Towards the production of oxalate precursors from NMC111 black mass via selective leaching of Li and Al and solvent extraction of Cu

A novel recycling route for spent lithium-ion batteries has been investigated. The end goal is to produce cathode active material (CAM) precursor directly from the recycled solution. The process begins with an oxalic acid leaching (0.6 M H 2 C 2 O 4 , 60 °C, 120 min, and S/L = 50 g/L), where Li is selectively recovered (along with Al) which reduces downstream contamination and enhances overall material efficiency. The resulting residue, a mixture of (Co,Ni,Mn)C 2 O 4 · 2H 2 O, graphite, and Cu, is then leached with sulfuric acid to dissolve the metals and separate them from the graphite. This second leaching operation is investigated, and the optimum parameters are demonstrated (2 M H 2 SO 4 , 65 °C, 120 min, S/L = 20 g/L), yielding more than 95 % recovery of Ni, Co, and Mn and about 70 % of Cu. Lower acidity or S/L leads to the reprecipitation of a Ni oxalate phase. Solvent extraction is selected for Cu removal at a limit of 5 ppm; a 30 % v/v Acorga M5640 in ESCAID is applied for 30 min at 25 °C, with θ = 4 and 4 stages. The resulting recycled solution, containing Co, Ni, and Mn, and free from Al, Li, and Cu, represents a promising feedstock for producing NMC 111 (LiNi 0.33 Mn 0.33 Co 0.33 O 2 ).