Traditional Porous Electrode Theory has provided an impressive amount of insight on the description of the intercalation kinetics of rechargeable batteries by describing the porous electrochemically active electrode as a diffusion and ohmic system with a spatial distribution of reversible interfacial reactions. Here, events such as phase transformations are fit into a curve by using the open circuit potential (OCP), and mass and interfacial reactions are described by starting from the classic reaction theory and fitted to experimental data. Recent experimental results highlight that the kinetics associated to phase transformations occurring during the intercalation/deintercalation process, are key to specifying battery performance and long term degradation. These kinetics, however, are theoretically and numerically complex to spatially resolve at a level that would make them practical to use in commercial applications. In this paper, we report on progress in the formulation of a coarse-grained description that naturally accounts for the volumetric electrochemical phase transformations and reactions in a porous rechargeable battery by starting from fundamental materials science principles.