. The nanosized-tin negative electrode material according to claim 2 , wherein in the tin-carbon nanosized material and the tin alloy nanosized material, the weight percentage content of tin is 2%-70%.

4. The nanosized-tin composite negative electrode material according to claim 1 , wherein the particle size of the copper particles is 0.5-100 nm; and the thickness of the copper film is 0.5-100 nm.

5. The nanosized-tin composite negative electrode material according to claim 1 , wherein the weight of the copper layer accounts for 2-70 wt % of the nanosized-tin-based negative electrode material; and the weight of the conductive protective layer accounts for 0.1-20 wt % of the nanosized-tin-based negative electrode material.

6. A method for preparing a nanosized-tin negative electrode material according to claim 1 , comprising the steps of:

(1) adding a tin-based nanosized material into a solvent to obtain a suspension, and then ultrasonically dispersing the suspension;

(2) adding a copper plating agent to the ultrasonically dispersed suspension, adding a reducing agent to perform chemical copper plating, and filtrating, washing and drying the same in a vacuum oven to obtain a copper-coated tin-based nanosized composite material; and

(3) coating a conductive protective layer on the surface of the copper-coated tin-based nanosized composite material

wherein the method further comprises coating a carbon layer on the surface of the nanosized-tin-based material before step (1).

7. The method according to claim 6 , wherein the method further comprises:

(4) treating the composite material obtained in step (3) with heat to cure it.

8. The method according to claim 6 , wherein the solvent in step (1) is one or more of water, methanol, ethanol, propanol, isopropanol, butanol, and ethylene glycol.

9. The method according to claim 6 , wherein the composition of the copper plating agent in step (2) comprises one or more of tetrakis(acetonitrile)copper(I) hexafluorophosphate, CuCl 2 , CuCl, CuC 2 O 4 , Cu(CH 3 COO) 2 , CuSO 4 or Cu(NO 3 ) 2 : 1-20 g·L −1 ; potassium sodium tartrate: 5-100 g·L −1 ; ethylenediaminetetraacetic acid or ammonia water: 5-100 g·L −1 ; 2,2-bipyridine: 1-50 mg·L −1 ; and the reducing agent is sodium borohydride, sodium hypophosphite, borane or formaldehyde, and the concentration of the reducing agent is 1-20 g·L −1 .

10. The method according to claim 6 , wherein the conductive protective layer in step (3) is one or more of carbon, polyaniline, polypyrrole, polythiophene, and polyacetylene.

11. A negative electrode which comprises a current collector and a negative electrode material, a conductive additive and a binder loaded on the current collector, wherein the negative electrode material is a negative electrode material of claim 1 or a negative electrode material prepared by a method according to claim 6 .

12. A lithium-ion battery which comprises a battery shell, an electrode assembly, and an electrolyte, the electrode assembly and electrolyte being sealed in the battery shell, and the electrode assembly comprising a positive electrode, a separator, and a negative electrode, wherein the negative electrode is a negative electrode of claim 11 .

13. The nanosized-tin negative electrode material according to claim 2 , wherein the tin nanosized-material, the tin-carbon nanosized-material or the tin alloy nanosized-material comprise nanoparticles, nanowires, or nanosheets.

14. The nanosized-tin negative electrode material according to claim 13 , wherein the nanoparticles have a particle size of 5-1000 nm; the nanowire has a length of 10-5000 nm, and a diameter of 5-1000 nm; and the nanosheet has a length and a width of 10-5000 nm and a thickness of 1-500 nm.

15. The nanosized-tin negative electrode material according to claim 2 , wherein the thickness of the copper layer is 0.5-100 nm, and the thickness of the conductive layer is 1-100 nm.

16. The nanosized-tin negative electrode material according to claim 3 , wherein the tin alloy is selected from one or more of tin-aluminum alloy, tin-tin alloy, tin-silver alloy, and tin-magnesium alloy.

17. The nanosized-tin negative electrode material according to claim 4 , wherein the particle size of the copper particles is 1-50 nm; and the thickness of the copper coating layer is 1-50 nm.

18. The nanosized-tin negative electrode material according to claim 5 , wherein the weight of the copper layer accounts for 10-30 wt % of the nanosized-tin-based negative electrode material; and the weight of the conductive protective layer accounts for 1-10 wt % of the nanosized-tin-based negative electrode material.