Correlating Processing Conditions to Short- and Long-Range Order in Coating and Drying Lithium-Ion Batteries

Processing conditions of battery slurries into electrodes are known to affect final battery performance. However, there is a lack of fundamental understanding of how the relationships between processing conditions, the slurry microstructure, and the film microstructure affect electrode performance. This study determines the effects of the coating shear rate and drying temperature on battery electrode performance via discharge capacity. We use rheological measurements and energy dispersive X-ray spectroscopy (EDS) to correlate slurry and electrode microstructures to trends in discharge capacity. The radial distribution function is used to quantify differences in the electrode microstructure. More specifically, we show that the correlation between carbon and active material EDS detections to be the most relevant in understanding battery performance. Electrodes with both short- and long-range carbon/active material orders have the highest discharge capacities. This microstructure can be obtained through high shear rates, which induce better carbon dispersion via strong hydrodynamic forces, or through high temperature drying by preventing unwanted time-dependent structural changes after flow cessation. This analysis provides concrete evidence for the importance of both short-range and long-range contacts between the conductive additive and active material on battery performance.