From Micro to Macro: Access to Long-Range Li+ Diffusion Parameters in Solids via Microscopic 6,7Li Spin-Alignment Echo NMR Spectroscopy

The development of highly conductive solids is a rapidly growing research area in materials science. In particular, the study of Li-ion conductors is driven by the ambitious effort to design powerful lithium-ion batteries. A deeper understanding of Li dynamics in solids requires the availability of a large set of complementary techniques to probe Li self-diffusion on different length and time-scales. We report on 7Li as well as 6Li spin-alignment echo (SAE) nuclear magnetic resonance (NMR) spectroscopy, which is capable of probing long-range diffusion parameters from a microscopic, that is, atomic-scale, point of view. So far, variable-temperature SAE NMR spectroscopy has been applied to a number of polycrystalline and glassy Li-ion conductors. The materials investigated serve as model systems to unravel the interesting features of the technique in determining reliable Li jump rates and hopping activation energies. In particular, the latter are compared with those probed by macroscopic techniques such as dc-conductivity measurements that are sensitive to long-range translational motions.