Self-Healable Hydrogel Electrolyte toward High-Performance and Reliable Quasi-Solid-State Zn–MnO₂ Batteries

Zinc-ion batteries are promising power sources, but their practical application is impeded by the Zn dendrite growth and side reactions at the electrode/electrolyte interface. Here, we report that such issues can be effectively addressed by a self-healable hydrogel electrolyte. The electrolyte is comprised of carboxyl-modified poly(vinyl alcohol) cross-linked by COO-Fe bonding in the presence of Zn(NO₃)₂ and MnSO₄. A quasi-solid-state Zn-MnO₂ battery using the electrolyte delivers a specific capacity up to 177 mAh g^-1 after 1000 cycles with a retention rate of 83%, which is much better than its equivalent using an aqueous electrolyte. The improvement is attributed to efficient suppression of the dendrite growth and side reactions at the electrode/electrolyte by the hydrogel electrolyte. More importantly, the battery autonomously recovery its energy-storage functions even after multiple physical damages, showing excellent robustness and reliability. The present investigation provides an effective strategy to address the energy-storage performance and reliability of a light-metal battery system.