Architectural influence of Iron Fluoride films on electrochemical failure modes.

摘要

Iron fluoride (FeF2) is an attractive material for use as nanocomposite conversion reaction based cathodes in lithium ion batteries because of its high specific theoretical capacity of 571mAh/g. However, despite the optimistic potential of FeF2 to advance battery cathodes, the cycling performance of the material requires further development for it to be a viable cathode candidate. A deeper understanding is required of how orientation, selective reaction fronts, and morphology impact the electrochemical performance. FeF2 films of various degrees of vertical porosity and thickness were fabricated through the use of dynamic glancing angle deposition. Respectable performance was obtained with film thicknesses of 850nm, well above the nanodimensions typically required to trigger electrochemical activity. The structure – electrochemical property relationships were used to formulate insights on the electronic and ionic transport limitations seen in typical nanocomposite powders.