A π-interactive additive unlocks enhanced zinc anode rechargeability: unveiling the critical role of adsorption layer dynamics

Abstract

Aqueous zinc-ion batteries are promising for a safe, inexpensive, and sustainable platform for stationary energy storage, but their reversibility remains limited by dendrite and corrosion-mediated failure of the zinc anode. While low-concentration electrolyte additives have emerged as scalable solutions, the mechanistic underpinnings of their interfacial dynamics that dictate whether they enable long-term rechargeability or trigger premature dendritic failure remain poorly understood. Here, we investigate a series of π-interactive aromatic alcohols and a cycloaliphatic reference additive and uncover how additive–zinc and additive–additive interactions jointly govern the formation, spatial organization, packing density, and mobility of the additive film. These interfacial dynamics govern Zn²⁺ transport, corrosion suppression, and zinc deposition morphology. Phenol, which strikes a balance between adsorption strength and interfacial mobility, forms a thick yet dynamic layer that suppresses hydrogen evolution mediated corrosion while promoting uniform zinc deposition. This leads to excellent cycling stability with nearly 2 Ah cm⁻² cumulative plated capacity in a practically relevant asymmetric configuration at 24% depth of discharge under demanding 4 mA cm⁻²–4 mAh cm⁻², including a thin separator and low electrolyte-to-capacity ratio, with the coulombic efficiency reaching 99.89% under kinetic control compared to 95.94% for the additive-free electrolyte. Full cell and pouch-cell tests further validate phenol's efficacy, establishing adsorption layer dynamics as a new paradigm for rationalizing electrolyte additives’ efficacy in regulating zinc anode reversibility in aqueous batteries.