Antisolvent Precipitation for Metal Recovery from Citric Acid Solution in Recycling of NMC Cathode Materials

Abstract

Lithium-ion batteries (LIBs) are widely used everywhere today, and their recycling is very important. This paper addresses the recovery of metals from NMC111 (LiNi1/3Mn1/3Co1/3O2) cathodic materials by leaching followed by antisolvent precipitation. Ultrasound-assisted leaching of the cathodic material was performed in 1.5 mol L−1 citric acid at 50 °C and at a solid-to-liquid ratio of 20 g/L. Nickel(II), manganese(II) and cobalt(II) were precipitated from the leach liquor as citrates at 25 °C by adding an antisolvent (acetone or ethanol). No lithium(I) precipitation occurred under the experimental conditions, allowing for lithium separation. The precipitation efficiencies of manganese(II), cobalt(II) and nickel(II) decreased according to the order Mn > Co > Ni. The precipitation efficiency increased when a greater volume of antisolvent to the leachate was used. A smaller volume of acetone than ethanol was needed to reach the same precipitation efficiency in accordance with the difference in the dielectric constants of ethanol and acetone and their associated solubility constants. After adding two volumes of acetone into one volume of the leach liquor, 99.7% manganese, 97.0% cobalt and 86.9% nickel were recovered after 120 h, leaving lithium in the liquid phase. The metal citrates were converted into metal oxides by calcination at 900 °C.

Keywords

• lithium-ion batteries
• NMC111
• cathode
• recycling
• hydrometallurgy
• antisolvent