Preparation of synthetic rutile and metal-doped LiFePO4 from ilmenite

The synthetic rutile and metal-doped LiFePO4 are prepared from the high-titanium residue and iron-rich lixivium, which are obtained from the ilmenite by a mechanical activation and leaching process. ICP results show that the rutile contains 92.01% TiO2, 1.59% Fe2O3, 0.034% MnO2 and 0.60% (MgO + CaO), which meet the requirement of the titanium dioxide chlorination process. The results also reveal that small amounts of Al3+, Ca2+ and Ti4+ precipitate in the FePO4·xH2O precursor. XRD and Rietveld-refine results show that the metal-doped LiFePO4 is single olivine-type phase and well crystallized, and Ti4+ occupy M1 site, Ca2+ occupy M2 site and Al3+ occupy both sites, which indicates the formation of cation-deficient solid solution. The sample exhibits a capacity of 123 mAh g−1 at 5C rate, and retains 94.3% of the capacity after 100 cycles.