Electrochemically intercalated intermediate induced exfoliation of few-layer MoS2 from molybdenite for long-life sodium storage

Abstract

Two-dimensional (2D) molybdenum disulfide (MoS2) holds significant promise as an energy storage material, whereas the exfoliation of MoS2 into few-layer from natural molybdenites remains a challenge. An efficient electrochemical strategy was proposed for the preparation of few-layer MoS2 through cationic intercalation. Few-layer MoS2 without the impurity phases was obtained with high yield through Raman mapping analysis, and the intermediate (TBA+)xMoS2x− was captured by in-situ Raman. Note that the charge transport kinetics of the exfoliated few-layer MoS2 was further enhanced by the introduction of graphene, which could efficiently enhance the Na+ diffusion mobility, alleviate the volume change of MoS2 and stabilize the reaction products. Commendably, the exfoliated MoS2/graphene hybrid shows a reversible specific capacity of 642.8 mA h g−1 at 0.1 A g−1, superior rate performance (447.8 and 361.9 mA h g−1 at 1 and 5 A g−1, respectively) and remarkable long-cycle stability with 328.7 mA h g−1 at 1 A g−1 after 1000 cycles for sodium-ion batteries (SIBs). Therefore, this efficient electrochemical exfoliation method can be driven to prepare other few-layer 2D materials for SIBs.