Insights into iron-based polyanionic cathodes for scale- energy storage

To further advance the utilization of renewable energy, there is an urgent need for developing high performance and cost-effective secondary ion batteries. Cathode materials directly affect the electrochemical performance and actual price of the battery, however, the scarcity of low cost and long cycle life of which poses a significant obstacle for scale-energy storage application. Polyanionic compounds offers a diverse range of structures and adjustable operating voltages, making it a promising alternative. Its robust 3D framework mitigates structural alterations during ion insertion/de-insertion, ensuring commendable cyclic stability and heightened safety. Among transition metals, iron stands out for its unparalleled natural abundance and rare earth yield. Consequently, iron-based polyanionic materials have emerged as prime candidates for developing low-cost and environmentally sustainable secondary ion batteries. This paper delves into the exploration of iron-based polyanionic compounds as cathode materials for secondary ion batteries. We encapsulates their crystal structure, electrochemical performance, and nuanced advantages and disadvantages. The focus is on scrutinizing and elucidating the principles and strategies for improving the energy density and cycling performance, providing the inspiration for advanced design of iron-based polyanionic cathodes for scale-energy storage.