Promising Electrolyte Additive-Induced Multifunctional Alloy Interphase Enabling Stable Zinc Anodes for Aqueous Zinc-Ion Batteries

Excessive dendrite formation and side reactions compromise the reversibility and stability of zinc anodes, obstructing the deployment of aqueous zinc-ion batteries. An economical, yet effective solution involves deploying electrolyte additives for the formation of a solid electrolyte interphase (SEI) on zinc metal anodes. Managing to fabricate an optimal SEI via these additives remains challenging. Here, we introduce a cost-effective copper sulfate additive, enabling the creation of a multifunctional copper–zinc alloy SEI. The SEI's superior electrical conductivity, zincophilic sites, ample free space, and elevated surface energy facilitate homogeneous Zn nucleation and deposition, thereby expediting electrochemical kinetics and mitigates dendrite formation. Additionally, the uniform alloy suppresses Zn corrosion and the hydrogen evolution reaction, augmenting Zn deposition/dissolution reversibility. Consequently, the Zn||Zn symmetric cells with the additive exhibiting a remarkable cycling stability of over 5000 h at 0.5 mA cm–2, with an extraordinary average Coulombic efficiency of 99.4% and a lifespan of 1600 h with a stable voltage hysteresis at 2 mA cm–2 for 2 mA h cm–2. This study proposes a suitable electrolyte additive for high-performance aqueous zinc-ion batteries.