Sequential separation of critical metals from lithium-ion batteries based on deep eutectic solvent and electrodeposition

Achieving High Solid-Liquid Ratio through Competitive Coordination towards Efficient Recovery of Metals from Spent Batteries

The recycling of critical metals from spent lithium-ion batteries represents a significant step towards meeting the enhancing resource requirements in the new energy industry. Nevertheless, achieving effective leaching of metals from the stable metal-oxygen (MO6) structure of spent ternary cathodes and separation of metal products simultaneously still remained a huge challenge towards industrial applications. Herein, a competitive coordination strategy was proposed to design a novel deep eutectic solvent (DESs), which improved both leaching and selective metal recycling capacity even at high solid-liquid ratio (1 : 10). The results demonstrated that the number of hydrogen bonds in designed ternary DESs was 16.5 % higher compared to those in the binary DESs, resulting in efficient reaction kinetics to break the metals-oxygen bond. More importantly, the competing-ligand (p-toluenesulfonic acid) could preferentially enter into the first nanostructure sheath and reduce the proportion of solvated oxalic acid (OxA) from 28.36 % to 17.76 % within the nanostructure, which enable OxA molecules to enhance the coordination interaction with metal for precipitating NiC2O4 ⋅ 2H2O product (~95.7 % purity) from spent cathodes. This work achieved impressive profitability ($16.05 per kg feedstock) and effectively reduction of GHG emissions during the recycling process, making it applicable to critical sustainability initiatives.

Study on the Ultrasonic-Assisted Extraction Process of Anthocyanin from Purple Cabbage with Deep Eutectic Solvent

In this paper, purple cabbage was used as raw material for ultrasonic-assisted extraction of anthocyanin with deep eutectic solvent. The effects of extraction solvent type, solid-liquid ratio, moisture, extraction temperature, and time on the yield of anthocyanin from purple cabbage were investigated by single factor test, and the feasibility of this extraction method was verified by standard addition recovery test. The test results showed that the optimal extraction results could be obtained when DES-5 (choline chloride/1, 2-propylene glycol/water) is used as extraction solvent, with solid-liquid ratio of 1:32, moisture of 50%, extraction temperature of 50 °C, and extraction time of 80 min. Under these conditions, the yield of anthocyanin extract purple cabbage reached 21.6%, and the recovery rates were 85.62-87.75%. Therefore, DES was a promising environmentally friendly solvent for extracting anthocyanins instead of organic solvent extraction.

Carbonate composite materials for the leaching remediation of uranium-contaminated soils: Mechanistic insights and engineering applications

In this study, a composite leaching agent consisting of Na2CO3, NaHCO3, H2O2, and deep eutectic solvents was synthesized, and its composition and application conditions were optimized to mitigate soil contamination resulting from uranium mining. Laboratory and pilot field tests revealed that the use of this agent facilitated up to 92.6 % removal of uranium from contaminated soils. Analytical characterization through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) revealed that CO32- readily formed complexes with uranium, increasing its mobility and desorption from soil particles. The safety of the leaching process was confirmed through plant growth tests and enzyme activity assays. Moreover, the leaching strategy not only adheres to environmentally sustainable principles but also replenishes carbon and nitrogen in the soil, thereby aiding in the restoration of its functional use.

Selective Extraction of Critical Metals from Spent Li-Ion Battery Cathode: Cation-Anion Coordination and Anti-Solvent Crystallization

Owing to continuing global use of lithium-ion batteries (LIBs), in particular in electric vehicles (EVs), there is a need for sustainable recycling of spent LIBs. Deep eutectic solvents (DESs) are reported as "green solvents" for low-cost and sustainable recycling. However, the lack of understanding of the coordination mechanisms between DESs and transition metals (Ni, Mn and Co) and Li makes selective separation of transition metals with similar physicochemical properties practically difficult. Here, it is found that the transition metals and Li have a different stable coordination structure with the different anions in DES during leaching. Further, based on the different solubility of these coordination structures in anti-solvent (acetone), a leaching and separation process system is designed, which enables high selective recovery of transition metals and Li from spent cathode LiNi1/3Co1/3Mn1/3O2 (NCM111), with recovery of acetone. Recovery of spent LiCoO2 (LCO) cathode is also evidenced and a significant selective recovery for Co and Li is established, together with recovery and reuse of acetone and DES. It is concluded that the tuning of cation-anion coordination structure and anti-solvent crystallization are practical for selective recovery of critical metal resources in the spent LIBs recycling.