122nd General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Grand Ballroom
Time 10월 18일 (목요일) 11:00~12:30
Code MAT.P-350
Subject Synthesis of mesoporous molybdenum disulfide with double-gyroid structure and Comparison in reaction pathway of bulk and nano-sized molybdenum disulfide
Authors Yun Seok Choi, Gyuseong Lee1, Zhiyong Zheng2, Ji Man Kim*
Department of Chemistry, Sungkyunkwan University, Korea
1Chemistry, Sungkyunkwan University, Korea
2Chemistry, Sungkyunkwan University, China
Abstract MoS2 has superior electrochemical properties suitable for lithium ion battery, such as high theoretical capacity (670 mAh/g), low volumetric expansion during cycle (~103%) and the week vdw forces between layers, which enables facile intercalation/deintercalation of Li+. The lithium storage mechanism of MoS2 is widely known as an irreversible intercalation reaction in the first cycle and a reversible conversion reaction (MoS2 + 4Li+ + 4e- ↔ Mo + 2Li2S). However, there are some recent studies that contradict above mentioned mechanism and suggesting different reversible reaction path (Li2S ↔ 2Li+ + S-), similar to a lithium-sulfur battery reaction. In order to clarify the lithium storage mechanism of MoS2, we first synthesized ordered mesoporous MoS2 as a model structure to ascertain the complete mechanism by obtaining the maximum reversible capacity from this material. We utilized synchrotron radiation based characterization techniques to directly observe the local and bulk structural changes in the well-synthesized mesoporous MoS2 model material during the electrochemical cycling. The oxidation state changes of Mo and S were observed during the 1st irreversible and 2nd reversible electrochemical cycle using XAS and XPS. The in situ XRD experiment was used to confirm the formation of Li2S and/or Mo metal during the reversible reaction. In addition, SAXS was also used to observe the pore structure dynamics during the cycling of mesopourous MoS2 electrode.
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