An Unexpected Pathway: 6Li-Exchange NMR Spectroscopy Points to Vacancy-Driven Out-of-Plane Li-Ion Hopping in Crystalline Li2SnO3

J. Langer, D. L. Smiley, A. D. Bain, G. R. Goward, M. Wilkening

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The development and engineering of new materials for modern electrochemical energy-storage systems requires an in-depth understanding of Li-ion dynamics, not only on the macroscopic length scale but also from an atomic-scale point of view. Hence, the study of suitable model systems is indispensable to understand the complexity of nonmodel systems already applied, for example, as active materials in rechargeable batteries. Here, Li2SnO3 served as such a model system to enlighten the elementary steps of ion hopping between the three magnetically distinct Li sites. Through high-resolution 1D and 2D NMR spectroscopies, we probed the favored exchange pathway. Both 1D and 2D NMR spectroscopies point to nonuniform ion dynamics and two independent exchange processes perpendicular to the ab plane, namely, between the sites 4e [Li(3)] and 8f [Li(1)] and between 4e and 4d [Li(2)]. 6Li selective-inversion NMR spectroscopy confirmed extremely slow Li exchange and yielded hopping rates on the order of 3 s-1 for 4e-8f and 0.7 s-1 for 4e-4d. Altogether, the findings provide evidence for a three-site, two-exchange model describing Li hopping along the c axis rather than in the Li-rich ab plane as one would expect at first glance. This unexpected result can, however, be understood when the site preference of Li vacancies is considered. Recent theoretical calculations predicted the preferred formation of Li vacancies at the Li(3) sites. This allows for localized Li-ion exchange involving Li(3), thus, perfectly corroborating the present findings obtained by 6Li MAS NMR spectroscopy.

Original languageEnglish
Pages (from-to)3130-3138
Number of pages9
JournalJournal of Physical Chemistry C
Volume120
Issue number6
DOIs
Publication statusPublished - 18 Feb 2016
Externally publishedYes

Fingerprint

Nuclear magnetic resonance spectroscopy
Vacancies
Ions
Crystalline materials
nuclear magnetic resonance
spectroscopy
Ion exchange
ions
Secondary batteries
energy storage
Energy storage
electric batteries
engineering
inversions
high resolution

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

An Unexpected Pathway : 6Li-Exchange NMR Spectroscopy Points to Vacancy-Driven Out-of-Plane Li-Ion Hopping in Crystalline Li2SnO3. / Langer, J.; Smiley, D. L.; Bain, A. D.; Goward, G. R.; Wilkening, M.

In: Journal of Physical Chemistry C, Vol. 120, No. 6, 18.02.2016, p. 3130-3138.

Research output: Contribution to journalArticleResearchpeer-review

@article{2371ca3e06b348adb5815dd1cf5f0318,
title = "An Unexpected Pathway: 6Li-Exchange NMR Spectroscopy Points to Vacancy-Driven Out-of-Plane Li-Ion Hopping in Crystalline Li2SnO3",
abstract = "The development and engineering of new materials for modern electrochemical energy-storage systems requires an in-depth understanding of Li-ion dynamics, not only on the macroscopic length scale but also from an atomic-scale point of view. Hence, the study of suitable model systems is indispensable to understand the complexity of nonmodel systems already applied, for example, as active materials in rechargeable batteries. Here, Li2SnO3 served as such a model system to enlighten the elementary steps of ion hopping between the three magnetically distinct Li sites. Through high-resolution 1D and 2D NMR spectroscopies, we probed the favored exchange pathway. Both 1D and 2D NMR spectroscopies point to nonuniform ion dynamics and two independent exchange processes perpendicular to the ab plane, namely, between the sites 4e [Li(3)] and 8f [Li(1)] and between 4e and 4d [Li(2)]. 6Li selective-inversion NMR spectroscopy confirmed extremely slow Li exchange and yielded hopping rates on the order of 3 s-1 for 4e-8f and 0.7 s-1 for 4e-4d. Altogether, the findings provide evidence for a three-site, two-exchange model describing Li hopping along the c axis rather than in the Li-rich ab plane as one would expect at first glance. This unexpected result can, however, be understood when the site preference of Li vacancies is considered. Recent theoretical calculations predicted the preferred formation of Li vacancies at the Li(3) sites. This allows for localized Li-ion exchange involving Li(3), thus, perfectly corroborating the present findings obtained by 6Li MAS NMR spectroscopy.",
author = "J. Langer and Smiley, {D. L.} and Bain, {A. D.} and Goward, {G. R.} and M. Wilkening",
year = "2016",
month = "2",
day = "18",
doi = "10.1021/acs.jpcc.5b09894",
language = "English",
volume = "120",
pages = "3130--3138",
journal = "The journal of physical chemistry (Washington, DC) / C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "6",

