期刊
ADVANCED MATERIALS
卷 30, 期 51, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.201804925
关键词
DFT calculations; in situ TEM; lithium-ion batteries; reversible phase transformations; tin selenides
类别
资金
- Clemson University
- U.S. DOE Office of Science Facility, at Brookhaven National Laboratory [DE-SC0012704]
- Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource [NSF ECCS-1542205]
- MRSEC program at the Materials Research Center [NSF DMR-1720139]
- International Institute for Nanotechnology (IIN)
- Keck Foundation
- State of Illinois, through the IIN
- Center for Electrochemical Energy Science, an Energy Frontier Research Center - U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences [DEAC02-06CH11357]
- Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231]
2D materials have shown great promise to advance next-generation lithium-ion battery technology. Specifically, tin-based chalcogenides have attracted widespread attention because lithium insertion can introduce phase transformations via three types of reactions-intercalation, conversion, and alloying-but the corresponding structural changes throughout these processes, and whether they are reversible, are not fully understood. Here, the first real-time and atomic-scale observation of reversible phase transformations is reported during the lithiation and delithiation of SnSe2 single crystals, using in situ high-resolution transmission electron microscopy complemented by first-principles calculations. Lithiation proceeds sequentially through intercalation, conversion, and alloying reactions (SnSe2 -> LixSnSe2 -> Li2Se + Sn -> Li2Se + Li17Sn4) in a manner that maintains structural and crystallographic integrity, whereas delithiation forms numerous well-aligned SnSe2 nanodomains via a homogeneous deconversion process, but gradually loses the coherent orientation in subsequent cycling. Furthermore, alloying and dealloying reactions cause dramatic structural reorganization and thereby consequently reduce structural stability and electrochemical cyclability, which implies that deep discharge for Sn chalcogenide electrodes should be avoided. Overall, the findings elucidate atomistic lithiation and delithiation mechanisms in SnSe2 with potential implications for the broader class of 2D metal chalcogenides.
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