SURFACE MODIFICATION OF SILICON PARTICLES FOR ELECTROCHEMICAL STORAGE
Silicon particles for active materials and electro-chemical cells are provided. The active materials comprising silicon particles 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, the silicon particles having an average particle size between about 10 nm and about 40 μm, wherein the silicon particles have surface coatings comprising silicon carbide or a mixture of carbon and silicon carbide, and 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.
1 . A composite material film comprising:
greater than 0% and less than about 90% by weight of silicon particles, wherein substantially all of the silicon particles have surface coatings comprising silicon carbide or a mixture of carbon and silicon carbide;
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.
2 . The composite material of claim 1 , wherein an average particle size of the silicon particles is from about 0.1 μm to about 30 μm.
3 . The composite material of claim 1 , wherein the silicon particles are from about 90% pure silicon to about 100% pure silicon.
4 . The composite material of claim 1 , wherein the surface coatings include silicon monoxide (SiO), silicon dioxide (SiO2), or silicon oxide (SiO x ).
5 . The composite material of claim 1 , wherein the surface coatings are a substantially continuous layer.
6 . The composite material of claim 1 , wherein the composite material is self-supported.
7 . The composite material 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.
8 . A lithium-ion battery electrode comprising the material of claim 1 .
9 . A method of forming a composite material comprising:
providing a mixture comprising a precursor and silicon particles; and
pyrolyzing the precursor to convert the precursor into one or more types of carbon phases; and
forming silicon carbide on at least a portion of silicon particles.
10 . The method of claim 9 , wherein the silicon carbide and/or one of the one or more types of carbon phases forms substantially continuous layers on the silicon particles.
11 . The method of claim 9 , wherein forming silicon carbide comprises reacting one of the one or more types of carbon phases with the silicon particles.
12 . The method of claim 11 , wherein reacting one of the one or more types of carbon phases with the silicon particles comprises reacting one or more types of carbon phases with native silicon oxide layers of the silicon particles.
13 . The method of claim 9 , wherein pyrolyzing the precursor comprises heating the mixture to a temperature of about 750° C. to about 1300° C.
14 . The method of claim 9 , wherein pyrolyzing the precursor comprises heating the mixture to a temperature of about 800° C. to about 1200° C.
15 . The method of claim 9 , wherein pyrolyzing the precursor comprises heating the mixture to a temperature of about 1175° C.
16 . 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.