Experimental Visualization of Interstitialcy Diffusion of Li Ion in β‑Li2TiO3
journal contributionposted on 18.07.2019 by Keisuke Mukai, Masatomo Yashima, Keisuke Hibino, Takayuki Terai
Any type of content formally published in an academic journal, usually following a peer-review process.
Monoclinic lithium metatitanate, β-Li2TiO3, is a member of the Li2MO3 (M = Ti, Mn, Sn, Ru, and/or Ir) series and an important cation conductor for various energy applications such as Li-ion batteries and nuclear fusion reactors. Comprehensive knowledge of the crystal structure is vital to understand the Li-ion diffusion mechanism, and several possibilities were proposed previously. However, the exact crystal structure and Li-ion diffusion paths of β-Li2TiO3 are still unclear. Here, the results of a neutron diffraction study of high-purity 7Li-enriched β-Li2TiO3 are reported. The occupancy factor 0.033(3) and the atomic coordinates of the interstitial Li ion in the Li–O layer are successfully refined by Rietveld analysis of the time-of-flight neutron diffraction data. The three-dimensional network of Li-ion diffusion pathways is visualized by a combined technique of high-temperature neutron-diffraction and maximum-entropy methods. An interstitialcy diffusion mechanism, in which a lithium ion migrates through both the interstitial tetrahedral and lattice octahedral sites, is proposed for the Li2MO3 series.