Study of the response characteristics of an online electrochemical mass spectrometry system for gas analysis of lithium-ion cells by using chronoamperometry

Abstract

Abstract Online electrochemical mass spectrometry (OEMS) is a promising analytical technique to monitor the gas evolution reactions, taking place while charging and discharging a lithium-ion cell. However, besides the manifold examples of these custom-made systems and their application, a clear analytical view on the origin of the evolving gases and their manifold interactions within the cell environment is missing and therefore studied in this work. To get a better understanding of the complexity of gas evolution associated with electrochemical reactions in lithium-ion cells, the use of chrono-amperometry as a fundamental analytical method was chosen. This led to a precise variation of the applied voltage and voltage-pulse length and enabled therewith a clear starting point of the electrochemical triggered reactions. It was found that the release of gaseous species strongly depends on the applied voltage and the cell configuration itself. The response time determination showed a response behavior within minutes with differences for the respective gases of interest. The herein presented methodology shows how an electroanalytical approach can help to gain further insight into advanced hyphenated methods, such as OEMS in the context of studies of lithium-ion cells.