Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe2 Single Crystals
- Northwestern Univ., Evanston, IL (United States); Clemson Univ., SC (United States)
- Northwestern Univ., Evanston, IL (United States); Harvard Univ., Cambridge, MA (United States)
- Northwestern Univ., Evanston, IL (United States)
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.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Center for Electrical Energy Storage (CEES); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States); Argonne National Laboratory (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-05CH11231; AC02-06CH11357; SC0012704
- OSTI ID:
- 1543461
- Alternate ID(s):
- OSTI ID: 1479535
- Journal Information:
- Advanced Materials, Vol. 30, Issue 51; ISSN 0935-9648
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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