Electrolyte compositions for batteries
An energy storage device comprising a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode comprises a self-supporting composite material film, a separator between the first electrode and the second electrode, and an electrolyte in contact with the first electrode, the second electrode, and the separator, wherein the electrolyte comprises at least one of a fluorine-containing cyclic carbonate, a fluorine-containing linear carbonate, and a fluoroether. The composite material film having greater than 0% and less than about 90% by weight of 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 that holds the composite material film together such that the silicon particles are distributed throughout the composite material film.
1. A composite material comprising:
more than about 50% by weight of silicon particles;
with the remainder being one or more types of carbon phases, wherein at least one of the one or more types of carbon phases is a continuous phase that holds the composite material together such that the silicon particles are distributed throughout the composite material; and
wherein the silicon particles are in contact with the continuous phase;
and wherein the silicon particles have an average largest dimension between about 5 μm and about 40 μm.
2. The composite material of claim 1 , wherein the at least one of the one or more types of carbon phases that is a continuous phase comprises pyrolytic carbon.
3. The composite material of claim 1 , wherein the one or more types of carbon phases comprises graphite particles.
4. The composite material of claim 1 , further comprising conductive particles.
5. The composite material of claim 1 , further comprising metal particles.
6. The composite material of claim 1 , wherein the composite material is electrochemically active.
7. The composite material of claim 1 , wherein the silicon particles are homogenously distributed throughout the composite material.
8. A battery electrode comprising the composite material of claim 1 .
9. A method of forming the composite material 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.
10. The method of claim 9 , wherein the at least one of the one or more types of carbon phases that is a continuous phase comprises pyrolytic carbon.
11. The method of claim 9 , wherein the mixture further comprises a solvent.
12. The method of claim 9 , wherein the precursor comprises a polyimide.
13. The method of claim 9 , wherein the precursor comprises a phenolic resin.
14. The method of claim 9 , wherein the precursor comprises a hydrocarbon compound.
15. The method of claim 9 , 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.
16. The method of claim 9 , further comprising forming a battery electrode from the composite material.
17. The composite material of claim 1 , wherein the silicon particles have an average largest dimension between about 5 μm and about 30 μm.
18. The composite material of claim 1 , wherein the silicon particles have an average largest dimension between about 5 μm and about 20 μm.