采用快速共沉淀法合成了立方体的层状无钴富锂固溶体正极材料0.6Li2MnO3-0.4LiNi0.5Mn0.5O2.通过X射线衍射(XRD), X射线光电子能谱(XPS),电感耦合等离子体(ICP),扫描电子显微镜(SEM),透射电子显微镜(TEM)及电性能测试等手段对材料进行了表征.结果表明,材料具有典型的α-NaFeO2六方层状晶体结构且具有与目标材料相似的化学组成. SEM和TEM结果表明,材料由粒径为40-200 nm的纳米颗粒组装成立方体结构.在文中给出了一个立方团聚体可能的形成机理.电化学性能测试(2.0-4.8 V电压范围内(vs Li/Li+))显示该材料具有优异的倍率性能, 0.1C和10C倍率下的放电比容量分别是243和143 mAh·g-1.此外,该材料具有良好的循环稳定性,即使在大倍率测试后, 0.5C倍率下循环72次仍显示出90.7%的高容量保持率.这种具有简易操作步骤和优异结果的共沉淀方法是一种经济的能够促进锂离子电池正极材料大规模应用的技术手段.
The cuboid layered 0.6Li2MnO3-0.4LiNi0.5Mn0.5O2 cobalt-free lithium-rich solid-solution cathode material was synthesized by a facile quick co-precipitation method. The prepared material was characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) spectroscopy, field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical measurements. It was found that the as-prepared material has a typical hexagonal α-NaFeO2 layered structure with R·\overline 3 $ m space group, and the chemical composition of this material is similar to the corresponding target material. SEM and TEM images reveal that the cuboid structures are assembled from nanoparticles with particle sizes of 40-200 nm. A possible formation mechanism of this cuboid aggregation is proposed. The electrochemical tests (in the voltage range 2.0-4.8 V vs Li/Li+) indicate that the as-prepared material exhibits excellent rate capability. It delivers approximately 243 and 143 mAh·g-1 corresponding to 0.1C and 10C, respectively. Moreover, the asprepared material has good cycling stability even after high rate measurement, delivering a high capacity retention of 90.7% after 72 cycles at 0.5C. This co-precipitation approach, which has facile operation processes and good results, is a economic technique that could facilitate the application of Li-rich cathode on a large scale