Enhancement Mechanism of the Difference of Hydrophobicity between Anode and Cathode Active Materials from Spent Lithium-Ion Battery Using Plasma Modification

In the context of resource utilization of spent lithium-ion batteries (LIBs), low-temperature plasma modification has the advantages of high efficiency and nonpollution over traditional recycling pathways. In this work, the technique of degrading the binder in electrode materials with low-temperature plasma is proposed to solve issues of poor direct flotation performance of anode and cathode materials and a low recovery rate. First, the analysis of contact angle measurement is carried out; second, the effect of low-temperature plasma on the difference of hydrophobicity of anode and cathode materials is verified by the results of particle-bubble adhesion, the recovery, and kinetics of single mineral flotation tests; finally, the mechanism of low-temperature plasma surface modification of exfoliated electrode materials is further characterized by X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Results show that low-temperature plasma oxidizes and degrades the binder through high-energy particles with the generated strong oxidizing active substances (-OH, -O, O-3, etc.), making the original surface of anode and cathode materials exposed, which in turn increases the difference of hydrophobicity between the two and improves the flotation separation performance.