Ion-confinement effect enabled by gel electrolyte for highly reversible dendrite-free zinc metal anode

The aqueous Zn-ion battery (ZIBs) is regarded as the most promising alternative energy storage system. However, the poor shelf life and restoration capacity caused by dendrite growth and the irreversible consumption of metal Zn anode, are remaining challenges for practical cell technologies. In this work, a hierarchically three-dimensional Zn2+-conductor gel electrolyte (Alg-Zn) is prepared based on ion-crosslinking to enable highly reversible dendrite-free zinc metal anode. The Alg-Zn possesses a high ionic conductivity of 1.83 ​× ​10−2 ​S ​cm−1 and superior mechanical performance for aqueous ZIBs applications. Given the ion-confinement capability in gel electrolyte and deliberated characterization of symmetric Zn/Zn over 270 ​h cycled testing, it can effectively suppress dendrite growth and reduce the generation of irreversible by-products. By coupling with this gel electrolyte, the Zn/MnO2 batteries exhibit good cycling stability and rate performance. Especially, after resting over 60 ​h, the capacity can rapidly recover and maintain ~320 ​mA ​h ​g−1. This work demonstrates that the gel electrolyte can effectively suppress the notorious parasitic reactions for static states usually in the Newtonian liquid electrolytes, and thus endow the Zn-based battery with outstanding shelf life and restoration capacity.