Anisotropic expansion of silicon-dominant anodes
Systems and methods for anisotropic expansion of silicon-dominant anodes may include a cathode, an electrolyte, and an anode, where the anode may include a current collector and an active material on the current collector. An expansion of the anode during operation may be configured by a thickness of the current collector. The expansion of the anode may be more anisotropic for thicker current collectors. A thicker current collector may be 10 μm thick or greater. The expansion of the anode may be more anisotropic for more rigid materials used for the current collector. A more rigid current collector may include nickel and a less rigid current collector may include copper. The expansion of the anode may be more anisotropic for a rougher surface current collector.
1. A method of forming a battery, the method comprising:
forming a battery comprising a cathode, an electrolyte, and an anode, the anode comprising a current collector and an active material on the current collector, the active material comprising a pyrolyzed binder and 50% or greater silicon by weight; and
controlling or adjusting an expansion of the anode during operation based on a selection of a thickness of the current collector so that the anode expands less in one of the x-y directions and the z-direction while expanding more in a different one of the x-y directions and the z-direction, wherein the thickness is selected, at least in part, based on a material of the current collector.
2. The method according to claim 1 , wherein the expansion of the anode is more anisotropic for the anode with a thicker current collector with more anode thickness expansion and less lateral expansion as compared to an anode with a thinner current collector.
3. The method according to claim 2 , wherein the thicker current collector is 6 μm thick or greater.
4. The method according to claim 2 , wherein the thicker current collector is 10 μm thick or greater.
5. The method according to claim 2 , wherein the thicker current collector is 20 μm thick or greater.
6. The method according to claim 1 , wherein lateral expansion of the anode is less than 2% with a 10 μm thick current collector.
7. The method according to claim 1 , wherein lateral expansion of the anode is less than 5% with a 6 μm thick current collector.