With more and more lithium-ion batteries (LIBs) being put into production and application, precious metals such as lithium and cobalt are scarce, so it is imminent to recover various strategic metal resources from spent LIBs. Meanwhile, the complex and difficult problem of separating and recovering metals from leaching solutions has been an urgent question that needs to be resolved. In this work, a phosphoric acid-based deep eutectic solvent (DES) was developed for extracting metals from spent LIBs and one-step selectively separating and efficiently recovering transition metal. The prepared DES shows excellent extraction performance for Li (100%) and Co (92.8%) at 100 ℃. In addition, the extraction system can effectively separate and precipitate Co through its own components, avoiding the introduction of new precipitants and the destruction of the original composition structure of DES. This also contributes to the good cycle stability of the extraction system with excellent extraction performance for Li (94.3%) and Co (80.8%) after 5 cycles. This work proposes a green method for one-step selectively separating and recovering valuable metals from spent LIBs.

Supported gold (Au) nanocatalysts have long played an important role in numerous heterogeneous catalysis. However, the dominant difficulty of poor thermodynamic stability hampers its practical application. Herein, a core–shell structured Au nanocatalyst with Au nanoparticles (NPs) confined in boron nitride (BN) shells is proposed for enhanced thermodynamic stability. The two-dimensional porous structure of BN not only functions as a physical separator for the sintering resistance of Au NPs, but also provides a microchannel for catalytic reaction substrates. Besides, owing to the confinement effect, a strengthened interaction between well-designed Au NPs and the BN can be expected, which further boosts the stability and catalytic activity. Detailed experiments show that a proper BN shell thickness is important to maintain the balance between the sintering resistance and catalytic activity. A significantly boosted performance of 97.2% conversion in oxidative desulfurization (ODS) was obtained with a proper number of BN coating layers, outperforming the one with a thicker BN shell. Moreover, the recyclability of the prepared catalyst was investigated with no obvious decrease in catalytic performance after 10 runs, greatly higher than that without a BN shell, suggesting excellent durability.