Abstract
Supercapacitors offer high specific power, short charge-discharge times, and long cycle life. This study presents a comparative analysis of the electrochemical performance of commercial activated carbon Kuraray YP80F and its modified analogue YP80FP, which was subjected to thermal treatment. High-temperature treatment of YP80FP led to changes in porosity and a reduction in electrochemical activity. Electrochemical studies were carried out using cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy, and self-discharge methods. The results show that YP80F exhibits higher specific capacitance and lower internal resistance owing to its well-developed microporous structure. The optimum operating voltage range was determined to be between 0.6–1.5 V, with YP80F showing the best performance for an aqueous sodium nitrate electrolyte. The results demonstrate that heat treatment of activated carbon may lead to the development of surface functional groups and the blocking of pores, affecting overall supercapacitor performance in aqueous electrolytes.