Silicon particles for battery electrodes
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 of silicon particles. The silicon particles have an average particle size between about 0.1 μm and about 30 μm and a surface including nanometer-sized features. The composite material also includes 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 is a substantially continuous phase.
1. A composite material, comprising:
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, and
wherein at least one of the one or more types of carbon phases comprises a continuous phase that holds the composite material together such that the silicon particles are distributed throughout the composite material;
wherein an average surface area per unit mass of the silicon particles is greater than about 2 m 2 /g and less than about 100 m 2 /g; and
wherein a median particle size of the silicon particles is between about 5 μm and about 44 μm.
2. The composite material of claim 1 , wherein the silicon particles have an average largest dimension less than about 1 μm.
3. The composite material of claim 1 , comprising about 20% to about 80% of the silicon particles by weight.
4. The composite material of claim 1 , wherein the at least one of the one or more types of carbon phases is electrochemically active and electrically conductive.
5. The composite material of claim 1 , wherein the continuous phase of the at least one of the one or more types of carbon phases comprises hard carbon.
6. The composite material of claim 1 , wherein the one or more types of carbon phases comprises graphite particles.
7. The composite material of claim 1 , further comprising conductive particles.
8. The composite material of claim 1 , further comprising metal particles.
9. The composite material of claim 1 , wherein the composite material is electrochemically active.
10. The composite material of claim 1 , wherein the silicon particles are homogenously distributed throughout the composite material.
11. The composite material of claim 1 , wherein the silicon particles are in contact with the continuous phase of the at least one of the one or more types of carbon phases.
12. The composite material of claim 1 , comprising greater than about 50% by weight of the silicon particles.
13. The composite material of claim 1 , comprising between about 60% and about 80% by weight of the silicon particles.
14. A method of using the composite material of claim 1 , comprising using the composite material only at a gravimetric capacity less than about 70% of a maximum gravimetric capacity of the composite material.
15. The composite material of claim 1 , wherein the average surface area per unit mass of the silicon particles is greater than 3 m 2 /g.
16. The composite material of claim 1 , wherein the average surface area per unit mass of the silicon particles is greater than 5 m 2 /g.
17. The composite material of claim 1 , wherein the average surface area per unit mass of the silicon particles is less than 30 m 2 /g.
18. A method, comprising:
providing a mixture comprising a precursor and silicon particles; and
pyrolysing the precursor to convert the precursor into one or more types of carbon phases and to form a composite material;
wherein the composite material comprises greater than 0% and less than about 90% by weight of silicon particles;
wherein the composite material comprises 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 comprises a continuous phase that holds the composite material together such that the silicon particles are distributed throughout the composite material; and
wherein an average surface area per unit mass of the silicon particles is greater than about 2 m 2 /g and less than about 100 m 2 /g; and
wherein a median particle size of the silicon particles is between about 5 μm and about 44 μm.
19. The method of claim 18 , wherein after pyrolysing the precursor, the mixture forms a self-supported composite structure.
20. The method of claim 18 , wherein the continuous phase of the at least one of the one or more types of carbon phases comprises hard carbon.
21. The method of claim 18 , wherein the composite material comprises about 20% to about 80% of the silicon particles by weight.
22. The method of claim 18 , wherein the mixture further comprises a solvent.
23. The method of claim 18 , wherein the precursor comprises a polyimide.
24. The method of claim 18 , wherein the precursor comprises a phenolic resin.
25. The method of claim 18 , wherein the precursor comprises a hydrocarbon compound.
26. The method of claim 18 , 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 the precursor by weight.
27. The method of claim 18 , further comprising:
casting the mixture on a substrate;
forming a film from the mixture on the substrate; and
removing the film from the substrate prior to the pyrolysing.
28. The method of claim 18 , further comprising forming a battery electrode from the composite material.
29. A battery electrode, comprising:
an active material layer;
wherein the active material layer comprises greater than 0% and less than about 90% by weight of silicon particles;
wherein the active material layer comprises 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 comprises a continuous phase that holds the active material layer together such that the silicon particles are distributed throughout the active material layer; and
wherein an average surface area per unit mass of the silicon particles is greater than about 2 m 2 /g and less than about 100 m 2 /g; and
wherein a median particle size of the silicon particles is between about 5 μm and about 44 μm.
30. The battery electrode of claim 29 , wherein the active material layer is self-supporting.
31. The battery electrode of claim 29 , further comprising:
a current collector; and
wherein the active material layer is on the current collector.
32. The battery electrode of claim 31 , wherein the current collector comprises a metal foil.
33. The battery electrode of claim 31 , wherein the current collector comprises a metal mesh.