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

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 Zn²⁺ onto 2D nanosheets of low-cost H₃Sb₃P₂O₁₄, 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-I₂ 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.