Linking electrode processing to carbon microstructure and battery performance via elemental mapping

The effect of processing parameters on final electrode performance has been a prevalent topic of research for lithium-ion batteries. This study investigates the microstructural changes in Ni 0.33 Mn 0.33 Co 0.33 O 2 (NMC111) cathodes using elemental mapping via energy-dispersive x-ray spectroscopy (EDS). The analysis uses a novel linear distribution function (LDF) to quantify the connections between active material and conductive carbon under different processing conditions, i.e., coating rates, drying temperatures, and wet film thicknesses. The LDF analysis demonstrates that calendering leads to increased short-range contacts between carbon and active material, independent of shear rate during coating, which improves electrode performance. Furthermore, the LDF analysis was used to identify electrodes with similar carbon-active particle microstructure, but different thicknesses and porosity, to determine the effect of ion transport on electrode performance. Consistent with theory, the ratio of electrode thickness to porosity correlates with the inverse of the critical discharge rate. These results have important implications for processing and design rules for lithium-ion batteries and demonstrate how processing parameters affect conductive electronic and ionic pathways, which ultimately dictate electrode performance. • Temperature, shear, and calendering effects on electrode microstructure. • Quantify carbon microstructure with linear distribution function of elements. • Calendering determines final electrode microstructure and conductive pathways. • Calendered thickness and porosity impact electrode performance via ion transport.