Enhancing Temperature-Optimized Ionic Liquid Electrolytes for High-Voltage, High-Energy Supercapacitors Utilizing Date Stone-Derived Carbon in Coin Cell Configuration

This study investigates the advancement of coin cell supercapacitors (SCs) for sustainable, high-performance energy storage by employing biomass-derived date stone activated carbon with various ionic liquid (IL) electrolytes at different temperatures. The research reveals that SCs demonstrate both pseudocapacitive and electrochemical double-layer characteristics. Among the tested ILs, 1-Butyl-3-methylimidazolium trifluoromethanesulfonate (BMIMOTf) emerges as the most effective, achieving an impressive energy density of 129.9 Wh kg⁻¹, a power density of 403.8 W kg⁻¹, and a specific capacitance of 103.9 F g⁻¹ at 0.5 A g⁻¹. After 5000 cycles, the supercapacitor utilizing BMIMOTf maintains 97.3% of its initial capacitance and exhibits a Coulombic efficiency approaching 100%. Additionally, temperature-dependent analyses from room temperature to 50°C reveal that higher temperatures boost the electrochemical performance of the SC, attributed to improved ionic conductivity. This research offers a more comprehensive understanding of how materials and electrolytes interact, emphasizing the capacity of BMIMOTf to foster innovations in eco-friendly energy storage solutions.