An analysis of the used electrolyte formulations was done via proton NMR. This allows for the investigation of the relative intensities of the signals originating from the solvent components, ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and the additives, FEC and VC. From these relative intensities information about the numerical ratio of the different molecules may be obtained. By using literature values for the molar mass of the molecules, information about the mass ratios can be obtained. This provides a means to check the mass ratios between the additives and the solvent.