Evaluation of low-cost high performance solid-state supercapacitor derived from physically and chemically activated oil palm fiber

•Optimization of activated carbon derived from palm fiber for supercapacitor.•Conversion of palm fiber to active material of supercapacitor electrode.•Optimization of solid electrolyte in the fabrication of solid state supercapacitor.•Electrochemical responses of solid electrolyte and palm fiber derived activated carbon. This study is geared towards harnessing the promises of Oil Palm Fiber (OPF) as a renewable substitute for electrode material of supercapacitor. Physical and chemical activation conversion methods were used to activate OPF. The structural and physiochemical properties of the activated carbon derived from OPF were studied and analyzed using FESEM, XRD, BET, XPS, and FTIR. The electrochemical properties of supercapacitors fabricated from P_OPF and C_OPF were studied and reported using cyclic voltammetry, Galvanostatic charge discharge and electrochemical impedance spectroscopy.