We herein demonstrated an automatic battery assembly system capable of not just automatically stacking of electrodes but also with active placement correction and highly accurate combinatorial electrolyte dispensing. This system was utilized to provide evidence towards the incorrectness of using solely the additive weight percentage in the electrolyte to describe SEI formation effects as this descriptor clearly does not capture effects related to different electrode surface areas. We furthermore provided a first suggestion towards a better descriptor to study the effect of additives which we believe is the amount of substance to electrode surface area descriptor.