Issue 25, 2023

Cation disorder dominates the defect chemistry of high-voltage LiMn1.5Ni0.5O4 (LMNO) spinel cathodes

Abstract

High-voltage spinel LiMn1.5Ni0.5O4 (LMNO) can exist in a Mn/Ni ordered P4332 or disordered Fd[3 with combining macron]m arrangement with a majority of literature studies reporting improved electrochemical performance for the disordered phase. Through modifying synthesis conditions, the Mn/Ni ordering can be tuned, however oxygen and Mn3+ stoichiometries are also affected, making it difficult to decouple these responses and optimise performance. Here, we investigate all intrinsic defects in P4332 LMNO under various growth conditions, using density functional theory (DFT) calculations. We find that the majority of defects are deep and associated with small polarons (Mn3+, Mn2+ and Ni3+) formation. The tendency for cation disorder can be explained by the low formation energy of the antisite defects and their stoichiometric complexes. The intrinsic Fermi level of LMNO varies from moderately n-type under oxygen-poor conditions to weakly p-type under oxygen-rich conditions. Our work explains experimental observations (e.g. the Mn/Ni disorder) and provides guidelines for defect-controlled synthesis.

Graphical abstract: Cation disorder dominates the defect chemistry of high-voltage LiMn1.5Ni0.5O4 (LMNO) spinel cathodes

Supplementary files

Article information

Article type
Paper
Submitted
30 yan 2023
Accepted
12 apr 2023
First published
12 apr 2023
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2023,11, 13353-13370

Cation disorder dominates the defect chemistry of high-voltage LiMn1.5Ni0.5O4 (LMNO) spinel cathodes

J. Cen, B. Zhu, S. R. Kavanagh, A. G. Squires and D. O. Scanlon, J. Mater. Chem. A, 2023, 11, 13353 DOI: 10.1039/D3TA00532A

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