High volumetric energy density annealed-MXene-nickel oxide/MXene asymmetric supercapacitor

A Ti3C2Tx MXene electrode decorated with NiO nanosheets was synthesized by a facile and cost-effective hydrothermal method. The NiO nanosheets were grown and immobilized on the carbon-supported TiO2 layer which was derived from Ti3C2Tx-MXene during a thermal annealing process. An electrode based on the NiO-grown derived-TiO2/C-Ti3C2Tx-MXene nanocomposite (Ni-dMXNC) exhibited a remarkable maximum specific capacity of 92.0 mA h cm(-3) at 1 A g(-1) and 53.9 mA h cm(-3) at 10 A g(-1). Furthermore, an asymmetric supercapacitor (ASC) device composed of Ni-dMXNC as the positive electrode and Ti3C2Tx MXene as the negative electrode was demonstrated to be better with a high energy density of 1.04 X 10(-2) W h cm(-3) at a power density of 0.22 W cm(-3), and cycling stability with 72.1% retention after 5000 cycles, compared to ASCs using previously reported Ti3C2Tx MXene materials. The enhanced capacitive performance is attributed to the newly formed high surface-area multilayers of the Ni-dMXNC architecture, the active surface of NiO layer, and a favourable synergetic behaviour of the Ti3C2Tx MXene negative electrode.