Facile synthesis of hetero-structured few-layer MoS2-coated MoO2 as superior anode materials of lithium ion batteries

A hetero-structured few-layer MoS2-coated MoO2 (MoS2@MoO2) has been fabricated and applied as an anode material for LIBs. The MoS2@MoO2 was synthesized via two-step fire process: reducing MoO3 vapor with H2 for producing Mo powder, and oxidizing-sulfurizing Mo powder with SO2. With the aid of thermodynamic computations, it is found that Mo oxidation under SO2 atmosphere produces limited amounts of S2 vapor, which will locally sulfurize the particles nearby, resulting in finite and even sulfurization. The as-prepared MoS2@MoO2 includes few-layer MoS2 (about 3 nm thick) covering the surface, which serves a well-spreading and active material that synergizes with inner MoO2 to boost the performance for LIBs. Thus, the MoS2@MoO2 could deliver a high reversible specific capacity of 1263 mA h g−1 after 40 cycles at 0.1 A g−1, and maintain a specific capacity of 1052 mA h g−1 after 150 cycles at 0.2 A g−1. Even at 0.5 A g−1, the specific capacity could still keep above 650 mA h g−1 for over 500 cycles. The new method for MoS2@MoO2 synthesis is facile and effective, and may be extended to produce hybrids composed of other transition metal oxides and sulfides.