Decoding the Zinc Depletion-Mediated Failure in Aqueous Zinc Batteries: On Limiting Parameters and Accurate Assessment

Dendritic zinc electrodeposition-mediated short-circuiting is the predominant failure mode reported for aqueous zinc batteries. While zinc corrosion is implicated in poor Coulombic efficiency, corrosion-mediated zinc depletion is rarely blamed for cell failure. This study critically examines corrosion-mediated zinc depletion and associated cell failure, considering cell configuration and key parameters: zinc reserve and electrolyte to capacity ratio. Surprisingly, zinc depletion emerges as a more significant issue than previously thought, even with a thin separator that can expedite short circuits. The second zinc electrode in the symmetric cell setup acts as a zinc reserve, inflating the battery's lifespan. Conversely, the asymmetric setup accurately simulates zinc-starved conditions, providing a precise evaluation of zinc depletion, consistent with full-cell cycling results. It is demonstrated that for a threshold electrolyte content the full-cell capacity decay primarily results from zinc corrosion and loss, and cell revival is achievable by replacing the spent anode with a fresh one.