Electrolyte Additive Engineered Durable and High-Energy-Density Nickel-Zinc Battery

The persistent challenge of the anode degradation in aqueous nickel-zinc (Ni-Zn) batteries, marked by dendrite growth, zinc corrosion, and irreversible “dead zinc” formation, requires effective mitigation strategies. Here, we introduce a trace quantity (0.05 wt%) of the ionic compound 1-ethyl-1-methylpyrrolidinium bromide (MEP[Br]) as the electrolyte additive to stabilize the anode function. Computational analysis revealed that MEP cations can bind to ZnO/Zn surfaces, forming a protective interfacial layer that ensures reversible Zn(OH)₄²⁻/Zn redox processes with greatly curtailed side reactions. Ni-Zn pouch cells incorporating this additive delivered a high voltage plateau of ∼1.7 V at 0.5 C and sustained stable cycling for 600 hours, outperforming bareelectrolyte cells that experienced voltage polarization and failed within 150 hours. Even under high-rate conditions, the pouch cells achieved stable cycling performance, completing 1000 cycles at 6 C and 2000 cycles at 20 C with minimal capacity decay rates of 0.91% and 0.04% per cycle, respectively. The feasibility and effectiveness of the MEP additive were further validated in scaled cylindrical cells, which yielded a high capacity (9.96 Ah) and energy density (207.2 Wh l⁻¹) with high safety. This work proposes a facile electrolyte additive approach that enables durable, high-energy, and inherently safe Ni-Zn batteries. © 2026 The Electrochemical Society (“ECS”). Published on behalf of ECS by IOP Publishing Limited.