Vanadium-Incorporated Metallic (1-T) Molybdenum Sulfide Nanoroses for High-Energy-Density Asymmetric Supercapacitors.

The metallic phase (1T) of molybdenum sulfide is critical, pertaining to its exceptional interlayer structure and metastability, but forms up with low content. Herein, 1T-phase-prominent vanadium-incorporated MoS2 (MVS) nanoroses were synthesized through a hydrothermal process. A significant increase in 1T content (50 %) occurred with the addition of vanadium, enhancing the prompt diffusion of lithium ions by two orders. More exposed electroactive basal planes increased the number of redox active sites to 84 %, suggesting an excellent charge storage of 451 F g-1 at 1 A g-1 . On assembling MVS with MnO2 to form an asymmetric cell (MnO2 ∥MVS), a high energy density (62.7 Wh kg-1 at 428 W kg-1 ) with a threefold increment from the MVS‖MVS symmetric cell (21.8 Wh kg-1 at 255 Wkg-1 ) was achieved. The asymmetric cell also exhibited a superior cycling stability with 98 % retention of its capacitance after 10 000 cycles.