Engineering Polymer Glue towards 90% Zinc Utilization for 1000 Hours to Make High‐Performance Zn‐Ion Batteries

Abstract Zinc (Zn) metal is considered the promising anode for “post‐lithium” energy storage due to its high volumetric capacity, low redox potential, abundant reserve, and low cost. However, extravagant Zn is required in present Zn batteries, featuring low Zn utilization rate and device‐scale energy/power densities far below theoretical values. The limited reversibility of Zn metal is attributed to the spontaneous parasitic reactions of Zn with aqueous electrolytes, that is, corrosion with water, passive by‐product formation, and dendrite growth. Here, a new ion‐selective polymer glue coated on Zn anode is designed, isolating the Zn anode from the electrolyte by blocking water diffusion while allowing rapid Zn 2+ ion migration and facilitating uniform electrodeposition. Hence, a record‐high Zn utilization of 90% is realized for 1000 h at high current densities, in sharp contrast to much poorer cyclability (usually < 200 h) at lower Zn utilization (50–85%) reported to date. When matched with the vanadium‐based cathode, the resulting Zn‐ion battery exhibited an ultrahigh device‐scale energy density of 228 Wh kg −1 , comparable to commercial lithium‐ion batteries.