Ionometallurgy is a new development aiming at the sustainable low‐temperature conversion of naturally occurring metal ores and minerals to their metals or valuable chemicals in ionic liquids (ILs) or deep eutectic solvents. The IL betainium bis((trifluoromethyl)sulfonyl)imide, [Hbet][NTf2], is especially suited for this process due to its redox‐stability and specific‐functionalization. The potentiostatic electrodeposition of zinc and lead starting directly from ZnO and PbO, which dissolve in [Hbet][NTf2] in high concentrations is reported. The initial reduction potentials of zinc(II) and lead(II) are about −1.5 and −1.0 V, respectively. The ionic conductivity of the solution of ZnO in [Hbet][NTf2] is measured and the effect of various temperatures and potentials on the morphology of the deposited material is explored. The IL proves to be stable under the chosen conditions. From IL‐solutions, where ZnO, PbO, and MgO have been dissolved, metallic Zn and Pb are deposited under potentiostatic control either consecutively by step‐electrodeposition or together in a co‐electrodeposition. Using the method, Zn is also deposited on 3D copper foam and assembles into high‐voltage zinc‐graphite battery. It exhibits a working‐voltage up to 2.7 V, an output midpoint discharge‐voltage of up to 2.16 V, up to 98.6% capacity‐retention after 150 cycles, and good rate performance.
The low temperature syntheses of AuTe2 and Ag2Te starting from the elements were investigated in the ionic liquids (ILs) [BMIm]X and [P66614]Z ([BMIm]+=1‐butyl‐3‐methylimidazolium; X = Cl, [HSO4]−, [P66614]+ = trihexyltetradecylphosphonium; Z = Cl−, Br−, dicyanamide [DCA]−, bis(trifluoromethylsulfonyl)imide [NTf2]−, decanoate [dec]−, acetate [OAc]−, bis(2,4,4‐trimethylpentyl)phosphinate [BTMP]−). Powder X‐ray diffraction, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy revealed that [P66614]Cl is the most promising candidate for the single phase synthesis of AuTe2 at 200 °C. Ag2Te was obtained using the same ILs by reducing the temperature in the flask to 60 °C. Even at room temperature, quantitative yield was achieved by using either 2 mol % of [P66614]Cl in dichloromethane or a planetary ball mill. Diffusion experiments, 31P and 125Te‐NMR, and mass spectroscopy revealed one of the reaction mechanisms at 60 °C. Catalytic amounts of alkylphosphanes in commercial [P66614]Cl activate tellurium and form soluble phosphane tellurides, which react on the metal surface to solid telluride and the initial phosphane. In addition, a convenient method for the purification of [P66614]Cl was developed.
Owing to the environmental problems of numerous metal production processes, there is a growing need for more energyefficient approaches. Cobalt is considered a strategic element that is extracted not only from ores but also from spent Li-ion batteries. One promising new approach is ionometallurgy, which is the extraction of metal oxides by ionic liquids (ILs). This study concerns new investigations into ionometallurgical processing of CoO, Co 3 O 4 , and LiCoO 2 in the IL betainium bis(trifluoromethylsulfonyl)imide, [Hbet][NTf 2 ]. Three crystal structures of cobaltÀ betaine complex compounds and combined spectroscopic and diffraction studies provide insights into the dissolution process. In addition, an optimized dissolution procedure for metal oxides is presented, avoiding the previously reported decomposition of the IL. Subsequent cobalt electrodeposition is only possible from cationic complex species, highlighting the importance of a thorough understanding of the complex equilibria. The presented method is also compared to other recently reported approaches.
Bi2S3 was dissolved in the presence of either AuCl/PtCl2 or AgCl in the ionic liquids [BMIm]Cl ⋅ xAlCl3 (BMIm=1‐n‐butyl‐3‐methylimidazolium; x=4–4.3) through annealing the mixtures at 180 or 200 °C. Upon cooling to room temperature, orange, air‐sensitive crystals of [BMIm](Bi4S4)[AlCl4]5 (1) or Ag(Bi7S8)[S(AlCl3)3]2[AlCl4]2 (2) precipitated, respectively. 1 did not form in the absence of AuCl/PtCl2, suggesting an essential role of the metal cations. X‐ray diffraction on single‐crystals of 1 revealed a monoclinic crystal structure that contains (Bi4S4)4+ heterocubanes and [AlCl4]− tetrahedra as well as [BMIm]+ cations. The intercalation of the ionic liquid was confirmed via solid state NMR spectroscopy, revealing unusual coupling behavior. The crystal structure of 2 consists of (Bi7S8)5+ spiro‐dicubanes, [S(AlCl3)3]2− tetrahedra triples, isolated [AlCl4]− tetrahedra, and heavily disordered silver(I) cations. No cation ordering took place in 2 upon slow cooling to 100 K.
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