Li-ion battery electrode manufacturing is raising broad interest from both experimental and computational perspectives, due to its impact on the electrode and cell cost, mechanical and electrochemical properties. Among the different manufacturing processes, drying can trigger heterogeneities within the electrode mesostructure because of additive migration. Despite acknowledging that these heterogeneities significantly affect electrode properties, the drying step is often under evaluated at the experimental level and modeled through homogenized approaches. In this work, we present the first physics-based three-dimensional model able to mimic additive migration during drying, unlocking the generation of three-dimensional heterogeneous electrode mesostructures. We analyzed the effect of drying rate on the final electrode mesostructure, the dynamics of additive migration and how the developed heterogeneities affect the following manufacturing step, i.e., calendering. The results are in agreement with previous experimental findings and indicate trends not previously disclosed. Lastly, the implementation of complex drying protocols (three-stage drying) was tested and compared to its experimental counterpart.