Toward Sustainable Li–S Battery Using Scalable Cathode and Safe Glyme-Based Electrolyte

High Resolution Image Download MS PowerPoint Slide The search for safe electrolytes to promote the application of lithium–sulfur (Li–S) batteries may be supported by the investigation of viscous glyme solvents. Hence, electrolytes using nonflammable tetraethylene glycol dimethyl ether added by lowly viscous 1,3-dioxolane (DOL) are herein thoroughly investigated for sustainable Li–S cells. The electrolytes are characterized by low flammability, a thermal stability of ∼200 °C, ionic conductivity exceeding 10 –3 S cm –1 at 25 °C, a Li + transference number of ∼0.5, electrochemical stability window from 0 to ∼4.4 V vs Li + /Li, and a Li stripping-deposition overpotential of ∼0.02 V. The progressive increase of the DOL content from 5 to 15 wt % raises the activation energy for Li + motion, lowers the transference number, slightly limits the anodic stability, and decreases the Li/electrolyte resistance. The electrolytes are used in Li–S cells with a composite consisting of sulfur and multiwalled carbon nanotubes mixed in the 90:10 weight ratio, exploiting an optimized current collector. The cathode is preliminarily studied in terms of structure, thermal behavior, and morphology and exploited in a cell using standard electrolyte. This cell performs over 200 cycles, with sulfur loading increased to 5.2 mg cm –2 and the electrolyte/sulfur (E/S) ratio decreased to 6 μL mg –1 . The above sulfur cathode and the glyme-based electrolytes are subsequently combined in safe Li–S batteries, which exhibit cycle life and delivered capacity relevantly influenced by the DOL content within the studied concentration range.