Insights into Polymorphism of Lithium Manganese Oxide, Li0.95Mn2.05O4: A Comprehensive Survey of the High-Pressure Properties

Abstract

Understanding the structural behavior of lithium manganese oxide (LMO) under high pressure, especially under nonhydrostatic pressure conditions, could provide more insights into control of the mechanochemical processes occurring during battery operation and allow predicting new applications for this type of oxides. Here, we report pressure-induced structural changes in Li0.95Mn2.05O4 at two temperatures, 300 and 380 K, investigated in situ through synchrotron X-ray powder diffraction up to 13 GPa in a diamond anvil cell. Compression-induced strain triggers a cascade of local structure deformations, which finally result in the structural phase transition to the high-pressure tetragonal phase. A comparison of bulk moduli at two temperatures reveal that due to the differences in the response of the structure to the strain, Li0.95Mn2.05O4 exhibits the rare property of “warm hardening”. Additionally, a direct correlation between hydrostaticity of the pressure-transmitting medium and structural transformations ...