Abstract

Since the loading of electrodes for Li-ion batteries with an excessive amount of moisture affects the performance of the cells, the moisture is partly removed in a post-drying process step. The drying time is thereby controlled by the amount of moisture that has to be removed as well as the mass transport kinetics of water. This mass transport kinetics is limited by various mass transport resistances, which in turn can be influenced by individual dryer settings. In this paper, we investigate water-based anodes for Li-ion batteries as well as selected materials, and distinguish between different possible mass transport resistances that affect the drying time. Determined diffusion coefficients can be used in future modeling of the post-drying process.

Special consideration needs to be bestowed upon the mass transport of water in the polymeric binders, since earlier investigations revealed that the moisture uptake of the anodes is particularly caused by sodium carboxymethyl cellulose (Na-CMC). This high water uptake by the binder in water-based electrodes leads to a polymer film drying process within the porous structure of the electrode. The diffusion of water in layers of binder is particularly dependent on the concentration as well as the temperature of the binder.

摘要

由于用于锂离子电池的电极的水分过多会影响电池的性能，因此在后干燥过程中会部分除去水分。因此，干燥时间由必须除去的水分量以及水的传质动力学控制。这种传质动力学受到各种传质阻力的限制，而这些阻力又会受到各个干燥机设置的影响。在本文中，我们研究了锂离子电池的水基阳极以及所选材料，并区分了影响干燥时间的不同可能的传质阻力。确定的扩散系数可用于以后的干燥过程建模。

由于聚合物中水的大量传输，需要特别考虑，因为较早的研究表明，阳极的水分吸收特别是由羧甲基纤维素钠（Na-CMC）引起的。粘合剂在水基电极中的高吸水率导致电极多孔结构内的聚合物膜干燥过程。水在粘合剂层中的扩散尤其取决于粘合剂的浓度以及温度。