共沉淀法制备NCM三元正极材料的优化模型研究

Ni, Co, Mn (NCM) ternary material is one of the most promising cathode materials for lithium-ion batteries. With the upgrading of industry, varieties of cathode materials with new NCM proportions should be developed urgently. NCM cathode material can be prepared by co-precipitation method with high efficiency and low energy consumption. Nevertheless, the co-precipitation process has been mainly optimized empirically, which is blind, costly and time-consuming. The aim of this project is to establish a scientific optimization method including the flow structure of reactor and the mechanism of co-precipitation reaction, thereby conducting co-precipitation process quickly and accurately. The specific research contents include four parts: (1) By combining the fluid dynamics of the reactor investigated through CFD simulations with the pattern and structure characteristics of the precursor obtained through experiments, the qualitative relationships between hydrodynamics and precursor feature will be clarified; (2) By means of analyzing co-precipitation mechanism and establishing equilibrium thermodynamic equations, the quantitative variations of the metal-ion for different operation conditions will be obtained; (3) Furthermore, after measuring reaction equilibrium constants for different temperatures, the mathematical optimization model of co-precipitation reaction under operation temperature will be built. (4) Eventually, by integrating hydrodynamic with thermodynamic models together, a scientific optimization method for co-precipitation process will be established and validated. This project is expected to scientifically optimize co-precipitation and help to develop high-performance cathode materials, and thus promote the development of energy power batteries.

镍、钴、锰（NCM）三元材料是最具潜力的锂电池正极材料之一。随着产业升级，多种新型配比的NCM材料亟待开发。共沉淀法可高效、低能耗制备NCM正极材料，目前主要采取经验性尝试的方法进行优化，盲目性强、花费高且周期长。为快速准确地指导该过程，本项目力求建立包含反应器流动结构和共沉淀反应机理的科学优化方法。具体研究内容主要包括四个部分：1）采用CFD数值模拟考察反应器中流体力学特性，并结合共沉淀实验所得前驱体形貌结构特征，阐明流场对前驱体的影响规律与作用机理；2）分析共沉淀反应机理，建立化学热力学平衡，获得金属离子浓度随工艺条件变化的定量规律；3）测定不同温度下各反应平衡常数，建立适用于操作温度下共沉淀过程的优化数学模型；4）结合流场影响规律，建立共沉淀过程的科学优化方法，并进行实验验证。本项目的成功实施将有助于科学指导优化共沉淀过程，有利于开发高性能的NCM正极材料，促进能源动力电池的发展。

镍、钴、锰（NCM）三元材料是最具潜力的锂电池正极材料之一。共沉淀法可高效、低能耗制备NCM正极材料，然而目前主要采取经验性尝试的方法进行优化，盲目性强、花费高且周期长。为快速准确地指导该过程，本项目通过实验室实验、CFD 数值模拟和理论分析等方法对共沉淀反应过程中流动及反应进行研究，研究了反应器结构对流动特性及反应的耦合影响，揭示了共沉淀反应器中流动与反应之间的内在关系，通过对共沉淀过程进行热力学分析及实验测定,总结出金属离子浓度比随操作条件的变化规律。重要研究结果包括：（1）随着安装高度减小，直径较小的搅拌桨更容易由双循环流型转变为单循环流型，如果排出流首先遇到搅拌槽的内壁，那么将会形成双循环流型，如果排出流首先遇到搅拌槽的底部，那么将会形成单循环流型；（2）研究表明，PT桨是制备振实密度超过2.0 g/ml的球形致密的Ni0.6Co0.2Mn0.2(OH)2前驱体的最佳选择，PT-NCM622具有最高的比放电容量，这是由于不同搅拌桨在反应器中所激发的流场不同，不同的流场提供了不同的晶体成核和生长环境；（3）通过热力学平衡分析，得到未沉淀[Ni]/[Co]和[Co]/[Mn]随pH和氨水浓度的变化，首次定量得出制备Ni1−x−yCoxMny(OH)2前驱体的理论最佳条件；（4）通过pH电位滴定实验及理论计算得到不同温度下的Ni(OH)2、Co(OH)2、Mn(OH)2活度积常数。.发表重要期刊论文10篇，国内会议论文2篇，授权中国发明专利2项，申请中国发明专利2项，申请PCT国际专利2项，其中一项进入美国，另一项进入美国和德国，培养出站博士后2名，毕业硕士1名，在读博士1名。本项目的成功实施将有助于科学指导优化共沉淀过程，有利于开发高性能的NCM正极材料，促进能源动力电池的发展。