Constructing MXene-PANI@MWCNTs heterojunction with high specific capacitance towards flexible micro-supercapacitor

Micro-supercapacitors (MSCs) are considered as the promising energy supply of miniaturized electronic devices. The electrode material, as one integral part, play a crucial role on the energy storage performance of MSCs. In our work, we constructed a heterojunction in MXene-PANI@MWCNTs (MPM) ternary composite, benefitting for the synergistic enhancement effect among MXene, polyaniline (PANI) and multiwall carbon nanotubes, an outstanding specific capacitance of 414 F g-1 (at 1 A g-1) has been achieved. MPM shows high capacitance retention at large current density (86.7%, at 10 A g-1) and long-term cycling stability of 90.4% for 10 000 cycles. Furthermore, we obtained MPM self-standing films, and constructed a flexible all-solid-state MSC based on the film electrode. A competitive charge storage capability of 30.2 mF cm-2 and long-term stability of 70.2% retention for 10 000 cycles was obtained in the MSC. Meanwhile, the MSC shows excellent flexibility, maintaining most capacitance under bending conditions. Moreover, using an integrated strategy, MSCs can obtain tunable voltages and currents that meet various practical requirements. All these results indicate that the MPM is an excellent charge storage material and will become a potential candidate for flexible energy-storage devices.