Agus Subagio, Heydar Ruffa Taufiq, Heri Sutanto, Risma Aimatul Qudsiyah, Markus Diantoro, Ishmah Luthfiyah, Agus Purwanto, Worawat Meeyasana
The limited electrical conductivity and pore utilization of conventional activated-carbon-based electrodes often restrict the achievable energy density of supercapacitors, especially when electrolyte conditions are not optimally engineered. This study aims to overcome these limitations by developing a multiwalled carbon nanotubes/activated carbon (MWCNTs/AC) composite electrode and systematically elucidating the role of H2SO4 electrolyte concentration on its electrochemical performance using a three-electrode configuration. The MWCNTs/AC composite was fabricated via a simple physical–chemical route and deposited on copper foil, while its structural and morphological characteristics were confirmed by XRD, SEM, and TEM analyses, which demonstrated successful integration of conductive MWCNT networks within the porous AC matrix. Electrochemical behavior was evaluated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy at H2SO4 concentrations of 0.05, 0.1, 0.5, and 1 M to clarify the correlation between ion availability, charge-transfer resistance, and double-layer formation. Optimized electrolyte engineering at 1 M H2SO4 yielded a high specific capacitance of 528.57 F g-1, with an energy density of 436.73 Wh g-1, a power density of 391 W g-1, and excellent cycling stability of 98.89% after 5,000 cycles, indicating efficient ion transport and low internal resistance. Compared with previous carbon-based systems, the combined strategy of tailoring both the MWCNTs/AC composite architecture and electrolyte concentration provides a clear pathway to simultaneously enhance capacitance, energy density, and durability, highlighting the MWCNTs/AC electrode as a promising candidate for high-performance aqueous supercapacitors. © 2026, Walailak University. All rights reserved.
Department of Physics, Faculty of Science and Mathematics, Universitas Diponegoro, Semarang, 50275, Indonesia; Department of Physics, Faculty of Mathematics and Sciences, Universitas Negeri Malang, Malang, 65145, Indonesia; Department of Chemical Engineering, Faculty of Engineering, Universitas Sebelas Maret, Surakarta, 57126, Indonesia; School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
