Direct Recycling Process for Production Scraps of Li-Ion Batteries Positive Electrode Based on Pressurized Co2

Due to the lack of adapted competitive recycling methods, Lithium-ion Batteries (LIB) production scraps are currently treated as spent batteries, despite their significant difference in characteristics. However, with the drastic increase in LIB production and consequently, the generation of scraps, various innovative recycling techniques have emerged and gained significant attention, aiming to offer greener, cheaper and more direct recycling routes. 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 direct recycling of positive electrode production scraps. The influence of various experimental parameters such as the TEP to acetone ratio, temperature, time, and solvent quantity was investigated to optimize the delamination parameters. The optimized experimental conditions to achieve a full delamination within 15 minutes are 120°C, a solvent mixture composed of 75% of TEP and 25% of acetone (v/v), a concentration of 1.5% of TEP to electrode ratio (w/w) and a CO2 pressure of 100 bar. Subsequent to the process, the active material LiNi0.6Mn0.2Co0.2O2 (NMC622) was easily separated from the current collector, enabling a comprehensive characterization. Meanwhile, the dissolved polyvinylidene difluoride (PVDF) in the delamination solvent could be recovered by precipitation in water as antisolvent. 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 pristine NMC622, affirming the promising potential of this approach.