(185i) Understanding the Mechanism of Energy Storage in Ti3CNTx mxene

Advanced energy storage devices are essential to meet the growing energy demands and enable more efficient, sustainable, and resilient power systems. Supercapacitors store charge in an electrochemical double-layer and, in some cases, a pseudocapacitive mechanism that involves fast surface redox reactions. Thus, these devices bridge the gap between batteries and electrolytic capacitors, offering higher energy density and rapid discharge capabilities. However, currently available electrode materials for supercapacitors lack high energy density. MXenes are promising candidates for supercapacitors owing to their 2D morphology, high conductivity, and large active surface area. While carbide MXenes have been extensively investigated, little attention has been given to nitride and carbonitride variants despite their higher properties for charge storage. Herein, we have investigated Ti₃CNT_x carbonitride MXene in a series of electrolytes encompassing different cations and anions. We use electrochemical impedance spectroscopy (EIS) to measure the charge transfer resistances and cyclic voltammetry (CV) to determine the redox reactions. Electrochemical charge-discharge experiments conducted in the different electrolytes reveal the total charge stored in the material. Preliminary results have shown that the highest charge storage derives from pseudocapacitance involving H+/e– couple transfer. Post-characterization investigations involving X-ray diffraction (XRD) and Raman spectroscopy reveal the structural stability of the material. Ultimately, these findings are precursors for the design of high-performance electrode materials based on carbonitride MXenes.