Synergetic effect of localized and delocalized π electron on Li storage properties of Si/C heterostructures

Abstract

The composition of two different categories of anode materials, i.e. layered and alloy type is the future of anode material in Li-ion batteries. In our work, using First-principles approach, we proposed multilayer heterostructure of graphene/graphite (layered type) with silicon monolayer (Si-ML) (origin is alloy type), as a potential anode material for LiB’s. The synergetic effect of the delocalized π electron of carbon and localized π electron of Si-ML plays a crucial role in maintaining the electron and ion conductivity increases the stability and specific capacity with moderate open circuit voltage. The model structures proposed in this work shows high specific capacities in the range of 748 to 438 mAh-gm−1. This indicates that we can tune the specific capacity using the different ratio of carbon and silicon layers. The localized π electron helps to restrict the volume expansion within 15% for a fully lithiated model structure. The low interlayer diffusion energy of Li-ion makes all the heterostructure as a potential anode material. The proposed study will help to understand the Li storage properties of the carbon/silicon based composite to develop the anode materials with a certain approach.