3D conductive iron fluoride (III) cathode with high loading for lithium-ion batteries

Abstract The conversion-typed FeF 3 cathode, while having high theoretical capacities, suffers seriously from low intrinsic conductivity, sluggish reaction kinetics, and side reactions in lithium ion batteries (LIBs). In particular, composites with high loading FeF 3 show poor cycling performance. This paper proposes an effective strategy for nanoconfinement in the 3D conductive matrix to address the aforementioned challenges of FeF 3 . FeF 3 nanoparticles are only 10–50 nm due to being nanoconfined. The loading of the composite is as high as 81.89%, which is the highest compared to other composites reported previously. The prepared iron fluoride-carbon nanofiber composites offer high reversible capacities of as high as 313 mAh g −1 at 0.1 C. Moreover, it shows an enhanced cycle stability of 88.4% after 100 cycles at 1 C. The improved electrochemical performance is attributed to the 3D conductive network as well as the nanoconfinement of FeF 3 , which achieve a good capacitance-controlled process by accelerating electron transport while shortening the ion transport path. It is believed that this work provides an efficacious strategy to enhance the electrochemical performance of conversion-typed metal fluoride cathodes for LIBs.