Reductive acid leaching of valuable metals from spent lithium-ion batteries using hydrazine sulfate as reductant

Hydrazine sulfate was used as a reducing agent for the leaching of Li,Ni,Co and Mn from spent lithium-ion batteries.The effects of the reaction conditions on the leaching mechanism and kinetics were characterized and examined.97%of the available Li,96%of the available Ni,95%of the available Co,and 86%of the available Mn are extracted under the following optimized conditions:sulfuric acid concentration of 2.0 mol/L,hydrazine sulfate dosage of 30 g/L,solid-to-liquid ratio of 50 g/L,temperature of 80℃,and leaching time of 60 min.The activation energies of the leaching are determined to be 44.32,59.37 and 55.62 k J/mol for Li,Ni and Co,respectively.By performing X-ray diffraction and scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy,it is confirmed that the main phase in the leaching residue is MnO2.The results show that hydrazine sulfate is an effective reducing agent in the acid leaching process for spent lithium-ion batteries.

Regeneration of Al-doped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material by simulated hydrometallurgy leachate of spent lithium-ion batteries

A uniform Al-doped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material was prepared using a coprecipitation method to take advantage of the positive effect of Al on regenerated NCM(Ni,Co,Mn)cathode materials and ameliorate cumbersome and high-cost impurity removal processes during lithium-ion battery recycling.When the Al^(3+) content in the leachate was 1 at.%with respect to the total amount of transition metals(Ni,Co,and Mn),the produced Al-doped NCM cathode material increased concentrations of lattice oxygen and Ni^(2+).The initial specific capacity at 0.1C was 167.4 mA·h/g,with a capacity retention of 79.1%after 400 cycles at 1C.Further,this Al-doped sample showed improved rate performance and a smaller electrochemical impedance.These findings provide a reference for developing industrial processes to resynthesize cathode materials with improved electrochemical performance by incorporating Al^(3+) impurities produced during lithium-ion battery recycling.

Sb_(2)S_(3) nanorods/porous-carbon composite from natural stibnite ore as high-performance anode for lithium-ion batteries

To avoid the high purity reagents and high energy consumption involved in the manufacturing of lithium-ion battery anode materials,Sb_(2)S_(3) nanorods/porous-carbon anode was prepared by remodeling natural stibnite ore with porous carbon matrix via a simple melting method.Due to the nanostructure of Sb_(2)S_(3) nanorods and synergistic effect of porous carbon,the Sb_(2)S_(3) nanorods/porous-carbon anode achieved high cyclic performance of 530.3 mA·h/g at a current density of 100 mA/g after 150 cycles,and exhibited a reversible capacity of 130.6 mA·h/g at a high current density of 5000 mA/g for 320 cycles.This shows a great possibility of utilizing Sb_(2)S_(3) ore as raw material to fabricate promising anodes for advanced lithium-ion batteries.

Preparation of Sb2O3/Sb2S3/FeOOH composite photoanodes for enhanced photoelectrochemical water oxidation

A novel Sb2O3/Sb2S3/FeOOH photoanode was fabricated via a simple solution impregnation method along with chemical bath deposition and post-sulfidation.The X-ray diffractometry,Raman measurement,and X-ray photoelectron spectroscopy show that the Sb2O3/Sb2S3/FeOOH thin films are successfully prepared.SEM−EDS analyses reveal that the surface of Sb2O3/Sb2S3 thin films becomes rough after the immersion in the FeCl3 solution.The optimized impregnation time is found to be 8 h.The FeOOH co-catalyst loaded Sb2O3/Sb2S3 electrode exhibits an enhanced photocurrent density of 0.45 mA/cm2 at 1.23 V versus RHE under simulated 1 sun,which is approximately 1.41 times compared to the photocurrent density of the unloaded one.Through the further tests of UV−Vis spectroscopy,the electrochemical impedance spectra,and the PEC measurements,the enhancement can result from the increased light-harvesting ability,the decreased interface transmission impedance,and the remarkably enhanced carrier injection efficiency.

