Synthesis of high surface area activated carbon from banana peels biomass for zinc-ion hybrid super-capacitor

The race to achieve cost-effective power sources has led to intense research to explore natural sources, and biomass sources are the front-runners. In this work, the chemical activation of the banana peel was carried out using phosphoric acid (H₃PO₄) to develop a high-performance zinc-ion hybrid super-capacitor (ZIHSC). SEM (Scanning Electron Microscopy) morphology of chemically activated BP-H₃PO₄ materials revealed a nano-porous structure, and BET (Brunauer-Emmett-Teller) further corroborates the enhancement in surface area (218.339 m² g⁻¹) of banana peel biochar. The process yields a low synthesis cost due to the facile conversion of biomass to biochar and activated biochar. The phosphoric acid (H₃PO₄) treated banana peel for the ZIHSC device showed an excellent specific capacitance of 228 F g⁻¹ (1 mV s⁻¹, scan rate), an energy density of 120 Wh Kg⁻¹, and a specific capacity of 73.98 mAh g⁻¹ (0.1 A g⁻¹, current density). The two-electrode Swagelok-based ZIHSC cell retains incredible capacity retention after 50,000 charge and discharge cycles.