【摘要】 本文构建的Li-Ni（Co,Mn）-H₂O系电位-pH图从热力学角度表明,在25～250°C温度范围和0.01～1.00活度范围内,LiNiO₂, LiCoO₂和LiMnO₂可以稳定存在于水溶液中。在Li-Ni-Co-Mn-H₂O系电位-pH图中,同时出现了LiNiO₂、LiCoO₂和LiMnO₂氧化物（即Li-Ni-Co-Mn复合氧化物）的优势区,并且该共沉淀优势区随温度的升高向低pH方向扩大,表明在水溶液中合成Li-Ni-Co-Mn复合氧化物是可能的。在此基础上,本文通过实验采用湿法过程合成了LiNi_0.5Co_0.2Mn_0.3O₂ （NCM523）正极材料,证明了上述理论的可行性。合成的锂化前驱体和NCM523材料均继承了氢氧化物前驱体的球形形貌,同时所得NCM523材料具有良好的六方α-NaFeO₂型晶体结构。在电位-pH图指导下,湿法合成工艺将一定程度上成为三元正极材料极具前景的制备方法之一。更多还原

【Abstract】 The constructed potential-pH diagrams of Li-Ni（Co, Mn）-H₂O system indicate that the LiNiO₂, LiCoO₂ and LiM n O₂ are thermodynamically stable in aqueous solution within the temperature range of 25-200 °C and the activity range of 0.01-1.00. A predominant co-region of LiNiO₂, LiCoO₂ and LiMnO₂ oxides（Li-Ni-Co-Mncomposite oxide） is found in the Li-Ni-Co-Mn-H₂O potential-pH diagrams, in which the co-precipitation region expands towards lower pH with rising temperature, indicating the enhanced possibility of synthesizing Li-Ni-Co-Mn composite oxide in aqueous solution. The experimental results prove that it is feasible to prepare the LiNi_0.5Co_0.2Mn_0.3 O₂ cathode materials（NCM523） by an aqueous routine. The as-prepared lithiated precursor and NCM523 both inherit the spherical morphology of the hydroxide precursor and the obtained NCM523 has a hexagonal α-NaFeO₂ structure with good crystallinity. It is reasonable to conclude that the aqueous routine for preparing NCM cathode materials is a promising method with the guidance of the reliable potential-pH diagrams to some extent.更多还原