Dimethyl sulfoxide-based electrolytes for rechargeable lithium batteries

Mixed solutions of dimethyl sulfoxide (DMSO) and low viscosity solvents have been examined as a solvent of the electrolyte for rechargeable lithium (Li) batteries. The electrolytic conductivities of LiClO4. LiBF4 and LiPF6 were measured as a function of the solvent composition. Maximum conductivities were observed in the DMSO concentration ranges of 60–80 mol% for LiClO4 and LiBF4, and 20–60 mol% for LiPF6. The highest conductivity of all examined systems was 1.6 × 10−2 S cm−1 in the solution containing 1,2-dimethoxyethane (DME) and LiPF6 as the co-solvent and the electrolyte, respectively. Polarization behavior and charge-discharge characteristics of the lithium electrode were investigated in the DMSO-based solutions. The cycling efficiency was markedly dependent not only on the co-solvent but also the Li salt. The highest efficiency on the nickel substrate was observed in LiPF6 (1 mol dm−3)/DMSO-DME (1:1 by volume). High rechargeability of Li was also expected in the solution containing LiClO4 or LiBF4 when aluminum was used as the substrate.