Coarse-grained molecular dynamics simulations of microstructure evolution and debonding in water-based cathode electrode drying

Using water-based solvent in Li-ion battery (LIB) cathode slurry preparation offers many advantages over the traditional N-methyl-2-pyrrolidone-based (NMP-based) solvent, but with challenges of undesirable microstructure heterogeneity and debonding particularly at high drying rates. In this paper, we aim to simulate and understand the microstructure evolution and debonding phenomena in the drying of water-based cathode electrodes through a Coarse-Grained Molecular Dynamics (CGMD) model. As a comparative study, the drying process of NMP-based cathode was also simulated. The simulations demonstrate that the final volume for the water-based coating is smaller than the NMP-based counterpart, thus leading to more compact AM distribution after drying, contributing to higher energy density albeit lower the ion transport efficiency due to increased tortuosity. The results also show that, compared to the NMP-based electrode, the water-based electrode does not bind active material particles sufficiently during the drying process. Another interesting prediction is that the interface debonding typical occurs in vicinity of large AM particles for both the NMP-based and water-based electrodes.