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

Phys Chem Chem Phys. 2022 Mar 9;24(10):5823-5832. doi: 10.1039/d1cp04993c.

Authors

D O Semykina¹, Ye A Morkhova^{1

2

3}, A A Kabanov^{1

2}, K V Mishchenko¹, A B Slobodyuk^{1

4}, M A Kirsanova⁵, O A Podgornova¹, A A Shindrov¹, K S Okhotnikov⁶, N V Kosova¹

Affiliations

¹ Institute of Solid State Chemistry and Mechanochemistry SB RAS, 18 Kutateladze, 630128 Novosibirsk, Russia.
² Samara State Technical University, Molodogvardeyskaya St. 244, 443100 Samara, Russia.
³ Samara University, Academician Pavlov Str. 1, 443011, Samara, Russia.
⁴ Institute of Chemistry, Far-Eastern Branch of the Russian Academy of Sciences, 159 pr. Stoletiya Vladivostoka, 690022 Vladisvostok, Russia.
⁵ Skolkovo Institute of Science and Technology, 3 Nobel str., 121205 Moscow, Russia.
⁶ Independent researcher, 31-421 Reduta 38/9, Kraków, Poland. kirill.okhotnikov@gmail.com.

PMID: 35224598
DOI: 10.1039/d1cp04993c

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.