イオン液体を用いた硫黄系二次電池 [in Japanese] Room-Temperature Ionic Liquid Electrolytes for Alkali Metal-Sulfur Batteries [in Japanese]
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Bis (trifluoromethanesulfonyl) amide (TFSA) based room-temperature ionic liquids (RTILs) were used as electrolytes for lithium-sulfur (Li-S) and sodium-sulfur (Na-S) batteries. The discharge-charge cycle stability and coulombic efficiency of Li-S cells with TFSA-based RTILs were found to be surprisingly superior to those of a cell with a conventional organic electrolyte consisting of tetrahydrofuran (THF) and a Li slat. The poor cycle stability of the cell with the conventional organic electrolyte was attributed to the dissolution of lithium or sodium polysulfides (<i>M</i><sub>2</sub>S<i><sub>m</sub></i>, <i>M</i> = alkali metal, 2 ≤ <i>m</i> ≤ 8), which were generated as reaction intermediates through redox processes at the S cathode in the <i>M</i>-S cell. TFSA-based RTILs have low donor ability owing to the weak Lewis basicity of [TFSA]<sup>−</sup> anion, whereas conventional ether-based molecular solvents, such as THF, have high donor ability. The dissolution of <i>M</i><sub>2</sub>S<sub><i>m</i></sub> was significantly suppressed owing to the weak donor ability of RTILs.
- Hyomen Kagaku
Hyomen Kagaku 34(6), 309-314, 2013-06-10
The Surface Science Society of Japan