Here, we report a new 4D (3D + time) model of a graphite/Si composite electrode, where the graphite and Si electrochemistry and mechanics are coupled. In particular, we show how the electrode microstructure changes upon galvanostatic discharge as a result of the interplay between Si and graphite. The pristine electrode microstructure, including graphite, Si particles and CBD is resolved with CGMD, similarly to what has been previously reported by our group .