THE ELECTROCHEMICAL-BEHAVIOR OF 2-METHYLTETRAHYDROFURAN SOLUTIONS

The electrochemical behaviour of 2-methyltetrahydrofuran (2Me-THF) solutions with lithium and noble metal electrodes was investigated. Surface-sensitive FTIR, X-ray microanalysis and scanning electron microscopy were applied in conjunction with electrochemical techniques in order to characterize the electrode surfaces in solutions and to correlate the cycling efficiency and surface morphology of lithium electrodes with their surface chemistry in solutions. The influence of a variety of contaminants, including oxygen, water, CO2, nitrogen, furans and paraffin oil, on the Li cycling efficiency, morphology and surface chemistry was also studied. It was found that the surface films formed on lithium in 2Me-THF contained several types of alkoxides. The presence of trace O2, water, CO2; and furans modifies the structure of these surface films and influences both the morphology and the Li cycling efficiency. The best efficiency of Li electrodes in charge-discharge cycling was obtained with uncontaminated LiAsF6 + 2Me-THF solutions. © 1990.