DC Method to Determine the MacMullin Number of Separators

Measuring MacMullin numbers via a simple direct current method

The MacMullin number is often measured by alternating current (AC) methods such as electrochemical impedance spectroscopy (EIS). While EIS is quite powerful and precise, it requires expensive equipment, and the acquired data is not always straightforward to interpret. For these reasons, direct current (DC) methods are sometimes preferable as a means of measuring conductivity.

In this application note, we describe the determination of the MacMullin number of a commercially available lithium-ion battery separator by a simple DC method, namely linear (current) sweep voltammetry (LSV), in a TCE Cell One test cell. In previous application notes we have shown how to use EIS for these calculations, using either a similar setup in the TCE Cell One or the “stacking method” in the TSC Battery cell.