Nanocrystal-constructed mesoporous CoFe₂O₄ nanowire arrays aligned on flexible carbon fabric as integrated anodes with enhanced lithium storage properties

A novel and facile two-step strategy is successfully developed for the large-scale fabrication of hierarchical mesoporous CoFe₂O₄ nanowire arrays (NWAs) on flexible carbon fabric as integrated anodes for highly efficient and reversible lithium storage. The synthesis involves the co-deposition of uniform bimetallic (Co, Fe) carbonate hydroxide hydrate precursor NWAs on carbon fabric and subsequent thermal transformation to spinel CoFe₂O₄ without damaging the morphology. The as-prepared CoFe₂O₄ nanowires have unique mesoporous structures, which are constructed by many interconnected nanocrystals with sizes of about 15-20 nm. The typical size of the nanowires is in the range of 70-100 nm in width and up to several micrometers in length. Such a hybrid nanostructure electrode presented here not only simplifies electrode processing, but also promises fast electron transport/collection and ion diffusion, and withstands volume variation upon prolonged charge/discharge cycling. As a result, the binder-free CoFe₂O₄/carbon fabric composite exhibits a high reversible capacity of 1185.75 mA h g^-1 at a current density of 200 mA g^-1, and a superior rate capability. More importantly, a reversible capacity as high as ∼950 mA h g^-1 can be retained and there is no obvious decay after 150 cycles.