Si/Co-CoSi2/reduced graphene oxide ternary nanocomposite anodes for Li-Ion batteries with enhanced capacity and cycling stability

Abstract

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 highperformance anodes for the next generation LIBs. (C) 2017 Elsevier B.V. All rights reserved.