New Iron-Based Intercalation Host for Lithium-Ion Batteries

The discovery of high-performance cathode materials is imperative for advances in current lithium-ion battery technology. Although extensive efforts have been focused on developing novel cathode materials, it has been a grand challenge to find candidates that can outperform state-of-the-art cathode materials such as layered, olivine, and spinel lithium transition-metal oxides. This issue arises because there are only a limited number of intercalation hosts with appropriate redox potential and lithium solubility. Here, we present a new iron-based intercalation host for lithium ion by exploring the “host formation reaction” from the nanocomposite of lithium and transition-metal compound hosts (i.e., LiF and FeO). Fluoride ions released from LiF decomposition during charging induce an unexpected phase transition of FeO to a new host structure of cubic-FeOF, a new polymorphic structure of Fe…