Amorphous carbon intercalated MoS2 nanosheets embedded on reduced graphene oxide for excellent high-rate and ultralong cycling sodium storage

Abstract

MoS₂ as a typical layered transition metal dichalcogenide (LTMD) has attracted considerable attention to work as sodium host materials for sodium-ion batteries (SIBs). However, it suffers from low semiconducting behavior and high Na⁺ diffusion barriers. Herein, intercalation of N-doped amorphous carbon (NAC) into each interlayer of the tiny MoS₂ nanosheets embedded on rGO conductive network is achieved, resulting in formation of rGO@MoS₂/NAC hierarchy with interoverlapped MoS₂/NAC superlattices for high-performance SIBs. Attributed to intercalation of NAC, the resulting MoS₂/NAC superlattices with wide MoS₂ interlayer of 1.02 nm facilitates rapid Na⁺ insertion/extraction and accelerates reaction kinetics. Theoretical calculations uncover that the MoS₂/NAC superlattices are beneficial for enhanced electron transport, decreased Na⁺ diffusion barrier and improved Na⁺ adsorption energy. The rGO@MoS₂/NAC anode presents significantly improved high-rate capabilities of 228, 207, and 166 mAh g⁻¹ at 20, 30, and 50 A g⁻¹, respectively, compared with two control samples of pristine MoS₂ and MoS₂/NAC counterparts. Excellent long-term cyclability over 10 000 cycles with extremely low capacity decay is demonstrated at high current densities of 20 and 50 A g⁻¹. Sodium-ion full cells based on the rGO@MoS₂/NAC anode are also demonstrated, yielding decent cycling stability of 200 cycles at 5C. Our work provides a novel interlayer strategy to regulate electron/Na⁺ transport for fast-charging SIBs.