2002 Volume 70 Issue 5 Pages 334-336
The electrolytic conductivity and charge-discharge characteristics of the lithium electrode were examined in ternary solvent systems made up of an ethylene carbonate (EC)-dimethyl carbonate (DMC) equimolar binary mixture with 3-methylsydnone (3-MSD) and 3-ethylsydnone (3-ESD). The electrolytes used were LiClO4, LiPF6, LiBF4, LiCF3SO3, LiN(CF3SO2)2, and LiN(C2F5SO2)2. The order of the decrease in conductivity of the ternary solvent electrolytes at a mol ratio 0.5 of 3-MSD and 3-ESD was LiPF6>LiClO4>LiN(CF3SO2)2>LiN(C2F5SO2)2>LiBF4>LiCF3SO3. The 1 mol dm3 LiN(CF3SO2)2 and LiN(C2F5SO2)2 electrolytes with large anions showed moderate conductivities of higher than 6-7 mS cm−1 at a mol ratio 0.5 of 3-MSD and 3-ESD. Addition of 3-MSD and 3-ESD to the EC-DMC equimolar binary mixtures containing LiClO4, LiBF4, LiCF3SO3, and LiN(CF3SO2)2 is effective for raising lithium electrode cycling efficiency. We found by using scanning electron microscope (SEM) that the cycling efficiency is dependent on the dendrite formation and the morphology of the film formed on the Ni (working) electrode.