(285a) Continuous Recycling of Lithium-Ion Batteries: Extraction of Cobalt with Cyanex 272 in a Taylor-Couette Disc Contactor

Lithium-ion batteries (LIBs) have been a key factor for the breakthrough in electric mobility (e.g., cars) and portable electrical devices (e.g., cell phones and laptops). The continuously increasing demand of LIBs and the growing scarcity of finite resources have led to the need for a sustainable recycling concept to recover the valuable substances in high purity. In recent years, there has been a strong focus on hydrometallurgical processes, which have the potential to recycle more than 90% of the spent battery raw materials. The main emphasis has been on recycling of lithium¹ and cobalt.

Within this work, we demonstrate a selective extraction process for cobalt using saponified Cyanex 272 as extraction agent. Multicomponent model solutions of cobalt, manganese, nickel, copper and iron in aqueous sulfuric acid (c = 2 mol/L) were used simulating the characteristics of a typical leaching solution. Experiments in batch mode were executed to measure the influence of various experimental parameters (pH of aqueous solution, saponification of extraction agent, phase ratio). The experiments consisted of two extraction steps. The first step was done with saponified (bis(2-ethylhexyl) phosphate) (D2EHPA) as extraction agent to extract manganese, iron and copper from the aqueous solution. The second step was done with saponified Cyanex 272 to extract cobalt from the aqueous solution. The saponification of the extraction agents and the pH adjustment were done with sodium hydroxide. 93% of manganese, 86% of copper and 95% of iron were extracted within the first extraction step. 75% of cobalt was extracted within the second extraction step with a high selectivity of more than 90%, whereby cobalt can be reused by stripping and precipitation. Afterwards, a continuously operated extraction process in a Taylor-Couette Disc Contactor was done using the optimized parameters of the batch experiments.

This process concept gives access to direct recycling of cobalt hydroxide and using it as raw material for new LIBs. Furthermore, implementation of a continuous process assures a high and constant product quality. As a next step, the process will be done using shredded electrode material.

Sources

[1] Greil et al., ACS Omega 2024 9 (7), 7806-7816, DOI: 10.1021/acsomega.3c07405