The redox processes of Li2Sn false(6⩽n⩽12false) at a glassy carbon electrode in THF was studied by programmed cyclic voltammetry in the range of +1300 to −2000 mV (vs. polysulfide reference electrode) at sweep rates of 2–200 mV/s. One anodic and up to three cathodic peaks were detected. The anodic peak seems to result from the oxidation of all PS's through the same intermediate to elemental sulfur. The first cathodic peak is caused by the reduction of all PS false(n>6false) to Li2S6 in a diffusion controlled reaction. The second reduction peak most likely arises from the reduction of S62− to S52− . This is apparently preceded by a chemical step. The third reduction peak is caused by the reduction of S52− to S22− or S2− or a mixture of both in a diffusion‐controlled reaction. The high Tafel slope of the third peak apparently results from passivation of the electrode by the precipitation of Li2S and Li2S2 .

The lithium‐sulfur battery recently developed in our laboratory shows 95%+ sulfur utilization but low rate capability due to its poorly conducting electrolyte, which is based on a THF:toluene solvent mixture. In order to increase the rate capability of this cell, dioxolane‐based electrolytes have been evaluated. The conductivity of LiClO4 electrolytes consisting of mixtures of THF, toluene, and dioxolane were measured in the temperature range −30° to +60°C. The compatibility of lithium with these electrolytes was also studied. It was found that dioxolane‐rich electrolytes are compatible with lithium and have one order of magnitude higher conductivity than do THF:toluene‐rich electrolytes. However, sulfur utilization in dioxolane‐rich electrolytes is only 50%, even at a very low discharge rate. This is due to a different discharge product, namely, Li2S2 .

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ChemInform Abstract Cyclic voltammograms of Li2Sn(6 ≤ n ≤ 12), recorded in THF at a glassy carbon electrode in the range +1300 to -2000 mV at sweep rates of 2-200 mV/s, show one anodic and up to three cathodic peaks. The anodic peak is assigned to the xidation of all polysulfides (PS) to elemental sulfur via the same intermediate. The first cathodic peak is caused by the reduction of all PS (n > 6) to Li2S6 in a diffusion controlled reaction. The second cathodic peak is most probably due to reduction of S62-to S52-. The hird reduction peak results from the reduction of S52-to S22-or S2-in a diffusion-controlled reaction. The high Tafel slope of the third peak is explained by passivation of the electrode by precipitation of Li2S and Li2S2.

ChemInform Abstract The conductivity of LiClO4 electrolytes consisting of mixtures of THF, toluene, and dioxolane is measured over the temp. range -30 to +60 rc C and the compatibility of Li with these electrolytes is studied. The conductivity of dioxolane-rich electrolytes, which are found to be compatible with lithium, is one order of magnitude higher than that of THF/toluene mixtures. However, the sulfur utilization in dioxolane-rich electrolytes is only 50%, whereas 95% is achieved with dioxolane-free electrolytes. This may be explained by the different discharge products, (Li2S2 in dioxolane-rich electrolytes and Li2S in THF/toluene mixtures).