Direct Recycling Process Using Pressurized CO₂ for Li-Ion Battery Positive Electrode Production Scraps

This study explores a novel solvent-based delamination method that employs a mixture of triethyl phosphate (TEP), acetone, and carbon dioxide (CO2) under pressure and temperature for the efficient and fast direct recycling of positive electrode production scraps. Optimization of experimental conditions led to achieve 100% of delamination within 15 min at 120 °C and 100 bar, with a low solvent consumption of 1.5 of TEP to electrode ratio (w/w). The CO2 allows decreasing the viscosity of the TEP and acetone mixture and so increasing its diffusivity; favoring the binder dissolution and accelerating the delamination process versus other reported processes. This original approach not only enables the reduction of solvent consumption (by 6.7×), but removes the need for stirring, which is often detrimental to solvent-based approaches for scaling up the process while maintaining 100% of delamination. Subsequent to the delamination process, the active material LiNi0.6Mn0.2Co0.2O2 (NMC622) in powder form was easily and fully separated from the current collector, enabling a comprehensive characterization. A more in-depth focus on the electrochemically active material revealed that its chemical composition, crystal structure, and microstructure remained preserved throughout the recycling process. Ultimately, the electrochemical performance of the recycled NMC622 closely resembled that of the pristine NMC622, affirming the promising potential of this approach.