废旧锂离子电池再生利用过程中氟的迁移与调控研究

This project is aimed at addressing the problems in the recycling of spent lithium ion battery (LIB) including the unknown migration and transformation of fluorine, the great difficulty in deep fluoride removal, as well as the unknown effect of trace fluorine on regenerated cathode material. Taking the recycling of spent ternary power LIB as an example, this project, on an overall and systematic basis, will analyze the migration and transformation of fluorine in the process of pyrolysis, leaching, impurity removal and regeneration of spent LIB, and the focus will be put on the migration rule of fluorine compounds pyrolysis products and their reaction with cathode material, the solution chemistry behaviors of fluorine ion and the co-deposition mechanism of fluorine and transition metals, as well as the effect of fluorine contents on the structure, morphology and electrochemical performance of regenerated material. The above-mentioned study will help clarify the fluorine migration in the process of spent LIB recycling. On this basis, this research also breaks through the technical shackles of traditional smelting of leaching-purification-material preparation. By reverse thinking from the perspective of material design, this research will form a directional migration and precise regulation mechanism of fluorine based on regenerated material design, in order to reduce the difficulty of removing fluorine in solution and make the harmful fluorine become helpful for the regenerated cathode material, thus laying theoretical foundation and technical support for the efficient recycling and clean production spent LIB.

针对目前废旧锂离子电池再生利用过程中氟组分迁移转变规律不清、溶液深度除氟难度过大、残余微量氟组分对再生正极材料产品影响作用不明等问题，本研究以废旧三元动力锂离子电池再生循环为例，系统解析废旧锂离子电池热解-浸出/除杂-材料再生过程中氟的迁移规律，重点探讨含氟化合物热解产物与正极材料的作用机制及其分配规律，氟离子的溶液化学行为，氟与过渡金属组分的共沉积机理和氟掺杂量对再生材料结构、形貌和电化学性能的影响。通过上述研究，理清废旧锂离子电池再生利用过程中氟元素的走向规律，并在此基础上，突破传统冶炼“浸出-净化-材料制备”的技术思路束缚，从材料设计角度逆向思维，将溶液中的杂质氟组分调控转化成对再生材料有益的掺杂元素，降低溶液除氟难度，从而形成以再生正极材料设计为导向的氟元素定向迁移和精准调控机制，为废旧锂离子电池高效再生利用和清洁生产奠定理论基础和技术支撑。

针对目前废旧锂离子电池再生利用过程中氟组分迁移转变规律不清、溶液深度除氟难度过大、残余微量氟组分对再生正极材料产品影响作用不明等问题，本研究以废旧动力锂离子电池再生循环为例，系统解析废旧锂离子电池热解-浸出/除杂-材料再生过程中氟的迁移规律，重点探讨含氟化合物热解产物与正极材料的作用机制及其分配规律，氟离子的溶液化学行为，氟与过渡金属组分的共沉积机理和氟掺杂量对再生材料结构、形貌和电化学性能的影响。结果表明，热解过程中45.71%的氟元素以含氟挥发性物质（如C6H3F3、C2H2F2、HF等）释放到大气中，而52.34%的氟元素向废正极材料晶格内发生迁移，并通过取代晶格O2-与过渡金属形成TM-F化学键，进而进入到浸出液和再生材料中。当浸出液中氟除杂深度控制在0.30g/L附近时，引入再生LiNi0.9Co0.05Mn0.05O2的氟元素没有引发明显的Li/Ni混排，并且由于Li-F和TM-F键分别强于Li-O和TM-O键，此时氟元素掺杂能够提升材料的结构稳定性，使其拥有最佳循环性能的同时没有牺牲明显的容量和倍率性能（1C、2.8-4.3V电压区间内，循环100圈后容量保持率高达95.7%）。项目执行期内发表SCI论文8篇，申请发明专利2项、软件著作权1项，部分技术得到产业化应用，获中国有色金属工业科学技术进步一等奖1项。项目理清了废旧锂离子电池回收过程中氟组分的迁移转化规律，确定了浸出液保留适量的氟元素，并再生制备了性能优异的高镍锂离子电池正极材料，为实现废旧锂离子电池毒害组分氟的调控与高附加值产品可控制备奠定了理论和技术基础。