Enhanced Li-Ion-Storage Performance of MoS 2 through Multistage Structural Design

Abstract

Inspired by a folded protein, multistage structural MoS 2 is designed as an advanced anode material for lithium-ion batteries (LIBs). Density functional theory (DFT) calculations are initially performed, demonstrating that the ideal primary structure (P−MoS 2 ) has saw-tooth-like edges terminated by Mo atoms and the desired secondary structure (C−MoS 2 ) may form via crumpling. For the latter, more exposed (002) planes exist within the wrinkled parts, creating more active sites and promoting isotropic Li + insertion. Importantly, the rate capability and capacity of a MoS 2 anode are enhanced after such a P−MoS 2 to C−MoS 2 transition: a superb specific capacity of 1490 mAh/g for C−MoS 2 at 0.1 A/g (vs. 1083 mAh/g for P−MoS 2 ), an excellent cycling stability (858 mAh/g after 450 cycles at 0.5 A/g), and an improved rate capability of 591 mAh/g at 1 A/g (vs. 465 mAh/g) are documented. The curving effects and mechanical properties of a single C−MoS 2 particle are further visualized by in situ TEM. Drastically enlarged spacing changes upon Li-insertion and high elasticity are confirmed, which lead to enhanced LIB performances and the excellent mechanical strength of C−MoS 2 . The present multistage design of a MoS 2 structure should pave the way toward high-energy MoS 2 anode materials for future LIBs.