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 roughness and/or thickness of the current collector, a metal used for the current collector, and/or a lamination process that adheres the active material to 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 a surface of the current collector, wherein the forming comprises:
applying an active material based mixture to the current collector;
performing pyrolysis to convert the active material based mixture to the active material; and
controlling a lateral expansion of the anode in directions parallel to the surface of the current collector during its subsequent operation,
wherein the controlling comprises selecting or adjusting roughness related features on the surface of the current collector,
wherein the roughness related features are selected or adjusted based on one or more characteristics of particles in the active material,
wherein the roughness related features are selected or adjusted to account for the lateral expansion of the anode in the directions parallel to the surface of the current collector, and
wherein the directions are perpendicular to a thickness of the active material.
2. The method according to claim 1 , wherein the expansion of the anode is more anisotropic for thicker current collectors.
3. The method according to claim 2 , wherein a thicker current collector is 10 μm thick or greater.
4. The method according to claim 1 , wherein the expansion of the anode is more anisotropic for more rigid materials used for the current collector.
5. The method according to claim 4 , wherein a more rigid current collector comprises nickel and a less rigid current collector comprises copper.
6. The method according to claim 1 , wherein the roughness related features are selected or adjusted based on predetermined anisotropic expansion characteristics of the anode.
7. The method according to claim 1 , wherein the roughness related features comprise etching features of removed material in the current collector.
8. The method according to claim 7 , wherein the etched features range from 5 to 50 μm across.
9. The method according to claim 1 , wherein the expansion of the anode is more anisotropic if the active material is roll press laminated to the current collector and is less anisotropic if the active material is flat press laminated to the current collector.