MXene/VS4 self-supporting thin film electrode for zinc-ion flexible supercapacitors

MXene materials, with their high electrical conductivity, pseudocapacitive energy storage mechanism, and high flexibility, are considered as highly potential materials for flexible supercapacitors. However, the strong inhibition of ion storage and transportation caused by the inherent stacking effect of the material limits its application. This issue can be effectively addressed by intercalating an interlayer agent. VS4, which serves as an excellent interlayer agent, has a larger interatomic spacing between atomic clusters in the crystal (5.6 Å) compared to the interlayer spacing of MXene. This facilitates the movement of ions, enabling them to traverse the material more freely. Furthermore, VS4 exhibits a more negative adsorption energy than MXene, making it easier for MXene to adsorb VS4. Therefore, we designed an MXene/VS4 composite electrode with good electrochemical performance and flexibility. Based on this composite electrode, we prepared a high-performance aqueous zinc ion flexible supercapacitor. Specifically, it exhibited a maximum power density of 13.33 W cm−3, an energy density of 39.88mWh cm−3 and a high capacitance retention of 88.5 % of its initial capacitance after 10,000 cycles. Even when bent to 150°, the capacitance retention of this flexible supercapacitor remained at 79 % of the initial value. Furthermore, after 2000 bending cycles, the supercapacitor retains 91.9 % of its initial capacitance.