Synthesis of high-density olivine LiFePO4 from paleozoic siderite FeCO3 and its electrochemical performance in lithium batteries

The lithium-ion cathode material olivine LiFePO 4 (LFP) has been synthesized for the first time from natural paleozoic iron carbonate (FeCO 3 ). The ferrous carbonate starting material consists of the mineral siderite at about 92 wt. % purity. Because FeCO 3 has divalent iron, the reaction with lithium dihydrogen phosphate (LiH 2 PO 4 ) provides a unique method to develop iron-(II) containing LFP in an inert atmosphere. Since siderite FeCO 3 is a common mineral that can be directly mined, it may, therefore, provide an inexpensive route for the production of LFP. After carbon-coating, the LFP yields a capacity in the range of 80–110 mAh g −1 LFP (in one chosen specimen sample), which is lower than commercially available LiFePO 4 (150–160 mAh g −1 LFP ). However, the tap density of LFP derived from siderite is noticeably high at 1.65 g cm −3 . The material is likely to be improved with powder purification, nanosized processing, and more complete carbon-coating coverage with increased optimization.