共沉淀法制备LiNi1-x-yCoxMnyO2正极材料工艺条件探究

Investigation on synthesis conditions of LiNi_(1-x-y)Co_xMn_yO_2 cathode material via co-precipitation

共沉淀法可高效、低能耗制备出较高纯度的球形层状Li Ni1-x-yCoxMnyO2正极材料,广泛应用于基础研究和工业生产中,主要包括液相共沉淀及高温煅烧过程。对这两个过程中涉及的机理进行了阐述,并分析相关影响因素,考察了共沉淀制备前体这个关键步骤中颗粒成核过程以及Ni、Co、Mn 3种金属离子发生的络合及沉淀反应。通过建立的反应和热力学平衡方程,分析未沉淀的3种金属离子及其相互之间比值随pH和氨水加入量的二维变化,首次定量得出制备所需Ni、Co、Mn配比三元正极材料的理论最佳条件。此外,从前体及正极材料的结构特性以及最终材料的电化学活性出发,定性探究了最优操作条件。最后,展望了三元正极材料工艺条件优化的科学方法。

Layer-structured spherical cathode material, LiNil-x-yCoxMnyO2, with high purity can be prepared by co-precipitation with high efficiency and low energy consumption. This method has been widely applied in both fundamental research and industrial production, mainly including co-precipitation and high-temperature calcination processes. The mechanisms and influence factors involved in each procedure were elaborated and analyzed. The nucleation process and the complexation and precipitation reactions of Ni, Co and Mn ions were investigated in the key step of co-precipitation for the preparation of precursor. Based on the established equilibrium equations of reactions and thermodynamics, the two-dimensional variations of the three non-precipitated metal concentrations and their mutual ratios for different pH and amounts of NH3 were thoroughly analyzed. Through the analysis results, theoretical optimum conditions for the cathode material with desired metal-ion ratios were thus proposed for the first time. In addition, by means of analyzing the structural characteristics of the precursor and cathode material as well as the electrochemical activity of the final material,the proper operation conditions were qualitatively investigated. Finally, the scientific method for optimizing the process conditions of LiNi1-x-yCoxMnyO2 cathode material was prospected.