Flexible supercapacitor based on MXene cross-linked organic gel electrolyte with wide working temperature

Recently, hydrogel materials have been widely used in flexible energy storage devices due to their excellent electrical conductivity and nearly solid mechanical properties. But, due to the plenty of water in the traditional hydrogel electrolyte, the disadvantages of high temperature water loss and low temperature icing are inevitable. In order to solve this problem, we have fabricated an organic gel electrolyte (OGE) and assembled it with activated carbon electrode into flexible organic gel electrolyte supercapacitors (OGESCs). In terms of gel design, the MXene crosslinked polyacrylic acid-N-hydroxyethyl acrylamide (PAA-NHEA-MXene) hydrogel network is replaced by a mixture of lithium chloride and ethylene glycol solvent, showing excellent electrical conductivity (3 and 19.8 mS/cm at −20 and 25 °C, respectively) and good mechanical properties. Due to the replacement of the solvent, the operating temperature of OGESCs is extended (-20-80 °C) and meets the needs of flexible wearable devices. In addition, OGESCs exhibit cyclic stability at both low and high temperatures (capacitance decreases by 3.2% after 10,000 cycles), laying a solid foundation for its application in complex and varied environments. • The supercapacitor exhibits broad temperature adaptability (from −20 to 80 °C). • The MXene cross-linked gel electrolyte displays excellent shape recovery property. • The device retains high capacitance retention under compressive and bending. • The device could retains 77.8% capacitance retention after storage at −20 °C for 15 days. • The supercapacitor has a 3.2% reduction in capacitance after 10,000 cycles.