标题：The phase structure and electrochemical performance of xLi2MnO3·(1 − x)LiNi1/3Co1/3Mn1/3O2during the synthesis and charge–discharge process
作者：Yuan, Ting ;Liu, Hong Quan ;Gu, Yi Jie ;Cui, Hong Zhi ;Wang, Yan Min
作者机构：[Yuan, Ting ;Liu, Hong Quan ;Gu, Yi Jie ;Cui, Hong Zhi ;Wang, Yan Min ] College of Materials Science and Engineering, Shandong University of Science a 更多
通讯作者：Liu, Hong Quan
来源：Applied Physics A: Materials Science and Processing
摘要：The lithium-rich layered xLi2MnO3·(1 − x)LiNi1/3Co1/3Mn1/3O2materials were simply prepared by the molten-salt method. The effects of reaction temperature and x value on the phase structure and electrochemistry were systemically studied by X-ray diffraction, galvanostatical charge/discharge and electrochemical impedance spectroscopy (EIS). It has been found that the obtained phase is sensitive to the reaction temperature and composition. A layered rock-salt form with hexagonal α-NaFeO2-type structure occurs at 700 °C, while a spinel LiMn2O4becomes the main phase at 800 °C. Besides, a spinel Li4Mn5O12component can be found in the lithium-rich layered material when x value decreases to 0.4. The 0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2material can deliver a high initial discharge capacity of 218 mAhg−1under 20 mAg−1current rate, then increase to the maximum 241 mAhg−1after 4 cycles. It is confirmed by different cycle dQ/dV profile change that the layer rock-salt transforms into the two phases with the layer rock-salt phase and the spinel phase step by step. According to the EIS analysis, the 0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2sample with the better electrochemical performance shows the smaller charge transfer resistance and Warburg impedance associated with Li-ion diffusion through cathode, which is attributed to contribution from a fast 3D Li-ion diffusion channel of appropriate Li4Mn5O12phase.
© 2016, Springer-Verlag Berlin Heidelberg.