VCT MXene as novel anode for aqueous asymmetric supercapacitor with superb durability in ZnSO electrolyte.

Despite of great interests in aqueous asymmetric supercapacitors (ASC), their performance is often restricted by unsatisfactory specific capacitance of anode materials. Herein, accordion-like VCT MXene has been prepared and exploited as novel anode material for aqueous ASC in neutral ZnSO electrolyte. Profitting from the layered structure with expanded interlayer distance, the VCT electrode exhibits a high specific capacitance of 481F g at 1 A g, a reasonable rate performance and intriguing cycling stability with capacitance retention of 84.3% after 60,000 cycles at 10 A g in 2 M ZnSO electrolyte. Furthermore, an ASC device based on the VCT as anode and activated carbon (AC) as cathode was successfully assembled in the ZnSO electrolyte, which achieves a wide potential window up to 1.8 V. Remarkably, the VCT//AC ASC delivers a high energy density of 34 W h kg at a power density of 954 W kg, as well as superb cycling stability with capacitance retention of 79% even after 100,000 charge/discharge cycles at 10 A g. The intriguing electrochemical performance, especially the ultralong cycling life, make the VCT MXene electrode promising in aqueous energy storage devices.