Lithium-ion diffusivity in complex hydrides: Pulsed-field-gradient NMR studies of LiLa(BH₄)₃Cl, Li₃(NH₂)₂I and Li-1-CB₉H₁₀

TY - JOUR

T1 - Lithium-ion diffusivity in complex hydrides

T2 - Pulsed-field-gradient NMR studies of LiLa(BH4)3Cl, Li3(NH2)2I and Li-1-CB9H10

AU - Skripov, A. V.

AU - Majer, G.

AU - Babanova, O. A.

AU - Skoryunov, R. V.

AU - Soloninin, A. V.

AU - Ley, M. B.

AU - Jensen, T. R.

AU - Orimo, S.

AU - Udovic, T. J.

N1 - Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/4

Y1 - 2021/4

N2 - The bimetallic borohydride-chloride LiLa(BH4)3Cl, the lithium amide-iodide Li3(NH2)2I, 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 cm2/s for LiLa(BH4)3Cl, 5 × 10−8 cm2/s for Li3(NH2)2I, and 10−6 cm2/s for Li-1-CB9H10. For LiLa(BH4)3Cl and Li3(NH2)2I, 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.

AB - The bimetallic borohydride-chloride LiLa(BH4)3Cl, the lithium amide-iodide Li3(NH2)2I, 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 cm2/s for LiLa(BH4)3Cl, 5 × 10−8 cm2/s for Li3(NH2)2I, and 10−6 cm2/s for Li-1-CB9H10. For LiLa(BH4)3Cl and Li3(NH2)2I, 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.

KW - Complex hydrides

KW - Diffusion

KW - Ionic conductors

KW - Nuclear magnetic resonance

KW - BOROHYDRIDES

KW - SUPERIONIC CONDUCTIVITY

KW - SODIUM

KW - ANION

KW - NUCLEAR-MAGNETIC-RESONANCE

KW - ATOMIC MOTION

KW - NA

KW - DYNAMICS

KW - METAL

KW - LI

UR - http://www.scopus.com/inward/record.url?scp=85101845173&partnerID=8YFLogxK

U2 - 10.1016/j.ssi.2021.115585

DO - 10.1016/j.ssi.2021.115585

M3 - Journal article

AN - SCOPUS:85101845173

SN - 0167-2738

VL - 362

JO - Solid State Ionics

JF - Solid State Ionics

M1 - 115585

ER -