Green Leaching of Lithium-Ion Battery Cathodes by Ascorbic Acid Modified Guanidine-Based Deep Eutectic Solvents

Abstract

The replacement of traditional solvents in lithium-ion battery recovery process by deep eutectic solvents (DESs) has been widely reported. This work proposed a DES modified by reducing agents for the efficient leaching of LiCoO2 (LCO) and lithium nickel cobalt manganese oxides (NCMs) to overcome the intractable difficulty of previous research (high viscosity, poor reuse performance, and operation conditions). The DES of guanidine hydrochloride (GUC) and lactic acid (LAC) with 1 wt % ascorbic acid could dissolve almost 100% of LCO and NCMs under a very mild condition at a solid–liquid ratio of 1:50. The maximum contents in GUC-LAC were 3188 ppm for Li and 19,045 ppm for Co. After stripping Co by oxalic acid and supplementing VC, GUC-LAC-VC could maintain the dissolution properties with at least three cycles. In addition, the acidity and reducibility were measured through Hammet acidity and cyclic voltammetry methods, as key factors for the dissolution of Li and Co.

Designing Low-Cost, Green, and Recyclable Deep Eutectic Solvents for Selective Separation and Recovery of Valuable Metals from Spent Li-Ion Batteries

“…It is a truism that the viscosity of DESs is mainly given van der Waals force, hydrogen bonding, and electrostatic interactions; the lower viscosity is more favorable to accelerate the liquid–solid reaction and the subsequent separation. , The kinematic viscosities of UC13-FA-DESs with different FA ratios measured at 20–140 °C are shown in Figure e (Table S2). Higher temperature leads to lower viscosity, even from 23.08 to 2.09 cP for the UC13-FA2.4-DESs.…”

Green recycling of spent Li-ion battery cathodes via deep-eutectic solvents

“…This boost was attributed to the stronger acidity of MAL–PSA combination, leading to increased solubility of LIBs in ternary DESs compared with binary DESs. Recently Yan et al 55 reported that GUC based DES exhibited higher acidity compared with DES based on ChCl, and that LA is more acidic than GA when used as HBD for both types of DES. Amongst the four DESs, Li and Co leaching efficiencies increased with increasing acidity.…”

“…half that the 1ChCl-1OA leaching of 7 vs. 14.2%. 112 For DESs with HBDs other than oxalic acid including, ChCl-2urea, 40 2ChCl-LA, 114 ChCl-LA, 50 and GUC-LA-VC, 55 oxalic acid is reportedly also used as a stripping reagent to separate transition metals from Li following leaching. The first step was coprecipitation of all transition metals or precipitation of individual metal by OA, followed by precipitation of Li + as Li 2 CO 3 39 or LiPO at Z11 (solvent extraction), and; then back to acidic pH 1.5 (stripping).…”

Deep Eutectic Solvents for Batteries and Fuel Cells: Biosubstitution, Advantages, Challenges, and Future Directions

“…Several deep eutectic solvents were tested as leaching agents in the presence of different types of additives (i.e., guanidine hydrochloride with ascorbic acid, phytic acid, etc. ). , The optimization of cobalt recovery was carried out by investigating various operating conditions such as reaction time, temperature, solid (black mass) to liquid (DES) ratio, additive type, and concentration. Leaching with the final selected DES ChCl (33%), lactic acid (53%), and citric acid (13%) at 55 °C achieved an extraction yield of more than 95% for cobalt.…”