Recycling spent lithium batteries – an overview of pretreatment flowsheet development based on metallurgical factors

Since soon a huge amount of the spent lithium-ion batteries (LIBs) will end up in landfills, their recycling would be essential in reducing potential environmental issues and covering the raised lithium demands. Therefore, recycling LIBs has turned into a hot research topic. While essential developments in our understanding of recycling LIBs have been achieved, a fully optimised flowsheet design, to some extent, remained the in-house know-how of manufacturing plants. Pretreatment (physical separation), as an initial step, unquestionably affects the performance of the entire recycling process of the spent LIBs. Nevertheless, surprisingly no detail was provided through investigations for each step of the physical separation processes applied for recycling spent LIBs based on the published reports. To tackle these issues, this work analyzed approximately all the possible pretreatment processes involved in the safe recycling of LIBs. Detailed assessments of these investigations indicated that several critical points did not consider or reported through original and reviewed research for recycling LIBs. The process optimisation, metallurgical responses of various pretreatment steps, particle size limitation of different pretreatment methods, magnetic, specific gravity, and surface properties of cathode and anode materials, and several other essential variables did not consider or reported through various investigations. Addressing these gaps will pave the way for the design and operation of the recycling LIBs flowsheet.