Appraising the environmental footprints of spent Li-ion batteries recycling via a pyro/hydrometallurgy hybrid approach

The growing demand for Li-ion batteries (LIBs), coupled with the scarcity of raw material resources, poses significant techno-economic and ecological challenges. Additionally, the increasing amount of spent LIB waste endangers the ecosystem. Recycling these batteries has been proven to be environmentally beneficial and economically sustainable compared to mining and extraction. This study analyzed the direct and background environmental footprints of recycling a mixed blend of LIBs and recovering lithium (Li) using a hybrid approach. This process combined two segments: pyrometallurgy and hydrometallurgy. Pyrometallurgy included the incineration process to liberate constituents, the smelting section to form Li-bearing slag, and the chlorination roasting process for chemically assisted transformation. This was followed by the hydrometallurgy segment, where Li was recovered. A specialized environmental life cycle assessment method was applied to evaluate the environmental burden of each section. The study showed that, due to the energy-intensive nature of the process and electricity being the sole source of energy, its background emissions impacts played a noticeable role, contributing to 97 % of the ozone depletion potential (ODP) and 41 % of the total CO₂ emissions. A sensitivity analysis was conducted using a global sensitivity approach with Latin hypercube sampling showed high sensitivity of global warming potential (GWP) and smog formation categories to N₂O and NO, respectively. Additionally, with the help of four different designed scenarios, uncertainty in various environmental categories was highlighted, demonstrating that a 20 % substitution of the current electricity source with renewable ones significantly reduced the environmental impacts of the process.