Qualitative and quantitative analysis of lithium ion battery electrolytes by different chromatographic methods

Abstract

Qualitative and quantitative analysis of lithium ion battery electrolytes by different chromatographic methods

Erwin Rosenberg(A)*, Chrysoula Kanakaki(A), Maria Antoniadou(A), Alfred Amon(B), Jürgen Kahr(B)

(A) Vienna University of Technology, Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164 AC, 1060 Vienna, Austria (B) AIT Austrian Institute of Technology GmbH, Electric Drive Technologies, Giefinggasse 2, 1210 Vienna, Austria *E-mail: erosen@mail.zserv.tuwien.ac.at

Lithium ion batteries (LIBs) are currently the most applied electrochemical energy storage systems in portable electric devices as well as for electromobility applications [1]. They have also become increasingly important as stationary storage systems, notably as "second life" applications [2]. This imposes great demands on the safety, reliability and efficiency (capacity and power) of LIBs. To this end, both novel electrode materials, separators and electrolytes are intensively investigated [3]. Given the high voltage of modern LIBs, only organic electrolytes provide a sufficiently wide electrochemical window of oxidation/ reduction stability. The mostly used electrolytes are ethylene carbonate (EC), dimethyl- (DMC) and diethyl carbonate (DEC) and mixtures thereof, with the addition of a lithium salt (e.g. LiPF6). Despite the presence of various additives, the electrolyte tends to degrade, particularly under conditions of heavy use and of abuse. The degradation of the LIB electrolyte compromises both its performance and its safety, making it thus necessary to better understand the processes and the conditions under which the LIB electrolyte suffers from degradation. In order to characterize the organic electrolyte and its degradation products, a variety of techniques have been developed and applied, both of spectroscopic and chromatographic nature. In this report we would like to present and critically assess the different approaches and techniques for chromatographic analysis of LIB electrolytes. Gas- and liquid chromatographic techniques with various sample preparation options will be introduced, and their merits for the analysis of LIBs discussed. Although the chromatographic techniques are well established, their application to LIB research is still challenging and requires adaptations due to the small sample amounts, the transient nature of the signals and the low concentrations of degradation products. We will present examples from our own and other published work on how these challenges can be overcome and important conclusions be drawn on the safety and stability of LIBs and their organic electrolytes.

KEYWORDS: lithum ion battery (LIB), gas chromatography liquid chromatography, ion chromatography, hyphenated techniques

ACKNOWLEDGMENTS: Financial support of part of this work through the Austrian Research Promotion Agency (FFG) under project nos. 835790 ("SiLithium") and 858298 ("DianaBatt") is gratefully acknowledged

REFERENCES: 1. O. Gröger, H.A. Gasteiger, J. -P. Suchsland, J. Electrochem. Soc. 2015, 62, A2605-A2622. 2. B. Dunn, H. Kamath, J.-M. Tarascon, Science 2011, 334 (6058) 928-935. 3. V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach, Energy Environ. Sci., 2011, 4, 3243-3262.