Sustainable Pre-treatment Method for Lithium-ion Production Scrap Material Recovery and Re-utilisation

The global market for lithium-ion batteries (LIBs) is experiencing substantial growth, with demand projected to rise further due to efforts to decarbonize transportation and energy sectors. Demand for LIBs is anticipated to grow from 700 GWh in 2022 to 4700 GWh by 2030. This steep growth has led to the establishment of numerous new Gigafactories worldwide. As battery production expands, the volume of scrap material generated will significantly rise. Due to high-quality standards in battery manufacturing, a notable portion of production will not meet these criteria, creating a growing stream of valuable resources surpassing end-of-life batteries. Conventional battery recycling relies on pyrometallurgical and hydrometallurgical processes, which are efficient in material recovery but are energy intensive and present environmental and economic burdens. Direct recycling, a novel approach, has recently been proposed to recover active material while conserving its original structure. Industrial upscaling of direct recycling of production scrap requires fast, cheap, and reliable structural analysis tools easily implemented in production sites. These tools optimize the steps needed for different material batches. However, direct recycling of LIBs production scraps presents challenges due to their inhomogeneity. This Thesis investigates direct recycling of LIBs production scraps, focusing on the most common cathode chemistries: Lithium Nickel Cobalt Manganese oxides (NMC) and Lithium Iron Phosphate (LFP) cathodes. Direct recycling was performed under different thermal treatment conditions (process temperatures: 20°C, 200°C, 300°C, 400°C, and 600°C, in air and inert N2 atmospheres, for 30 min) followed by manual detachment of the cathodic material. The recycled materials were then used to produce new LIBs coin cells to test electrochemical behavior. Energy consumption was directly measured during experiments to evaluate economic and environmental costs of the different conditions. Thermal treatment at 400°C in air for 30 minutes provided high recovery rates for LFP (91% P, 95% Fe) and NMC (97% Mn, 96% Co, 96% Ni) electrodes while keeping impurity rates below 0.2%. These values are comparable to current industrial recycling methods. Economic and environmental performance evaluations showed economic benefits and a CO2 emission reduction of 22% compared to production from pristine elements. LFP material performed well in electrochemical tests, achieving a discharge capacity of 125 mAh/g and a coulombic efficiency above 95%. In contrast, NMC direct recycling still requires optimization due to structural alterations during thermal treatment. In conclusion, this Thesis demonstrates that low-temperature thermal treatment can enhance the economic and environmental sustainability of recycling production scrap while maintaining electrochemical performance, especially for LFP material. This approach offers a promising avenue for future research and industrial application in lithium-ion battery material recycling.