High-Conductivity\nand Ultrastretchable Self-Healing\nHydrogels for Flexible Zinc-Ion Batteries

Aqueous\nzinc-ion batteries are promising candidates for flexible\nenergy storage devices due to their safety, economic efficiency, and\nenvironmental friendliness. However, the uncontrollable dendrite growth\nand side reactions at the zinc anode hinder their commercial application.\nHerein, we designed and synthesized a dual network self-healing hydrogel\nelectrolyte with zwitterionic groups (PAM–PAAS-QCS), which\ncan be used for the large deformations of flexible devices due to\nits excellent stretchability (ε = 5100%). The incorporation\nof zwitterionic groups into the PAM–PAAS-QCS hydrogel electrolyte\nendows it with high ionic conductivity (33.61 mS/cm), a wide electrochemical\nstability window, and the ability to suppress zinc dendrite formation\nand side reactions. Besides, the Zn//Zn symmetric cell with PAM–PAAS-QCS\ncan stably plate and strip zinc for 1500 h at 0.5 mA/cm<sup>2</sup>, and the Zn//Polyaniline full cell retains 82.4% of its capacity\nafter 1500 cycles at 1 A/g. Additionally, flexible batteries based\non both the original and self-healed PAM–PAAS-QCS hydrogel\nelectrolytes demonstrate good cycling stability and stable charge–discharge\nperformance under various bending conditions. This self-healing hydrogel\nelectrolyte with excellent stretchability and high ionic conductivity\nis expected to pave the way for the development of high-performance\nflexible energy storage and wearable devices.