A compressible asymmetric supercapacitor based on carbon Felt/MWCNT@PANI and MXene

Compressible supercapacitors are novel energy storage devices for commercial portable and flexible electronics. Substantial efforts have been made to develop compressible supercapacitors with high voltage output, good mechanical stability, and electrochemical performance. This study investigates the performance of a compressible asymmetric supercapacitor configuration based on a polyaniline-modified carbon felt/multi-walled carbon nanotube composite (a-CF/MWCNT@PANI) as the positive electrode and a titanium carbide-MXene (Ti₃C₂T_x) as the negative electrode. The acid-functionalized MWCNTs were loaded into activated carbon felt by dipping and drying and subsequently were coated by polyaniline via the chemical oxidation polymerization method. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) confirmed the formation of the dendritic structure of PANI on the surface of 3D porous composite (a-CF/MWCNT@PANI) positive electrode. X-ray diffraction (XRD), SEM, and cyclic voltammetry (CV) measurements revealed 2D layered morphology and pseudocapacitive behavior of Ti₃C₂T_x-MXene. The specific capacitance of the assembled asymmetric supercapacitor was found as 1.6 F cm⁻² at 5 mA cm⁻², the corresponding energy density and power density were 262 μWh cm⁻² and 2.7 mW cm⁻², respectively. The asymmetric cell exhibited a retention rate of 92.4 % after 1000 cycles. Above 50 % strain, the supercapacitor showed a favorable CV profile, which is owing to the enhanced electrical conductivity of the CF composite electrode caused by compression. The capacitance retention retained more than 90 % over 200 compression-recovery cycles.