LiF/Fe/V2O5 nanocomposite as high capacity cathode for lithium ion batteries

•We prepared LiF/Fe/V2O5 nanocomposite in discharge state for practical application as cathode by simple ball milling method.•The composite showed high reversible capacity.•Heat-treated nanocomposite showed high and stable capacity.•We performed ex-situ TEM and -XRD to support reaction mechanism.•Electrochemical impedance spectroscopy (EIS) was carried out to understand the electrode kinetics.

Iron fluoride based conversion cathode materials, LiF/Fe/V2O5 nanocomposites with high activity and good cyclic stability have been prepared in the discharged state by employing high energy ball milling and characterized by using XRD, SEM and TEM techniques. Li cycling behavior have been investigated by using galvanostatic cycling and cyclic voltammetry. It has been inferred that addition of V2O5 significantly enhanced the performance of the LiF/Fe nanocomposites by improving its electronic as well as its ionic conductivity. LiF/Fe/V2O5 (15 wt.%, 30 h ball milled) shows the best cycling performance. A high first cycle discharge capacity of ∼510 (±5) mA h g−1 is observed. At the end of 50th cycle, the capacity observed is ∼270 (±5) mA h g−1. The heat treated LiF/Fe/V2O5 (15 wt.%, 20 h ball milled) nanocomposite shows a notable improvement in cycling stability than the as prepared nanocomposite and a reversible capacity of ∼310 (±5) mA h g−1 is observed at the end of 50 cycles. The average charge–discharge potentials observed in CV are ∼2.9 and ∼1.7 V, respectively. Ex-situ XRD, TEM and EIS measurements are performed on cycled electrodes of LiF/Fe/V2O5 (15 wt.%; 30 h ball milled) at selected voltages to understand the reaction mechanism.