Effect of pressure on the structural properties of Li[Li0.1Ni0.35Mn0.55]O2

Li-rich cathode material Li[Li0.1Ni0.35Mn0.55]O2 was synthesized by a sol-gel method. The morphology and a-NaFeO2 type structure of the material at ambient conditions were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The high-pressure behavior of the material was studied at pressure up to 19.7 GPa by using angle dispersive synchrotron X-ray powder diffraction (ADXD). The studies affirmed that the a-NaFeO2 type structure existed up to at least 19.7 GPa. Rietveld refinement analysis indicated that the c/a lattice parameter ratio decreased and the Li-O bond length shrunk with the increasing pressure, however, the Li+/Ni2+ ions exchange increased under elevated pressure. The pressure-volume data of the material were fitted to the third-order Birch-Murnaghan equation of state and bulk modulus obtained upon compression from the fitting was 117 (1) GPa.