N2O as a Universal Reaction Gas to Overcome Spectral Interference in Determining Metal Impurities in Mg(TFSI)2 Electrolytes for Rechargeable Magnesium Batteries by Inductively Coupled Plasma Tandem Mass Spectrometry.

A new strategy for the determination of metal impurities in magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) electrolytes for rechargeable magnesium batteries using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was proposed. Mg(TFSI)2 was dissolved in 1,2-dimethoxyethane (DME), and 13 metal impurity elements were directly determined. Since N2 has a lower O atom affinity (1.6 eV) than the O atom (5.2 eV), N2O was a more effective O atom transfer gas than O2. In the MS/MS mode, N2O was selected as the reaction gas, and high sensitivities and low limits of detection (LODs) of analytes were obtained by mass shift methods. The accuracy of proposed analytical methods was assessed by the spike recovery experiments and comparative analyses using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). LODs were in the range of 0.18-26.6 ng kg-1, the recoveries were 92.5%-107%, and the relative standard deviation (RSD) was 2.0%-5.3%. No significant difference was observed between the ICP-MS/MS and SF-ICP-MS results at a 95% confidence level. The measurement realized the rapid determination of 13 metal impurity elements in Mg(TFSI)2 using N2O as a reaction gas with high sensitivity, accuracy, and precision. The method was applied for the analysis of Mg(TFSI)2 products with satisfactory results.