A review on FexOy-based materials for advanced lithium-ion batteries

FexOy-type iron oxides, especially alpha-Fe2O3 and Fe3O4, are powerful alternatives to the currently available graphitic anode materials for lithium-ion batteries (LIBs) owing to their high theoretical capacity, natural abundance, environmental benignity, non-flammability, and enhanced safety. In this context, compositional engineering is a widely used strategy to improve the electrochemical performance of electrode materials; in this method, the synergetic effects of individual components in a hybrid material are harnessed for improved performance. To improve FexOy-based materials in terms of compositional engineering, in this review, the factors affecting the electrochemical performance of pure FexOy and different kinds of additives combined with FexOy for LIB anodes via doping or compositing and their effects on the electrochemical performance of the anodes are discussed in detail. Several approaches that can enhance the performance of FexOy-based LIB anodes via compositional engineering are highlighted and the importance of a proper combination of compositional and structural engineering for achieving the desired physical/electrochemical properties in FexOy-type anodes is described. In the near future, such approaches may provide effective and efficient ways to obtain advanced rechargeable LIBs with a high energy/power density, long cycle life, and low cost.