Self-healable hydrogel electrolyte for dendrite-free and self-healable zinc-based aqueous batteries

Abstract The poor stability of zinc anodes caused by uneven deposition/stripping of zinc has inevitably limited the practical application of zinc-based aqueous batteries (ZABs). And the self-healing property is very necessary for improved lifespan and reliability of the flexible batteries under various deformations during their daily usage. In this work, a new self-healable hydrogel electrolyte (SHE) with rigid-flexible backbones is synthesized by cross-linking polymerization and composite strengthening. Owing to porous crosslinking network and more hydrophilic groups, the SHE possesses high ionic conductivity (23.1 mS/cm at 25 °C) and excellent mechanical strength, and the hydrophilic groups are conductive to improve interfacial compatibility between electrode and electrolyte, prompting much more disciplined Zn metal plating/stripping. And the dynamic hydrogen bonds derived from the hydroxyl groups of the polymer backbone can prompt self-healing and stretchable property of SHEs. As a result, the assembled flexible zinc-manganese dioxide batteries delivered a high capacity of 304 mAh g−1 at 0.5 A g−1 and good cycling stability with a capacity retention of 83.1% (vs. 62.5% with polyacrylamide) after 1500 charge/discharge cycles at 5.0 A g−1. Furthermore, the flexible batteries with SHEs can recover electrochemical performance with over 95% healing efficiency after 5 cycles of complete breaking/healing.