THE ELECTROCHEMICAL-BEHAVIOR OF TETRAHYDROFURAN AND PROPYLENE CARBONATE WITHOUT ADDED ELECTROLYTE

The electrochemical behaviour of tetrahydrofuran (THF) and propylene carbonate (PC) was investigated in the absence of deliberately added electrolyte using ultramicroelectrodes to minimize the effects of solution resistance. THF was found to breakdown anodically at > / 4 V vs. Li/Li+ (1 M) but was not reduced even at -2 V vs. Li/Li+ (1 M). PC was stable up to +5 V vs. Li/Li+ (1 M) and was reduced at potentials ≤1 V vs. Li/Li+ (1 M). The addition of 0.5% 2-methylfuran to THF inhibited the anodic breakdown of THF. The addition of 1,2-propanediol to PC produced a reduction wave at +1.4 V vs. Li/Li+ (1 M). Water in PC and THF was reduced at +2 V vs. Li/Li+ (1 M). The addition of water to PC also enhanced the cathodic limiting current. The implications for the behaviour of THF and PC in secondary Li cells are discussed. © 1990.