Leaching performance of Al-bearing spent LiFePO4 cathode powder in H2SO4 aqueous solution
(1. School of Metallurgy, Northeastern University, Shenyang 110819, China;
2. CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
3. Materials Science & Engineering, University of Utah, Salt Lake City 84112, USA;
4. Faculty of Chemistry and Food Chemistry, Technische Universit？t Dresden, Dresden 01062, Germany)
2. CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;
3. Materials Science & Engineering, University of Utah, Salt Lake City 84112, USA;
4. Faculty of Chemistry and Food Chemistry, Technische Universit？t Dresden, Dresden 01062, Germany)
Abstract: The leaching performance and leaching kinetics of LiFePO4 (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.
Key words: LiFePO4; aluminum; leaching performance; leaching kinetics