Influences of plasma treatment parameters on the hydrophobicity of cathode and anode materials from spent lithium-ion batteries.

[Display omitted] • Contact angles of anode and cathode materials are modified using plasma modification. • Interactions between plasma parameters are evaluated by Box-Behnken design. • Plasma treatment enhances flotation separation selectivity of electrode materials. • Flotation of anode and cathode materials obeys to the first order-kinetic model. • The contact angle increase of anode materials plays a major role in plasma treatment. The recycling of spent lithium-ion batteries (LIBs) can not only reduce the potential harm caused by solid waste piles to the local environment but also provide raw materials for manufacturing new batteries. Flotation is an alternative approach to achieve the selective separation of cathode and anode active materials from spent LIBs. However, the presence of organic binder on the surface of hydrophilic lithium transition-metal oxides results in losses of cathode materials in the froth phase. In this study, plasma treatment was utilized to remove organic layers from cathode and anode active materials. Firstly, the correlations between plasma treatment parameters (e.g., input power, air flowrate, and treatment time) were explored and the contact angles of cathode and anode active materials were investigated by the response surface methodology. Secondly, differences in the flotation recoveries of cathode and anode active materials were enhanced with plasma modification prior to flotation, which is consistent with the contact angle measurement. Finally, the plasma-modification mechanisms of hydrophobicity of cathode and anode active materials were discussed according to Fourier Transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The proposed method could be a promising tool to enhance the flotation separation efficiency of cathode and anode active materials for the recycling of spent LIBs. [ABSTRACT FROM AUTHOR]