Organohydrogel electrolyte-based flexible zinc-ion hybrid supercapacitors with dendrite-free anode, broad temperature adaptability and ultralong cycling life

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) are promising energy storage devices for the safety in portable and wearable electronics, but they still suffer from deformation-induced failure, narrow operating temperature windows, zinc dendrites and poor cycling life. Herein, a robust flexible ZHSC is fabricated by using an anti-freezing and anti-drying organohydrogel electrolyte (OHE). The OHE consists of a poly(2-acrylamido-2-methylpropane-sulfonic acid)/polyacrylamide (PAMPS/PAAm) double-network matrix and a binary solvent electrolyte system−ethylene glycol/H2O (EG/H2O with a water content of 10% v/v) containing ZnCl2/NH4Cl salts. The OHE exhibits good conductivity (1 mS/cm at −30 °C) and stable flexibility in the temperature ranging from −30 °C to 120 °C. The obtained ZHSC is resistant to mechanical damage under various bending angles and pressures. Moreover, a high energy density of 45.9 Wh/kg and a high power density of 320.0 W/kg are achieved for the flexible ZHSC. The ZHSC displays broad temperature adaptability, retains 95.7% capacitance after storage at −30 °C for 63 days, and retains 88.6% capacitance after 12000 cycles at 80 °C and 5 A/g. As compared with the control hydrogel electrolyte-based ZHSC, the OHE-based ZHSC has features of wide-temperature tolerance, dendrite-free and decreased hydrogen evolution altogether.