Experimental & simulative assessment of mixing quality for dry Li-Ion cathode production in an Eirich intensive mixer

We investigated the possibility to characterize the dry-mixing in Li-Ion battery production by a simple quality parameter, the bulk density. We present a dimensionless number that allows to calculate the bulk density of the mixture in dependence on mixing parameters. Suitability of the dry powders for cell production was investigated with electrical conductivity measurements. The highest powder conductivity of 1 S/m was measured for the highest mixing tool velocity of 25 m/s after a mixing time of 4000 mixing tool revolutions in the EL0.1 mixing vessel. This indicates that high energy mixing for a short mixing time can result in a beneficial electrical conductivity in the bulk. Longer mixing times generally led to lower powder conductivities for all investigated mixing tool speeds between 5 m/s and 25 m/s in both mixing vessels. The experimental results were incorporated into a DEM simulation model and analyzed further.