Flotation recovery for direct recycling of anode active material from lithium-ion battery scrap and its electrochemical behavior: Experiments and simulations

Abstract

Scaled-up flotation separation of lithium-ion battery scrap was used to recover anode active material that was then used to assemble half-coin cells. Additional cells were assembled using pristine graphite. The recovered active material consisted of particles that were finer than the pristine graphite and cracked. Additionally, aluminum, silicon, and fluoride traces remained in the recovered active material after the recycling process. Early-cycling measurements were used to optimize homogeneous electrochemical simulations. Subsequently, those optimized parameters were used for additional heterogeneous electrochemical simulations that accounted for realistic particle size distributions. The specific capacity of the recovered active material was lower than that of the pristine graphite in the 1st cycle and higher in the 30th cycle. The initial impedance of the recovered active material was lower than that of the pristine graphite. Characterization and simulation results suggest that the particle size distribution, particle fraction, and chemical composition, as well as the lithium concentration and stress on particles, influenced the specific capacity and impedance. An environmental assessment suggested that flotation separation is environmentally friendlier than pyrometallurgy or hydrometallurgy. However, an economic assessment suggested that cathode active material should be included in the flotation flowsheet to generate profits higher than those from pyrometallurgy or hydrometallurgy. This study is the first to model the electrochemical behavior of recovered anode active materials.