An Image Based 3D Modelling Framework for Li-S Batteries

Traditionally, 1D volume-averaged continuum approaches are used to model Li-S battery performance at varying C-rates. For the first time, we present a working three-dimensional electrochemical model of a Li-S battery based on real electrode microstructure. In this study we evaluate the gaps between a volume-averaged 1D electrochemical model and a microstructurally resolved 3D image-based electrochemical model to accurately predict the effects of the localised heterogeneities present in Li-S cathodes on the battery performance at varying C-rates. The real microstructure of the commercial electrode was obtained using micro–X-ray computed tomography and used as a framework for an image-based 3D electrochemical model of the Li-S battery. The extent of heterogeneities present in the electrode architecture and the adequacy of using the representative elementary volume to capture the effect of complex electrode microstructure on the cell performance were analysed by mapping the 3D electrode microstructure. In this study, three-dimensional, microstructurally-resolved, image-based electrochemical models were developed on sub-volumes of the electrode to evaluate the effect of heterogeneous structure on the localised performance, which are further compared with the 1D model developed using the volume-averaged effective microstructural properties obtained from the X-ray CT image. Finally, the future modelling framework that would aid in optimising the S/C structure for improved and uniform cell performance is discussed.