On Repeatability of Electrochemical Zinc Nucleation and Growth From Aqueous Zinc Sulfate Electrolytes

Abstract Electrodeposition of zinc is critical to enabling rechargeable zinc batteries. Historically, zinc batteries have employed zinc foil or powder zinc anodes, and the anode research has focused on improving the reversibility of zinc electrodeposition through a combination of material modifications and electrical controls. With breakthroughs in anode-free lithium batteries, an appealing possibility is to leverage the anode-free configuration. The very first step in such an operation is nucleation and growth of zinc on a substrate. Hence, to conclusively study how this early stage electrodeposition is influenced by factors such as electrolyte composition, substrate choice, and operating conditions, it is essential to obtain repeatable electrochemical signatures corresponding to nucleation and growth. Surprisingly, our experiments electrodepositing zinc on stainless steel find appreciable cell-to-cell variability across identical testing conditions. While we still do not conclusively understand the underlying mechanism(s) causing such variability, the present study quantifies the contributions to variability resulting from surface cleaning, formation step, and zinc counter electrode.