Fabrication of Nano‐CaSO4 From Phosphogypsum: Effect on the Mechanical, Flame Retardant, and Electrochemical Performance of PEO Solid Electrolytes

ABSTRACT Reusing phosphogypsum (PG) is of great significance as the negative effect of increasing PG pollution on the environment is now incontrovertible. Herein, nano‐CaSO 4 particles were fabricated using PG through a facile yet effective solvent‐thermal method, and their influence on the thermomechanical properties and electrochemical properties of polymeric solid electrolytes was further investigated. Results indicated that cubic nano‐CaSO 4 particles could be obtained by regulating the concentrations and types of surfactants and concentrations of H 2 SO 4 and HNO 3 . Furthermore, nano‐CaSO 4 fillers at a content of 10 wt.% could simultaneously improve the mechanical properties, flame retardancy, and ionic conductivity of polyvinyl oxide‐based solid electrolytes. Nano‐CaSO 4 (10 wt.%) could enhance the strength by two times and modulus by more than four times, improve the limiting oxygen index from 19.5% to 23.1%, reduce the total heat release rate from 17.9 to 16.2 kJ/g, and increase ionic conductivity by more than two times at 60°C. This study provides a facile yet economic strategy for fabricating cubic nano‐CaSO 4 using PG and exhibits an excellent utilization prospect for high‐safety all‐solid‐state batteries.