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Computational analysis of composition-structure-property-relationships in NZP-type materials for Li-ion batteries

: Mutter, D; Uraban, F.; Elsässer, C.

Postprint urn:nbn:de:0011-n-5496035 (4.4 MByte PDF)
MD5 Fingerprint: 2bd169e1826b6758c48f4e933e000cc2
Created on: 5.7.2019

Journal of applied physics 125 (2019), No.21, Art. 215115, 10 pp.
ISSN: 0021-8979
ISSN: 1089-7550
Deutsche Forschungsgemeinschaft DFG
El 155/26-1
Journal Article, Electronic Publication
Fraunhofer IWM ()
activation energy; electrolyte; transition metal oxide; battery

Compounds crystallizing in the structure of NaZr2(PO4)3 (NZP) are considered as promising materials for solid state electrolytes in Li-ion batteries. Using density functional theory (DFT), a systematic computational screening of 18 NZP compounds, namely, LiX2(LO4)3 with X=Ti, V, Fe, Zr, Nb, Ru, Hf, Ta, Os, and L=P, Mn, is performed with respect to their activation energies for vacancy-mediated Li migration. It is shown how the different ionic radii of the cationic substitutions influence structural characteristics such as the octahedron volumes around Li ions on the initial-state and transition-state sites, which affect the activation energies (“composition-structure-property” relationships). The prevalent assumption that structural bottlenecks formed by triangularly arranged oxygen atoms at a certain location along the migration path determine the energy barriers for Li migration is not supported by the DFT results. Instead, the ionic neighborhood of the migrating ion in the initial and in the transition state needs to be taken into account to relate the structure to the activation energies. This conclusion applies to Na-containing NZP compounds as well.