ADVANCED CHARACTERIZATION OF HIERARCHICAL POROUS CARBON ELECTRODES FOR SUPERCAPACITOR APPLICATIONS

Abstract

The development of hierarchical porous carbon has been recognized as one of the best electrode materials for supercapacitors owing to its high specific surface area, good electrical conductivity, and porous nature. In this work, hierarchical porous carbon has been prepared from a precursor such as polyacrylonitrile (PAN) by a controlled process of carbonization, followed by KOH activation, in order to prepare a suitable electrode material for electrochemical energy storage applications. Different structural and physicochemical studies have been carried out for the sample using FESEM, TEM, XRD, Raman, FTIR, BET surface area measurement, TGA, and electrical conductivity testing techniques. Results of characterization showed that a three-dimensional interconnected hierarchical porous carbon structure with partial graphitic ordering, microporosity, mesoporosity, and appropriate surface oxygen functional groups was successfully synthesized, which improved electrolyte accessibility and electron transport. Electrochemical properties were characterized by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and cycling stability measurements. The hierarchical porous carbon electrode showed typical characteristics of the electric double-layer capacitor (EDLC), fast ion diffusion, low internal resistance, good rate performance, and outstanding cycling stability. The exceptional electrochemical properties were owing to the cooperative effect of hierarchical porosity, high surface area, better electrical conductivity, and optimized surface chemistry. Nevertheless, this work proves that rational modification of the pore structure and carbon microstructure can be an efficient method of designing highly efficient carbon electrodes for the future generation of supercapacitors.