A Ti3C2Tx MXene/alginic acid-derived mesoporous carbon nanocomposite as a potential electrode material for coin-cell asymmetric supercapacitors†

In this study, we demonstrate MXene (Ti₃C₂T_x)-based coin-cell asymmetric supercapacitor (coin-cell ASC) exhibiting high energy density and high power density along with good capacitance. We synthesized mesoporous carbon (MC) by annealing alginic acid at varying temperatures (900 °C, 1000 °C and 1100 °C). Among the prepared samples, MC-1000 exhibited a highly porous structure and a higher surface area. We then developed a Ti₃C₂T_x/MC (MC-1000) nanocomposite using a simple and efficient solvothermal method. The synthesized nanocomposite displayed the layered morphology of MXene alongside the amorphous characteristics of carbon, indicating a strong interaction between the two materials. Notably, the Ti₃C₂T_x/MC-9 nanocomposite features a higher number of pores and a larger surface area than either MXene or MC-1000, significantly enhancing its capacitive performance. We evaluated the performance using a three-electrode system, revealing an impressive specific capacitance (C_sp) of 1629 F g⁻¹ at 1 A g⁻¹, with a retention of 99.9% even after 35 000 cycles. Furthermore, the fabricated coin-cell ASC using (MC-1000//Ti₃C₂T_x/MC-9) electrodes demonstrated a C_sp of 80.3 F g⁻¹ at 1 A g⁻¹ and a high energy density of 56 W h kg⁻¹, corresponding to a maximum power density of 10 423 W kg⁻¹ at 5 A g⁻¹. The key factors contributing to the enhanced electrochemical performance include the strong connection between MXene and MC-1000, along with the large specific surface area and high porosity of the electrode materials.