Recent Progress in Aqueous Zinc-ion Batteries at High Zinc Utilization.

Abstract

Aqueous zinc ion batteries (AZIBs) are promising candidates for next-generation energy storage systems due to their low cost, high safety, and environmental friendliness. As the critical component, Zn metal with high theoretical capacity (5855 mAh cm-3), low redox potential (-0.763 V vs standard hydrogen electrode), and low cost has been widely applied in AZIBs. However, the low Zn utilization rate (ZUR) of Zn metal anode caused by the dendrite growth, hydrogen evolution, corrosion, and passivation require excess Zn installation in current AZIBs, thus leading to increased unnecessary battery weight and decreased energy density. Herein, approaches to the historical progress toward high ZUR AZIBs through the perspective of electrolyte optimization, anode protection, and substrate construction are comprehensively summarized, and an in-depth understanding of ZUR is highlighted. Specifically, the main challenges and failure mechanisms of Zn anode are analyzed. Then, the persisting issues and promising solutions in the reaction interface, aqueous electrolyte, and Zn anode are emphasized. Finally, the design of 100% ZUR AZIBs free of Zn metal is presented in detail. This review aims to provide a better understanding and fundamental guidelines on the high ZUR AZIBs design, which can shed light on research directions for realizing high energy density AZIBs.