Short-range Li diffusion vs. long-range ionic conduction in nanocrystalline lithium peroxide Li2O2—the discharge product in lithium-air batteries Dunst, A. Epp, V. Hanzu, I. Freunberger, Stefan Alexander ; https://orcid.org/0000-0003-2902-5319 Wilkening, M. 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. RSC 2014 info:eu-repo/semantics/article doc-type:article article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/7302 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. <i>Energy &#38; Environmental Science</i>. 2014;7(8):2739-2752. doi:<a href="https://doi.org/10.1039/c4ee00496e">10.1039/c4ee00496e</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1039/c4ee00496e info:eu-repo/semantics/altIdentifier/issn/1754-5692 info:eu-repo/semantics/altIdentifier/issn/1754-5706 info:eu-repo/semantics/closedAccess