Double-Transition-Metal Mo₂Ti₂C₃ Mxene-Polyaniline Composites for High-Performance Supercapacitors

The optimized integration of two-dimensional (2D) MXene and conducting polymer composites offers an effective strategy for developing high-performance supercapacitor electrodes, owing to their exceptional flexibility, large surface area, and high capacitance. Herein, the double-transition-metal (DTM) MXene Mo₂Ti₂C₃ (M), derived from its MAX phase Mo₂Ti₂AlC₃ via selective chemical etching, was combined with polyaniline (PANI) through in situ polymerization to obtain composites with varying M/PANI ratios to enhance electrochemical performance. The structural, chemical, and morphological properties of the synthesized materials were systematically investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), confirming the successful formation of MXene and its effective integration with PANI fibers. The electrochemical behavior of all the prepared electrode materials was investigated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in an organic electrolyte. As a result, the optimized composite exhibits a high specific capacitance of 704 F g^-1 at a current density of 2 A g^-1. Furthermore, an asymmetric supercapacitor device assembled using the optimized composite as the positive electrode delivers a specific capacitance of 384.9 F g^-1 at 1 A g^-1, along with an energy density of 104.8 Wh kg^-1, and a power density of 1400 W kg^-1. These results highlight the significant potential of DTM M/PANI nanocomposites as advanced electrode materials for efficient energy storage applications.