Sulfones with different length of oligo ethylene glycol segments have been synthesized and tested for use in rechargeable lithium batteries. Relative to the model compound ethylmethyl sulfone (EMS), which has a melting point of 36.5°C, the new sulfones have low melting points, mostly depressed below room temperature. Their conductivities are lower than that of EMS. The highest ambient temperature conductivity of 10-2.58 S cm-1 was obtained for 0.7 M LiTFSI/MEMS solution (MEMS is methoxyethylmethylsulfone). The sulfones showed wide electrochemical stability windows, in excess of 5.0 V vs. Li/Li+, increasing with decreasing length of the oligoether chains. Unlike their fluorinated analogs, the present sulfones prove incompatible with graphite anode hosts, but a cell with lithium metal anode and manganate cathode performed well, maintaining good coulomb efficiency over 200 cycles.
- Cell cycling
- Electrochemically stable solvents
- Ionic conductivity
- Lithium batteries
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