Investigation of thermal aging and hydrolysis mechanisms in commercial lithium ion battery electrolyte

Abstract Novel methods based on hyphenated analytical techniques for the analysis of LiPF 6 commercially available battery electrolytes are presented. PF 6 − and the formed main decomposition products F − , PO 2 F 2 − and HPO 3 F − were separated by ion chromatography (IC) and detected by electrospray ionization mass spectrometry (ESI-MS). Inductively coupled plasma optical emission spectroscopy (ICP-OES) on the phosphorous trace supported the results obtained by ESI-MS. Samples, which were stored at room temperature and at 5 °C, were analyzed several times over a period of two weeks to demonstrate the progress of the hydrolysis of LiPF 6 in aqueous solution and commercially available electrolyte (EC/DEC (3:7 w/w) 1 M LiPF 6 ). Subsequently, the same commercially available electrolyte system was analyzed to prove the usefulness of the proposed method to investigate the influence of the thermal aging in lithium-ion batteries.