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 V 2 O 5 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.