3D resolved computational modeling to simulate the electrolyte wetting of a lithium-ion battery cell with 18650 format

Electrolyte wetting in a lithium-ion battery (LIB) cell is a time-intensive, quality-critical manufacturing step that determines the degree of homogeneity of lithium ion's transport within the electrode and separator pores, affecting ionic conductivity and current density. If the electrolyte is inadequately distributed, it can compromises cell performance. In this work, we introduce a novel engineering-oriented model to simulate electrolyte wetting in a LiNi₀.₃₃Mn₀.₃₃Co₀.₃₃O₂–Graphite 18650 cylindrical LIB cell. Cell geometry was based on commercial specifications. Governing equations employed a pressure-saturation formulation incorporating Darcy’s law and phase-transport equations, solved through the finite element method in COMSOL Multiphysics. The model was parameterized with experimental data extracted from literature, and free parameters were optimized via a sensitivity analysis to maximize wetting. Results indicate overall saturation is predominantly controlled by capillary pressure and spatial electrolyte distribution across the different functional layers of the jelly roll (electrodes and separator). An electrolyte saturation of 86% is obtained, consistent with saturation values reported in literature obtained with different methodologies. Our 3D-resolved modelling approach uniquely captures how 18650 cell spiral geometry and component properties influence electrolyte distribution and, to the best of our knowledge, is the first to simulate wetting behavior in a full-scale cylindrical LIB cell.