A wide temperature-tolerant hydrogel electrolyte mediated by phosphoric acid towards flexible supercapacitors

Conventional hydrogel electrolytes tend to deteriorate significantly or even deactivate at high or low operating temperatures, which has become the main obstacle to the development of current temperature-tolerance supercapacitors. Herein, a groundbreaking temperature-tolerant strategy was firstly proposed that a novel hydrogel electrolyte with wide operating temperature was successfully prepared. Phosphoric acid (PA) and water as mixed solvents were utilized to dissolve chitosan (CS) in the chemical crosslinking polyacrylamide (PAAm) network to obtain tough and adhesive CS-PAAm hydrogels. Meanwhile, based on the existence of phosphoric acid molecules, the CS-PAAm hydrogels showed extremely high conductivity and wide range of temperature-tolerance from −60 °C to 100 °C. Surprisingly, the adhesiveness and toughness remained almost unchanged. Then, CS-PAAm hydrogels as electrolytes were successfully coupled with activated carbon electrodes to construct supercapacitors, which presented excellent flexibility and electrochemical stability over a wide temperature range from −60 °C to 100 °C. Therefore, it is foreseeable that this simple and effective strategy would provide novel insight and opportunity for a new generation of flexible energy storage devices with wide temperature-tolerance.