Spent lithium-ion battery recycling: investigation into the inhibition and separation between Li(I) and Al(III) ions

The recovery of NCM (LiNi x Co y Mn 1-x-y O 2 , abbreviated as NCM) cathode materials from retired lithium-ion batteries is a research hotspot in resource recycling field. Nevertheless, due to aluminum impurities mixed in raw materials, Li(I) and Al(III) ions are easy to combine to form water-insoluble LiAlO 2 during reduction, affecting Li(I) ions’ water-leaching efficiency. In this study, the LiAlO 2 formation environment is analyzed. Thermodynamic analysis reveals that there is generally less spontaneity in the reaction of Li (I) ions with aluminum monomers compared to Al 2 O 3 , and the introduction of CO 2 can inhibit Li-Al-O substance production. Li-Al binding experiments show that there is almost no direct reaction between Li 2 CO 3 and aluminum monomers, but under Ar atmosphere, Li 2 CO 3 and Al 2 O 3 can easily lead to Li-Al binding, a kinetic analysis considers that binding is controlled by chemical reaction, with an activation energy of 57.78 kJ/mol, and the activation energy increases to 88.028 kJ/mol with CO 2 atmosphere. Under reduced optimization conditions (reduction temperature: 500 °C, time: 6 h, and m NCM : m Al  = 1: 0.25), the carbonation water-leaching efficiency can reach 95.1% for Li(I) ions and less than 1% for Ni(II), Co(II), Mn(II), and Al(III) ions. Thus, this work offers a theoretical basis for the industrial Li(I) ions’ recovery from aluminum-containing NCM materials.