Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides

D. O. Semykina; Ye. A. Morkhova; A. A. Kabanov; K. V. Mishchenko; A. B. Slobodyuk; M. A. Kirsanova; O. A. Podgornova; A. A. Shindrov; K. S. Okhotnikov; N. V. Kosova

doi:10.1039/D1CP04993C

Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides†

D. O. Semykina,

^a Ye. A. Morkhova,

^abc A. A. Kabanov,

^ab K. V. Mishchenko,

^a A. B. Slobodyuk,

^ad M. A. Kirsanova,

^e O. A. Podgornova,

^a A. A. Shindrov,

^a K. S. Okhotnikov

^f and N. V. Kosova

*^a

Author affiliations

* Corresponding authors

^a Institute of Solid State Chemistry and Mechanochemistry SB RAS, 18 Kutateladze, 630128 Novosibirsk, Russia

^b Samara State Technical University, Molodogvardeyskaya St. 244, 443100 Samara, Russia

^c Samara University, Academician Pavlov Str. 1, Samara, Russia

^d Institute of Chemistry, Far-Eastern Branch of the Russian Academy of Sciences, 159 pr. Stoletiya Vladivostoka, 690022 Vladisvostok, Russia

^e Skolkovo Institute of Science and Technology, 3 Nobel str., 121205 Moscow, Russia

^f Independent researcher, 31-421 Reduta 38/9, Kraków, Poland
E-mail: kirill.okhotnikov@gmail.com

Abstract

Lithium-excess oxides Li_1.2Ti_0.4Mn_0.4O₂ and Li_1.3Nb_0.3Mn_0.4O₂ with a disordered rock-salt structure and Mn³⁺/Mn⁴⁺ as a redox couple were compared to analyze the effect of different d⁰ metal ions on the local structure and Li⁺ ion migration. These cathode materials were obtained by mechanochemically assisted solid-state synthesis. Using XRD, ⁷Li NMR and EPR spectroscopy and transmission electron microscopy it was shown that the Mn ions are prone to form clusters, while d⁰ metal ions are evenly distributed in the crystal lattice. The presence of Nb⁵⁺ ions contributes to the formation of noticeably larger Mn clusters and larger gaps in the Li⁺ migration maps as compared to Ti⁴⁺. These results were confirmed by the geometrical–topological method, BVSE simulation and DFT calculations, and are in good agreement with the Li diffusion coefficient determined by GITT, which is 1.5 orders of magnitude higher in Li_1.2Ti_0.4Mn_0.4O₂ than that in Li_1.3Nb_0.3Mn_0.4O₂.

Physical Chemistry Chemical Physics

Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides†

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Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides

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