Enhancing the lithium storage performance of iron oxide composites through partial substitution with Ni2+ or Co2+

In this article, a simple route for modifying the morphology and lithium storage performance of iron oxide composites has been developed by using Ni2+ or Co2+ to substitute Fe3+. The as-prepared MFe2O4 (M = Ni, Co) nanoparticles (similar to 5 nm) were uniformly distributed on the surface of the carbon substrates. When evaluated as anode materials for lithium ion batteries, these composites showed high specific capacity, excellent cycling performance and rate capabilities. For example, the CoFe2O4/graphene sheets composite delivered a high reversible capacity of 950 mA h g(-1), even higher than the theoretical value, as well as excellent cycling performance.