Artificial cathode solid electrolyte interphase to endow highly stable lithium storage of FeF2 nanocrystals

Abstract

Iron difluoride (FeF2) is considered a high-capacity cathode material for lithium-ion batteries. However, its specific capacity and stability are limited by the poor electrochemical kinetics of conversion reactions. Herein, the conversion reaction is confined in a localized nanosized space by encapsulating FeF2 nanoparticles in polymer gelatin. The FeF2 nanocrystal-coated polyvinylidene fluoride-based layer (defined as FeF2@100%G-40%P) was synthesized by glucose-assisted in-situ gelatinization to construct an artificial cathode solid electrolyte interphase via a solvothermal process. Thanks to the improved kinetics of the localized conversion reaction, the obtained FeF2@100%G-40%P electrodes show good cyclic stability (313 mA h g−1 after 150 cycles at 100 mA g−1, corresponding to a retention of 80%) and a high rate performance (186.6 mA h g−1 at 500 mA g−1).