Solution synthesis of VSe2 nanosheets and their alkali metal ion storage performance

Vanadium diselenide (VSe2) is a transition metal dichalcogenide with metallic conductivity, which makes it a potentially promising electrode material for electrochemical applications. However, the development of VSe2 electrodes for such applications has been severely hampered by the difficulty of preparing nanosized products. In this work, a new facile solvothermal synthesis process is developed and optimized to synthesize ultrathin VSe2 nanosheet assemblies. To obtain the ultrathin nanosheets, N-methyl pyrrolidone, which has similar surface energy to many transition metal dichalcogenides, was used as the solvent to limit the crystal growth along the caxis direction. The resulting ultrathin VSe2 nanosheets exhibit good performance toward alkaline ion (Li+ and Na+) storage, which can be significantly enhanced by carbon coating. Specifically, the carbon-coated VSe2 nanosheets can deliver high capacities of 768 mA h g(-1) (Li+ storage) and 571 mA h g(-1) (Na+ storage) along with outstanding stability.