期刊
ACS APPLIED MATERIALS & INTERFACES
卷 7, 期 3, 页码 1709-1719出版社
AMER CHEMICAL SOC
DOI: 10.1021/am5072942
关键词
Li-S batteries; Raman spectroscopy; sulfur reduction; kinetic of polysulfides formation and decomposition; partial discharge; carbon disulfide
资金
- Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub - U.S. Department of Energy, Office of Science, Basic Energy Sciences
In situ Raman spectroscopy and cyclic voltammetry were used to investigate the mechanism of sulfur reduction in lithium-sulfur battery slurry cathodes with 1 M lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (TEGDME)/1,3-dioxolane (DIOX) (1/1, v/v). Raman spectroscopy shows that long-chain polysulfides (S-8(2-)) were formed via S8 ring opening in the first reduction process at similar to 2.4 V vs Li/Li+ and short-chain polysulfides such as S4(2-), S-4(-), S-3(-), and S2O42- were observed with continued discharge at similar to 2.3 V vs Li/Li+ in the second reduction process. Elemental sulfur can be reformed in the end of the charge process. Rate constants obtained for the appearance and disappearance polysulfide species shows that short-chain polysulfides are directly formed from S8 decomposition. The rate constants for S8 reappearance and polysulfide disappearance on charge were likewise similar. The formation of polysulfide mixtures at partial discharge was found to be quite stable. The CS2 additive was found to inhibit the sulfur reduction mechanism allowing the formation of long-chain polysulfides during discharge only and stabilizing the S-8(2-) product.
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