Electroactive materials for metal-ion batteries

Patent metadata

Field	Value
Publication number	US-11710819-B2
Application number	US-201816619064-A
Country	US
Kind code	B2
Filing date	Jun 18, 2018
Priority date	Jun 16, 2017
Publication date	Jul 25, 2023
Grant date	Jul 25, 2023

Abstract

This invention relates to particulate electroactive materials consisting of a plurality of composite particles, wherein the composite particles comprise a plurality of silicon nanoparticles dispersed within a conductive carbon matrix. The particulate material comprises 40 to 65 wt % silicon, at least 6 wt % and less than 20% oxygen, and has a weight ratio of the total amount of oxygen and nitrogen to silicon in the range of from 0.1 to 0.45 and a weight ratio of carbon to silicon in the range of from 0.1 to 1. The particulate electroactive materials are useful as an active component of an anode in a metal ion battery.

First claim

The invention claimed is:

1. A method for preparing a particulate material consisting of a plurality of composite particles that comprise a plurality of silicon nanoparticles dispersed within a conductive pyrolytic carbon matrix, the method comprising the steps of:
(a) milling a silicon starting material in the presence of a non-aqueous solvent to obtain a dispersion of silicon-containing nanoparticles having a D 50 particle diameter in the range of 30 to 500 nm in the solvent;
(b) contacting the dispersion of silicon nanoparticles in the solvent with a pyrolytic carbon precursor comprising one or more compounds comprising at least one oxygen or nitrogen atom;
(c) removing the solvent to provide silicon nanoparticles coated with the pyrolytic carbon precursor;
(d) heating the coated silicon nanoparticles to a temperature in a range of 100 to 400° C. for a period of time before step (e); and
(e) pyrolysing the coated silicon nanoparticles at a pyrolysis temperature in a range of from 600 to 1200° C. to form said plurality of composite particles that comprise a plurality of silicon nanoparticles dispersed within a conductive pyrolytic carbon matrix.

2. A method according to claim 1 , wherein the particulate material prepared by the method consists of a plurality of composite particles, wherein the composite particles comprise a plurality of silicon nanoparticles dispersed within a conductive carbon matrix, wherein:
the silicon nanoparticles comprise a nanoparticle core and a nanoparticle surface, wherein the nanoparticle surface comprises a compound of oxygen or a compound of nitrogen or a mixture thereof disposed between the nanoparticle core and the conductive carbon matrix;
the particulate material comprises 40 to 65 wt % silicon;
the particulate material comprises at least 6 wt % and less than 20 wt % oxygen;
a weight ratio of a total amount of oxygen and nitrogen to silicon in the particulate material is in a range of from 0.1 to 0.45; and
the weight ratio of carbon to silicon in the particulate material is in a range of from 0.1 to 1.

3. A method according to claim 1 , wherein the temperature to which the coated silicon nanoparticles are heated in step (d) is in a range of 200 to 400° C.

4. A method according to claim 1 , wherein the period of time for which the coated silicon nanoparticles are heated in step (d) is from 5 minutes to 10 hours.

5. A method according to claim 1 , wherein step (d) is carried out in presence of oxygen gas.

6. A method according to claim 1 , wherein step (d) is carried out in presence of air.

7. A method according to claim 1 , wherein the pyrolytic carbon precursor comprises a carbon-containing compound comprising one or more electrophilic functional groups.

8. A method according to claim 7 , wherein the pyrolytic carbon precursor is polyvinylpyrrolidone (PVP) or a copolymer of vinylpyrrolidone with one or more other ethylenically unsaturated monomers.

9. A method according to claim 7 , wherein step (d) comprises crosslinking the silicon nanoparticles and the pyrolytic precursor by a reaction between nucleophilic functional groups on a surface of the silicon nanoparticles and the one or more electrophilic functional groups of the pyrolytic carbon precursor.

10. A method according to claim 9 , wherein the pyrolytic carbon precursor is polyvinylpyrrolidone (PVP) or a copolymer of vinylpyrrolidone with one or more other ethylenically unsaturated monomers.

11. A method according to claim 7 , wherein step (d) comprises crosslinking the silicon nanoparticles and the pyrolytic carbon precursor under conditions such that a temperature increase in a reaction mixture comprising the silicon nanoparticles and the pyrolytic carbon precursor is controlled to no more than 5° C./min and a maximum temperature of the reaction mixture is maintained below 270° C. for the duration of the crosslinking reaction.

12. A method according to claim 7 , wherein step (d) comprises mixing or agitating the coated silicon nanoparticles so as to ensure a homogenous reaction temperature during the crosslinking step.

13. A method according to claim 12 , wherein the pyrolytic carbon precursor is polyvinylpyrrolidone (PVP) or a copolymer of vinylpyrrolidone with one or more other ethylenically unsaturated monomers.

14. A method according to claim 7 , wherein step (d) further comprises maintaining the coated silicon nanoparticles at a temperature in the range of from 100 to 400° C. for a period of time after completion of the crosslinking reaction.

15. A method according to claim 14 , wherein the pyrolytic carbon precursor is polyvinylpyrrolidone (PVP) or a copolymer of vinylpyrrolidone with one or more other ethylenically unsaturated monomers.

16. A method according to claim 1 , wherein the solvent is selected from the group consisting of alcohols and ketones.

17. A method according to claim 1 , wherein the solvent is isopropyl alcohol.

18. A method according to claim 1 , wherein the solvent is removed in step (c) by rotary evaporation or by spray drying.

19. A method according to claim 1 , further comprising the step of (f) reducing a size of the composite particles from step (e).

20. A method according to claim 1 , further comprising the step of (f) sieving the composite particles from step (e).

21. A method according to claim 1 , further comprising the step of (f) coating the composite particles from step (e) with a carbon coating.

22. A method according to claim 1 , wherein the particulate material comprises 40 to 65 wt % silicon.

23. A method according to claim 1 , wherein a weight ratio of a total amount of oxygen and nitrogen to silicon in the particulate material is in a range of from 0.1 to 0.45.

24. A method according to claim 1 , wherein a weight ratio of a total amount of oxygen and nitrogen to silicon in the particulate material is at least 0.2.

25. A method according to claim 1 , wherein step (d) comprises heating the coated silicon nanoparticles at a temperature in the range of 100° C. to below 200° C. for a first period of time and then heating the coated silicon nanoparticles at temperature in the range of 200 to 400° C. for a second period of time.

26. A method according to claim 25 , wherein the second period of time is from 5 minutes to 10 hours.

Assignees

• Nexeon Ltd

Inventors

• Bogart Timothy
• Foxon Simon
• Farrell James
• Bent David
• Scarlett Daniel

Classifications

• 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

• H01M4/386 Primary

  Silicon or alloys based on silicon · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/364 Primary

  as mixtures · CPC title