}

TY - JOUR

T1 - An Unexpected Pathway

T2 - 6Li-Exchange NMR Spectroscopy Points to Vacancy-Driven Out-of-Plane Li-Ion Hopping in Crystalline Li2SnO3

AU - Langer, J.

AU - Smiley, D. L.

AU - Bain, A. D.

AU - Goward, G. R.

AU - Wilkening, M.

PY - 2016/2/18

Y1 - 2016/2/18

N2 - The development and engineering of new materials for modern electrochemical energy-storage systems requires an in-depth understanding of Li-ion dynamics, not only on the macroscopic length scale but also from an atomic-scale point of view. Hence, the study of suitable model systems is indispensable to understand the complexity of nonmodel systems already applied, for example, as active materials in rechargeable batteries. Here, Li2SnO3 served as such a model system to enlighten the elementary steps of ion hopping between the three magnetically distinct Li sites. Through high-resolution 1D and 2D NMR spectroscopies, we probed the favored exchange pathway. Both 1D and 2D NMR spectroscopies point to nonuniform ion dynamics and two independent exchange processes perpendicular to the ab plane, namely, between the sites 4e [Li(3)] and 8f [Li(1)] and between 4e and 4d [Li(2)]. 6Li selective-inversion NMR spectroscopy confirmed extremely slow Li exchange and yielded hopping rates on the order of 3 s-1 for 4e-8f and 0.7 s-1 for 4e-4d. Altogether, the findings provide evidence for a three-site, two-exchange model describing Li hopping along the c axis rather than in the Li-rich ab plane as one would expect at first glance. This unexpected result can, however, be understood when the site preference of Li vacancies is considered. Recent theoretical calculations predicted the preferred formation of Li vacancies at the Li(3) sites. This allows for localized Li-ion exchange involving Li(3), thus, perfectly corroborating the present findings obtained by 6Li MAS NMR spectroscopy.

AB - The development and engineering of new materials for modern electrochemical energy-storage systems requires an in-depth understanding of Li-ion dynamics, not only on the macroscopic length scale but also from an atomic-scale point of view. Hence, the study of suitable model systems is indispensable to understand the complexity of nonmodel systems already applied, for example, as active materials in rechargeable batteries. Here, Li2SnO3 served as such a model system to enlighten the elementary steps of ion hopping between the three magnetically distinct Li sites. Through high-resolution 1D and 2D NMR spectroscopies, we probed the favored exchange pathway. Both 1D and 2D NMR spectroscopies point to nonuniform ion dynamics and two independent exchange processes perpendicular to the ab plane, namely, between the sites 4e [Li(3)] and 8f [Li(1)] and between 4e and 4d [Li(2)]. 6Li selective-inversion NMR spectroscopy confirmed extremely slow Li exchange and yielded hopping rates on the order of 3 s-1 for 4e-8f and 0.7 s-1 for 4e-4d. Altogether, the findings provide evidence for a three-site, two-exchange model describing Li hopping along the c axis rather than in the Li-rich ab plane as one would expect at first glance. This unexpected result can, however, be understood when the site preference of Li vacancies is considered. Recent theoretical calculations predicted the preferred formation of Li vacancies at the Li(3) sites. This allows for localized Li-ion exchange involving Li(3), thus, perfectly corroborating the present findings obtained by 6Li MAS NMR spectroscopy.

UR - http://www.scopus.com/inward/record.url?scp=84959016661&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.5b09894

DO - 10.1021/acs.jpcc.5b09894

M3 - Article

VL - 120

SP - 3130

EP - 3138

JO - The journal of physical chemistry (Washington, DC) / C

JF - The journal of physical chemistry (Washington, DC) / C

SN - 1932-7447

IS - 6

ER -