Hydrometallurgical Processes on Recycling of Spent Lithium-lon Battery Cathode: Advances and Applications in Sustainable Technologies

Abstract

Rechargeable lithium-ion batteries (LIBs) have garnered global attention as a prominent solution for storing intermittent renewable energy, addressing energy scarcity, and mitigating environmental pollution. In the previous century, Sony introduced the “lithium-ion battery” concept, heralding a new era for LIBs and effectively bringing them into commercial use. The initial commercially available LIBs utilized lithium cobalt oxide as the cathode material and graphite as the anode material. Capitalizing on their attributes encompassing elevated energy density, substantial specific capacity, portability, and ecological compatibility, LIBs have secured substantial market share throughout the commercialization trajectory. Their commercial viability and scope have been markedly enhanced through the continuous advancement of LIBs’ cathode materials and innovative implementations encompassing battery design, assembly, and thermal management. In recent years, the rapid expansion of sectors such as cellular phones and new energy vehicles, coupled with the drive towards “carbon peaking” and “carbon neutrality,” has propelled the robust growth of the LIBs sector, which has resulted in widespread adoption across diverse industrial domains and daily applications spanning road transportation, materials, chemicals, and information technology. However, the swift proliferation of the LIBs industry has incited an influx of end-of-life (EOL) batteries, which pose risks of flammability, explosiveness, and the presence of toxic and hazardous elements, including fluorides. These aspects collectively pose a formidable environmental and human health hazard, warranting urgent and harmless disposal measures. Simultaneously, EOL LIBs are rich reservoirs of resources like lithium, nickel, cobalt, and manganese, boasting metal contents in cathode waste that significantly exceed those found in their natural mineral counterparts, presenting a substantial opportunity for resource reclamation. Therefore, extracting valuable metals from LIBs cathode waste simultaneously addresses critical environmental and human health concerns linked to improper EOL LIBs disposal while playing a pivotal role in mitigating metal resource shortages. This dual-purpose endeavor aligns with the overarching goal of promoting sustainable resource circulation. The recovery of LIBs cathode materials is a central topic of global research discussion. This study comprehensively overviews valuable metal extraction from LIBs cathode waste using hydrometallurgical methodologies. It delves deeply into diverse approaches encompassing inorganic, organic, and deep eutectic solvents (DESs), scrutinizing environmental, technical, and industrial feasibilities. The objective is to optimize extraction techniques and mitigate their environmental impact. Furthermore, this paper meticulously discusses the utilization of environmentally friendly reducing agents like green biomass waste, coupled with the efficient and eco-conscious EOL LIBs internal cycle mechanical activation technology, to enhance the leaching of valuable metals from cathode waste. This inquiry culminates in identifying potential research avenues and challenges within the EOL LIBs recycling process.

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