The FeF3·0.33H2O/C nanocomposite with open mesoporous structure as high-capacity cathode material for lithium/sodium ion batteries

The novel FeF3·0.33H2O/C nanocomposite with open mesoporous structure is successfully prepared using a one-pot chemical method and mechanical ball milling route. The structure and morphology of the samples are examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED). The results show that the as-synthesized FeF3·0.33H2O/C nanocomposite exhibits a particle size of about 1–5 μm, open mesoporous structure with average pore diameters of 16.5 nm. Although the particles size is large up-to micron scale, the sample displays excellent electrochemical performance due to its open mesoporous structure, which is beneficial to the Li+diffusion and electron transportation. When FeF3·0.33H2O/C is used as cathode material of LIBs, it exhibits a specific capacity of 276.4 mAh g−1and excellent cyclic performance with a capacity of 193.5 mAh g−1after 50 cycles at 1 C for LIBs. Moreover, it also exhibits a high reversible capacity of 102 mAh g−1after 40 cycles at 1 C for SIBs. Therefore, FeF3·0.33H2O/C will be a promising cathode material for high-performance LIBs and SIBs.