An Electroanalytical Perspective on the Competitive Interplay between Zinc Deposition and Hydrogen Evolution in Aqueous Zinc Metal Batteries

This perspective highlights the consequences of the intricate interplay between the hydrogen evolution reaction (HER) and zinc electrodeposition on anode stability in aqueous zinc metal batteries (AZMBs), considering both cycling and resting conditions. Recent advances in the precise quantification of HER kinetics and its mechanistic origin are discussed, alongside accurately probing the kinetics of zinc plating using fast-scan voltammetry. From an electroanalytical standpoint, we emphasize on how measurement science has informed electrolyte and additive design, SEI engineering, charge–discharge protocols, and interfacial pH effects. The findings discussed help rationalize observed phenomena, such as paradoxically high Coulombic efficiencies at high current densities. Importantly, challenges during resting states are highlighted, where spontaneous HER and corrosion lead to active loss of zinc inventory (12–37%). Taken together, this work underscores the need for standardized kinetic evaluation and comprehensive stability metrics to guide the rational design of next-generation AZMB anodes.