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.
| Original language | English |
|---|---|
| Article number | 1804925 |
| Journal | Advanced Materials |
| DOIs | |
| Publication status | Accepted/In press - Jan 1 2018 |
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Keywords
- DFT calculations
- in situ TEM
- lithium-ion batteries
- reversible phase transformations
- tin selenides
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
Cite this
Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe2 Single Crystals. / Kim, Sungkyu; Yao, Zhenpeng; Lim, Jin Myoung; Hersam, Mark C; Wolverton, Chris; Dravid, Vinayak P.; He, Kai.
In: Advanced Materials, 01.01.2018.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe2 Single Crystals
AU - Kim, Sungkyu
AU - Yao, Zhenpeng
AU - Lim, Jin Myoung
AU - Hersam, Mark C
AU - Wolverton, Chris
AU - Dravid, Vinayak P.
AU - He, Kai
PY - 2018/1/1
Y1 - 2018/1/1
N2 - 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.
AB - 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.
KW - DFT calculations
KW - in situ TEM
KW - lithium-ion batteries
KW - reversible phase transformations
KW - tin selenides
UR - http://www.scopus.com/inward/record.url?scp=85055726219&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85055726219&partnerID=8YFLogxK
U2 - 10.1002/adma.201804925
DO - 10.1002/adma.201804925
M3 - Article
JO - Advanced Materials
JF - Advanced Materials
SN - 0935-9648
M1 - 1804925
ER -