Modeling Electrode Geometry Changes in Zinc-Based Batteries Using Comsol Multiphysics®

Zinc-based batteries are a major topic of interest in the search for energy storage technologies beyond lithium-ion batteries. In comparison to lithium, zinc's relative abundance, lower cost, higher volumetric capacity, and ability to be paired with aqueous electrolytes make it an attractive option for next generation batteries. However, zinc batteries' practical applications are limited because of low rechargeability. During battery charge, zinc is continuously plated onto the working electrode; during discharge, zinc is stripped from the working electrode. Over numerous battery cycles, inhomogeneous zinc deposition leads to the formation of dendrites, or small tree-branch-like growths of metal. These dendrites are responsible for zinc-based batteries' low rechargeability because they can (1) bridge the gap between the working and counter electrodes, causing the electrochemical cell to short circuit, or (2) break off at the root, forming "dead zinc" which has no electrical contact with either electrode and leads to capacity losses. An attractive approach to suppressing dendrite formation over multiple battery cycles involves changing the geometry of the working electrode to achieve uniform zinc electrodeposition. In this investigation, COMSOL Multiphysics® software was used to model the plating and stripping of zinc onto and from a zinc metal electrode in a two-electrode cell. As expected, greater plating/stripping of zinc was observed at the points on the two electrodes closest to each other where electrode current density is highest. The models generated in this study lay the groundwork for zinc electrode geometry optimization in the future, in which electrodes are designed to achieve homogeneous zinc electrodeposition over many battery cycles.