Negative electrode active material, process for preparing the same, and battery, battery module, battery pack and apparatus related to the same

1. A negative electrode active material, comprising a core material and a polymer modified coating on at least part of a surface of the core material;

wherein the core material is one or more of a silicon-based negative electrode material and a tin-based negative electrode material; and

wherein the negative electrode active material has a weight loss rate satisfying 0.2%≤weight loss rate≤2% in a thermogravimetric analysis test wherein temperature is elevated from 25° C. to 800° C. under a non-oxidizing inert gas atmosphere.

2. The negative electrode active material according to claim 1 , wherein the weight loss rate satisfies 0.3%≤weight loss rate≤1%.

3. The negative electrode active material according to claim 1 , wherein the polymer modified coating comprises nitrogen element and a —C═N— bond.

4. The negative electrode active material according to claim 3 , wherein the nitrogen element has a mass percentage of from 0.1% to 0.65% in the negative electrode active material.

5. The negative electrode active material according to claim 4 , wherein the nitrogen element has a mass percentage of from 0.15% to 0.5% in the negative electrode active material.

6. The negative electrode active material according to claim 1 , wherein the polymer modified coating comprises sulfur element and a —C—S— bond and/or a —S—S— bond.

7. The negative electrode active material according to claim 1 , wherein the negative electrode active material has a volume particle size distribution width (Dv90-Dv10)/Dv50 of from 0.5 to 2.5.

8. The negative electrode active material according to claim 7 , wherein the negative electrode active material has a volume particle size distribution width (Dv90-Dv10)/Dv50 of from 0.8 to 2.0.

9. The negative electrode active material according to claim 1 , wherein the negative electrode active material has a number particle size Dn10 of from 0.17 μm to 3 μm.

10. The negative electrode active material according to claim 9 , wherein the negative electrode active material has a number particle size Dn10 of from 0.2 μm to 1.5 μm.

11. The negative electrode active material according to claim 1 , wherein an X-ray diffraction spectrum of the negative electrode active material has a diffraction peak whose full width at half maxima is from 4° to 12° at the diffraction angle 2θ of from 19° to 27°.

12. The negative electrode active material according to claim 11 , wherein the full width at half maxima is from 5° to 10°.

13. The negative electrode active material according to claim 1 , wherein a Raman spectrum of the negative electrode active material has scattering peaks at positions where Raman shifts are from 1320 cm −1 to 1410 cm −1 and from 1550 cm −1 to 1650 cm −1 respectively, wherein the scattering peak at the position where the Raman shift is from 1320 cm −1 to 1410 cm −1 has an intensity denoted as I D , and the scattering peak at the position where the Raman shift is from 1550 cm −1 to 1650 cm −1 has an intensity denoted as I G and wherein I D and I G satisfy 1.60≤I D /I G ≤2.50.

14. The negative electrode active material according to claim 13 , wherein the I D and I G satisfy 1.80≤I D /I G ≤2.40.

15. The negative electrode active material according to claim 1 , wherein the negative electrode active material has a compaction density of from 1.1 g/cm 3 to 1.7 g/cm 3 measured under a pressure of 5 tons (equivalent to 49 KN).

16. The negative electrode active material according to claim 15 , wherein the negative electrode active material has a compaction density of from 1.2 g/cm 3 to 1.5 g/cm 3 measured under a pressure of 5 tons (equivalent to 49 KN).

17. The negative electrode active material according to claim 1 , wherein the silicon-based negative electrode material is one or more selected from elemental silicon, a silicon-carbon compound, a silicon-oxygen compound, a silicon-nitrogen compound, and a silicon alloy; and

the tin-based negative electrode material is one or more selected from elemental tin, a tin-oxygen compound, and a tin alloy.

18. The negative electrode active material according to claim 1 , wherein the silicon-based negative electrode material is selected from the silicon-oxygen compound.

19. A process for preparing the negative electrode active material according to claim 1 , comprising steps of:

dissolving a polymer precursor in a solvent, and stirring until uniform dispersion, to obtain a solution of the polymer precursor;

adding a core material into the solution of the polymer precursor, and stirring, to obtain a mixed slurry, wherein the core material is one or more selected from a silicon-based negative electrode material and a tin-based negative electrode material;

placing the mixed slurry in a spray dryer or a wet coating machine, and drying it under an non-oxidizing inert gas atmosphere, to obtain a solid powder; and

performing heat treatment to the solid powder under a non-oxidizing inert gas atmosphere at a temperature of from 200° C. to 450° C., to obtain the negative electrode active material;

wherein the negative electrode active material comprises the core material and a polymer-modified coating on at least a part of a surface of the core material; the core material is one or more of a silicon-based negative electrode material and a tin-based negative electrode material; and the negative electrode active material has a weight loss rate satisfying 0.2%≤weight loss rate≤2% in a thermogravimetric analysis test wherein the temperature is elevated from 25° C. to 800° C. under a non-oxidizing inert gas atmosphere.

20. A battery, comprising the negative electrode active material according to claim 1 .

21. A battery module, comprising the battery according to claim 20 .

22. A battery pack, comprising the battery module according to claim 21 .

23. An apparatus, comprising the battery according to claim 20 .