Silicon/carbon composite anode materials for lithium-ion batteries: materials design and synthesis, current state, progress, and future perspectives

The global need for high-energy-density batteries has pushed for the development of high-performance battery materials such as cathodes and anodes to meet the huge energy demands in our modern society. Graphite (Gr) is the dominant anode material for lithium-ion batteries but possesses a lower theoretical capacity of 372 mAh g ⁻¹, which hinders the fabrication of more powerful batteries. On the other hand, silicon (Si) possesses an extremely higher theoretical capacity than graphite (4200 mAh g ⁻¹ in a composite of Li _4.4Si vs graphite: 372 mAh g ⁻¹). Unfortunately, Si anode has issues with high volume changes (up to 400%) during cycling. Mixing/compositing silicon with carbon (Si/C) is set to be a realistic strategy to overcome issues related to the volume changes of Si and the low capacity of graphite. Instead, coupling both elements enables the combination of the two main materials’ properties, such as the high lithiation performance of Si and outstanding mechanical stability and conductivity of the carbon, which allows the battery to reach high storage capacity under elevated stability over longer cycles. In this review, Si/C materials anode materials synthesis methods, structural and morphological characteristics, and electrochemical performances are discussed as well as major challenge to overcome pulverization of Si during the charge/discharge process, and potential challenges of designing Si/C.