Comparative Analysis of Facile and Novel Graphite Recovery Methods from Spent Lithium-Ion Batteries: Environmental and Economic Implications

Recycling graphite from spent Li-ion batteries (LiBs) is critical due to its role in battery manufacturing and increasing global demand. This study evaluated three recovery processes: (1) a cold process, based on mechanical separation; (2) a hot process, using CaO-assisted annealing; and (3) a wet process, employing acid leaching to dissolve copper. The processes were optimized for efficiency, characterized via SEM-EDS, XRF, XRD, CHN, and Raman spectroscopy, and assessed for environmental and economic performance by using life cycle approaches. Chemical analyses revealed that the wet process produced the highest-purity graphite (81% carbon) with minimal impurities, making it suitable for advanced applications. The hot process yielded 74% carbon with the lowest interlayer spacing (0.354 nm) due to annealing. While yielding lower-purity graphite, the cold process demonstrated superior environmental performance (single score impact (SSI) of −432 μPt) and a cost savings of $40/kg due to minimal energy inputs and copper recovery. In contrast, the wet process incurred significant costs ($420/kg) and environmental degradation (SSI 695 μPt), with the hot process balancing environmental and economic impacts (SSI 317 μPt, $159/kg). The wet process is ideal for high-quality applications, while the cold process is suitable for general uses. The hot process strikes the best balance, making it a highly versatile option.