Design and synthesis of yolk–shell Fe2O3/N-doped carbon nanospindles with rich oxygen vacancies for robust lithium storage

Abstract

Ferric oxide (Fe₂O₃) is an attractive anode material for lithium-ion batteries (LIBs) with a high theoretical capacity of 1005 mA h g⁻¹. However, its practical application is greatly restrained by the rapid capacity fading caused by the large volume expansion upon lithiation. To address this issue, we have designed and synthesized a unique yolk–shell Fe₂O₃/N-doped carbon hybrid structure (YS-Fe₂O₃@NC) with rich oxygen vacancies for robust lithium storage. The obtained results show that YS-Fe₂O₃@NC delivers a high reversible capacity of 578 mA h g⁻¹ after 300 cycles at a current density of 5 A g⁻¹, about 11 times that (53.7 mA h g⁻¹) of pristine Fe₂O₃. Furthermore, a high specific capacity of 300.5 mA h g⁻¹ even at 10 A g⁻¹ is achieved. The high reversible capacities, excellent rate capability and cycle stability of YS-Fe₂O₃@NC might be attributed to the elaborate yolk–shell nanoarchitecture. Moreover, electron percolation and a local built-in electric field induced by oxygen vacancies in the Fe₂O₃ matrix could also enhance the kinetics of Li⁺ insertion/deinsertion.