The effect of Ti₃C₂T_x MXene etched at different temperatures (25  C, 50  C, and 80  C) on the capacitance
of supercapacitors without the use of conducting carbon-black or a binder was studied. The MXene etched
using concentrated HCl acid (12 M)/LiF was used as an active electrode and Ni-foil as a current collector. It
was observed that the elevated etching temperature facilitates the etching of the MAX phase and the
exfoliation of MXene layers. However, this led to the formation of additional functional groups at the
MXene surface as the temperature was increased to 80  C. The specific capacitance of Ti₃C₂T_x-based
supercapacitors increased from 581 F g 1 for MXene etched at 25  C to 657 F g 1 for those etched at
50  C at the scan rate of 2 mV s 1. However, the specific capacitance reduced to 421 F g 1 as the
etching temperature was increased to 80  C at the same scan rate. The supercapacitors based on
MXenes etched at the intermediate temperature (50  C) exhibited higher specific capacitance in a wide
range of scan rate, symmetry in charge/discharge curves, high cyclic stability at a scan rate of 1000 mV
s 1 for up to 3000 cycles. The electrochemical impedance spectroscopy studies indicated low series
resistance, reduced charge-transfer resistance, and decreased Warburg impedance for the
supercapacitor based on the MXene etched at the intermediate temperature.