Nano-framework electroplating enabled by chloride electrolyte engineering for long-life and high-reversibility aqueous zinc-ion batteries

The widespread realization of aqueous zinc-ion batteries (AZIBs) is hampered by waterborne side reactions such as dendrite formation, corrosion, passivation, and hydrogen evolution. To counter these issues and achieve high Zn reversibility, we adopted a composite electrolyte additive strategy using Cl − and 3-mercapto-1-propanesulfonic acid sodium salt (MPS) to achieve strict regulation of Zn electroplating. The strategy induced a unique nano-unit electroplating mode through a complex interfacial network constructed by Cl − -Zn 2+ - and a solid electrolyte interface (SEI), enabling dense and uniform deposition morphology affording ultra-stable Zn cycling for over 430 h under harsh testing conditions (15 mA cm −2 , 51.2% DOD). Notably, Cl – played a key role in the suppression of side reactions through interfacial stabilization and the reconstruction of hydrogen bonding and solvation structures. Combined with the protective adsorption and SEI layer at the interface, a high average Coulombic efficiency of 99.80% was achieved. As validation, a V 2 O 5–x full cell exhibits a high capacity retention of 96.1% after 1600 stable cycles. Besides, the cells also have an impressive rate performance, with a 450 mAh g –1 capacity at 10 A g –1 , benefiting from the enhanced ion conductivity and Zn 2+ transport kinetics. This work delivers valuable design principles for engineering aqueous electrolytes in metal-ion batteries.