Microwave‐Assisted Leaching and Mixed Oxalates Precipitation as Closed‐Loop NMC532 Recycling Process

This work aims to advance the research on microwave (MW)‐assisted hydrometallurgical recycling of Li(Ni/Mn/Co)O 2 (NMC) cathode materials, with a special focus on leaching and mixed oxalate precipitation. Traditional (hot plate and magnetic stirring) setup and MW‐assisted one have been systematically compared across different organic‐based leaching recipes. Pristine NMC532 MW‐assisted leaching achieves near quantitative recovery (>99%) for Ni, Mn, Co while reducing the reaction times by up to 75%. Characterization of the obtained oxalates reveals that, while the leaching media do not affect the composition, mechanical stirring plays a major role during the precipitation, ensuring uniform growth and morphology. Consequently, the hybrid setup (MW‐assisted leaching and “standard” precipitation) has been chosen for the best‐performing recipe scale up, followed by cathode recovery and electrochemical testing. Quantitative green chemistry metrics further confirm the process efficiency, demonstrating a 40%–60% reduction in specific energy consumption and 35% reduction in process mass intensity via direct solid‐oxalate addition. The resynthesized cathodes demonstrate electrochemical performance comparable with the pristine commercial benchmark, demonstrating the feasibility of the proposed recycling routes. Finally, the procedure was successfully validated on real NMC622 spent battery black mass, confirming the efficiency and transferability of the proposed method as a sustainable hydrometallurgical recycling route.