Metathesis‐Synthesized [BMIM][HPO ₄ ]: Physicochemical and Electrochemical Characterization for Supercapacitor Applications

Abstract Ionic liquids (ILs) are widely recognized for their high thermal and electrochemical stability, making them promising candidates for integration into batteries and supercapacitors (SCs). In this study, an IL synthesized from BMIMCl and disodium hydrogen orthophosphate through a metathesis approach shows exceptional thermal stability up to 618 °C. Comprehensive electrochemical tests are conducted using activated carbon‐based electrodes to assess their potential in SC applications. Detailed physicochemical characterization is also performed. The synthesized IL demonstrates a 2.2 V electrochemical stability window, a specific capacitance of 91.6 F/g, a power density of 1.8.47 kW/kg at a current density of 1 A/g, and an energy density of 61.57 Wh/kg.