Calibration of Li‐Ion Cathode Materials for Discrete Element Method Simulations

The flow behavior of cohesive NMC‐622 cathode active material is studied in a Schulze RST‐01 ring shear cell and a rotating drum. For both devices, experiments and simulations are done to characterize the dynamic behavior of the material and to calibrate all relevant parameters for a coarse‐grained simulation model based on the discrete element method (DEM). The experimental values are directly used to simulate both of the calibration devices to verify a robust simulation model. It is found that for a coarse‐graining factor of 200 the characteristic flow mechanics in the experiments and simulations are in overall good agreement. It is further investigated if the aging process of NMC‐622 active material has an influence of the macroscopic flow characteristics of the powder. For this, the material was stored in ambient atmosphere for 12 months and investigated afterward by means of ring shear cell measurements and scanning electron microscope imaging. It is found that the aging of NMC‐622 leads to changed values for friction coefficients, which can be explained by possible surface reactions of the material in ambient atmosphere. The calibrated DEM model is suitable to be used in further work to provide simulative insides into the production of Li‐Ion batteries.