SUPPRESSION OF ELECTROCHEMICAL DECOMPOSITION OF PROPYLENE CARBONATE AT A GRAPHITE ANODE IN LITHIUM-ION CELLS

The decomposition of propylene carbonate (PC) at a graphite anode in l ithium-ion cells is suppressed remarkably by choosing a proper mixing ratio of PC with co-existing solvents. For example, the decomposition of PC is essentially inhibited using PC-diethyl carbonate (DEC), PC-me thylethyl carbonate (MEG) or PC-dimethyl carbonate (DMC) with 1:4 (v/v ) mixed solvent solution containing a volume % of PC of less than 25%. Conductivity measurements show that all PC molecules can be solvated to Li+ ions as Li(PC)? in these mixed solvents, where 1.0 M LiPF6 and 25 vol. % of PC are used. This suggests that the solvated PC molecules are not decomposed at graphite anode.