Mo-MoO₃-graphene nanocomposites as anode materials for lithium-ion batteries: scalable, facile preparation and characterization

The development of high-performance anode materials, along with simple synthesis processes, is of main issues to replace the commercial graphite anode and to achieve practical applications of Li-ion batteries (LIBs). Herein, we report a facile, scalable preparation of multiple Mo-MoO₃-graphene nanocomposites using a simple wire-explosion process, followed by heat treatment in air, and their electrochemical performance as anode materials of LIBs. In this process, Mo wire is electrically exploded in methanol containing graphene at room temperature, resulting in well-dispersed Mo nanoparticles anchored on graphene. Subsequently, partial oxidation of Mo nanoparticles to MoO₃ is achieved at 300 °C in air, forming Mo-MoO₃-graphene nanocomposites. For comparison, Mo-MoO₃ nanocomposites are also prepared under the same conditions, without using graphene. Systematic phase and microstructural characterizations of both nanocomposites, as well as the as-synthesized Mo nanoparticles, are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. Their Li-storage performances are also evaluated and compared. Since graphene acts as a mechanical support to prevent Mo nanoparticle aggregation, and both Mo nanoparticles and graphene play an important role in providing effective electron pathways between active MoO₃ nanoparticles, Mo-MoO₃-graphene nanocomposites exhibit the conductivity and Li⁺ diffusivity enhancements (3.35 × 10⁻¹⁴ cm² s⁻¹), and structural stability, resulting in not only enhanced cycling performance, with a reversible capacity of 611 mA h g⁻¹ after 50 cycles at a constant current rate of 0.1C, but also a better rate performance than Mo-MoO₃ nanocomposites. These synergistic functions are responsible for the better Li-storage performance of Mo-MoO₃-graphene nanocomposite, which can lead to the promising candidates for LIB anode materials.