Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries

A. Dunst, V. Epp, I. Hanzu, S.A. Freunberger, M. Wilkening, Energy & Environmental Science 7 (2014) 2739–2752.

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Journal Article | Published | English
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Abstract
Understanding charge carrier transport in Li2O2, the storage material in the non-aqueous Li-O2 battery, is key to the development of this high-energy battery. Here, we studied ionic transport properties and Li self-diffusion in nanocrystalline Li2O2 by conductivity and temperature variable 7Li NMR spectroscopy. Nanostructured Li2O2, characterized by a mean crystallite size of less than 50 nm as estimated from X-ray diffraction peak broadening, was prepared by high-energy ball milling of microcrystalline lithium peroxide with μm sized crystallites. At room temperature the overall conductivity σ of the microcrystalline reference sample turned out to be very low (3.4 × 10−13 S cm−1) which is in agreement with results from temperature-variable 7Li NMR line shape measurements. Ball-milling, however, leads to an increase of σ by approximately two orders of magnitude (1.1 × 10−10 S cm−1); correspondingly, the activation energy decreases from 0.89 eV to 0.82 eV. The electronic contribution σeon, however, is in the order of 9 × 10−12 S cm−1 which makes less than 10% of the total value. Interestingly, 7Li NMR lines of nano-Li2O2 undergo pronounced heterogeneous motional narrowing which manifests in a two-component line shape emerging with increasing temperatures. Most likely, the enhancement in σ can be traced back to the generation of a spin reservoir with highly mobile Li ions; these are expected to reside in the nearest neighbourhood of defects generated or near the structurally disordered and defect-rich interfacial regions formed during mechanical treatment.
Publishing Year
Date Published
2014-08-01
Journal Title
Energy & Environmental Science
Volume
7
Issue
8
Page
2739-2752
IST-REx-ID

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Dunst A, Epp V, Hanzu I, Freunberger SA, Wilkening M. Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries. Energy & Environmental Science. 2014;7(8):2739-2752. doi:10.1039/c4ee00496e
Dunst, A., Epp, V., Hanzu, I., Freunberger, S. A., & Wilkening, M. (2014). Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries. Energy & Environmental Science, 7(8), 2739–2752. https://doi.org/10.1039/c4ee00496e
Dunst, A., V. Epp, I. Hanzu, Stefan Alexander Freunberger, and M. Wilkening. “Short-Range Li Diffusion vs. Long-Range Ionic Conduction in Nanocrystalline Lithium Peroxide Li2O2—the Discharge Product in Lithium-Air Batteries.” Energy & Environmental Science 7, no. 8 (2014): 2739–52. https://doi.org/10.1039/c4ee00496e.
A. Dunst, V. Epp, I. Hanzu, S. A. Freunberger, and M. Wilkening, “Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries,” Energy & Environmental Science, vol. 7, no. 8, pp. 2739–2752, 2014.
Dunst A, Epp V, Hanzu I, Freunberger SA, Wilkening M. 2014. Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries. Energy & Environmental Science. 7(8), 2739–2752.
Dunst, A., et al. “Short-Range Li Diffusion vs. Long-Range Ionic Conduction in Nanocrystalline Lithium Peroxide Li2O2—the Discharge Product in Lithium-Air Batteries.” Energy & Environmental Science, vol. 7, no. 8, RSC, 2014, pp. 2739–52, doi:10.1039/c4ee00496e.

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