(439e) How Powder Characterization Can Improve Battery Electrode Production

To produce an electrode, the raw materials, consisting of the active material, the conductive additive, and the binder are more and more handled in dry conditions. In many dry processes, the first step is the dry mixing. The aim of this step is not only to obtain a homogeneous blend, but also to induce some changes in the powder properties. A typical example is the deagglomeration of carbon black particles during dry mixing, due to the undergone shear rate. These changes are important since they directly influence the performance of the electrode after production, such as the electronic conductivity for the case of deagglomerated carbon black. The obtained changes according to the mixing parameters are however unpredictable while they control the performance of the electrode and thus on the final battery. Preparing composite powders is another way to prepare powder blends to obtain a material with intermediate or new properties compared to dry mixed powders. For such material, it is also challenging to predict its properties and its influence on the performance of the battery.

Fibrillation is also a common initial step to prepare a powder batch for dry process. It consists of elongating the agglomerated fibril existing in the binder (generally polytetrafluoroethylene) by shearing the powder blend. The level of fibrillation depends on different parameters such as temperature, shear rate, and time of fibrillation. It directly influences the quality of the produced free-standing film while it remains hard to quantify this level of fibrillation.

Because initial steps such as dry mixing, fibrillation, and composite preparation of the powder materials influence directly the performance of the produced electrode and thus of the battery, it is important to characterize the powder materials to improve these processes. Through different user cases, we show how powder characterization methods can be used as a quality control, can quantify the level of fibrillation of a powder, and predict the performance of a composite blend compared to a dry mixed powder. In addition, we address how these characterization methods can be used to calibrate DEM simulation to have a deeper analysis of the phenomena occurring during dry mixing, fibrillation, or other processes. The combination of these different characterization tools and the information that they bring opens the way for a strong improvement in battery manufacturing.