Operando detection of gas evolution from lithium-ion batteries

Abstract

The aim of this study was to investigate commercially relevant lithium-ion battery materials, using operando pressure measurements in conjunction with conventional electrochemical analysis techniques. Quantifying gas evolution provides important insights about the reactions taking place during the operation of lithium-ion battery materials; for instance, the reaction of SEI formation on graphite, which is critical to achieve good battery performance, involves gas evolution. This thesis focused on the study of the gas evolution properties of a high-performance graphite anode and the effect of the presence of electrolyte additives and dissolved transition metals.
Electrolyte additives are used in commercial lithium-ion batteries to drastically improve their performance, thus understanding their effect on the gas evolution properties of graphite anodes is important to elucidate their effect on the reactions of SEI formation. Dissolved transition metals are produced as a result of degradation of cathode materials, and understanding their effect on the battery gas evolution properties of the graphite anode is important to unravel crosstalk effects that lead to exacerbated battery degradation.
Firstly, galvanostatic cell cycling was employed to evaluate the electrochemical performance of industry standard electrode materials and electrolyte additives. From these experiments, it was then possible to see the electrochemical impact from varying the cell environment, such as differences in cell capacity and efficiency when changing electrode production methods or the introduction of various electrolyte additives.
Secondly, a highly sensitive operando pressure measurement technique, developed from adapted Swagelok union cell parts, was used to monitor gas evolution events during the electrochemical cycling of cells. This technique, when used in conjunction with Galvanostatic cycling, reveals clear impacts of additives and transition metals on key gassing events within lithium-ion batteries.
The clear impact of electrolyte additives and transition metal dissolution was observed in both the electrochemical performance and gas evolution volume. Transition metal dissolution predictably decreased electrochemical performance whilst increasing gas evolution volume, whilst the presence of commercially relevant electrolyte additives such as Vinylene Carbonate exhibited its clear ability to suppress gassing reactions and improve electrochemical performance.

More information

Identifiers

ORCID for Nuria Garcia-Araez: orcid.org/0000-0001-9095-2379

Catalogue record

Export record