Scalable synthesis of high-quality transition metal dichalcogenide nanosheets and their application as sodium-ion battery anodes†
Layered transition metal dichalcogenides (TMDs), such as MoS2, WS2, MoSe2, WSe2, etc., have received considerable interest recently due to their unique properties and fascinating applications. In this work, we proposed a NaCl template-assisted in situ chemical vapor deposition (CVD) strategy for synthesizing high-quality two-dimensional (2D) WS2, MoS2, MoSe2 and WSe2 nanosheets with a single-crystalline structure on a large scale. During the synthesis, 3D self-assembly of cubic NaCl particles can not only provide smooth surfaces to support the lateral growth, but also create a 2D confined space to restrict the thickening of TMD nanosheets, while the high-temperature annealing during the CVD process ensures high crystallinity and structural stability as well as remarkably promoting the conductivity of the TMD nanosheets. When evaluated as sodium-ion battery anodes, the representative WS2 nanosheets exhibited a high reversible specific capacity of 453 mA h g−1 at a current density of 0.1 A g−1, an excellent cycling performance and a greatly enhanced rate capability. The charge storage mechanism together with the microstructure evolution of WS2 nanosheets during the sodiation/disodiation processes is responsible for their superior sodium storage performance.