Comparison of the Ammoniacal Leaching Behavior of Layered LiNixCoyMn1–x–yO2 (x = 1/3, 0.5, 0.8) Cathode Materials

Recycling of spent lithium-ion batteries has received widespread concern on account of the high content of hazardous and valuable metals contained therein. In this research, ammonia leaching process is adapted to extract valuable metals selectively from LiNixCoyMn1–x–yO2 (x = 1/3, 0.5, 0.8) cathode materials. By employing ammoniacal solution as the leaching agent and sodium sulfite as reductant, Ni, Co, and Li are leached from lixivium either as complexes or metallic ion. Manganese is first leached from lixivium as Mn2+ and subsequently deposited from Mn3O4 to (NH4)2Mn(SO3)2·H2O as sodium sulfite is added. Compared with the agglomerated (NH4)2Mn(SO3)2·H2O tightly wrapped on the surface of the unreacted material, loose and porous Mn3O4 is more favorable to ion diffusion and leaching reaction. Amounts of 93.3% Li, 98.2% Co, and 97.9% Ni can be leached from LiNi1/3Co1/3Mn1/3O2 material by the introduced two-step leaching process, much higher than that with the one-step process. Simultaneously, 94.4% Li, 99.7% Co, and 99.5% Ni can be leached from LiNi0.5Co0.2Mn0.3O2 material, while the leaching efficiency of Li, Ni, and Co reaches 95.0%, 98.4%, and 96.9% for LiNi0.8Co0.1Mn0.1O2 material by a one-step leaching process.