Flexible Ti3C2Tx@Al Electrodes with Ultrahigh Areal Capacitance: in Situ Regulation of Interlayer Conductivity and Spacing

Although Ti3C2 MXene has shown great potential in energy storage field, poor conductivity and restacking between MXene flakes seriously hinders the maximization of its capacitance. Herein, a new strategy to solve the problems is developed. Gallery Al atoms in Ti3AlC2 are partially removed by simple hydrothermal etching to get Ti3C2Tx reserving appropriate Al interlayers (Ti3C2Tx@Al). Ti3C2Tx@Al keeps stable layered structure rather than isolated Ti3C2Tx flakes, which avoids flake restacking. The removal of partial Al frees up space for easy electrolyte infiltration while the reserved Al as “electron bridges” ensures high interlayer conductivity. As a result, the areal capacitance reaches up to 1087 mF cm−2 at 1 mA cm−2 and over 95% capacitance is maintained after 6000 cycles. The all‐solid‐state supercapacitor (ASSS) based on Ti3C2Tx@Al delivers a high capacitance of 242.3 mF cm−2 at 1 mV s−1 and exhibits stable performance at different bending states. Two ASSSs in tandem can light up a light‐emitting diode under the planar or wrapping around an arm. The established strategy provides a new avenue to improve capacitance performances of MXenes.