Multi-Healable, Mechanically Durable Double Cross-Linked Polyacrylamide Electrolyte Incorporating Hydrophobic Interactions for Dendrite-Free Flexible Zinc-Ion Batteries

Flexible aqueous zinc-ion batteries (ZIBs) are considered as one of the most promising energy storage candidates for wearable electronics, owing to their environmental friendliness, low cost, high safety, and high theoretical capacity. However, the practical application of flexible ZIBs is significantly impeded by the Zn dendrite growth and the poor mechanical endurability at the electrolyte-electrode interface. Mechanically durable hydrogel electrolyte with dendrite growth restriction and self-healing ability is highly desirable to improve the durability and extend the lifetime of the flexible ZIBs. However, it is still a big challenge to simultaneously endow hydrogel electrolytes with all necessary properties. Herein, multi-healable and mechanically durable hydrogels are fabricated by the synergy effect of strong chemical cross-linking and dynamic physical hydrophobic associations. The obtained double cross-linked polyacrylamide electrolyte (PAAm-O-B) has good tensile strain, strength, and stable electrochemical performance, with tensile strength up to 75 kPa, high self-healing efficiency up to 50 broken-healed cycles and lifespan up to 900 h dendrite inhibition behavior. The flexible Zn//MnO2 batteries using PAAm-O-B hydrogel electrolytes exhibit good mechanical durability with high specific capacity and long cycle lifespan even under 1000 bending deformations and superior self-healing ability.