Self-standing porous MXene film via in situ formed microgel induced by 2-methylimidazole for high rate supercapacitor

Ti3C2Tx MXene has been considered a potential supercapacitor electrode material on account of its fast electron transfer performance, large volume pseudocapacitance, excellent hydrophilicity and mechanical properties. However, the serious stacking of MXene nanosheets reduced the exposed active sites and hindered diffusion of ions, leading to bad electrochemical property. Here, we report a strategy to transform MXene nanosheets into 3D MXene microgels induced by 2-methylimidazole. Benefitting from the existence of microgels, it facilitates the rapid vacuum filtration to prepare the porous MXene film, thus enhancing the ion transfer efficiency. Furthermore, 2-methylimidazole can also act as an intercalated agent to increase the layer spacing of MXene nanosheets. Therefore, the as-prepared porous MXene film demonstrates a superior rate capacity, and its capacitance reaches 223.4 F g-1 at the scan rates of 1000 mV s-1. Moreover, the assembled MXene//AC asymmetrical supercapacitor displays a 16.88 Wh kg- 1 at a power density of 799 W kg- 1, and maintains 13.11 Wh kg- 1 at a power density of 8 kW kg- 1. This work develops a simple way to prepare the porous MXene film for supercapacitors with excellent electrochemical performance.