MoO@MoS Core-Shell Structured Hybrid Anode Materials for Lithium-Ion Batteries.

We explore a phase engineering strategy to improve the electrochemical performance of transition metal sulfides (TMSs) in anode materials for lithium-ion batteries (LIBs). A one-pot hydrothermal approach has been employed to synthesize MoS nanostructures. MoS and MoO phases can be readily controlled by straightforward calcination in the (200-300) °C temperature range. An optimized temperature of 250 °C yields a phase-engineered MoO@MoS hybrid, while 200 and 300 °C produce single MoS and MoO phases. When tested in LIBs anode, the optimized MoO@MoS hybrid outperforms the pristine MoS and MoO counterparts. With above 99% Coulombic efficiency (CE), the hybrid anode retains its capacity of 564 mAh g after 100 cycles, and maintains a capacity of 278 mAh g at 700 mA g current density. These favorable characteristics are attributed to the formation of MoO passivation surface layer on MoS and reactive interfaces between the two phases, which facilitate the Li-ion insertion/extraction, successively improving MoO@MoS anode performance.