Solid-State NMR to Study Translational Li Ion Dynamics in Solids with Low-Dimensional Diffusion Pathways

Abstract

Fundamental research on lithium ion dynamics in solids is important to develop functional materials for, e.g. sensors or energy storage systems. In many cases a comprehensive understanding is only possible if experimental data are compared with predictions from diffusion models. Nuclear magnetic resonance (NMR), besides other techniques such as mass tracer or conductivity measurements, is known as a versatile tool to investigate ion dynamics. Among the various time-domain NMR techniques, NMR relaxometry, in particular, serves not only to measure diffusion parameters, such as jump rates and activation energies, it is also useful to collect information on the dimensionality of the underlying diffusion process. The latter is possible if both the temperature and, even more important, the frequency dependence of the diffusion-induced relaxation rates of actually polycrystalline materials is analyzed. Here we present some recent systematic relaxometry case studies using model systems that exhibit spatially restricted Li ion diffusion. Whenever possible we compare our results with data from other techniques as well as current relaxation models developed for 2D and 1D diffusion. As an example, 2D ionic motion has been verified for the hexagonal form of LiBH

Investigation of Li-ion transport in Li7P3S11 and solid-state lithium batteries

“…The temperature dependent impedance data reflect the total lithium ion conductivity ( σ Li ) and not the individual contributions of the bulk and grain-boundary conductivities. Measuring the NMR spin-lattice relaxation (SLR) rate allows to specifically measure the bulk conductivity σ Li in fast ionic conductors [38,46] . Temperature-dependent 7 Li NMR SLR relaxation rates in the static laboratory frame ( T 1 ) were measured at a Larmor frequency of 155.506 MHz, shown in Fig.…”

Spatial confinement – rapid 2D F−diffusion in micro- and nanocrystalline RbSn2F5

“…Focussing here on rapid anion dynamics, ternary fluorides provide some very encouraging materials useful as model substance to test NMR relaxation models proposed for 2D diffusion. [49][50][51] Here, RbSn 2 F 5 attracted our attention. It belongs to the family of the pseudo-binary system MF-SnF 2 where M is a monovalent cation such as Rb + , K + , Na + or Cs + .…”

Multi-Quanta Spin-Locking Nuclear Magnetic Resonance Relaxation Measurements: An Analysis of the Long-Time Dynamical Properties of Ions and Water Molecules Confined within Dense Clay Sediments

“…As a consequence, numerous theoretical and experimental studies were devoted to that problem in order to quantify the influence of the geometrical and thermodynamical properties [31][32][33][34][35][36][37][38][39] of the porous media on the NMR relaxation mechanisms of their confined fluids. In addition to NMR relaxation measurements performed at a limited number of available magnetic fields [16,33], spin-locking relaxation measurements [16,33,[40][41][42][43] were initially performed to extend the investigation of the dispersion curves to lower magnetic fields. These two complementary procedures lead however to a large gap within the dispersion curves that was successfully filled recently by field cycling NMR relaxometry [29][30][31][32][44][45][46][47][48].…”