Thermodynamic Analysis and Experimental Optimization for the Purification of Ni-Co-Mn Mixed Sulfate Solution from the Recovery Process of Lithium-Ion Batteries

Based on the principles of mass conservation, chemical equilibrium, and electron charge neutrality, a thermodynamic equilibrium system was established for the nickel-cobalt-manganese sulfate leaching solution in the recovery process of spent lithium-ion batteries. By changing the ion concentration in the system, calculating the pH value, and identifying the complexes of Cu2+, Fe3+, PO43-, Al3+, and F- in the system, the results were obtained and used to draw the thermodynamic diagram. The solution thermodynamic calculation and experiment were combined to purify the nickel-cobalt-manganese-rich leachate. The results show that the main Cu2+, Fe3+, PO43-, Al3+, and F- impurity ions could all be reduced to less than 10 ppm under the optimized process parameters.