Unusual Compressional Behavior of Lithium–Manganese Oxides: A Case Study of Li₄Mn₅O₁₂

Abstract

Lithium-rich spinel oxide has been synthesized in a long-term low temperature sintering process via the intermediate defected phase. Synchrotron X-ray diffraction studies under pressure have been performed on Li4Mn5O12, and some similarity of its behavior under compression to that of LiMn2O4 has been demonstrated. Li4Mn5O12 reveals a bulk modulus value of K0 = 118(1) GPa, and K0′ = 4.5(3) GPa. This value is far below 200 GPa, which is typical of most spinel oxides. The local compressibility of LiO4 tetrahedra is responsible for these unusual elastic properties of lithium–manganese spinel oxides both with Mn4+ only and Mn3+/Mn4+ ions in octahedral sites.