A review of gas evolution in lithium ion batteries

This is a review on recent studies into the gas evolution occurring within lithium ion batteries and the mechanisms through which the processes proceed. New cathode materials such as lithium nickel manganese cobalt oxides are being heavily researched for the development of higher specific capacity electrodes. These materials often suffer from rapid degradation which coincides with gas evolution. Further sources of gas evolution include electrolyte reduction at the anode during the initial cycles culminating in formation of a solid electrolyte interphase and surface layer compounds formed on the cathode during production and storage. There have been several techniques established for detection and quantification of gas evolution in ex situ and in situ studies, primarily gas chromatography mass spectrometry and differential/on-line electrochemical mass spectrometry.