机械力化学强化含钴动力电池正极废料选择性回收的机理研究

In this research, mechanochemical enhancement is proposed to improve the recycling efficiency of spent lithium-ion batteries for electric vehicles by increasing the leaching selectivity of lithium. The recycling process of spent lithium-ion battery can be shortened by adjusting the physiochemical properties of the leaching solution and mass transfer intensification. In the process of mechanochemical activiation, the relationship between the mineralogy as well as the energy storage, passivation process and selective leaching of lithium will be investigated to subsequently understand the thermodynamics; the leaching kinetics of cathode waste is investigated for different leaching parameters including pH, ion activities, temperature, solid-to-liquid ratio with which the correlation between selective recovery of lithium and physiochemical properties of the leaching solution can be derived. By using in-situ observation the dissolution behavior of particles of cathode waste and the mass transfer coefficient can be obtained quantitatively. Together with understanding the structure and properties of the product layer, leaching selectivity and recovery rate of lithium can be both improved by mechanochemical processing during leaching. As a result, systematic understanding of the mechanical-chemical enhancement of selective lithium recovery process can be achieved and a new method for clean recovery of spent lithium-ion battery can be implemented.

本项目针对目前含钴动力电池正极废料回收过程提取选择性差、分离除杂流程长、二次污染重等问题，从提取反应原理上提出以机械力与化学反应耦合强化浸出过程的思路，结合浸出液的物理化学性质调控和原位反应界面传质强化，实现锂元素的高效选择性提取，大幅度缩减分离、除杂过程，促进正极废料的短程金属回收。主要研究内容包括通过研究含钴正极废料矿物学性质以及活化过程机理，揭示机械力化学活化对强化正极废料浸出的物理化学规律，探明溶液特性调控与锂浸出的相关关系；解析机械力化学活化对产物层特性演化和界面离子传质系数的影响机制，建立锂元素提取的界面传质强化调控方法，形成较为系统的应力场-化学耦合强化锂元素选择性提取基础理论，为动力电池正极废料清洁短程回收开辟新路径。

本项目针对含钴动力电池正极废料回收过程中存在回收流程长，有价金属损失严重的问题，尤其是锂的提取与回收困难的问题，从提取反应原理上提出了以机械力与化学反应耦合强化浸出过程的思路。项目研究过程中，通过热力学计算分析了元素液相转化规律、进行了液相和固相选择提锂工艺开发、解析了机械力化学活化含钴废料的活化机制、活化对液相和固相反应过程的强化机制以及机械力活化对产物层的影响机制等内在机理，建立了锂元素提取的界面传质强化调控方法，深入阐明了对机械力与化学反应耦合的强化机理，在实现多种含钴正极废料中锂的选择性提取的同时，推动了机械力场-化学耦合强化锂元素选择性提取基础理论的发展，为动力电池正极废料清洁短程回收开辟新路径。