Rational synthesis of a hierarchical Mo₂C/C nanosheet composite with enhanced lithium storage properties

Transition metal carbides have been studied extensively as anode materials for lithium-ion batteries (LIBs), but they suffer from sluggish lithium reaction kinetics and large volume expansion. Herein, a hierarchical Mo₂C/C nanosheet composite has been synthesized through a rational pyrolysis strategy, and evaluated as an anode material with enhanced lithium storage properties for LIBs. In the hierarchical Mo₂C/C nanosheet composite, large numbers of Mo₂C nanosheets with a thickness of 40-100 nm are uniformly anchored onto/into carbon nanosheet matrices. This unique hierarchical architecture can provide favorable ion and electron transport pathways and alleviate the volume change of Mo₂C during cycling. As a consequence, the hierarchical Mo₂C/C nanosheet composite exhibits high-performance lithium storage with a reversible capacity of up to 868.6 mA h g^-1 after 300 cycles at a current density of 0.2 A g^-1, as well as a high rate capacity of 541.8 mA h g^-1 even at 5.0 A g^-1. More importantly, this hierarchical composite demonstrates impressive cyclability with a capacity retention efficiency of 122.1% over 5000 successive cycles at 5.0 A g^-1, which surpasses the cycling properties of most other Mo₂C-based materials reported to date.