Crumpled graphene-molybdenum oxide composite powders: Preparation and application in lithium-ion batteries

Crumpled graphene-MoO₂ composite powders are directly prepared by means of spray pyrolysis and from a stable graphene oxide colloidal solution in the presence of Mo ions. The crumpled graphene-MoO₂ composite powders are transformed into MoO₃-based composite powders after post-treatment at 300C. The transmission electron microscopy and dot-mapping images of the post-treatment composite powders show uniform distribution of MoO₃ nanocrystals in the crumpled graphene powders. The two typical D and G bands of graphene are observed at 1350 and 1590?cm^-1, respectively, in the Raman spectrum of the graphene-MoO₃ composite. In addition, the crumpled graphene-MoO₃ powders exhibit superior electrochemical behavior compared to that of pure MoO₃ as an anode material for lithium-ion batteries. The initial discharge capacities of the graphene-MoO₃ composite and bare MoO₃ powders at a current density of 2?Ag^-1 are 1490 and 1225?mAhg^-1, respectively. The capacity retention of the graphene-MoO₃ composite is 87% after the first cycle, whereas that of bare MoO₃ is 47%, as measured after 100 cycles. The reversible discharge capacity of the graphene-MoO₃ composite decreases slightly from 1228 to 845?mAhg^-1 as the current density increases from 0.5 to 3?Ag^-1.