Enhanced electrochemical performance of Ti3C2T MXene film based supercapacitors in H2SO4/KI redox additive electrolyte

Abstract The introduction of redox additives into the electrolyte is considered to be an effective and facile approach to increase the specific capacitance of supercapacitors (SCs), as these additives facilitate redox reactions at the electrode/electrolyte interfaces. Herein, a freestanding titanium carbide Ti3C2Tx (MXene) film was prepared through lithium fluoride/hydrochloric acid (LiF/HCl) etching method and subsequent vacuum filtration process. Subsequently, the electrochemical behavior of freestanding Ti3C2Tx film based symmetric SCs was improved via the addition of potassium iodide (KI), as a redox additive. The optimized Ti3C2Tx//H2SO4/KI//Ti3C2Tx redox additive electrolyte SCs (RAESs) assembled using Ti3C2Tx film as both positive and negative electrodes and H2SO4/KI as electrolyte show a volumetric capacitance of 601 F cm−3 and a volumetric energy density of 83.5 Wh L–1 at a power density of 1800 W L–1. These results suggest the importance of KI redox additive electrolyte in developing Ti3C2Tx based SCs.