Facile strategy of hollow polyaniline nanotubes supported on TiC-MXene nanosheets for High-performance symmetric supercapacitors.

Titanium carbide MXene (TiC) has attracted significant research interest because of its extraordinary advantages as advanced electrode material for energy storage. In this work, we explored a facile strategy to construct TiC-based hierarchical composite materials by surface modification using pseudocapacitive materials. The method involved the synthesis of the exfoliation of ultrathin TiC nanosheets, followed by one-pot in situ polymerization and surface decoration using polyaniline nanotubes (PANI-NTs). Herein, the self-aggregation of TiC layers had been effectively suppressed, resulting in an enhanced interlamellar spacing and enlarged ion contact area. Furthermore, the novel hierarchical structure of TiC/PANI-NTs can facilitate the electrolyte ions diffusion, which also boosted more electrochemical active sites to become more accessible. In addition, the electrochemical test in the three-electrode system demonstrated that the specific capacitance of the TiC/PANI-NTs-1 composite can be as high as 596.6F g at 0.1 A g, remaining 94.7% retention of initial capacitance after 5000 cycles of charge/discharge. Moreover, the symmetric supercapacitor device based on TiC/PANI-NTs-1 composite exhibited a maximum energy density of 25.6 Wh kg (at 153.2 W kg) and an impressive power density of 1610.8 W kg (at 13.2 Wh kg), as well as outstanding cycling stability (81.1% retention of the capacitance after 4000 cycles). These electrochemical measurements indicated that the performance of TiC-based supercapacitors could be immensely improved by designing and constructing the hierarchical structure with abundant pseudocapacitive materials. Furthermore, this strategy could be extended to other MXenes composite materials as advanced electrodes by taking full advantage of their potentials for new symmetric supercapacitors.