[论文解读] Pore-scale modeling of capillary-driven binder migration during battery electrode drying

Marcel Weichel, Martin Reder+6 more|arXiv (Cornell University)|Mar 19, 2026

Advancements in Battery Materials被引用 0

一句话总结

论文开发了一种孔尺度连续模型，明确解析在电极干燥过程中由毛细力驱动的粘结剂传输，应用于硬碳微结构以研究颗粒大小、蒸发速率和表面张力如何影响粘结剂分布。

ABSTRACT

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.

研究动机与目标

• 理解毛细力在电极干燥时孔隙排空过程中驱动粘结剂迁移的机理。
• 开发耦合溶剂蒸发、毛细传输和粘结剂沉积的时空分辨模型。
• 将模型应用于硬碳微结构，以将干燥条件与最终粘结剂分布联系起来。
• 为优化干燥过程以改善电极完整性与性能提供见解。

提出的方法

• 将两相孔尺度框架扩展为包含粘结剂传输与沉积系统。
• 使用相场（Allen–Cahn）动力学来建模液-气界面与润湿，与不可压缩Navier–Stokes流耦合。
• 引入三场粘结剂模型，含移动粘结剂和沉积粘结剂，包括沉积源项与全局质量守恒。
• 在包含指示函数以区分溶剂和空气的全域上实现弥散界面、多相耦合。
• 使用PACE3D框架在笛卡尔网格上以分步有限差分法求解，并进行MPI并行化。
• 在全面耦合之前，探索限制情形以验证质量守恒和蒸发效应。

Figure 1 : Spatial representation of the phase-field variable $\varphi_{2}$ (top) and the concentration $cI$ (middle) for the three dimensionless time points ( $t^{*}=\sqrt{g/R}$ ): $t^{*}=0$ , $t^{*}=1.46$ , and $t^{*}=2.83$ .

实验结果

研究问题

• RQ1 在孔隙排空时的毛细传输如何驱动干燥电池电极中的粘结剂迁移？
• RQ2 微结构（颗粒大小分布）和工艺参数（蒸发速率、表面张力、黏度）如何影响粘结剂分布？
• RQ3 粘结剂沉积进入空气相以及全局质量守恒在决定最终粘结剂模式中的作用？
• RQ4 扩展的孔尺度模型能否预测优化粘结剂均匀性与电极完整性的条件？

主要发现

• 更小的颗粒尺寸使粘结剂在电极微结构中分布更均匀。
• 更高的蒸发速率和更大表面张力促使更强的粘结剂梯度和非均匀性。
• 溶剂黏度的变化对粘结剂迁移影响较小，除非存在亲水/疏水效应。
• 在孔尺度上进行显式的毛细传输描述对准确预测粘结剂迁移至关重要。
• 该框架为针对性优化电极干燥过程提供了基础。

Figure 2 : Schematic representation of the validation setup for the binder evolution in a drying fluid.