2.2 Global Warming Potential and Ecotoxicity Across Treatment Routes
Life-cycle impact characterization underscores clear differentiation in emissions and material retention across treatment configurations. Thermal smelting methods recover valuable transition metals but lose lithium and graphite to slag phases while generating substantial direct off-gas emissions, requiring significant secondary refining steps that elevate overall global warming burdens [8]. Conversely, hydrometallurgical leaching operates at lower direct process temperatures, shifting primary environmental hotspots toward the embodied impacts of acid reagents and neutralizing agents [8]. Direct recycling, which preserves cathode crystalline morphology, avoids both extensive chemical breakdown and thermal reduction, yielding the lowest cumulative greenhouse gas footprint per functional unit [8]. However, domestic implementation of direct recovery remains constrained by cathode heterogeneity, rapid cell chemistry evolution, and the current distribution of proprietary processing patents, which have historically focused on cell design rather than post-consumer disassembly in North America [6]. Consequently, hydrometallurgical pathways serve as the principal near-term bridge for high-purity mineral reclamation, provided that reagent recycling and wastewater neutralization are tightly integrated within industrial closed loops [6], [8].