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The extraction and separation of ferrum and copper from waste ternary cathode material by Cyanex 302 (the main component is di(2,4,4-trimethylamyl) monothiophosphoric acid) was studied. The effects of H+ concentration, extractor concentration and temperature on the extraction and separation performance of Cyanex 302 were investigated. And the technological conditions for the stripping of ferrum and copper in supported organic phase were determined. The process flow of extracting ferrum and copper from waste ternary cathode material leaching solution is designed. The results show that the optimal extraction conditions are 0. 1 mol/L Cyanex 302 concentration, 0. 1 mol/L H+ concentration, room temperature. Under these conditions, the extraction rates of ferrum and copper are over 99. 9 %, while the extraction rates of Ni (II), Co (II), Mn (II), and Li (II) are all below 0. 003%. The optimal stripping agent for ferrum is 1 mol/L H2SO4 and that for copper is 1. 5 mol/L HNO3. The process can effectively separate copper and ferrum from the leaching solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel DES based on phenylphosphinic acid was used to leach NCM cathode materials. • Leaching efficiencies for Li, Ni, Co, and Mn were>93%. • The coordination configurations of metals in the leaching solution were revealed. • Compared to the other DESs, the leaching conditions were milder and safer. Deep eutectic solvents (DESs) play an important role in efficient recovery of spent lithium-ion batteries (LIBs). In this study, we proposed an efficient and safe method by using a choline chloride-phenylphosphinic acid DES as a lixiviant for the leaching of LiNi x Co y Mn z O 2 (NCM) cathode active materials of spent LIBs. The leaching conditions were optimized based on the leaching time, liquid–solid ratio, and leaching temperature. Under optimal experimental conditions, the leaching efficiencies of Li, Co, Ni, and Mn reached 97.7 %, 97.0 %, 96.4 %, and 93.0 %, respectively. The kinetics of the leaching process were well-fitted using the logarithmic law equation. The apparent activation energies for Li, Co, Ni, and Mn have been reported to be 60.3 kJ/mol, 78.9 kJ/mol, 99.3 kJ/mol, and 82.1 kJ/mol, respectively. UV–visible spectroscopy and Fourier transform infrared analysis revealed that the coordination configurations of Ni and Co in the leaching solution were octahedral and tetrahedral, respectively. In addition, the P O bond in phenylphosphinic acid was involved in coordination during leaching. This finding may provide an effective and safe approach for leaching valuable metals from spent LIBs. [ABSTRACT FROM AUTHOR]

It is highly important to develop low-cost hydrogen evolution cathode materials. In this paper, Ni(OH) 2 /NF electrode was prepared by a hydrothermal method using nickel foam (NF) as a substrate, and NiTe-Ni(OH) 2 /NF cathode with high efficiency and low cost was prepared by secondary hydrothermal method. The material was characterized by physical characterization and electrochemical performance tests. Ni(OH) 2 /NF electrode materials prepared by a one-step hydrothermal method had a three-dimensional petal-like pore space structure. This special structure provided abundant active points for the two-step hydrothermal preparation of NiTe-Ni(OH) 2 /NF, which helps to improve the efficiency of HER. Compared with NF and Ni(OH) 2 /NF, NiTe-Ni(OH) 2 /NF cathode exhibited better HER catalytic performance. The results shown that NiTe-Ni(OH) 2 /NF is possesed excellent hydrogen evolution performance, and density functional theory can confirm this. At a current density of 10 mV∙cm−2, the NiTe-Ni(OH) 2 /NF electrode has an overpotential of only 129 mV, long-term stability, and an electrochemically active specific surface area (ECSA) of 91.75 cm−2. The Tafel slope was 31.5 mV∙dec−1, and the charge transfer resistance obtained by electrochemical impedance analysis was 9.81 Ω. This article provided valuable insights into the rational regulation of crystal phases on nickel telluride to improve HER properties. • The synergistic effect of porous petal-like Ni(OH) 2 /NF and uniform nanorod-like NiTe effectively maintained the stable structure of NiTe-Ni(OH) 2 /NF. • NiTe-Ni(OH) 2 /NF nanobars could provide excellent conductive networks and abundant H+ transfer active sites. • The NiTe-Ni(OH) 2 /NF composite had a low overpotential, abundant electrocatalytically active sites, and ultralong stability. • Density functional theory confirmed that NiTe-Ni(OH) 2 /NF had a low hydrogen adsorption energy and excellent kinetic properties. [ABSTRACT FROM AUTHOR]