With the rapid development of lithium-ion batteries (LIB), selective recovery of lithium and other valuable metals from spent LIBs is in urgent need because of the shortage of Li and...

Spent Li-ion battery (LIB) recovery has become the hot research area due to its surge in quantity and release of heavy metals and toxic substances harmful to the environment. Green and efficient recovery methods are of great significance for the recovery of valuable metals. Herein, an oxalic acid-based deep eutectic solvent (DES) with the weak acidic character and reducibility of oxalic acid was designed for the recovery of valuable metals from spent LIBs via a sustainable and convenient process. Nearly 96.1% of Li and 96.3% of Co can be extracted from lithium cobalt oxide at 120 °C. The DES can extract valuable metals from cathode materials and separate metal ions by itself after extraction without destroying its own structure in a one-pot extraction process. The composition and the structure of DES have been maximum retained and could be intact recycled for another recovery process. After five cycles, the Li and Co extraction efficiencies were maintained above 92.9 and 74.5%, respectively. This work provides a sustainable one-pot recovery process with inexpensive and simple operations for valuable metal recovery from spent LIBs.

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The controlled exfoliation of hexagonal boron nitride (h-BN) into single-or few-layered nanosheets remains ag rand challenge and becomes the bottleneckt oe ssential studies and applications of h-BN.Here,wepresent an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) using an ovel gas exfoliation of bulk h-BN in liquid N 2 (L-N 2 ). The essence of this strategy lies in the combination of ahigh temperature triggered expansion of bulk h-BN and the cryogenic l-N 2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with ah igh mass yield of 16-20 %. N 2 sorption and desorption isotherms show that the BNNS-10 exhibited amuchhigher specific surface area of 278 m 2 g À1 than that of bulk BN (10 m 2 g À1 ). Through the investigation of the exfoliated intermediates combined with at heoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently,t he l-N 2 penetrates into the interlayers of h-BN along the curling edge,f ollowed by an immediate drastic gasification of l-N 2 ,f urther peeling off h-BN.T his novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications,b ut also can be extended to produce other layered materials in high yields.