Revisiting the origin of cycling enhanced capacity of Fe3O4 based nanostructured electrode for lithium ion batteries

We identify that reversible formation/decomposition of lithium oxide, pulverization of Fe3O4 nanoparticles, and electrolyte reactions, are contributors to the enhanced capacity observed in the Fe3O4 electrode upon long cycling. Introducing three-dimensional graphene foam to form a composite with Fe3O4 nanoparticles largely increases the capacity (similar to 1220 mA h g(-1) vs. similar to 690 mA h g(-1)) and promotes the cycling induced capacity enhancement (an earlier capacity rise and a faster rising rate) of the Fe3O4 electrode. Together with Fe3O4 nanoparticles, the presence of graphene effectively promotes the electrolyte reactions and reversible formation/decomposition of lithium oxide. At the same time, activation of GF also occurs in the presence of Fe3O4 nanoparticles, further increases the capacity of the nanocomposite.