Dresden 2006 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 3: Poster Session
DF 3.13: Poster
Montag, 27. März 2006, 09:30–17:00, P1
Investigation of Li diffusion in spinel-type structured Li4Ti5O12 by means of solid state NMR and impedance spectroscopy — •M. Wilkening, W. Iwaniak, R. Amade, and P. Heitjans — Hannover University, Institute of Physical Chemistry andElectrochemistry, D-30167 Hannover
The cubic spinel oxides Li1+xTi2−xO4 (0 ≤ x ≤ 1/3, space group Fd3m) are promising anode materials for lithium-ion rechargeable batteries. The end member of the Li-Ti-O series, Li4Ti5O12, can accommodate Li ions up to the composition Li7Ti5O12. Whereas a number of studies focus on the electrochemical behaviour of Li insertion into and Li diffusion in the Li intercalated material, only few investigations of Li dynamics in the non-intercalated host material Li4Ti5O12 are reported so far. Here, the Li diffusion in pure-phase microcrystalline Li4Ti5O12 with an average particle size in the µm range was probed by 7Li solid state NMR spectroscopy using spin-alignment echo (SAE) and spin-lattice relaxation (SLR) measurements. Between T = 295 K and 400 K extremely slow Li jump rates 1/τ ranging from 1 s−1 to 1000 s−1 were directly obtained by recording the decay of spin-alignment echoes at a Larmor frequency of 155 MHz as a function of mixing time and constant evolution time. 1/τ(1/T) follows Arrhenius behaviour with an activation energy EASAE of about 0.85 eV. Interestingly, EASAE is comparable to activation energies deduced from conductivity measurements rather than from SLR-measurements, EASLR ≈ 0.28 eV.