Sodium-ion batteries employing hard carbon electrodes are considered a drop-in technology for lithium-ion batteries. Electrode drying is a critical manufacturing step, as binder migration during pore emptying impacts the mechanical integrity and electrical performance of the electrode. Existing modeling approaches predominantly rely on the film shrinkage phase in a one dimensional way or neglect the capillary transport, resulting in a lack of physically consistent microstructure resolved predictions of binder migration. In this work, a spatially resolved pore scale continuum model is extended to explicitly describe capillary driven binder transport during pore emptying. The model is applied to hard carbon microstructures with varying mean particle diameters. The simulations reveal that smaller particle sizes lead to a more homogeneous binder distribution, whereas higher evaporation rates and increased surface tension promote stronger binder gradients. Variations in solvent viscosity show only a minor influence on binder migration, as long as no hydrophilic or hydrophobic behavior is present. Finally, the simulations demonstrate that an explicit description of capillary transport and microstructural effects is essential for accurately predicting binder migration and provides a basis for the targeted optimization of electrode drying processes.

翻译：采用硬碳电极的钠离子电池被视为锂离子电池的可替代技术。电极干燥是关键制造步骤，因为孔隙排空过程中粘结剂迁移会影响电极的机械完整性和电性能。现有建模方法主要依赖一维方式的膜收缩阶段，或忽略毛细管输运，导致缺乏物理一致性的微结构解析粘结剂迁移预测。在本研究中，扩展了一种空间解析的孔隙尺度连续模型，以显式描述孔隙排空过程中毛细驱动的粘结剂传输。该模型应用于具有不同平均粒径的硬碳微结构。模拟表明，较小的粒径导致更均匀的粘结剂分布，而较高的蒸发速率和增大的表面张力会促进更强的粘结剂梯度。只要不存在亲水或疏水行为，溶剂粘度的变化对粘结剂迁移的影响较小。最后，模拟证明，显式描述毛细管输运和微结构效应对于准确预测粘结剂迁移至关重要，并为电极干燥过程的目标优化提供了基础。