Dispersed Solid Conductors: Fast Interfacial Li-Ion Dynamics in Nanostructured LiF and LiF:gamma-Al2O3 Composites: Fast Interfacial Li-Ion Dynamics in Nanostructured LiF and LiF γ-Al 2 O 3 Composites

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Abstract

Lithium fluoride serves as a model substance to study Li and F hopping processes in a material solely composed of mobile ions with an opposite charge. In its microcrystalline form, it is known to be a very poor ionic conductor. Here, we tried to boost ion dynamics in LiF by taking advantage of size effects and the introduction of structural disorder. Compared to micro-LiF, we observed an increase of the ion conductivity by 2 orders of magnitude for nanocrystalline LiF prepared by high-energy ball milling. A further boost might be achieved in nanocrystalline two-phase systems consisting of LiF and an insulator, such as amphoteric γ-Al 2 O 3 . In such dispersed ionic conductors, percolating conductor/insulator pathways are anticipated enabling the ions to move quickly over long distances. Indeed, for nano-LiF:Al 2 O 3 , another drastic increase of ionic conductivity by 3 orders of magnitude (393 K) is achieved by interface engineering. The activation energy characterizing long-range ion transport is reduced from 0.98 eV (nanocrystalline LiF) to 0.79 eV for (LiF) 0.86 (Al 2 O 3 ) 0.14 . 7 Li nuclear magnetic resonance (NMR) measurements showed that Li + is mainly responsible for this increase seen for nano-LiF:Al 2 O 3 . 27 Al magic angle spinning NMR revealed that pentacoordinated Al species act as anchor sites for F - anions (and Li + ). This mechanism is assumed to lead to a 3D network of fast Li + diffusion pathways along the conductor/insulator interfaces.

Original languageEnglish
Pages (from-to)5222-5230
Number of pages9
JournalJournal of Physical Chemistry C
Volume123
Issue number9
DOIs
Publication statusPublished - 7 Mar 2019

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conductors
Ions
composite materials
Composite materials
insulators
ions
acceleration (physics)
Nuclear magnetic resonance
Magnetic resonance measurement
lithium fluorides
nuclear magnetic resonance
binary systems (materials)
Magic angle spinning
Ball milling
Ionic conductivity
Anchors
metal spinning
ion currents
Anions
balls

ASJC Scopus subject areas

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

Cite this

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title = "Dispersed Solid Conductors: Fast Interfacial Li-Ion Dynamics in Nanostructured LiF and LiF:gamma-Al2O3 Composites: Fast Interfacial Li-Ion Dynamics in Nanostructured LiF and LiF γ-Al 2 O 3 Composites",
abstract = "Lithium fluoride serves as a model substance to study Li and F hopping processes in a material solely composed of mobile ions with an opposite charge. In its microcrystalline form, it is known to be a very poor ionic conductor. Here, we tried to boost ion dynamics in LiF by taking advantage of size effects and the introduction of structural disorder. Compared to micro-LiF, we observed an increase of the ion conductivity by 2 orders of magnitude for nanocrystalline LiF prepared by high-energy ball milling. A further boost might be achieved in nanocrystalline two-phase systems consisting of LiF and an insulator, such as amphoteric γ-Al 2 O 3 . In such dispersed ionic conductors, percolating conductor/insulator pathways are anticipated enabling the ions to move quickly over long distances. Indeed, for nano-LiF:Al 2 O 3 , another drastic increase of ionic conductivity by 3 orders of magnitude (393 K) is achieved by interface engineering. The activation energy characterizing long-range ion transport is reduced from 0.98 eV (nanocrystalline LiF) to 0.79 eV for (LiF) 0.86 (Al 2 O 3 ) 0.14 . 7 Li nuclear magnetic resonance (NMR) measurements showed that Li + is mainly responsible for this increase seen for nano-LiF:Al 2 O 3 . 27 Al magic angle spinning NMR revealed that pentacoordinated Al species act as anchor sites for F - anions (and Li + ). This mechanism is assumed to lead to a 3D network of fast Li + diffusion pathways along the conductor/insulator interfaces.",
author = "S. Breuer and V. Pregartner and S. Lunghammer and Wilkening, {H. M.R.}",
year = "2019",
month = "3",
day = "7",
doi = "10.1021/acs.jpcc.8b10978",
language = "English",
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pages = "5222--5230",
journal = "The journal of physical chemistry (Washington, DC) / C",
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TY - JOUR

T1 - Dispersed Solid Conductors: Fast Interfacial Li-Ion Dynamics in Nanostructured LiF and LiF:gamma-Al2O3 Composites

T2 - Fast Interfacial Li-Ion Dynamics in Nanostructured LiF and LiF γ-Al 2 O 3 Composites

AU - Breuer, S.

AU - Pregartner, V.

AU - Lunghammer, S.

AU - Wilkening, H. M.R.

PY - 2019/3/7

Y1 - 2019/3/7

N2 - Lithium fluoride serves as a model substance to study Li and F hopping processes in a material solely composed of mobile ions with an opposite charge. In its microcrystalline form, it is known to be a very poor ionic conductor. Here, we tried to boost ion dynamics in LiF by taking advantage of size effects and the introduction of structural disorder. Compared to micro-LiF, we observed an increase of the ion conductivity by 2 orders of magnitude for nanocrystalline LiF prepared by high-energy ball milling. A further boost might be achieved in nanocrystalline two-phase systems consisting of LiF and an insulator, such as amphoteric γ-Al 2 O 3 . In such dispersed ionic conductors, percolating conductor/insulator pathways are anticipated enabling the ions to move quickly over long distances. Indeed, for nano-LiF:Al 2 O 3 , another drastic increase of ionic conductivity by 3 orders of magnitude (393 K) is achieved by interface engineering. The activation energy characterizing long-range ion transport is reduced from 0.98 eV (nanocrystalline LiF) to 0.79 eV for (LiF) 0.86 (Al 2 O 3 ) 0.14 . 7 Li nuclear magnetic resonance (NMR) measurements showed that Li + is mainly responsible for this increase seen for nano-LiF:Al 2 O 3 . 27 Al magic angle spinning NMR revealed that pentacoordinated Al species act as anchor sites for F - anions (and Li + ). This mechanism is assumed to lead to a 3D network of fast Li + diffusion pathways along the conductor/insulator interfaces.

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