Recovery of active cathode materials from lithium-ion batteries using froth flotation

Elsevier, Sustainable Materials and Technologies, Volume 17, 2018, e00062, ISSN 2214-9937
Authors: 
Ruiting Zhan, Zachary Oldenburg, Lei Pan

An ability to separate battery electrode materials while preserving functional integrity is essential to close the loop of material use in lithium-ion batteries. However, a low-energy and low-cost separation system that selectively recovers electrode materials has not yet been established. In this study, froth flotation experiments were carried out with a variety of new and spent lithium-ion batteries using kerosene as the collector. The products were characterized using thermogravimetric and chemical analysis. It was found that over 90% of anode materials were floated in froth layers, while 10–30% of cathode materials were floated. Thermogravimetric analysis showed that the presence of binders and conductive additives might be responsible for the partial floatability of the liberated cathode materials. Separability of mixed electrode materials was evaluated using a modified procedure based on release analysis. Results showed that the froth flotation process using kerosene as the collector produced a tailing product having cathode materials of higher purity than those obtained without kerosene. For spent lithium-ion batteries, a low purity of cathode materials in tailings might be improved by fine grinding, at which freshly liberated hydrophobic surfaces are exposed and consequently anode materials become floatable. The present result confirms that the froth flotation technique is a viable and versatile technique in producing high purity cathode materials from lithium-ion batteries.