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Journal of the Electrochemical Society, Vol.166, No.3, A5131-A5138, 2018
Carbon Coated Si-Metal Silicide Composite Anode Materials Prepared by High-Energy Milling and Carburization for Li-Ion Rechargeable Batteries
In this article, we report a novel Si-Metal silicides/Carbon composite anode material for lithium-ion rechargeable batteries. The composite powder comprised of Si, FeSi2 and CrSi2 were synthesized by high-energy mechanical milling and then a primary carbon was formed over the Si-silicide at 900 degrees C. The prepared composite powder was agglomerated and subsequently a thin carbon layer was coated. The X-ray diffraction results revealed that the Si and silicide crystal size decrease with respect to milling time. The critical milling time to achieve the completely nano-scale powders was 5 h. The composite powder exhibits randomly distributed carbon-coated Si-silicide. The TEM microstructure revealed homogeneous distribution of nanocomposite powder consists a very fine nanoparticles of the order of similar to 30 nm. The prepared Si-silicide/C composite powders exhibited good capacity retention with an average coulombic efficiency of 99.6%. The composite powders showed good cyclability, 1076 mAh g(-1) at 50th cycle and 959 mAh g(-1) at 100th cycle. The electrode internal microstructure revealed a shell-like carbon-coated Si-silicide phases, and a complete amorphization of nanocrystalline Si during the initial cycling, while the inactive silicide phase remains unchanged. Consequently, the size reduction of Si-silicide and carbon coating over it greatly enhanced the cycling performance of the electrode. (c) The Author(s) 2018. Published by ECS.