Tailored MoO₃-encapsulated FeF₃·0.33H₂O composites as high performance cathodes for Li-ion batteries

Iron fluoride based on conversion reaction has drawn more and more attention as an alternative cathode material for Li-ion batteries owing to its high specific capacity and low-cost. In order to ameliorate its low conductivity and poor cycling stability, MoO₃-encapsulated FeF₃·0.33H₂O composites are designed and prepared via a facile wet coating process. The influence of MoO₃ coating layer on the structural and electrochemical performance of FeF₃·0.33H₂O cathode material for Li-ion batteries is examined. The results show that the electrochemical performance of MoO₃/FeF₃·0.33H₂O composite is improved due to the tailored encapsulation of MoO₃ layer. Compared with the pristine FeF₃·0.33H₂O, 7 wt% MoO₃ encapsulated FeF₃·0.33H₂O delivers the highest discharge capacity of 215.7 mAh g⁻¹ at 23.7 mA g⁻¹ after 50 cycles and exhibits superior rate capability as well as greatly enhanced cycle stability. The outstanding electrochemical features are ascribed to the fact that the suitable thickness MoO₃ coating layer not only can improve the conductivity of cathode material, but also can provide a highway for Li ions diffusion during cyclic process.