期刊
SOLID STATE IONICS
卷 362, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.ssi.2021.115585
关键词
Complex hydrides; Ionic conductors; Diffusion; Nuclear magnetic resonance
资金
- Russian Science Foundation [19-12-00009]
- Independent research fund Denmark [DFF-9041-00226B, DFF-4181-00462]
- JSPS KAKENHI [JP18H05513]
- Russian Science Foundation [19-12-00009] Funding Source: Russian Science Foundation
The study examined the diffusion of Li+ cations in complex hydrides, revealing fast Li+ diffusivities and superionic conductivity at room temperature or slightly above it. The experiments found that Li+ diffusion coefficients in the compounds follow Arrhenius behavior, providing new insights into the unusual dynamical properties of these superionic materials.
The bimetallic borohydride-chloride LiLa(BH4)(3)Cl, the lithium amide-iodide Li-3(NH2)(2)I, and the lithium monocarba-closo-decaborate Li-1-CB9H10 represent complex hydrides showing superionic conductivity at room temperature or slightly above it. To study the Li-ion diffusivity that is closely related to the ionic conductivity, we have measured the diffusion coefficients of Li+ cations in these compounds using the pulsed-field-gradient (PFG) spin-echo technique over the temperature range of 298-403 K. The experiments have revealed fast Li+ diffusivities in all these complex hydrides: at 400 K, the measured diffusion coefficients exceed 10(-7) cm(2)/s for LiLa (BH4)(3)Cl, 5 x 10(-8) cm(2)/s for Li-3(NH2)(2)I, and 10(-6) cm(2)/s for Li-1-CB9H10. For LiLa(BH4)(3)Cl and Li-3(NH2)(2)I, the diffusion coefficients are found to follow the Arrhenius behavior over the entire temperature ranges studied with the activation energies of 268(6) meV and 224(6) meV, respectively. For Li-1-CB9H10, the Arrhenius behavior with the activation energy of 265(6) meV is observed in the disordered high-temperature polymorph (360-403 K), whereas below 360 K the measured diffusivity drops significantly due to the transition to the ordered phase. Comparison of the measured Li+ diffusion coefficients with the ionic conductivity results and the data on the cation and anion jump rates provides new insights into the unusual dynamical properties of these superionic materials.
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