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 po-larization 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.

Automated summary

Rechargeable aqueous zinc-ion batteries (ZIBs) are a promising technology for grid-scale energy storage systems. However, the growth of zinc dendrites and side reactions on the anodes have hindered practical applications. In this study, the relationship between zinc dendrite growth and internal stress accumulation during zinc plating is revealed. A zinc metal anode with patterned micro-grooves is proposed to release plating-induced stress and inhibit dendrite growth. Coupled with a Nafion film coating, this anode shows stable cycling performance, low electrochemical polarization, and voltage hysteresis in deep discharge/charge performance. The proposed strategy is also successfully applied to a Zn|MnO2 flexible pouch cell, demonstrating impressive capacity, electrochemical stability, and mechanical flexibility. This study provides valuable insights into the design of reversible aqueous zinc-ion batteries.