Encapsulating flower-like MoS2 nanosheets into interlayer of nitrogen-doped graphene for high-performance lithium-ion storage

Abstract

Layered molybdenum disulfide (MoS2) is a promising anode material for lithium-ion storage and its coupling with graphene can further improve the specific capacity and cycling stability. In this work, a feasible polyacrylamide (PAM)-assisted approach to prepare the flower-like MoS2 nanosheets encapsulated by nitrogen-doped graphene (FL-MoS2/N-G) is proposed. The PAM is taken as the directing agent for the layered assembly of graphene and further confined growth of FL-MoS2 in the interlayers of the graphene. The unique encapsulation construction of MoS2 and N-doped graphene leads to the high loading of active species and stabilized structural integrity after the continuous Li+ ion intercalations. Theoretical simulation results reveal that the MoS2 nanosheets coupled with N-doped graphene can accelerate the charge transfer process and create extra lithiation sites with decreased diffusion resistance of Li+ ions. As the anode material in lithium-ion batteries (LIBs), the target FL-MoS2/N-G composite exhibits a high reversible capacity of about 1202 mAh g−1 at 0.2 A g−1 and it can remain 835 mAh g−1 even at 5 A g−1, highlighting an excellent rate capacity. Additionally, the FL-MoS2/N-G anode is also capable of delivering a long-term cycling performance with a capacity retention of about 78% after 800 cycles. Furthermore, benefiting from the fast charge transfer process of the FL-MoS2/N-G dominated by surface capacitive behavior, the lithium-ion hybrid capacitor with good electrochemical performance was fabricated to brighten its practical application prospect. The current work presents a new insight into the fabrication of high-loading MoS2/N-doped graphene composites with unique nanostructures for high-performance lithium-ion storage.