Diffusion-induced 7Li NMR spin-lattice relaxation of fully lithiated, mixed-conducting Li7Ti5O12

Walter Schmidt, Martin Wilkening

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Li4Ti5O12 (LTO) belongs to one of the most promising anode materials for lithium-ion batteries. Its superior cycling performance and negligible aging make it a potential candidate to be used in, e.g., stationary applications. Besides this application-oriented interest it serves as an excellent model system to study Li ion transport in a 3D mixed conducting host crystallizing with spinel structure. Whereas Li ion diffusion in Li4Ti5O12 was the subject of several studies that appeared over the past years; Li ion transport in mixed conducting Li7Ti5O12 crystallizing with rock-salt type structure is, however, much less frequently investigated. Li7Ti5O12 is the compound that is formed after an LTO-type battery has been fully charged. In the present study we used spin-lock NMR relaxometry to quantify Li ion diffusion in terms of jump rates, activation energies and microscopic Li ion self-diffusion coefficients. Extending the measurements to higher temperatures enabled us to record the diffusion induced rate maxima from which Li+ self-diffusion coefficients were obtained directly. Compared to the non-lithiated source material Li4Ti5O12, showing poor Li ion diffusivity, Li ion diffusivity in Li7Ti5O12 is clearly enhanced but by far as high as recently reported for spinel-type Li4+xTi5O12, with x being significantly smaller than 1. Obviously, the small number of vacant 16c sites in Li7Ti5O12 as well as repulsive the 8a-16c interactions are responsible for the low Li ion diffusivity found.

Original languageEnglish
Pages (from-to)77-82
Number of pages6
JournalSolid State Ionics
Volume287
DOIs
Publication statusPublished - 1 Apr 2016

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Keywords

  • Anode materials
  • Diffusion
  • Ion hopping
  • Local structures
  • Solid-state NMR

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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