期刊
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
卷 163, 期 2, 页码 A223-A228出版社
ELECTROCHEMICAL SOC INC
DOI: 10.1149/2.0421602jes
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资金
- LG Chem. Co.
- National Research Foundation of Korea - MEST [NRF-2010-C1AAA001-2010-0029065]
- Korea Research Institute of Chemical Technology (KRICT)
We report here that the low-temperature performance of graphite electrode is improved by adding a small amount of elemental sulfur (S-8) into the graphite negative electrode. The reversible capacity at -30 degrees C is much larger for the sulfur-added graphite electrode. The origin of this beneficial feature is examined through impedance analysis, which illustrates that the charge transfer resistance is much smaller in the sulfur-added graphite electrode at low temperatures. In the first lithiation step, the elemental sulfur is electrochemically reduced to be lithium polysulfide (Li2S8), which is soluble in the working solvent (carbonate-based ones). Organic thiocarbonates are generated by the chemical reaction between the lithium polysulfide and carbonate solvents. The as-generated thiocarbonates are then electrochemically decomposed to form the sulfur-containing surface film. The superior low-temperature performance of the sulfur-added graphite is thus attributed to the presence of sulfur-enriched surface film, which seems to facilitate the charge transfer reaction between the graphite and lithium. (C) The Author(s) 2015. Published by ECS.
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