MXene titanium carbide synthesized by hexagonal titanium aluminum carbide with high specific capacitance and low impedance

Abstract

The electrochemical properties of the MXene titanium carbide, Ti₃C₂, which has received much attention in the application of electrode materials for supercapacitors, are affected by the different morphologies of its precursor. In particular, the increase of layer spacing and specific capacitance, as well as the decrease of impedance and the dynamics analysis of Ti₃C₂ etched from hexagonal Ti₃AlC₂ precursors, are still not clear, and need to be further studied and explored. In this work, MXene Ti₃C₂ was synthesized efficiently in 2 hours by microwave assisted selective etching with hexagonal Ti₃AlC₂ as the precursor material. The specific capacitance of the Ti₃C₂ electrode is up to 357.85 F g⁻¹, while the ohmic resistance R_Ω of the whole electrochemical energy storage system is 0.234 ohm and the charge transfer resistance R_ct is 0.875 ohm. By analyzing the structural evolution and electrochemical properties from hexagonal Ti₃AlC₂ to Ti₃C₂, it is revealed that Ti₃C₂ prepared with hexagonal Ti₃AlC₂ as the precursor material has larger atomic layer spacing, more active sites, smaller diffusion impedance and higher energy storage efficiency than that prepared with ordinary Ti₃AlC₂. These lay a structural foundation for improving the energy storage performance of Ti₃C₂ supercapacitor electrodes.