Sustainable biomass enabled adhesive hydrogel electrolytes for highly stable and bendable zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHSCs) containing hydrogel electrolytes exhibit superior advantages to most energy storage devices, but weak electrolyte-electrode interface and poor environmental adaptability of hydrogel electrolytes often limit the electrochemical performances of supercapacitors under specific conditions. Inspired by sustainable and highly sticky nature of crops containing rich amylopectin (Amy), molecular engineering of adhesive hydrogel electrolytes containing chemically cross-linked polyacrylamide (PAM) network semi-interpenetrated by Amy is proposed to address the above issues. Because of the branched molecular structure and abundant polar groups, Amy endows the hydrogel electrolytes with high adhesiveness, and high-concentration ZnCl₂ is introduced to make the hydrogel electrolytes excellent environmental adaptability. Well-constructed hydrogel electrolytes provide a robust electrolyte-electrode interface and lowered interfacial impedance. Consequently, high charge/discharge stability (>32,000 cycles) and capacity retention (81 % after 32,000 cycles) have been achieved. Moreover, such ZHSCs also exhibit outstanding cycling stability in deformed states and subzero conditions. Bio-inspired adhesive hydrogel electrolytes herein are expected to provide a promising strategy for promoting the electrochemical performances of energy storage devices in harsh conditions.