Determination of the MacMullin number

The main components of a battery are the positive and negative electrodes, together with the electrolyte, which provides only the ionic conductivity. The most common electrolytes are in the liquid state. Therefore, a separator is needed to provide a physical separation between the electrodes. The separator is soaked with electrolyte. The MacMullin number is a parameter used to determine the quality of a separator, in terms of ionic conductivity, when soaked with an electrolyte. The MacMullin number can be calculated, using the results of data fitting of two EIS experiments and the geometric factors of the measurement cells. In this application note, a commercial electrolyte is employed, together with a porous filter, used as a separator.