Silicon (Si) is a promising anode material for high-performance Li-ion batteries (LIBs), but it undergoes rapid capacity fading through severe volumetric expansion during Li insertion/extraction. Although alloying Si with various metal sources has been pursued to mitigate the structural deterioration, the resulting materials have shown the intrinsic problem of low electrical conductivity. To address this conflicting issue, here we describe a novel ternary nanocomposite of Si/Co-CoSi2/reduced graphene oxide (rGO) made using a facile process of mechanical mixing of Si nanoparticles, Co3O4 microparticles, and rGO nanosheets, followed by carbothermal reduction. Specifically, rGO, which has high electrical conductivity and structural integrity, could work as both a conductive matrix and a reducing agent in forming the Co-CoSi2 phase inside the Si domains during thermal treatment. The proposed ternary nanocomposites exhibited a noteworthy specific capacity of 952 mA h g−1 with 79.3% capacity retention after 80 cycles at a current density of 100 mA g−1. We attribute the improved electrochemical performance to the increased structural stability offered by the Co-CoSi2 phase and the interconnected conductive framework of the rGO nanosheets. Therefore, we expect our design process for Si/Co-CoSi2/rGO ternary nanocomposites to be applicable to other materials that can eventually be used as high-performance anodes for the next generation LIBs.
Bibliographical noteFunding Information:
This work was supported by research grants of the NRF (2014M3A7B4052200, 2014M3C1A3053035) and Basic Science Research Program (2010-0027955) funded by the National Research Foundation under the Ministry of Science, ICT & Future, Korea. The authors also acknowledge the funding support from KIST institutional program and Samsung SDI.
© 2017 Elsevier B.V.
- Cobalt silicide
- Lithium-ion batteries
- Reduced graphene oxide
- Ternary nanocomposites