Abstract:

Employing efficient recycling techniques to recover the important components from used LiFePO₄/C powder is crucial for resource conservation and environmental preservation. Now, for a large number of retired lithium iron phosphate batteries, the majority of studies were concentrated on the selective leaching of lithium without taking into account the leaching behavior of other priceless components like iron, phosphorus, aluminum and copper. This work studied the spent LiFePO₄/C powder leaching process condition optimization and macroscopic kinetic studies. Systematically examined were the effects of temperature, acid concentration and duration on the leaching process of iron, phosphorus, lithium, aluminum and copper. The macroscopic kinetics of lithium, iron, phosphorus, aluminum and copper leaching from the powder were thoroughly investigated. The results of the experiments under optimized conditions indicated that the leaching rates of iron, phosphorus, lithium, aluminum and copper were 97.2%, 96.9%, 89.7%, 76.1% and 43.4%, respectively. The internal diffusion model predicted that iron, phosphorus, lithium and copper leached over time, and the diffusion reaction governed this process. The diffusion reaction and chemical reaction-controlled mixed control model, which governed aluminum leaching, was accurate. According to the kinetic model, the apparent activating energies of Fe, Al and Cu leaching were 8.20kJ/mol, 34.11kJ/mol and 11.49kJ/mol, respectively. This article elucidated the leaching kinetics of diverse elements in spent lithium iron phosphate offered theoretical guidance for the selective leaching of these elements.

Key words: spent lithium iron phosphate, sulphuric acid, leaching, kinetics, recovery, kinetic modeling

摘要：

采取有效方法回收利用废旧磷酸铁锂中的有价组分对环境保护和资源循环具有重要意义。大量退役的磷酸铁锂电池，现有研究大多只针对其中锂的选择性浸出，并未考虑其他元素（如铁、磷、铝、铜等）的浸出行为紧密相关的问题。本文对废旧磷酸铁锂粉料的硫酸浸出过程进行了条件优化和宏观动力学研究，系统探究了温度、酸料比及反应时间对铁、磷、锂、铝和铜元素浸出过程的影响规律，讨论了以上元素浸出的宏观动力学。结果表明：优化条件下铁、磷、锂、铝和铜的浸出率分别为97.2%、96.9%、89.7%、76.1%和43.4%。其中，铁、磷、锂和铜的浸出符合内扩散模型，受扩散反应控制；铝的浸出符合混合控制模型，受扩散反应和化学反应协同控制。根据动力学模型拟合得出铁、铝和铜浸出的表观活化能分别为8.20kJ/mol、34.11kJ/mol和11.49kJ/mol。本研究明晰了废旧磷酸铁锂中各元素的浸出动力学，为元素的选择性浸出提供理论指导。

关键词: 废旧磷酸铁锂, 硫酸, 浸取, 动力学, 回收, 动力学模型