Ultraslow Li diffusion in spinel-type structured Li4Ti5O12—A comparison of results from solid state NMR and impedance spectroscopy

摘要: The cubic spinel oxides Li1+xTi2−xO4 (0 ≤ x ≤ 1/3) are promising anode materials for lithium-ion rechargeable batteries. end member of the Li–Ti–O series, Li4Ti5O12, can accommodate Li ions up to composition Li7Ti5O12. Whereas a number studies focus on electrochemical behaviour insertion into and diffusion in intercalated material, only few investigations about low-temperature dynamics non-intercalated host material Li4Ti5O12 have been reported so far. In present paper, pure-phase microcrystalline with an average particle size μm range was probed by 7Li solid state NMR spectroscopy using spin-alignment echo (SAE) spin–lattice relaxation (SLR) measurements. Between T = 295 K 400 extremely slow jump rates τ−1 ranging from 1 s−1 2200 were directly measured recording decay echoes as function mixing time constant evolution time. results point out Li4Ti5O12· τ−1 (1/T) follows Arrhenius activation energy EASAE 0.86 eV. Interestingly, is comparable energies deduced conductivity measurements (0.94(1) eV) SLR rotating frame (0.74(2) rather than those performed laboratory frame, EAlow-T 0.26(1) eV at low T.