High Gravimetric Capacitance MXene Supercapacitor Electrode Based on Etched Ti3C2T x by Chemical Etching

Ti 3 C 2 T x MXene is one of the most promising electrode materials for supercapacitors, but it often suffers in poor experiment gravimetric capacitance, which limits practical applications in industry needs. Herein, etched Ti 3 C 2 T x MXene with high gravimetric capacitance is prepared by chemical etching of MXene with concentrated alkaline solution. The intercalation of K + and the scissor role of OH − can simultaneously enlarge the interlayer spacing and cut the size of sheets, which lead to the high active-site concentration and cation diffusion. As a result, the etched Ti 3 C 2 T x MXene displays high gravimetric capacitance of 368.1 F g −1 at 2 A g −1 and outstanding cycling stability without capacitance loss over 5000 cycles at 6 A g −1 ,and the surface capacitance contribution in etched Ti 3 C 2 T x MXene occurs to a greater extent compared with the pristine MXene. Moreover, the effect of chemical etching on the supercapacitor performance and energy-storage mechanism indicates that the active-size concentration and cation diffusion could be maximized when the chemical etching conditions are appropriate, leading to the highest performance of etched Ti 3 C 2 T x MXene. Herein, it is demonstrated that the chemical etching approach is applicable to design MXenes with high gravimetric capacitance to maximize their potential applications in energy-storage applications and other fields.