Strong Coupling of MoS2 Nanosheets and Nitrogen-Doped Graphene for High-Performance Pseudocapacitance Lithium Storage

Layered material MoS2 is widely applied as a promising anode for lithium-ion batteries (LIBs). Herein, a scalable and facile dopamine-assisted hydrothermal technique for the preparation of strongly coupled MoS2 nanosheets and nitrogen-doped graphene (MoS2/N-G) composite is developed. In this composite, the interconnected MoS2 nanosheets are well wrapped onto the surface of graphene, forming a unique veil-like architecture. Experimental results indicate that dopamine plays multiple roles in the synthesis: a binding agent to anchor and uniformly disperse MoS2 nanosheets, a morphology promoter, and the precursor for in situ nitrogen doping during the self-polymerization process. Density functional theory calculations further reveal that a strong interaction exists at the interface of MoS2 nanosheets and nitrogen-doped graphene, which facilitates the charge transfer in the hybrid system. When used as the anode for LIBs, the resulting MoS2/N-G composite electrode exhibits much higher and more stable Li-ion storage capacity (e.g., 1102 mAh g(-1) at 100 mA g(-1)) than that of MoS2/G electrode without employing the dopamine linker. Significantly, it is also identified that the thin MoS2 nanosheets display outstanding high-rate capability due to surface-dominated pseudocapacitance contribution.