Synthesis of NiCl2-enhanced carbon electrodes from oil palm fronds (Elaeis Guinness Jacq) for high-performance supercapacitor

Abstract

The performance of supercapacitors can be enhanced by adding catalysts that improve graphitization and electrical conductivity. This study uses NiCl₂ as a catalyst in carbon electrodes from oil palm fronds (OPF) to evaluate its effect on supercapacitor performance. The OPF was converted into activated carbon through pre‑carbonization, chemical activation with KOH, and physical activation with CO₂. NiCl₂ catalysts at 0.1 M and 0.2 M concentrations were added during the chemical activation, enhancing nanofibril formation. OPF-01 achieved the best graphitization with a specific surface area of 688.80 m²g⁻¹. The OPF-01 demonstrated the highest specific capacitance at 359 Fg⁻¹ and maintained strong performance at a 10 mVs⁻¹ scan rate (221 Fg⁻¹), outperforming OPF and OPF-02 electrodes. However, at a NiCl₂ concentration of 0.2 M, OPF-02 faced aggregation issues, causing pore blockage and reduced electrochemical performance. These results suggest that NiCl₂ is an effective catalyst for enhancing carbon-based electrodes in supercapacitors, with optimal performance at a 0.1 M concentration.