Enhancing the lithium storage capacity of FeF₃ cathode material by introducing C@LiF additive

Iron fluorides based on conversion chemistry are developed as alternative cathode materials for Li-ion batteries due to their high capacity, also suffering from some drawbacks, such as poor electrical conductivity and structural instability. In order to improve the electrochemical performance of iron fluoride, in this work, we focus on the enhancement of the lithium extraction capability of FeF₃ by introducing extra C@LiF additive. FeF₃/C@LiF composites are fabricated by high energy ball milling. Due to the compact connection between LiF and conductive carbon in FeF₃/C@LiF composites, LiF can not only act as high-active reactant for lithium extraction process, but also provide active sites for subsequent charge/discharge reaction. Electrochemical study results suggest that a suitable content of LiF enables FeF₃/C@LiF composite to deliver a satisfactory electrochemical performance, which retain a capacity of 229 mAh g^{− 1} at a current rate of 40 mA g^{− 1} after 50 cycles (10% higher than that of FeF₃/C composite).