Nonflammable Supramolecular Polymer Electrolytes for Flexible and High-Performance Supercapacitor Applications

The present work reports on high-performance and flexible supercapacitors assembled using a cost-effective and nonflammable electrolyte with activated carbon electrodes. The electrolyte was prepared by rapidly blending a ternary system comprising poly(vinyl alcohol)(P)/glycerol (G)/boric acid (B) hydrogel doped with LiNO₃ (Li),─henceforth denoted as PGBLi,─at ambient temperature. Once partial in situ cross-linking occurred between P and B, the polymer electrolytes were cast onto the carbon electrodes. The doped PGBLi hydrogel electrolyte retained excellent flexibility and high ionic conductivity in a broad temperature domain, while the performance of the assembled supercapacitor devices measured at low and high temperatures confirmed the high stability. Moreover, the supercapacitor exhibited 396 F g^-1 specific capacitance at 1 A g^-1 and 27.41 Wh kg^-1, obtained at a power density of 118 W kg^-1, while 95.4% capacitive performance was maintained after 10 000 cycles, indicating adequate cyclic stability. Thus, the as-doped PGBLi hydrogel electrolyte is inexpensive, biocompatible, and nonflammable and meets the criteria for flexible wearable electronics; it can be considered for a variety of applications.