Sulfone-based electrolytes for nonaqueous Li-O2 batteries

We investigated the use of sulfone-based electrolytes for the Li-O 2 battery. The study compared the behavior of three commercially available sulfones: ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS), also called sulfolane, and ethyl methyl sulfone (EMS). First, we carried out a preliminary investigation of the oxygen reduction reaction and oxygen evolution reaction (ORR/OER) as a function of solvent type and Li+ concentration. Then, TMS and EMS were tested (LiTFSI salt) in Li-O2 cells. The cells exhibited initial capacities around 1800 and 2000 mAh.g -1carbon, respectively. The capacity retention on cycling was quite low. We analyzed the reaction products during discharge and charge by means of powder X-ray diffraction, infrared spectroscopy, 1H-nuclear magnetic resonance, and mass spectrometry. Although EVS was at first sight the most attractive sulfone, since it is a liquid at room temperature, it was the least stable in the presence of oxygen; its vinyl group was attacked by reduced O2 species. On the other hand, both TMS and EMS performed better during the first five cycles; Li2O2 formation and decomposition was the main reaction, although some byproducts formed during cycling. After five cycles, there was still a considerable amount of Li 2O2 formed, but decomposition to form Li 2CO3 became significant, and it accumulated at the O 2 electrode. This was the likely reason for capacity fading. © 2014 American Chemical Society.

Publication year:2014

Keywords:Physical chemistry, Materials science

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BOF-publication weight:2

CSS-citation score:2

Authors:International

Authors from:Private, Higher Education

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