Lithium-ion batteries have become crucial for powering electric vehicles and supplying smart devices. However, the increasing demand for batteries poses significant challenges. The insufficient capacity of cobalt, nickel, and lithium mining to meet global demands can be compensated by recycling of spent batteries. Further, this minimizes environmentally damaging disposal.
This study concerns the recycling of the 'black material' a fraction within the established recycling route for spent lithium-ion batteries. Hence, a hydrometallurgical approach consisting of a leaching process followed by isolation and purification of the present metals is investigated.
The leaching process is crucial for the extraction, where high acid concentrations and the aid of reductants enhances the yield. However, excess acid should be minimized to reduce the subsequent brine consumption. Other parameters investigated were reductant concentration, solid/ liquid ratio, and temperature. The reactive solvent extraction of manganese was subsequent studied with the optimized leaching liquor. The commercially available liquid ion exchanger di(2-ethylhexyl) phosphoric acid was used as the extractant. The optimal pH-value and D2EHPA concentration was determined in batch experiments. The optimization was achieved with respect to a high manganese extraction at low coextraction of cobalt and nickel.
Since multiple equilibrium steps are necessary for complete extraction, further investigations are carried out on a pilot scale extraction column. However, an inherently short residence time and the lack of pH-control within the column determine the mass transfer. In this study we demonstrate, that suitable operation conditions (phase ratio, column loading, and feed pH value) enables the extraction of 99 % of the manganese. The manganese-free leaching liquor can thus be fed to the cobalt/nickel separation known from the literature.
Forschungs-