Negative electrode material, preparation method therefor and application thereof, and lithium-ion battery

Patent metadata

Field	Value
Publication number	US-12355070-B2
Application number	US-202017754742-A
Country	US
Kind code	B2
Filing date	Sep 29, 2020
Priority date	Oct 9, 2019
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A negative electrode material of the lithium-ion battery, a preparation method therefor and an application thereof, and a lithium-ion battery include the same are provided. The negative electrode material has a core-shell structure. The core has a silicon-containing material while the shell has an organic lithium salt and a porous carbon film, and at least part of lithium ion is intercalated in the porous carbon film. The negative electrode material is prepared by (1) mixing a silicon source and a carbon source, and then calcining the mixture; (2) mixing the calcined product obtained in the step (1) with the organic lithium salt; and (3) subjecting the materials obtained in the step (2) of mixing to vacuum freeze-drying.

First claim

The invention claimed is:

1. A negative electrode material having a core-shell structure,
wherein a core of the negative electrode material comprises a silicon-containing material, a shell of the negative electrode material comprises an organic lithium salt and a porous carbon film, and at least part of lithium ion in the organic lithium salt is intercalated in the porous carbon film, and,
based on the total amount of the negative electrode material, the organic lithium salt is present in an amount of 5-34 wt %, the silicon-containing material is present in an amount of 65-90 wt %, and the porous carbon film is present in an amount of 1-10 wt %.

2. The negative electrode material of claim 1 , wherein the negative electrode material further comprises a phosphorus-containing coating layer disposed between the core and the shell.

3. The negative electrode material of claim 1 , wherein,
based on the total amount of the negative electrode material, the organic lithium salt is present in an amount of 10-30 wt %, the silicon-containing material is present in an amount of 68-86 wt %, and the porous carbon film is present in an amount of 1-6 wt %.

4. The negative electrode material of claim 1 , wherein the negative electrode material has a median particle size of 0.1-20 μm.

5. The negative electrode material of claim 1 , wherein the organic lithium salt is at least one selected from the group consisting of lithium polyacrylate, lithium polymethacrylate, lithium polymaleate, lithium polyfumarate, lithium carboxymethylcellulose, and lithium alginate;
the silicon-containing material is at least one selected from the group consisting of elemental silicon, a SiOx wherein 0.6<x<1.5, and a silicon-containing alloy, the silicon-containing alloy being at least one selected from the group consisting of silicon-aluminum alloy, silicon-magnesium alloy, silicon-zirconium alloy, and silicon-boron alloy.

6. A method for preparing a negative electrode material, comprising:
(1) mixing a silicon source and a carbon source, and then calcining the mixture;
(2) mixing the calcined product obtained in the step (1) with an organic lithium salt; and
(3) subjecting the materials obtained in the step (2) of mixing to vacuum freeze-drying.

7. The method of claim 6 , wherein the silicon source is at least one selected from the group consisting of elemental silicon, a SiOx wherein 0.6<x<1.5, and a silicon-containing alloy, wherein the silicon-containing alloy is at least one selected from the group consisting of silicon-aluminum alloy, silicon-magnesium alloy, silicon-zirconium alloy, and silicon-boron alloy;
the carbon source is at least one selected from the group consisting of petroleum pitch, coal tar pitch, natural pitch, and modified pitch; and
a mass ratio of the silicon source to the carbon source is 1:(0.04-0.12).

8. The method of claim 6 , wherein the step (1) comprises: adding the silicon source and the carbon source into an organic solvent, and then stirring ultrasonically.

9. The method of claim 6 , wherein the organic lithium salt is at least one selected from the group consisting of lithium polyacrylate, lithium polymethacrylate, lithium polymaleate, lithium polyfumarate, lithium carboxymethylcellulose and lithium alginate;
the organic lithium salt is used in an amount of 0.05-0.5 parts by weight, in relative to 1 part by weight of the silicon source;
the step (2) comprises adding the calcined product obtained in the step (1) and the organic lithium salt into the solvent and stirring for 4-48 h.

10. The method of claim 6 , wherein the vacuum freeze-drying of the step (3) is carried out at a temperature of not higher than −65° C. and a vacuum degree of not higher than 120 Pa for a time of 4-48 h.

11. The method of claim 6 , wherein the method further comprises: adding graphite in the step (1) and/or the step (2).

12. The method of claim 6 , wherein the method further comprises: forming a phosphorus-containing coating layer prior to the step (1) by a method comprising the steps of:
(a) contacting the silicon-containing material, a phosphorus source and a solvent at 30-80° C. to graft the phosphorus source to the surface of the silicon-containing material; and
(b) subjecting to a temperature programmed calcining to convert the phosphorus source around the silicon-containing material into the phosphorus-containing coating layer comprising a polymer having polycyclic aromatic hydrocarbon structural segments,
wherein the temperature programmed calcining comprises:
heating to a first temperature of 400-500° C. at a first heating rate,
heating to a second temperature of 600-800° C. at a second heating rate, wherein the second heating rate is lower than the first heating rate, and
keeping at the second temperature.

13. The negative electrode material prepared by the method of claim 6 .

14. A lithium ion battery comprising the negative electrode material of claim 1 , a lithium-containing positive electrode material, a separator and an electrolyte, wherein the lithium ion battery is a liquid lithium ion battery, a semi-solid lithium ion battery, or a solid lithium ion battery.

15. The negative electrode material of claim 2 , wherein the phosphorus-containing coating layer comprises a polymer having polycyclic aromatic hydrocarbon structural segments, and the phosphorus-containing coating layer is made from phytic acid.

16. The negative electrode material of claim 3 , wherein the negative electrode material further comprises graphite; and
a mass ratio of a total amount of the silicon-containing material, the organic lithium salt, and the porous carbon film to an amount of graphite is 1:1-10.

17. The method of claim 8 , wherein the organic solvent is at least one selected from the group consisting of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, and the calcining is carried out under an inert atmosphere at a temperature of 600-1000° C. for 10-240 min.

18. The method of claim 6 , further comprising a step (4) of: mixing the product obtained in the vacuum freeze-drying in the step (3) with graphite, and the graphite is used in an amount of 1-15 parts by weight in relative to 1 part by weight of the product obtained in the vacuum freeze-drying in the step (3).

19. The method of claim 12 , wherein the phosphorus source is selected from the group consisting of organic polybasic phosphoric acid, esters, and salts thereof;
the solvent is at least one selected from the group consisting of toluene, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; and
the temperature programmed calcining comprises heating to a first temperature of 450-500° C. at a first heating rate of 1-10° C./min; then heating to a second temperature of 600-650° C. at a second heating rate of 1-5° C./min; and keeping at the second temperature for 1-8 h.

Assignees

• China Petroleum & Chem Corp
• Shanghai Res Inst Petrochemical Tech Sinopec

Inventors

• Sun Sai
• Zhang Siyu
• Gao Huanxin

Classifications

• H01M2004/027

  Negative electrodes · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title