Catalytic effects of NH4+ on hydrogen evolution and manganese electrodeposition on stainless steel

The effects of(NH4)2SO4 concentration(c((NH4)2SO4))on hydrogen evolution and Mn electrodeposition on stainless steel(SS)in different potential ranges were investigated by linear sweep voltammetry(LSV),electrochemical impedance spectroscopy(EIS),potentiostatic polarization,chronoamperometry,scanning electron microscope(SEM)and X-ray diffraction(XRD)techniques.The results show that the NH4^+discharge reaction(NDR)intensifies the overall hydrogen evolution kinetics,and the NDR is catalyzed by increasing c((NH4)2SO4)and over-potential.The electro-crystallization of Mn on SS follows a three-dimensional progressive nucleation and diffusion-limited growth mechanism.Increasing the over-potential could accelerate the nucleation rate and also cause the decline of the nucleation density.The absorbed Mn^2+preferably discharges at low over-potential.Increasing c((NH4)2SO4)at medium over-potential could improve the current efficiency and produce more block-like grains.The nucleation process is suppressed by increasing c((NH4)2SO4)at high over-potential,at which the formation of columnar grains with higher hydrogen contents becomes prevailing.

Three-dimensional antimony sulfide anode with carbon nanotube interphase modified for lithium-ion batteries

Antimony sulfide(Sb_(2)S_(3))is a promising anode for lithium-ion batteries due to its high capacity and vast reserves.However,the low electronic conductivity and severe volume change during cycling hinder its commercialization.Herein our work,a three-dimensional(3D)Sb_(2)S_(3) thin film anode was fabricated via a simple vapor transport deposition system by using natural stibnite as raw material and stainless steel fiber-foil(SSF)as 3D current collector,and a carbon nanotube interphase was introduced onto the film surface by a simple dropping-heating process to promote the electrochemical performances.This 3D structure can greatly improve the initial coulombic efficiency to a record of 86.6% and high reversible rate capacity of 760.8 mAh·g^(-1) at 10 C.With carbon nanotubes interphase modified,the Sb_(2)S_(3) anode cycled extremely stable with high capacity retention of 94.7% after 160 cycles.This work sheds light on the economical preparation and performance optimization of Sb_(2)S_(3)-based anodes.

Comparison of corrosion and oxygen evolution behaviors between cast and rolled Pb–Ag–Nd anodes

The corrosion and oxygen evolution behaviors of cast and rolled Pb–Ag–Nd anodes were investigated by metalloscopy, environmental scanning electron microscopy, X-ray diffraction analysis, and various electrochemical measurements. The rolled anode exhibits fewer interdendritic boundaries and a dispersed distribution of Pb–Ag eutectic mixtures and Nd-rich phases in its cross-section. This feature inhibits rapid interdendritic corrosion into the metallic substrate along the interdendritic boundary network. In addition, the anodic layer formed on the rolled anode is more stable toward the electrolyte than that formed on the cast anode, reducing the corrosion of the metallic substrate during current interruption. Hence, the rolled anode has a higher corrosion resistance than the cast anode. However, the rolled anode exhibits a slightly higher anodic potential than the cast anode after 72 h of galvanostatic polarization, consistent with the larger charge transfer resistance. This larger charge transfer resistance may result from the oxygen-evolution reactive sites being blocked by the adsorption of more intermediates and oxygen species at the anodic layer/electrolyte interfaces of the rolled anode than at the interfaces of cast anode.

Synthesis of Cu_2ZnSnS_4 thin film from mixed solution of Cu_2SnS_3 nanoparticles and Zn ions

The Cu2ZnSnS4 thin film was prepared by a facile solution method without vacuum environment and toxic substance. The formation mechanism of the film was studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Raman scattering measurements. Through cyclic voltammetry and photo-electricity tests, the electrocatalytic activity of the prepared film as the counter electrode of dye-sensitizedsolar cell was also studied. The results show that the mixed precursor solution mainly consists of Cu2SnS3 nanoparticles and Zn ions.After 550 °C annealing process on the precursor film prepared from the mixed solution, Cu2ZnSnS4 thin film is obtained. Besides, itis found that the prepared Cu2ZnSnS4 thin film has the electrocatalytic activity toward the redox reaction of I3?/I? and the dye-sensitized solar cell with the prepared Cu2ZnSnS4 thin film as the counter electrode achieves the efficiency of 1.09%.