Fabrication of bio-based activated carbon modified graphite electrode and its performance as supercapacitor

Abstract

Electrochemical energy storage systems have been a focus of research in order to solve the challenge of energy storage. Supercapacitors (SCs) are energy storage devices that have distinct advantages over batteries and conventional capacitors, making them promising candidates in energy storage technology. Over the past decade, several novel electrode materials and cell designs have been studied in attempt to boost the energy density of SCs. Having porous structure, high specific surface area, superior electrical conductivity, and good chemical and thermal stability, Carboneous materials activated carbon (AC) has attracted tremendous attention for its potential applications as an electrode material or an electrode modifier in supercapacitor technologies. In this study, the modification of highly porous activated carbon (AC) electrodes fabricated from banana leaves with a series of polymeric binders like polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC), along with examining their suitability in AC-based supercapacitor applications. To fulfill this objective, first banana leaf activated carbon (AC) was synthesized using the activated agent K2CO3. Furthermore, different polymeric binders were employed to analyze the electrochemical behavior of the biomass-based activated carbon supercapacitor. These composites of different binders were evaluated using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared (FT-IR) spectroscopy. The composites were deposited on a graphite substrate using binder by solution casting method. The materials were electrochemically investigated in a 0.5 M Na2SO4 solution using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance techniques to determine their capacitive behavior.The effects of binders, composite compositions, applied current density, potential scan rate, and stability were investigated in many different ways. During the study, a greater CV curve area was exhibited for the PVA binder than for PVDF and CMC. Moreover, all of the binders' GCD curves were found to be quasi-symmetrical. However, the PVA binder showed a relatively better triangular shape and longer discharge time compared to CMC and PVDF. The specific capacitance (Cs) values of AC-PVA are generally achived to be higher than that of AC-PVDF and AC-CMC. The high Cs, power density and longer life time demonstrate that PVA binder can be a better choice as a polymer binder in AC-based supercapacitors.