Design and synthesis of carbon-coated α-Fe_2O_3@Fe_3O_4 heterostructured as anode materials for lithium ion batteries

摘要

In this study, carbon-coated alpha-Fe2O3@Fe3O4 heterostructures were designed and synthesized by a simple ballmilling and an auxiliary rheological phase method combined with carbothermal reduction. Due to the synergistic effect between alpha-Fe2O3 and Fe3O4, the carbon-coated alpha-Fe2O3@Fe3O4 heterostructures have an excellent electrochemical performance. In order to elucidate the reaction process, the types of gases produced during the pyrolysis of citric acid are preliminarily examined, and the possible chemical reactions are deduced from the experimental results. The Mossbauer spectrum is used to determine the relative ratio of alpha-Fe2O3@Fe3O4. As an anode material for lithium ion batteries, a carbon-coated Fe2O3@Fe3O4 electrode exhibits a high initial discharge/charge capacity of 1462.2/968.2 mAh g(-1) and a good reversible capacity (971.5 mAh g(-1) ) at a current density of 0.1 A g(-1). Moreover, even after 200 cycles, a reversible capacity of 711.0 mAh g(-1) can be maintained at a current density of 0.5 A g(-1).