Nickel-Copper Bimetallic Oxide Nanoparticles Prepared by Simple Coprecipitation Method as High Performance Electrode Materials for Asymmetric Supercapacitors.

Supercapacitors with transition bimetallic oxides as pseudocapacitive materials have been of wide concern for their excellent energy storage performance. In this work, a simple coprecipitation method was used to synthesize the precursor, followed by calcination to prepare Ni-Cu bimetallic oxide materials. The structure, morphology and properties of the materials prepared by different precipitating agents and different calcination temperatures of NCO-H2C2O4 precursor were investigated. The optimum precipitant was determined to be H2C2O4, and Ni-Cu nanoparticles with regular lamellar microstructure were obtained at the calcination temperature of 400 °C. The nanostructure and morphology provide a large active channel for the rapid diffusion of electrolyte ions, and the specific capacitance of NCO-H2C2O4-400 electrode material can reach 740.31 F/g Cs at 1 A/g. The investigation of charge storage mechanism shows that the contribution rate of capacitance and diffusion control is about 37.9% and 67.2%, respectively. The electrochemical test results of the asymmetric supercapacitors (ASC) constructed with NCO-H2C2O4-400 and activated carbon show that the specific capacitance, energy density, and power density of the capacitor are 52.66 F/g, 16.45 Wh/kg, and 759.51 W/kg, respectively. Even after 5000 charge/discharge cycles at 5 A/g, it can still keep 90.57% of its initial capacity. This work not only provides competitive electrode materials for energy storage devices but also provides a feasible strategy for producing complex transition metal oxide materials with high capacitance performance.

An Efficient and Eco-Friendly Recycling Route of Valuable Metals from Spent Ternary Li-Ion Batteries: Kinetics Evaluation of Chlorination Processes and Regeneration of LiNi0.8Co0.1Mn0.1O2 Cathode Materials.

The recycling of spent Li-ion batteries is urgent, and the effective recovery of valuable metals from spent cathode material is an economic and eco-friendly approach. In this study, Ni, Cu, Co, and Mn were extracted synchronously from spent LiNixCoyMn1-x-yO2 by chlorination and the complexation reaction of ammonium chloride at low temperatures. The kinetics of the chlorination process was investigated by nonisothermal thermal analysis to determine the rate equation of metal conversion, and the apparent activation energies were calculated to be 99.96 kJ·mol-1 for lithium and 146.70 kJ·mol-1 for nickel, cobalt, and manganese, respectively. The separation of valuable metals from polymetallic leaching solution and the regeneration of cathode materials were further investigated to promote the industrialization of the process. The recoveries of Ni, Co, Mn, and Li can reach 97.75, 99.99, 99.99, and 92.23%, respectively. The prepared LiNi0.8Co0.1Mn0.1O2 precursor is a multilayer spherical particle formed by stacking primary hexagonal nanosheets along the (010) crystal axis, the formation mechanism of which was discussed. The effect of temperature, time, and mixed lithium ratio on the performance of single crystal LiNi0.8Co0.1Mn0.1O2 cathode in the synthesis process was investigated to determine the optimum conditions. Compared with commercial materials, the prepared single crystal LiNi0.8Co0.1Mn0.1O2 cathode has a more regular crystal structure and higher initial discharge capacity (215.9 mAh·g-1 at 0.1 C).

A clean and efficient process for simultaneous extraction of Li, Co, Ni and Mn from spent Lithium-ion batteries by low-temperature NH4Cl roasting and water leaching.

The recycling of valuable metals from spent lithium-ion batteries (LIBs) has great significance for environmental protection and resource conservation. In this paper, a low-temperature clean chlorination roasting-water leaching process was proposed to simultaneously extract Li, Ni, Co and Mn from cathode material (NCM) of spent LIBs. The temperature range of chlorination roasting was determined by thermodynamic analysis to be 250-600 °C. The effect of some factors on the conversion of valuable metals in the process of chlorination roasting and water leaching was systematically studied. The results showed that more than 98 % of Li, Co, Ni and Mn could be extracted under optimized chlorination roasting and water leaching conditions. The chlorination roasting mechanism and phase transformation evolution was determined by means of thermodynamic analysis, TG-DTA, XRD, SEM and EDS. The extraction of valuable metals was realized by the reaction of the metal oxides produced by the decomposition of NCM with NH4Cl or its evolved HCl to form water-soluble metal chlorides or chlorinated metal-ammonium complexes. The chlorination technique using NH4Cl provided an effective and clean approach for the simultaneous extraction of Li, Co, Ni and Mn from spent LIBs.

Design strategy of a Cu-based catalyst for optimizing the performance in the electrochemical CO2 reduction reaction to multicarbon alcohols.

The electrochemical CO2 reduction reaction (ECRR) is a promising method to reduce excessive CO2 emissions and achieve a sustainable carbon cycle. Due to the high reaction kinetics and efficiency, copper-based catalysts have shown great application potential for preparing multicarbon (C2+) products. C2+ alcohols have high economic value and use-value, playing an essential role in modern industry. Therefore, we summarize the latest research progress of the ECRR to synthesize C2+ alcohols on Cu-based catalysts and discuss the state-of-the-art catalyst design strategies to improve CO2 reduction performance. Moreover, we analyzed in detail the specific reaction pathways for the conversion of CO2 to C2+ alcohols based on DFT calculations. Finally, we propose the problems and possible solutions for synthesizing C2+ alcohols with copper-based catalysts. We hope that this review can provide ideas for devising ECRR catalysts for C2+ alcohols.

Optimization of Synergistic Leaching of Valuable Metals from Spent Lithium-Ion Batteries by the Sulfuric Acid-Malonic Acid System Using Response Surface Methodology.

A new environmentally friendly and economical recycling process for extracting metals from spent lithium-ion batteries (LIBs) using sulfuric acid and malonic acid as leaching agents is proposed. By applying Box-Behnken design (BBD) and response surface methodology (RSM) optimization techniques, the global optimal solution of the maximum leaching rate of metals in spent LIBs is realized. The results show that under the optimal conditions of 0.93 M H2SO4, 0.85 M malonic acid, and a liquid/solid ratio of 61 g·L-1, a temperature of 70 °C and 5 vol % of 30% H2O2, 99.79% Li, 99.46% Ni, 97.24% Co, and 96.88% Mn are recovered within 81 min. The error between the theoretical value and the actual value of the metal leaching rate predicted by the regression model is less than 1.0%. Additionally, the study of leaching kinetics reveals that the leaching process of Li, Ni, Co, and Mn in spent cathode materials was affected by the synergistic effect of interfacial mass transfer and solid product layer diffusion. Economic analysis reveals that evaluation index should be fully considered when formulating recovery processes for different metals. This process can reduce the environmental risks of heavy metal disposal and allow the reuse of metals recovered from spent LIBs.