Sustainable regeneration of high-performance LiCoO2 from completely failed lithium-ion batteries.

Utilising the solid-state synthesis method is an easy and effective way to recycle spent lithium-ion batteries. However, verifying its direct repair effects on completely exhausting cathode materials is necessary. In this work, the optimal conditions for direct repair of completely failed cathode materials by solid-state synthesis are explored. The discharge capacity of spent LiCoO2 cathode material is recovered from 21.7 mAh g-1 to 138.9 mAh g-1 under the optimal regeneration conditions of 850 °C and n(Li)/n(Co) ratio of 1:1. The regenerated materials show excellent electrochemical performance, even greater than the commercial LiCoO2. In addition, based on the whole closed-loop recycling process, the economic and environmental effects of various recycling techniques and raw materials used in the battery production process are assessed, confirming the superior economic and environmental feasibility of direct regeneration method.

Leaching valuable metals from spent lithium-ion batteries using the reducing agent methanol.

When considering resource shortages and environmental pressures, salvaging valuable metals from the cathode materials of spent lithium-ion batteries (LIBs) is a very promising strategy to realize the green and sustainable development of batteries. The reductive acid leaching of valuable metals from cathode materials using methanol as a reducing agent was studied. The results show that the leaching efficiencies of Co and Li are 99% under optimal leaching conditions. The leaching kinetics of cathode materials in a H2SO4-methanol system indicate that the leaching of Co and Li is controlled by diffusion, with activation energies of 69.98 and 10.78 kJ/mol, respectively. Detailed analysis of the leaching reaction mechanism indicates that methanol is ultimately transformed into formic acid through a two-step process to further enhance leaching. No side reactions occur during leaching. Methanol can be a sustainable alternative for the reductive acid leaching of valuable metals from spent LIBs due to its high efficiency, application maturity, environmental friendliness, and low cost.

Porous ZnO Nanosphere Inherently Encapsulated in Carbon Framework as a High-Performance Anode For Ni-Zn Secondary Batteries.

Nickel-zinc (Ni-Zn) secondary battery that is environmentally friendly and inexpensive has been regarded as a promising rechargeable battery system. However, the generation of deformation and dendrites of the traditional zinc anode during the cycling can cause capacity degradation and impede its practical application. Herein, we design a hierarchical ZnO nanosphere coated with an inherently derived ZIF-8 porous carbon shell (ZnO@CZIF-8) using a simple controllable method. The conductive carbon shell and porous ZnO core can provide more active sites, allow the fast transfer of electrons, and buffer the volume expansion of the electrode effectively. Benefiting from the synergistic effect amid the inherently ZIF-8-derived carbon shell and ZnO core, ZnO@CZIF-8 nanospheres exhibit a satisfying capacity of 316 mAh g-1 at a current density of 1 A g-1 after 50 cycles and an outstanding rate capacity when acting as the anode for a Ni-Zn secondary battery with merchant agglomerative Ni(OH)2 as the cathode. These results imply that the ZnO@CZIF-8 nanosphere is a hopeful anode for a high-energy Ni-Zn secondary battery.

Synthesis of flower-like MnO2 nanostructure with freshly prepared Cu particles and electrochemical performance in supercapacitors.

Four types of flowerlike manganese dioxide in nano scale was synthesized via a liquid phase method in KMnO4-H2SO4 solution and Cu particles, wherein the effect of Cu particles was investigated in detail. The obtained manganese dioxide powder was characterized by XRD, SEM and TEM, and the supercapacity properties of MnO2 electrode materials were measured. The results showed that doping carbon black can benefit to better dispersion of copper particles, resulting in generated smaller size of Cu particles, and the morphology of MnO2 nanoparticles was dominated by that of Cu particles. The study of MnO2 synthesis by different sources of Cu particles showed that the size of MnO2 particles decreased significantly with freshly prepared fine copper powder compared with using commercial Cu powder, and the size of MnO2 particles can be further reduced to 120 nm by prepared Cu particles with smaller size. Therefore, it was suggested that the copper particles served as not only the reductant and but also the nuclei centre for the growth of MnO2 particles in synthesis process MnO2, and that is the reason how copper particles worked on the growth of flower-like MnO2 and electrochemical property. In the part of investigation for electrochemical property, the calculated results of b values indicated that the electrode materials have pseudo capacitance property, and the highest specific capacitance of 197.2 F g-1 at 2 mV s-1 and 148 F/g at 1 A/g were obtained for MCE electrode materials (MnO2 was synthesized with freshly prepared copper particles, where carbon black was used and dispersed in ethanol before preparation of Cu particles). The values of charge transfer resistance in all types of MnO2 materials electrodes were smaller than 0.08 Ω. The cycling retention of MCE material electrode is still kept as 93.8% after 1000 cycles.

Radical bromination-induced ipso cyclization-ortho cyclization sequence of N-hydroxylethyl-N-arylpropiolamides.

A facile procedure is reported for the synthesis of various 2-bromo-1-phenyl-5,6-dihydro-3H,7aH-benzo[b]pyrrolo[2,1-c][1,4]oxazin-3-ones via a radical bromination-induced ipso cyclization-ortho cyclization sequence of N-arylpropiolamides in the presence of TBAB and oxone. The radical cyclization sequence involves a radical bromo α-addition into the alkyne, ipso-cyclization, and ortho-trapping of the spirocyclic intermediate.

Abatement of tetrafluoromethane by chemical absorption with molten aluminum.

Chemical absorption with molten aluminum to abate tetrafluoromethane (CF4) was investigated in this paper. The experiments were conducted at a series of different temperatures of 973 K, 1003 K, 1103 K, and 1188 K and the abatement rate of CF4 was calculated. It was found that CF4 can be adsorbed firstly and then react with molten aluminum automatically. The initial abatement rate of CF4 in molten aluminum was 3.10 × 10-2 mol·m-3·s-1 at 973 K, while it reached its maximum value of 1.08 × 10-1 mol·m-3·s-1 at the temperature of 1103 K. The highest abatement efficiency was 48.4%, reached at 1003 K. Higher temperatures up to 1188 K did not affect the abatement efficiency, however, they accelerated slightly the initial reaction rate. The products of the chemical absorption are white solid AlF3 and black graphite powder identified by XRD and SEM-EDS analysis. Due to density differences, solid AlF3 and graphite powder in the product tend to accumulate on the top of molten aluminum where they form two separate layers. This makes them recover more easily. The gas-liquid reaction process between CF4 and molten aluminum is accorded with the two-film theory model, diffusion process is considered to be the control step of the whole process.