THE ELECTROCHEMICAL-BEHAVIOR OF 1,3-DIOXOLANE-LICLO4 SOLUTIONS .2. CONTAMINATED SOLUTIONS

The electrochemical behavior of contaminated 1,3-dioxolane (DN)-LiClO4 solutions with lithium and noble metals (e.g gold, platinum) electrodes was investigated using surface sensitive FT-ir, scanning electron microscopy, (SEM), X-ray microanalysis, linear sweep voltammetry and other electrochemical techniques. The contaminants included products of polymerization of DN, water and oxygen. It was found that the above contaminants considerably influence surface chemistry of lithium or noble metal electrodes in DN solution. The presence of polymeric species (resulting from solvent reactions) in solutions increases the solubility of solvent, water or oxygen reduction products and therefore reduces the "natural" passivation of lithium or noble metals at low potentials in solutions. Consequently, water or solvent reduction at low potentials is more feasible compared to other polar aprotic systems. Thus, the voltammetric behavior of contaminated DN solutions is quite different compared to other ethereal solutions. The presence of the above contaminants in DN solutions is detrimental to the performance of Li electrodes. This is in contrast to several polar aprotic systems where the presence of O2 or even H2O increases Li cycling efficiency. © 1990.