Dergi makalesi Açık Erişim

Features of cycling of lithium-sulfur cells with electrolytes based on sulfolane solutions of LiPF6 and LiBF4

2022    Karaseva, E. V.; Khramtsova, L. A.; Lobov, A. N.; Kuzmina, E. V.; Eroglu, D.; Kolosnitsyn, V. S.

In lithium-sulfur batteries, cell design, specifically electrolyte design, has a key impact on the battery perfor-mance. Development of sulfolane based electrolytes may grant the use of more available lithium salts such as LiClO4, LiPF6 and LiBF4, which are typically not preferred in lithium-sulfur batteries due to their reactive anions. Herein, in order to assess the reactivity of lithium polysulfides with various dimensions (with different lengths of the polysulfide chain) towards the anions of lithium electrolyte salts, the cycling of lithium-sulfur cells with 1 M solutions of LiPF6, LiBF4, and LiClO4 in sulfolane is studied in a wide (1.5-2.8 V) and narrow (limited) voltage ranges, corresponding to the high-voltage (2.1-2.8 V) and low-voltage (2.3-1.5 V) plateaus on the discharge curves. It is shown that the electrochemical characteristics of lithium-sulfur cells with sulfolane based electro-lytes of lithium perchlorate and lithium hexafluorophosphate differ significantly from those for sulfolane elec-trolyte based on lithium tetrafluoroborate. We believe that these differences are due to the direct chemical interaction of lithium polysulfides with the BF4 anion, which is confirmed by chronopotentiometry, 7Li and 11B NMR spectra, UV-Vis and electrochemical impedance spectroscopy of sulfolane solutions of the studied lithium salts, saturated with lithium polysulfides.