Ion and gas chromatography mass spectrometry investigations of organophosphates in lithium ion battery electrolytes by electrochemical aging at elevated cathode potentials
Abstract
The electrochemical aging of commercial non-aqueous lithium hexafluorophosphate (LiPF6)/organic carbonate solvent based lithium ion battery electrolyte has been investigated in view of the formation of ionic and non-ionic alkylated phosphates. Subject was a solvent mixture of ethylene carbonate/ethyl methyl carbonate EC:EMC (1:1, by wt.) with 1 M LiPF6 (LP50 Selectilyte™, BASF). The analysis was carried out by ion chromatography coupled with electrospray ionization mass spectrometry (ESI-MS) for ionic compounds and (headspace) gas chromatography mass spectrometry ((HS)-GC-MS) for non-ionic compounds. The electrochemical aging was performed by galvanostatic charge/discharge cycling and potentiostatic experiments with LiNi0.5Mn1.5O4 (LMNO) as cathode material at increased cut-off potentials (>4.5 V vs. Li/Li+). A strong dependence of the formation of organophosphates on the applied electrode potential was observed and investigated by quantitative analysis of the formed phosphates. In addition, new possible ;fingerprint; compounds for describing the electrolyte status were investigated and compared to existing compounds.
- Publication:
-
Journal of Power Sources
- Pub Date:
- February 2016
- DOI:
- 10.1016/j.jpowsour.2015.12.025
- Bibcode:
- 2016JPS...306..193W
- Keywords:
-
- IC-MS;
- GC-MS;
- LIBs;
- Electrolyte;
- Organophosphates;
- Elevated cathode potentials