Layered-to-Spinel Phase Transformation in Li$_{0.5}$NiO$_2$ from First Principles

Cem Komurcuoglu; Alan C. West; Alexander Urban

paper

Layered-to-Spinel Phase Transformation in Li $_{0.5}$ NiO $_{2}$ from First Principles

arXiv:2403.02520

Abstract

The phase transition layered Li $_{0.5}$ NiO $_{2}$ to spinel Li(NiO $_{2}$ ) $_{2}$ is a potential degradation pathway in LiNiO $_{2}$ -based lithium-ion battery cathodes. We investigated the mechanism of this phase transformation from first principles. Consistent with experimental observations reported in the literature, our results indicate a high energy barrier for the transformation due to high defect-formation energies, a complex charge-transfer mechanism, and electronic frustration. Our results suggest that partially inverse spinel phases are unlikely to form for Li $_{0.5}$ NiO $_{2}$ , a qualitative difference from the chemically similar Li $_{0.5}$ MnO $_{2}$ , in which the transformation occurs at room temperature. We show that Ni and Li atoms migrate concertedly towards their respective spinel sites for the layered-to-spinel transformation to occur. We investigated the charge ordering in layered phases along the LiNiO $_{2}$ -NiO $_{2}$ composition line, finding a pronounced impact of the symmetry and space group on the layered-to-spinel transition in Li $_{0.5}$ NiO $_{2}$ . Finally, we evaluated the relative stability of different spinel space groups, finding that previously reported experimental observations are consistent with a temperature-averaged structure rather than the 0 Kelvin ground-state structure of Li(NiO $_{2}$ ) $_{2}$ spinel.

29 pages and 8 figures in the main manuscript, and 15 pages and 7 figures of supplementary information

Layered-to-Spinel Phase Transformation in Li0.5​NiO2​ from First Principles

Abstract

Layered-to-Spinel Phase Transformation in Li $_{0.5}$ NiO $_{2}$ from First Principles