Leaching performance of Al-bearing spent LiFePO_(4) cathode powder in H_(2)SO_(4) aqueous solution

The leaching performance and leaching kinetics of LiFePO_(4)(LFP)and Al in Al-bearing spent LFP cathode powder were systematically studied.The effects of temperature(273−368 K),stirring speed(200−950 r/min),reaction time(0−240 min),acid-to-material ratio(0.1:1−1:1 mL/g)and liquid-to-solid ratio(3:1−9:1 mL/g)on the leaching process were investigated.The results show that the concentration of reactants and the temperature have a greater impact on the leaching of Al.Under the optimal conditions,leaching efficiencies of LFP and Al are 91.53%and 15.98%,respectively.The kinetic study shows that the leaching of LFP is kinetically controlled by mixed surface reaction and diffusion,with an activation energy of 22.990 kJ/mol;whereas the leaching of Al is only controlled by surface chemical reaction,with an activation energy of 46.581 kJ/mol.A low leaching temperature can effectively suppress the dissolving of Al during the acid leaching of the spent LFP cathode material.

废旧磷酸铁锂正极粉磷酸浸出过程的优化及宏观动力学

随着新能源汽车产业快速发展,磷酸铁锂动力电池退役量爆发式增长,回收需求迫切,但面临回收利用经济性较差的难题。正极材料价值较高,本文提出采用磷酸浸出废旧正极材料以制备电池用磷酸铁,但铝等杂质的分离是关键。本文以含铝的磷酸铁锂正极粉为原料,开展了磷酸浸出过程优化及宏观动力学研究,重点研究了酸料比、浸出温度、液固比、搅拌速度等参数对磷酸铁锂及铝浸出效果的影响规律,并考察了磷酸铁锂在磷酸溶液中浸出的宏观动力学。研究结果表明,在酸料比1.1mL/g、温度20℃、液固比(5∶1)mL/g、搅拌速度400r/min、浸出时间120min条件下,磷酸铁锂浸出率大于93%,铝浸出率小于20%;磷酸铁锂正极粉磷酸浸出过程符合无固态产物层的收缩核模型,表观活化能为24.62kJ/mol,浸出过程受扩散控制。