Ti₃C₂T_x MXene with High Mass Loading as a Binder Free Electrode for Supercapacitor

Titanium carbide MXene being the most studied member of the 2D transition metal carbides/nitrides (MXene) family, has found applications in the field of energy storage and energy generation, due to its dynamic but tunable surface chemistry, good hydrophilicity and electrical conductivity. Conductive and clay like, in situ HF etched titanium carbide MXene can be used as supercapacitor electrodes and are prospective candidates in flexible electronics for commercial supercapacitor application. Commercial supercapacitors also require high energy storage capability, for which a high mass loading is necessary. Herein a high mass loading electrode with high areal capacitance has been fabricated using a simple brush coating of clay like titanium carbide MXene on carbon cloth. A controlled alkalization of titanium carbide using a weak base, ammonium hydroxide has been carried out in the synthesis of titanium carbide MXene. The in situ alkalization process reduces the time of synthesis and causes an inherent expansion of the interlayer spacing, making the diffusion of ions easier. The structural, morphological, optical, and electronic properties have been studied using X-ray diffraction, scanning electron microscope, UV visible absorption spectroscopy, X-ray photoelectron spectroscopy analysis and Fourier transform infrared spectroscopy analysis. The prepared MXene has the characteristic (002) diffraction peak and a layered morphology, similar to the open accordion morphology of HF etched MXene. The optical studies indicated ease of delamination from the evolution of the plasmonic peak in the NIR region. XPS and FTIR studies indicated presence of –O, -F and –OH functional groups. Titanium carbide MXene electrode on glassy carbon and on carbon cloth were fabricated. Nafion-assisted coating in glassy carbon electrode was replaced by binder free coating of MXene clay, while using carbon cloth. A simple brush coating onto pre-heated carbon cloth produced uniform films, with good electrochemical performance. The prepared electrode exhibited good gravimetric capacitance of 109 F/g at a current density of 0.5 A/g and areal capacitance of 2500 mF/cm² at a current density of 11 mA/cm². High mass loading combined with high areal capacitance make the prepared electrode a potential candidate for commercial applications.