Composite materials for electrochemical storage
Composite materials and methods of forming composite materials are provided. The composite materials described herein can be utilized as an electrode material for a battery. In certain embodiments, the composite material includes greater than 0% and less than about 90% by weight silicon particles, and greater than 0% and less than about 90% by weight of one or more types of carbon phases. At least one of the one or more types of carbon phases can be a substantially continuous phase. The method of forming a composite material can include providing a mixture that includes a precursor and silicon particles, and pyrolyzing the precursor to convert the precursor into one or more types of carbon phases to form the composite material.
1. A composite material film comprising:
greater than 0% and less than about 90% by weight of silicon particles;
greater than 0% and less than about 90% by weight of one or more types of carbon phases, wherein at least one of the one or more types of carbon phases is a substantially continuous phase that holds the composite material film together such that the silicon particles are distributed throughout the composite material film; and
wherein the composite material film is self-supported.
2. The composite material film of claim 1 , wherein the silicon particles have an average largest dimension less than about 1 μm.
3. The composite material film of claim 1 , comprising about 20% to about 80% of the silicon particles by weight.
4. The composite material film of claim 1 , wherein the at least one of the one or more types of carbon phases that is a substantially continuous phase is electrochemically active and electrically conductive.
5. The composite material film of claim 1 , wherein the at least one of the one or more types of carbon phases that is a substantially continuous phase comprises hard carbon.
6. The composite material film of claim 1 , wherein the one or more types of carbon phases comprises graphite particles.
7. The composite material film of claim 1 , further comprising conductive particles.
8. The composite material film of claim 1 , further comprising metal particles.
9. The composite material film of claim 1 , wherein the composite material film is substantially electrochemically active.
10. A battery electrode comprising the composite material film of claim 1 .
11. A method of using the composite material film of claim 1 , comprising using the composite material film only at a gravimetric capacity less than about 70% of a maximum gravimetric capacity of the composite material film.
12. A method of forming the composite material film of claim 1 comprising:
providing a mixture comprising a precursor and silicon particles; and
pyrolysing the precursor to convert the precursor into the one or more types of carbon phases to form the composite material film.
13. The method of claim 12 , wherein after pyrolysing the precursor, the mixture forms a self-supported composite structure.
14. The method of claim 12 , wherein the at least one of the one or more types of carbon phases that is a substantially continuous phase comprises hard carbon.
15. The method of claim 12 , wherein the composite material film comprises about 20% to about 80% of the silicon particles by weight.
16. The method of claim 12 , wherein the mixture further comprises a solvent.
17. The method of claim 12 , wherein the precursor comprises a polyimide.
18. The method of claim 12 , wherein the precursor comprises a phenolic resin.
19. The method of claim 12 , wherein the precursor comprises a hydrocarbon compound.
20. The method of claim 12 , wherein the mixture comprises greater than 0% and less than about 80% of the silicon particles by weight, and about 5% to about 80% of precursor by weight.
21. The method of claim 12 , further comprising:
casting the mixture on a substrate;
drying the mixture to form a film;
removing the film from the substrate; and
curing the film in a hot press.
22. The method of claim 12 , further comprising forming a battery electrode from the composite material film.
23. The composite material film of claim 1 , wherein the silicon particles are homogenously distributed throughout the composite material film.
24. The composite material film of claim 1 , wherein the silicon particles are in contact with the substantially continuous phase.