Charge-driven flocculation strategy for lean-water quasi-solid electrolyte enabling stable aqueous Zn metal batteries

• A charge-driven flocculation strategy forms a lean-water Zn-ion quasi-solid electrolyte (LWZQE). • LWZQE achieves 13.75 M Zn salt concentration with only 16.4 wt % water, reducing side reactions and widening the electrochemical window. • The stable ZnF 2 SEI layer improves compatibility between LWZQE and the Zn anode. • The lean-water feature of LWZQE ensures exceptional stability and suppresses the shuttle effect of the iodine cathode. The practical applications of zinc-based aqueous batteries have been impeded by their dendrite growth, hydrogen evolution, and corrosion, which stem from the side reactions related to free water in conventional electrolytes. Instead of traditional high-concentration aqueous electrolytes, in this study, we propose a charge-driven flocculation strategy via aggregating Zn 2+ onto 2D nanosheets of low-cost H 3 Sb 3 P 2 O 14 , resulting in a highly concentrated lean-water Zn-ion quasi-solid electrolyte (LWZQE). This electrolyte features a Zn salt concentration of 13.75 M with just 16.4 wt % water content, and this lean-water characteristic significantly mitigates the side reactions from free water in the electrolyte, improves compatibility with the Zn anode, and suppresses the shuttle effect of the iodine cathode. The assembled symmetric batteries demonstrate dendrite-free Zn plating/stripping over 5500 h. The Zn-I 2 full cell endows a remarkable reversibility of 8000 cycles, with a capacity retention of 79.1 %. This charge-driven flocculation strategy opens up a new avenue for developing cost-effective, highly concentrated aqueous electrolytes for the next generation Zn-based batteries. Instead of traditional high-concentration aqueous electrolytes, in this study, we propose a novel charge-driven flocculation strategy via aggregating Zn 2+ onto 2D nanosheets of low-cost H 3 Sb 3 P 2 O 14 . The elaborated concentrated lean-water Zn-ion quasi-solid electrolyte (LWZQE), with only 16.4 wt % water content, significantly enhances the stability and performance of current aqueous Zn metal batteries, offering promising prospects for improved efficiency and cycle life.