Elucidating lithium-ion and proton dynamics in anti-perovskite solid electrolytes

Abstract

Combined computational and experimental examination of lithium-ion and proton dynamics in next-generation anti-perovskite solid electrolytes.

Understanding Li‐Ion Dynamics in Lithium Hydroxychloride (Li2OHCl) Solid State Electrolyte via Addressing the Role of Protons

“…For both 7 Li and 1 H nuclei, the spin‐lattice relaxation rate R 1 , which is the inverse of T 1 , was recorded between −40 and +80 °C ( Figure 2 ). Notably, we observed at most temperatures a nonexponential T 1, which is contrast to previous studies, suggesting inhomogeneous spatial structure of the Li 2 OHCl with different mobilities, likely associated with spatial fluctuation induced by the defect sites. To describe it and provide a good fit for measured data we had to use bi‐exponential function with two different relaxation times T 1 (fast) and T 1 (slow) for both 1 H and 7 Li (Figure S5, Supporting Information), Equation …”

“…A slight reduction in the linewidth still occurs above 40 °C (Stage IV) due to the change in the crystal structure, which eliminates the remaining minor dipolar coupling with the onset of Li + translational motions . In the high temperature (HT) cubic structure, the Li + translation motion is consistent with what has been found in previous studies . However, a remaining open question is why Li + translational motion appears to occur only above 40 °C, while a significant amount of line‐narrowing and associated rotational motion occurs below 40 °C.…”

“…Solid‐state nuclear magnetic resonance (NMR) is uniquely positioned to study fundamentals of ionic motions in SSEs . While several previous NMR studies conducted for Li‐antiperovskites have founded a reduction of the linewidth in 7 Li spectra with Li‐ionic conductivity, there is no comprehensive examination of Li‐ion diffusion. Moreover, there is no experimental evidence of proton dynamics, which prohibits our understanding of the possible scope of Li 2 OHCl use.…”

Implications of Oxygen–Sulfur Exchange on Structural, Electronic Properties, and Stability of Alkali‐Metal Hexatitanates

“…Furthermore, research into solid electrolytes for all‐solid‐state batteries has seen a rapid rise in recent years. Both oxide and sulfide compounds, such as Li 10 GeP 2 S 12 , Li 10 SnP 2 S 12 , Li 7 La 3 Zr 2 O 12 , Li 3 OCl, and Li 3x La 2/3− x TiO 3 have been investigated as solid‐state electrolytes . Li 2 TiS 3 and Li 3 NbS 4 have also been tested as positive electrodes in the search for the best superionic conductors for all‐solid‐state batteries …”

Application of Magnetic Resonance Techniques to the In Situ Characterization of Li-Ion Batteries: A Review

“…Lithium diffusivity in solid electrolytes is typically 2-3 orders of magnitude slower than in liquids, however, implementation of diffusion probes providing strong gradient pulses makes PFG NMR experiments in solids possible, when the NMR signal relaxation is not extremely fast. For example, garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (D Li = 1.9 × 10 −13 m 2 s −1 at 298 K) [44], anti-perovskite type Li 2 OHCl (D Li = 6.0 × 10 −13 m 2 s −1 at 373 K) [45], and halide-rich argyrodites Li 5.5 PS 4.5 Cl 1.5 (D Li = 1.0 × 10 −11 m 2 s −1 at 300 K) [46] were studied that way.…”