Halide Salt‐Catalyzed Crosslinked Polyurethanes for Supercapacitor Gel Electrolyte Applications

Gel polymer electrolytes are an important advancement in energy storage technology due to their enhanced safety and practical ionic conductivities at ambient temperatures. Herein, a simple one‐step facile synthesis of chemically crosslinked polyurethanes containing polyethylene oxide (PEO) and polypropylene oxide (PPO) macromolecular segments was developed, using ubiquitous non‐toxic tetrabutylammonium or potassium chloride and bromide salts as catalysts. These salts were shown to catalyze the gelation of diol‐diisocyanate polyaddition reactions within minutes. When impregnated with a liquid electrolyte, the resulting gel electrolyte exhibited a practical ionic conductivity of 1.1×10−4 S cm−1 at 40 °C and low segmental chain motion activation energy (11 kJ mol−1). These findings further promote PEO‐PPO polyurethanes as a biocompatible class of materials suitable for further exploration as gel polymer electrolytes for supercapacitors. Crosslinked supercapacitors: Cheap and ubiquitous halide salts of tetrabutylammonium and potassium are able to catalyze the formation of crosslinked polyurethanes within minutes. The poly(ethylene oxide) and poly(propylene oxide)‐containing crosslinked polymer can be formulated into gel polymer electrolytes that exhibit practical ionic conductivities at 40 °C, demonstrating its potential for usage as supercapacitors.