Comparison of Si/C, Ge/C and Sn/C composite nanofiber anodes used in advanced lithium-ion batteries

Alloy anodes (Si, Ge and Sn) electrospun into carbon nanofibers as binder-free electrodes were synthesized and studied for rechargeable lithium-ion batteries. Alloy anode materials suffer from serious volume changes and nanoparticle aggregations during lithium insertion and extraction, resulting in rapid pulverization and capacity loss. Carbon nanofibers could help preserve the alloy anode materials during repeated cycling, and consequently maintain the cycling stability. In this work, it was found that with the increase in the amount of Si, Ge and Sn, the cycling stability was decreased due to the formation of large clusters within the carbon nanofiber matrix. Compared with Si/carbon nanofibers, Ge/carbon and Sn/carbon exhibited better cycling performance due to their improved nanopartide distribution and smaller volume changes. The failure mechanism of the Si/carbon structure was explained in this article. It is believed that this study on Si/carbon, Ge/carbon and Sn/carbon composite nanofiber electrodes could help in designing alloy-based carbon composites with various structures for advanced lithium-ion batteries. (C) 2013 Elsevier B.V. All rights reserved.