Engineering sphere‐like porous FeF 3 @C cathode with rational interfacial designing towards high‐power batteries

Abstract Due to the high theoretical capacity and energy density, conversion‐type metal fluorides have captured plenty of attentions but still suffer from the inferior kinetic behaviors and serious capacity fading. For addressing the issues above, the strategies of surface/interface engineering are utilized for the preparation of sphere‐like porous FeF 3 @C materials, where the as‐resulted sample displays the uniform particle size (~ 150 nm in radii) and the ultra‐thin carbon layers (thickness of ~ 10 nm). Significantly, benefitting from the rich oxygen of precursor, the interfacial chemical bonds FeOC are successfully constructed between carbon matrix and FeF 3 materials, accompanying by the enhancements of ions/electrons (e) conductivity and stability. When used as Li‐storage cathodes, the initial lithium‐ions storage capacity could reach up to ~ 400 mAh·g −1 at 0.1 A·g −1 . Even at 1.0 A·g −1 , the capacity could be still remained at about 210 mAh·g −1 , with the retention of 85% after 400 cycles. Assisted by the detailed kinetic behaviors, the considerable electrochemical properties come from the enhanced diffusion‐controlled contributions, whilst the segregation of Fe with LiF is effectively alleviated by unique architecture. Moreover, during cycling, solid electrolyte interface film is reversibly formed/decomposed. Thus, this work is expected to offer rational exterior/interfacial designing strategies for metal‐based samples.