Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe2 Single Crystals

Sungkyu Kim, Zhenpeng Yao, Jin Myoung Lim, Mark C Hersam, Chris Wolverton, Vinayak P. Dravid, Kai He

Research output: Contribution to journalArticle

6 Citations (Scopus)

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 languageEnglish
Article number1804925
JournalAdvanced Materials
DOIs
Publication statusAccepted/In press - Jan 1 2018

Fingerprint

Chalcogenides
Alloying
Phase transitions
Single crystals
Tin
Intercalation
High resolution transmission electron microscopy
Lithium
Metals
Electrodes
Lithium-ion batteries

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 journalArticle

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 SnSe2 Single Crystals. In: Advanced Materials. 2018.
@article{4d53e5fd3d5c4f8eb233bef34fa48cbf,
title = "Atomic-Scale Observation of Electrochemically Reversible Phase Transformations in SnSe2 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.",
keywords = "DFT calculations, in situ TEM, lithium-ion batteries, reversible phase transformations, tin selenides",
author = "Sungkyu Kim and Zhenpeng Yao and Lim, {Jin Myoung} and Hersam, {Mark C} and Chris Wolverton and Dravid, {Vinayak P.} and Kai He",
year = "2018",
month = "1",
day = "1",
doi = "10.1002/adma.201804925",
language = "English",
journal = "Advanced Materials",
issn = "0935-9648",
publisher = "Wiley-VCH Verlag",

}

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

C2 - 30368925

AN - SCOPUS:85055726219

JO - Advanced Materials

JF - Advanced Materials

SN - 0935-9648

M1 - 1804925

ER -