Benzyltrimethylammonium Chloride-Assisted Positive Electrolyte Optimization for Advanced Vanadium Flow Batteries

As a chlorinated cationic surfactant, benzyltrimethylammonium chloride (BTMAC) is capable of reducing electrolyte viscosity, improving ionic conductivity, and selectively binding to VO(OH)3 monomers within the electrolyte matrix. This inhibits the dimerization of VO(OH)3 and the subsequent formation of V2O5 precipitation, significantly improving the high-temperature stability of the electrolyte. For a 1.7 M V(IV) electrolyte, visible precipitation begins after just 3 h at 50 °C and 2.5 h at 60 °C in the absence of BTMAC. The addition of 400 ppm of BTMAC extends this stabilization period to 5.5 h at 50 °C and 3 h at 60 °C. After 9 h at 60 °C, the precipitation rate decreases from 33.27% to 25.99%, and it effectively slows down the capacity decay rate of the battery at 45 °C. This finding offers an effective approach for developing low-cost and high-performance vanadium electrolytes.