Quasi-solid single Zn-ion conductor with high conductivity enabling dendrite-free Zn metal anode

Aqueous Zn-ion batteries (ZIBs) have great potential in the field of large-scale energy storage. However, the dendrite formation on Zn anodes hinders the practical applications of ZIBs. Herein, a zincic perfluorinated sulfonic acid membrane (ZPSAM) is prepared as a quasi-solid single-ion conductor. In this membrane, Zn-ions move along with the negatively charged branched chains which possess a limited degree of freedom, forming fast Zn-ion transport channels. Consequently, ZPSAM exhibits high conductivity (similar to 1.17 x 10(-3) S cm(-1)), enabling stable Zn plating and stripping processes at a current density of 2 mA cm(-2) over 2000 cycles. In addition, due to the confined anion matrix in the membrane, dendrite formation and side reaction are both effectively suppressed. Finally, by applying the electrolyte in both aqueous super-capacitor and Zn-ion batteries, significantly improved cycling performance can be achieved. This work demonstrates a promising solution for the practical use of Zn metal anode in neutral aqueous media, and thus benefits the development of low-cost, high-performance aqueous energy storage devices.