Hydrothermal synthesis and potential applicability of rhombohedral siderite as a high-capacity anode material for lithium ion batteries

Natural siderite is a valuable iron mineral composed of ferrous carbonate (FeCO3), which is commonly found in hydrothermal veins and contains no sulfur or phosphorus. In this paper, micro-sized FeCO3 crystallites are synthesized via a facile hydrothermal route, and almost all of them possess a rhombohedral shape similar to that of natural products. When applied as an anode material for lithium ion batteries, the synthetic siderite can deliver an initial specific discharge capacity of similar to 1587 rnAh g(-1) with a coulombic efficiency of 68% at 200 mA g(-1), remaining a reversible value of 1018 mAh g(-1) over 120 cycles. Even at a high current density of 1000 mA g(-1), after 120 cycles the residual specific capacity (812 mAh g(-1)) is still higher than the theoretical capacity of FeCO3 (463 mAh g(-1)). Moreover, a novel reversible conversion mechanism accounts for the excellent electrochemical performances of rhombohedral FeCO3 to a great extent, implying the potential applicability of synthetic siderite as lithium ion battery anodes. (C) 2013 Elsevier B.V. All rights reserved.