Iron fluoride microspheres by titanium dioxide surface modification as high capacity cathode of Li-ion batteries

The spherical FeF3·0.33H2O cathode material is successfully modified with a TiO2 coating via a simple solvothermal method. The effects of nanosized TiO2 coating on the morphology structure, and electrochemical performance of spherical FeF3·0.33H2O cathode material are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical test, respectively. The results demonstrate that FeF3·0.33H2O sample is spherical morphology with the average particle size of about 1.0 μm and good dispersity, as well as the nanosized TiO2 layer is uniformly coated on the surface of the FeF3·0.33H2O spheres. Besides, the nanosized TiO2-coated FeF3·0.33H2O sample exhibits a high initial discharge capacity of 654 mAh g−1 and the corresponding charge capacity of 522 mAh g−1 at 0.1 C between 1.5 V and 4.5 V. Especially, the nanosized TiO2-coated FeF3·0.33H2O sample still possesses good cycling stability of 264 mAh g−1 after 200 cycles at 0.2 C. Thus, the modification of spherical FeF3·0.33H2O with nanosized TiO2 layer will be a promising strategy for improving cycle life and structure stability, and promoting its wide application in high performance LIBs.