Influences of electrolyte composition and electrode type on cement-based supercapacitor performance

Cement-based supercapacitors (CBSC) offer safe and low-cost energy storage with structural functionality. This study systematically investigates the effects of electrolyte concentration, electrolyte type, and electrode architecture on their electrochemical performance using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Results show that optimal electrolyte concentration depends critically on electrode material. For graphite conductive adhesive electrodes, optimal NaOH concentration lies between 1.5 mol/L and 2.5 mol/L, while optimal KOH concentration exceeds 2 mol/L. For activated carbon electrodes, optimal NaOH and KOH concentrations exceed 3.5 mol/L and 2 mol/L, respectively. Devices employing K + -based electrolytes exhibit superior capacitance to those with Na + , attributable to the smaller hydrated radius and higher mobility of K + . The electric double layer formation efficiency at the activated carbon electrode-electrolyte interface substantially exceeds that of the graphite conductive adhesive electrode, resulting in approximately 225% higher energy storage capacity for the activated carbon system. These findings provide quantitative guidance for optimizing CBSC through coordinated selection of electrolyte composition and electrode architecture.