Enhanced stability of smoothly electrodeposited amorphous Fe₂O₃@electrospun carbon nanofibers as self-standing anodes for lithium ion batteries

Fe₂O₃ and carbon nanofiber (Fe₂O₃@CNFs) composite anodes for lithium ion batteries (LIBs) were fabricated by electrospinning and electrodeposition of naturally abundant, environmentally friendly, and cost effective materials to provide a simple route for modulating the morphology of the anodes and their performance. These anodes offer the advantage of being self-supporting to avoid increased mass of the electrodes from the binder, carbon black and the current collector, so the performance is reported on the basis of the full mass of the electrode (0.5-0.8 mg cm^-2). Anodes consisting of nanofibers with a flat morphology without nanoscale roughness exhibit a superior cyclic stability (692 mA h g^-1 in the 2nd cycle vs. 518 mA h g^-1 after 100 cycles at 0.05 A g^-1) compared with an anode with nanoscale roughness, where the capacity faded by 36.6% under the same conditions. The improvement in the cyclic performance for the flat morphology was attributed to the formation of a stable solid-electrolyte interface layer on the smooth sample combined with the enhanced contact between Fe₂O₃ and the CNFs, which inhibited degradation from the volume change of Fe₂O₃ during the successive charge and discharge. The Fe₂O₃@CNFs with flat morphology also exhibit reasonable performance (232 mA h g^-1) at a high current density of 2.5 A g^-1. These studies provide insights about how morphology impacts performance, namely the flat morphology at the nanoscale can stabilize the interfaces between the electrolyte and electrode composed of carbon and high performance active materials to promote long cycle life.