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

Abstract

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, 7wt% MoO3 encapsulated FeF3·0.33H2O delivers the highest discharge capacity of 215.7 mAh g−1 at 23.7mAg−1 after 50cycles 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.