Two-Dimensional Water-Coupled Metallic MoS2 with Nanochannels for Ultrafast Supercapacitors.

MoS2 is a promising electrode material for energy storage. However, the intrinsic multilayer pure metallic MoS2 (M-MoS2) has not been investigated for use in supercapacitors. Here, an ultrafast rate supercapacitor with extraordinary capacitance using a multilayer M-MoS2-H2O system is first investigated. Intrinsic M-MoS2 with a monolayer of water molecules covering both sides of nanosheets is obtained through a hydrothermal method with water as solvent. The super electrical conductivity of the as-prepared pure M-MoS2 is beneficial to electron transport for high power supercapacitor. Meanwhile, nanochannels between the layers of M-MoS2-H2O with a distance of ∼1.18 nm are favorable for increasing the specific space for ion diffusion and enlarging the surface area for ion adsorption. By virtue of this, M-MoS2-H2O reaches a high capacitance of 380 F/g at a scan rate of 5 mV/s and still maintains 105 F/g at scan rate of 10 V/s. Furthermore, the specific capacitance of the symmetric supercapacitor based on M-MoS2-H2O electrodes retain a value as high as 249 F/g under 50 mV/s. These findings suggest that multilayered M-MoS2-H2O system with ion accessible large nanochannels and efficient charge transport provide an efficient energy storage strategy for ultrafast supercapacitors.