Pseudocapacitance and diffusion-controlled dual modes of MoS2 nano-particles enable high long-cycle anode capacity

Abstract

Molybdenum disulfide (MoS2), which generally possesses a graphene-like two-dimensional layered structure and unique physicochemical and electrical properties, is an emerging material to next-generation high-energy-density storage beyond the reach of current anode technologies. However, pristine layered MoS2 suffers from low conductivity and poor cycle stability, thus hindering its development in lithium ion batteries (LIBs). Herein, we prepare a self-assembled MoS2 nano-particle structure induced by 1-dodecanethiol (DDT) through a bottom-up approach. The superior rate and high capacity of LIBs are attributed to the large specific surface area (64.29 m2 g−1) and short internal distance, giving rise to the pseudocapacitance and diffusion-controlled process in the electrochemical behavior, respectively. In situ Raman, Density Function Theory (DFT) calculation and X-ray photoelectron spectroscopy verify the conversion from MoS2 to Mo in the lithiation process, and the strong binding energy between Mo and LiF contributes to a stable solid electrolyte interphase during Li+ intercalation/de-intercalation reversible process. The cell using MoS2 nano-particles anode delivers a preferable discharge capacity of 600 mA h g−1 after 1000 cycles at the current density of 1.0 A g−1 than commercial and recently reported MoS2 anodes. This work inspires the development of nano-structure for resistance to large-volume expansion/shrinkage and high stability.

Keywords

• MoS2 nano-structure
• Pseudocapacitance
• Diffusion-controlled effect
• Solid electrolyte interphase
• Lithium ion batteries