Researching the Feasibility of Utilizing Industrial Solid Waste for Separating Cathode Material and Aluminum Foil from Spent Lithium-Ion Batteries

During the thermochemical pretreatment of spent lithium-ion batteries (LIBs), the decomposition of polyvinylidene fluoride (PVDF) can be a major concern due to the potential release of dioxins and fluoride, which presents a serious obstacle to the global decarbonization of electric vehicles. In this study, we propose the use of alkaline solid waste as a dual-functional effective medium to mitigate the potential environmental risks associated with PVDF thermochemical decomposition. Our results show that when red mud was used as an alkaline medium, the peeling temperature of cathode material particles and aluminum foil can be significantly reduced to 325°C, resulting in a separation efficiency of 98.3 wt.% after a holding time of 10.0 min. The mechanism analysis conducted demonstrated that the fundamental oxides present in red mud can accelerate the advanced thermal degradation of PVDF. Iron oxide found in red mud can absorb and capture the organic fluorine present in PVDF in-situ. Density functional theory confirmed that oxide can effectively eliminate hydrogen and fluorine atoms from PVDF molecules via electron transfer and facilitate its disintegration. These findings may lead to potential measures for pollution control during recycling of spent LIBs by providing a means to curb the hazards of organic fluorine emission.