Abstract:
The growing demand for electronic devices has significantly increased the need for efficient
and sustainable power sources. Supercapacitors, including electrochemical double layer
capacitors (EDLCs) and pseudocapacitors, have gained more attention due to their high
power density, longer lifespan, and energy densities surpassing conventional capacitors.
EDLCs are widely used in backup power systems owing to their durability and rapid charge-
discharge capabilities. Various carbon-based materials are commonly employed as
electrodes in EDLC fabrication. This study focuses on the development of an EDLC utilizing
a gel polymer electrolyte (GPE) composed of polyvinylidene fluoride-hexafluoropropylene
(PVdF-HFP), ethylene carbonate (EC), propylene carbonate (PC), and zinc acetate [Zn
(CH3COO)2]. The GPE was synthesized via solvent casting, while electrodes were
fabricated using a composite of coconut shell charcoal powder, natural graphite, and PVdF
binder. Optimization of the electrode composition was achieved by varying the ratios of
coconut shell charcoal and natural graphite, aiming to maximize specific capacitance. The
optimal electrode composition was found to be 10 wt. % PVdF, 40 wt. % of natural graphite,
and 50 wt. % of coconut shell charcoal. The optimized EDLC exhibited a highest single
electrode specific capacitance of 1.82 μF/g[at the scan rate of 0.1v/s], determined through
equivalent circuit analysis using NOVA 1.11 software. Electrochemical impedance
spectroscopy (EIS), cyclic voltammetry (CV), and charge-discharge testing were conducted
to evaluate the performance of the EDLC, while EIS and DC polarization tests assessed the
ionic conductivity of the GPE. The temperature-dependent conductivity variation confirmed
that the GPE functions as a purely ionic conductor. This research contributes to the
development of sustainable, cost-effective energy storage devices by utilizing natural and
renewable carbon materials, supporting advances in eco-friendly supercapacitor
technologies.
