Direct Detection of Manganese Ions in Organic Electrolyte by UV-vis Spectroscopy

Lithium manganese oxide cathodes used in Li-ion batteries suffer from manganese dissolution and capacity fade. We present a new technique for directly measuring the manganese ion (Mn2+) concentration in a typical Li-ion carbonate electrolyte using 4-(2-pyridylazo) resorcinol (PAR) as a UV-vis probe. Chelation between PAR and Mn2+ ion induces a characteristic absorption peak where the peak intensity corresponds to Mn2+ ion concentration in the electrolyte. Electrochemical stability of the probe is verified by performing potential hold and cyclic voltammetry. The in situ characterization of Mn dissolution in a customized battery cell is performed during cyclic voltammetry.