TU Darmstadt / ULB / TUbiblio

7Li NMR studies of lithium ion dynamics in polymer-derived silicon oxycarbide ceramics

Haaks, Michael and Kaspar, Jan and Franz, Anjuli and Graczyk-Zajac, Magdalena and Riedel, Ralf and Vogel, Michael (2016):
7Li NMR studies of lithium ion dynamics in polymer-derived silicon oxycarbide ceramics.
In: Solid State Ionics, Elsevier Science Publishing, pp. 28-35, 287, ISSN 01672738,
[Online-Edition: http://dx.doi.org/10.1016/j.ssi.2016.01.041],
[Article]

Abstract

7Li NMR spin–lattice relaxation, line-shape, and stimulated-echo analyses are performed to investigate lithium ionic motion in a polymer-derived silicon oxycarbide (SiOC) ceramic. In particular, we compare microscopic jump dynamics in lithiated and delithiated compounds. We find that the large variety of lithium environments in the studied SiOC ceramic results in broad distributions of correlation times for the jump motion of the lithium ions, but the experimental results yield no evidence that clearly distinguishable lithium dynamics can be attributed to various electrochemically active lithium sites in different regions of structurally heterogeneous carbon-rich materials. Moreover, we observe that the lithium ionic jumps are, on average, faster in the lithiated than in the delithiated compound at ambient temperatures. Specifically, the mean logarithmic correlation times amount to τm = 2 ⋅ 10-4 s and τm = 1 ⋅ 10-2 s for the former and latter samples at 300 K, respectively. On the other hand, the temperature dependence of lithium jumps is higher for lithiated than for delithiated SiOC so that the difference in the ionic mobilities is reduced upon cooling. Finally, we show that the prepared lithiated and delithiated samples undergo irreversible changes when heating to 400 K. Specifically, when subject to thermal treatment, 7Li spin–lattice relaxation becomes slower for one lithium fraction, while it remains unaffected for another lithium fraction.

Item Type: Article
Erschienen: 2016
Creators: Haaks, Michael and Kaspar, Jan and Franz, Anjuli and Graczyk-Zajac, Magdalena and Riedel, Ralf and Vogel, Michael
Title: 7Li NMR studies of lithium ion dynamics in polymer-derived silicon oxycarbide ceramics
Language: English
Abstract:

7Li NMR spin–lattice relaxation, line-shape, and stimulated-echo analyses are performed to investigate lithium ionic motion in a polymer-derived silicon oxycarbide (SiOC) ceramic. In particular, we compare microscopic jump dynamics in lithiated and delithiated compounds. We find that the large variety of lithium environments in the studied SiOC ceramic results in broad distributions of correlation times for the jump motion of the lithium ions, but the experimental results yield no evidence that clearly distinguishable lithium dynamics can be attributed to various electrochemically active lithium sites in different regions of structurally heterogeneous carbon-rich materials. Moreover, we observe that the lithium ionic jumps are, on average, faster in the lithiated than in the delithiated compound at ambient temperatures. Specifically, the mean logarithmic correlation times amount to τm = 2 ⋅ 10-4 s and τm = 1 ⋅ 10-2 s for the former and latter samples at 300 K, respectively. On the other hand, the temperature dependence of lithium jumps is higher for lithiated than for delithiated SiOC so that the difference in the ionic mobilities is reduced upon cooling. Finally, we show that the prepared lithiated and delithiated samples undergo irreversible changes when heating to 400 K. Specifically, when subject to thermal treatment, 7Li spin–lattice relaxation becomes slower for one lithium fraction, while it remains unaffected for another lithium fraction.

Journal or Publication Title: Solid State Ionics
Volume: 287
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: 7Li NMR, Lithium ion dynamics, Lithium-ion battery, Anode material, Silicon oxycarbide ceramic
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
05 Department of Physics > Institute for condensed matter physics
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
05 Department of Physics
Date Deposited: 11 Apr 2016 12:06
Official URL: http://dx.doi.org/10.1016/j.ssi.2016.01.041
Identification Number: doi:10.1016/j.ssi.2016.01.041
Funders: Funding of the Deutsche Forschungsgemeinschaft (DFG) through grants VO 905/12-1, SFB595/A4, and SPP1473/JP8 is gratefully acknowledged.
Export:
Suche nach Titel in: TUfind oder in Google

Optionen (nur für Redakteure)

View Item View Item