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 MoS 2 (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 MnO 2 to form an asymmetric cell (MnO 2 ∥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.