Papers by Author: Li Zhu Zhao

Abstract: A compound as the lithium ion battery cathode materials were synthesized by high temperature solid phase synthesis method. The material is mainly the hexagonal structure and space group, and there is a little other phase. The XPS spectra display in the materials the Mn element existed by Mn4+ and the Ni element existed by the mix valent state between Ni2+ and Ni3+; the energy loss spectrum and ICP results are consistent, to ensure that the compounds is LiNi0.45Mn0.55O2 which we need; SEM figure shows it has a loose structure, particle size is about 0.2μm. At a current density 30mA/g at room temperature AC impedance analysis results show that an initial discharge capacity of 298 mAh/g ,which is higher than theoretical capacity of LiMnO2 285 mAh/g, that may be because of the synthesis LiNi0.45 Mn0.55 O2 is composite materials.After 13 circles it dropped to 93.2mAh/g and was steady, the efficiency reached 91.3%.

Abstract: The nanocrystalline orthorhombic LiMnO2 was successfully synthesized with the raw materials of MnO2, Mn (CH3COO)2 and LiOH by hydrothermal synthesis method, which has the properties of small size, less stacking faults and single phase. High resolution electron microscopy images show that along the b axis of the orthogonal LiMnO2, MnO6 and LiO6 octahedron arrange alternately and regularly. The orthorhombic LiMnO2 is proved to be p-type semiconductor by the Hall test. XPS tests indicate that the trivalent Mn in the o-LiMnO2 is in the high-spin state. And the magnetic study shows that there is reentrant spin glass behavior in o-LiMnO2. The contrast study of Raman spectroscopy and magnetic susceptibility shows that the characteristic mode softening of structural phase transition corresponds to the magnetic phase transition temperature, indicating a possible interaction between phonons and spin.

Abstract: In this paper, we synthesized LiMnO2 compounds doped with different amount of Ni by coprecipitation. The composition of the sample can be determined by ICP tests and energy loss spectroscopy. We found that the grain size decrease with more Ni doped .We found that the space group of the material is R-3m through XRD and Raman spectroscopy and with more Ni doped there is a blue shift in Raman spectroscopy. We can say that with more Ni doped, the material contains more Mn4 + through XPS analysis. But when Ni is doped excessively, there will be Ni3 + in the material. SEM analysis showed that corrosive effect of LiOH may have fatal effects on the electrochemical properties of the material.