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Title: Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe 2 Single Crystals

Abstract

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.

Authors:
 [1];  [2];  [3];  [3];  [3];  [3]; ORCiD logo [1]
  1. Department of Materials Science and Engineering, Clemson University, Clemson SC 29634 USA; Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA
  2. Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge MA 02138 USA
  3. Department of Materials Science and Engineering, Northwestern University, Evanston IL 60208 USA
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1543461
DOE Contract Number:  
AC02-05CH11231; AC02-06CH11357; SC0012704
Resource Type:
Journal Article
Journal Name:
Advanced Materials
Additional Journal Information:
Journal Volume: 30; Journal Issue: 51; Journal ID: ISSN 0935-9648
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
Chemistry; Science & Technology - Other Topics; Materials Science; Physics

Citation Formats

Kim, Sungkyu, Yao, Zhenpeng, Lim, Jin-Myoung, Hersam, Mark C., Wolverton, Chris, Dravid, Vinayak P., and He, Kai. Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe 2 Single Crystals. United States: N. p., 2018. Web. doi:10.1002/adma.201804925.
Kim, Sungkyu, Yao, Zhenpeng, Lim, Jin-Myoung, Hersam, Mark C., Wolverton, Chris, Dravid, Vinayak P., & He, Kai. Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe 2 Single Crystals. United States. doi:10.1002/adma.201804925.
Kim, Sungkyu, Yao, Zhenpeng, Lim, Jin-Myoung, Hersam, Mark C., Wolverton, Chris, Dravid, Vinayak P., and He, Kai. Thu . "Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe 2 Single Crystals". United States. doi:10.1002/adma.201804925.
@article{osti_1543461,
title = {Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe 2 Single Crystals},
author = {Kim, Sungkyu and Yao, Zhenpeng and Lim, Jin-Myoung and Hersam, Mark C. and Wolverton, Chris and Dravid, Vinayak P. and He, Kai},
abstractNote = {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.},
doi = {10.1002/adma.201804925},
journal = {Advanced Materials},
issn = {0935-9648},
number = 51,
volume = 30,
place = {United States},
year = {2018},
month = {10}
}

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