A functional hydrogel electrolyte doped with graphene oxide enabling ultra-long lifespan zinc metal batteries by inducing oriented deposition

Abstract

The progress of zinc (Zn) metal batteries (ZMBs) is greatly limited by poor cycling stability because of the mutual restrictions of dendrite growth, corrosion reactions, and passivation. In this work, an ultra-long lifespan (∼7800 h), dendrite-free Zn metal anode is enabled via fabricating a functional hydrogel electrolyte out of polyacrylamide/graphene oxide (GO)/agarose (PGA) with a multifully cross-linked network. The synergetic integration of GO nanosheets and double-network structure endows the PGA hydrogel electrolyte with high ionic conductivity and excellent mechanical performance. More importantly, the abundant hydrophilic groups and stable three-dimensional cross-linked network of PGA electrolyte effectively constrain Zn2+ diffusion laterally along the Zn surface, which simultaneously prohibits water-induced corrosion and thus significantly enhances Zn anode reversibility. Both theoretical simulations and experiments reveal that the PGA electrolyte is capable of optimizing de-solvation kinetics and harmonizing Zn2+ flux at the electrolyte–electrode interface, ensuring uniform Zn2+ deposition. Consequently, an ultra-long lifespan of 7800 h is achieved in the symmetric cell with the PGA electrolyte. Even at a high Zn utilization of 42.7 %, it still delivers stable cycling over 1100 h. This work provides a practical and beneficial approach to dramatically extending the lifespan of the Zn anode and thus achieving high-performance ZMBs.