Releasing plating-induced stress for highly reversible aqueous Zn metal anodes

Rechargeable aqueous zinc-ion batteries (ZIBs) have become one of the most potential technologies for grid-scale energy storage systems. The practical application, however, has been severely plagued by the uncontrollable dendrite growth and side reactions on ZIB anodes with planar structure, making it urgent to develop efficient strategies to stabilize Zn anodes. Herein, it is revealed that the Zn dendrite growth is strongly associated with the internal stress accumulation during Zn plating. Moreover, a Zn metal anode with patterned micro-grooves structure that can effectively release the plating-induced stress and inhibit the dendrite growth. Notably, the groove-patterned Zn anodes coupling with Nafion film coating could effectively depress the side reactions and present ultra-stable cycling over 1200 h at a high current density of 10 mA cm−2, a low electrochemical polarization for the rate performance range from 1 to 20 mA cm−2 as well as a stable voltage hysteresis in deep discharge/charge performance at 10 mA cm−2 and 10 mAh cm−2. The feasibility of the proposed strategy is further confirmed and implemented in the Zn|MnO2 flexible pouch cell which delivers an impressive capacity of 186 mAh g−1, high electrochemical stability, and outstanding mechanical flexibility. The finding of this study is expected to provide a deep insight into the design of highly reversible aqueous Zn-ion batteries.