This study examines the effect of the heterogeneous distribution of the active and conductive components in a commercial S/C architecture, obtained using X-ray microtomography, and the effect of this on the discharge performance at varying C-rates using a three dimensionally resolved image-based model -the first of its kind in the literature, to the authors' knowledge. This new 3D model is also compared with a traditional 1D model developed using the effective microstructural properties obtained from the X-ray CT image. The results demonstrate the benefits of the 3D image-based modelling approach to evaluate localised performance of the battery electrodes and potentially highlights the causes of cell-degradation. Finally, future modelling frameworks that may aid in optimising the S/C structure for improved and uniform cell performance are discussed.