VSe ₂ /carbon-nanotube compound for all solid-state flexible in-plane supercapacitor

Two-dimensional (2D) metallic transition-metal dichalcogenide (MTMD)/carbon-nanotube (CNT) compounds are competitive electrode materials for solid-state flexible in-plane supercapacitors, resulting from the synergistic effect of the large specific surface area of 2D MTMDs and the excellent mechanical properties of the CNT. In this paper, the high-quality VSe ₂ /CNT electrode material is prepared by the one-step chemical vapor deposition (CVD) method. The CVD method offers a facile and safe way to synthesize a pure VSe ₂ /CNT compound. The VSe ₂ nanosheets are vertically grown on the surface of the CNT cluster. The vertical configuration of the VSe ₂ nanosheets on the conductive CNT cluster takes full advantage of the large specific surface area of the VSe ₂ nanosheets to store charges. The ductile and conductive CNT cluster offers good mechanical and electrical connections to the VSe ₂ nanosheets. The VSe ₂ /CNT compound is applied as the electrode material of a solid-state flexible in-plane supercapacitor which achieves a specific area capacitance of 1854 μF/cm ² and stable cycling stability, ∼7% degradation after 10 000 times of current cycling. The VSe ₂ /CNT also presents a desirable mechanical stability, and ∼ 90% capacitance is retained after bending up to 40°. This work promotes the application of 2D MTMD compounds in the field of energy storage and wearable devices.