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 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 copper current collector and an active material on the current collector, the active material having a silicon content of 50% or more by weight; and
configuring an expansion of the anode during operation,
wherein the copper current collector comprises copper-based material;
wherein the expansion of the anode during operation is controlled or adjusted based on a selection of the copper-based material used for the current collector to ensure 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, and
wherein the selection of the copper-based material comprises selecting among a plurality of different types or options for the copper-based material.
2. The method according to claim 1 , wherein the anode expands less in lateral directions and expands more in a z-direction with a more rigid material as compared to a less rigid material, wherein the vertical direction is with respect to a top surface of the anode.
3. The method according to claim 1 , wherein a more rigid current collector comprises nickel.
4. The method according to claim 1 , wherein a more rigid current collector comprises copper coated with carbon.
5. The method according to claim 4 , wherein expansion of the anode in lateral directions is less than 0.5% for copper coated with carbon.
6. The method according to claim 1 , wherein the current collector comprises a copper foil.
7. The method according to claim 6 , further comprising applying the active material to the copper current collector using flat pressing, and wherein expansion of the anode in lateral directions is less than 4% when the active material is flat pressed on the copper current collector.
8. The method according to claim 6 , further comprising applying the active material to the copper current collector using roll pressing, and wherein expansion of the anode in lateral directions is less than 2% when the active material is roll pressed on the copper current collector.