Highly Efficient Recovery and Recycling of Cobalt from Spent Lithium-Ion Batteries Using an N-Methylurea–Acetamide Nonionic Deep Eutectic Solvent

Abstract

The growing demand for lithium-ion batteries (LiBs) for the electronic and automobile industries combined with the limited availability of key metal components, in particular cobalt, drives the need for efficient methods for the recovery and recycling of these materials from battery waste. Herein, we introduce a novel and efficient approach for the extraction of cobalt, and other metal components, from spent LiBs using a nonionic deep eutectic solvent (ni-DES) comprised of N-methylurea and acetamide under relatively mild conditions. Cobalt could be recovered from lithium cobalt oxide-based LiBs with an extraction efficiency of >97% and used to fabricate new batteries. The N-methylurea was found to act as both a solvent component and a reagent, the mechanism of which was elucidated.

A Review of Lithium-Ion Battery Recycling: Technologies, Sustainability, and Open Issues

“…Moreover, in the case of inorganic acid leaching, the formation of hazardous gas species such as NO x , SO x , and HCl need to be accounted for as a source of secondary pollution [6,82,83]. Solvometallurgy is based on the use of alternative leaching systems such as ionic liquids and deep eutectic solvents (DESs); particularly, this last class of compounds has led to appealing results since the first report of their exploitation for cathode recycling [84][85][86][87].…”

“…The range of explored conditions is wide, with the main parameters affecting the leaching process being the time (60 min-48 h), temperature (80-240 • C), and the liquidsolid ratio [81,84,86,[93][94][95][96][97][98][99][100]. The mechanism driving the leaching is still not completely clear; the presence of a reducing agent seems to be necessary to force the Co 3+ /Co 2+ reduction and favor the degradation of the LCO materials [93][94][95]103].…”

Waste-to-Resources: Leaching of Cobalt from Spent Cobalt Oxide Catalyst

“…Despite the fact that Umicore and Inmetco companies operate LiB recycling installations [28], in general, the LiB recycling and metal recovery technologies appear to be still in an early stage of development. Therefore, numerous and varied proposals have ranged from pyrometallurgy [29], hydrometallurgy [28,30], and a combination of both [31,32] to electrometallurgy [33]. Among them, a novel system using deep eutectic solvent (N-methylurea-acetamide) as a leaching solution has been reported to recover 97% of the cobalt from lithium cobalt-oxide-based LiBs and reuse this metal in new batteries [30].…”

“…Therefore, numerous and varied proposals have ranged from pyrometallurgy [29], hydrometallurgy [28,30], and a combination of both [31,32] to electrometallurgy [33]. Among them, a novel system using deep eutectic solvent (N-methylurea-acetamide) as a leaching solution has been reported to recover 97% of the cobalt from lithium cobalt-oxide-based LiBs and reuse this metal in new batteries [30]. Furthermore, a system of 0.5 M HCl and 0.5 M L-ascorbic acid has been shown to perform ultra-fast leaching of spent cathode materials (97.72% Li and 97.25% Co leached in the S/L ratio: 10 g/L, at 90 • C in 10 min) [28].…”

A case study using spectroscopy and computational modelling for Co speciation in a deep eutectic solvent

“…3 The current recovery process of cobalt from spent LIB cathodes is mainly based on hydrometallurgical methods involving leaching (using traditional concentrated acids or alkali), separation steps (e.g., solvent extraction, ion exchange resins), and product recovery steps (e.g., precipitation, electrodeposition). 4,5 The use of deep eutectic solvents (DESs) for metal recovery has received a great deal of attention since they can be safer and more environmentally friendly compared to conventional solvents such as H 2 SO 4 , HNO 3 , and HCl, which are currently used in metal recovery. [6][7][8][9] DESs can be easily tuned by mixing different hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA) to form a liquid at room temperature.…”