Sulfation Roasting for Sustainable Lithium-First Recovery from Spent NCM Batteries: Minimizing Acid Consumption, Process Time, and Energy Demand

Sulfation roasting has emerged as a promising alternative for lithium-first recovery from spent lithium-ion batteries, while reducing hydrometallurgical complexity. This study investigated the sulfation roasting of nickel–cobalt–manganese oxide (NCM) black mass to maximize lithium recovery while minimizing sulfuric acid consumption and thermal treatment time. The effects of preliminary calcination, sulfuric acid dosage, and roasting time were systematically investigated at 550 °C. Lithium and coextracted metals were quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES), while phase transformations were analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF). Statistical evaluation identified sulfuric acid dosage as the only factor significantly affecting lithium extraction. An integrated success index was developed to assess lithium recovery, contaminant dissolution, reagent consumption, and thermal treatment time. Under the optimum conditions (nLi:nH2SO4 = 1:0.95, without preliminary calcination, 45 min), lithium recovery reached 90.8%, with a 75% reduction in thermal treatment time compared with previously reported sulfation roasting routes. A mass balance showed that sulfuric acid consumption corresponded to only 7.8% of that required for conventional hydrometallurgical leaching. These findings demonstrate that sulfation roasting substantially improves the sustainability of lithium-first recovery by reducing chemical reagent and energy while maintaining high recovery efficiency.