Sustainable Recycling of Electrode Materials in Spent Li-Ion Batteries through Direct Regeneration Processes

Abstract

The prevalence of electric vehicles (EVs) globally could generate a huge number of spent Li-ion batteries (LIBs) as they reach their end of life. It is expected that by 2030, 11 million metric tons of EOL LIBs will be generated cumulatively, with annual waste flows of EV batteries reaching 34,000 t by 2040. Recycling spent LIBs in a sustainable and effective manner is a matter of utmost importance. Conventional recycling strategies such as pyrometallurgy and hydrometallurgy decompose the crystal structures of value-added electrode materials to element levels, presenting fatal drawbacks in high greenhouse gas emissions, cost, and energy consumption. The burgeoning direct recycling processes provide viable options to rejuvenate LIB compounds without chemical change, thus retaining their original composition as well as the embedded energy. Relithiation and defect restoration are the critical steps for electrode regeneration, which determine the performance of recovered material. Here, the authors provide a detailed discussion and analysis on different regeneration methods for LIB electrodes based on their degradation mechanisms. The advancements of direct recycling among other recycling technologies are highlighted through discussions of its process benefits. Physical pretreatments including deactivation, disassembly, and black mass separation are introduced. Perspectives toward scaled applications of direct recycling are also demonstrated on the basis of developing trends of future LIBs.

Enabling Aqueous Processing of Ni‐Rich Layered Oxide Cathode Materials by Addition of Lithium Sulfate

“…[9] The conversion of electrodes into black mass, which typically consists of active material, binder, and conductive additives, is expected to be easier and cheaper for aqueouslyprocessed cathodes (e. g., by using fluorine-free binders). [10] However, Ni-rich NCM CAMs are highly sensitive towards moisture, inevitably leading to surface reconstruction and formation of surface species accompanied by lithium leaching upon contact to water during processing or exposure to ambient atmosphere (e. g., Li 2 CO 3 or Ni-based carbonates/ hydroxides), which deteriorate cell performance and cycle life. [11][12][13] When exposed to water, Li + /H + exchange can take place, which leaches Li + from the bulk of the NCM material and dissolves into the electrode paste dispersion during processing.…”

“…Furthermore, recycling of LIBs, and especially of the cathode material, will become a highly relevant topic in the coming years [9] . The conversion of electrodes into black mass, which typically consists of active material, binder, and conductive additives, is expected to be easier and cheaper for aqueously‐processed cathodes (e. g., by using fluorine‐free binders) [10] …”

“… [9] The conversion of electrodes into black mass, which typically consists of active material, binder, and conductive additives, is expected to be easier and cheaper for aqueously‐processed cathodes (e. g., by using fluorine‐free binders). [10] …”

Retrieving Spent Cathodes from Lithium‐Ion Batteries through Flourishing Technologies

“…It is another method for the direct relithiation of spent cathode under mild condition. The ionic liquid supplies strong coulombic interaction between the ions, which subsequently served as both solvents and potential structure‐directing agent in the solid [33,62] . Wang and co‐workers [63] demonstrated novel ionothermal relithiation of delithiated NCM cathode using ionic liquids as recyclable solvents.…”

“…The ionic liquid supplies strong coulombic interaction between the ions, which subsequently served as both solvents and potential structure-directing agent in the solid. [33,62] Wang and co-workers [63] demonstrated novel ionothermal relithiation of delithiated NCM cathode using ionic liquids as recyclable solvents. The ionic liquids are the conventional molten salts leading to various advantages like negligible vapour pressure, negligible flammability, excellent thermal conductivity and much more flexibility in synthesis.…”