Hydrothermal synthesis and potential applicability of rhombohedral siderite  as a high-capacity anode material for lithium ion batteries
Shiqiang Zhao, Yue Yu, Shanshan Wei, Yuxi Wang, Chenhao Zhao, Rui Liu, Qiang Shen*

Journal of Power Sources 253 (2014) 251-255

2014.5.1-赵世强-journal of power sources[5.211].pdf

http://www.sciencedirect.com/science/article/pii/S0378775313020338

DOI: 10.1016/j.jpowsour.2013.12.055

a b s t r a c t
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 ofw1587 mAh 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.
                                                                                             2013 Elsevier B.V. All rights reserved.

Keywords:
Lithium ion battery
Anode material
Hydrothermal synthesis
Ferrous carbonate
Rhombohedral crystallite

4. Conclusions
Rhombohedral FeCO₃ (or synthetic siderite) has been facilely synthesized by a hydrothermal method, possessing an average size of 1.4±0.2 mm. Tentatively applied as LIB anodes, the excellent durability and high-rate performance of these micro-rhombohedra can be reproducibly observed. Even at 1000 mA g^-1, the reversible capacity (w800 mAh g^-1) is still higher than the theoretical capacity of FeCO₃ (463 mAh g^-1). As for the novel electrochemical activity of FeCO₃ towards metal lithium, the simultaneous formation of unknown Fe³⁺-containing derivatives and possible C^-1-containing Li₂C₂ incompletely answers the high-capacity characteristics of FeCO₃ (e.g., the 120th reversible value w1000 mAh g^-1 at 200 mA g^-1). Therefore, the lithium storage mechanism of FeCO₃  needs to be further conducted in future.