Synthesis of Boron-Doped Non-Flammable Anhydrous Electrolytes for Flexible Quasi-Solid-State Supercapacitor Applications

The quasi-solid-state electrolytes for flexible energy storage devices have indicated a great advancement during the last decade. However, further progress is still required to resolve nonflammability issues, high ionic conductivity, as well as electrochemical stability. Herein, we designed a new complex gel electrolyte with glycerol (Gly)/boric acid (BA) to address the non-flammability and maintained high conductivity by doping with potassium hydroxide (KOH). The Gly/3KOH/3BA combination was the optimum composition in terms of stability as well as hierarchical array for improved ionic conductivity to 2.9 X 10(-3) S cm(-1). Flexible electrochemical double-layer supercapacitors were assembled by using carbon composite electrodes, and the device provided a specific capacitance of 327 F g(-1) at 1 A g(-1). A remarkable cyclic stability of 93.4% capacitive performance is maintained after 10,000 cycles. The device indicated a specific energy of 45.4 W h kg(-1) at a power of 920 W kg(-1). Highly flexible devices constructed by using boron-incorporated gel electrolytes can provide a new strategy to assemble flexible devices for wearable electronics.