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Safe and harmless treatment of electrolyte is a critical environment issue for spent lithium‐ion battery recycling; the effective separation of cathode materials from aluminum foil is a key technology for resource utilization. Previous studies have never considered the two as a whole. This study introduced supercritical CO2 technology to realize the integrated treatment of electrolyte removal and cathode material exfoliation. The results indicated that the optimum parameter was obtained at a temperature of 38 °C, a time of 15 min and a pressure of 10 MPa. The peeling efficiency of cathode material from Al foil reached 98.86 wt.%. Mechanism analysis confirmed that the separation of Al foil and cathode material was the result of the weakened adhesion of electrode interface, which can be attributed to the removal of the organic component including carbonate‐based organic solution and organic binder caused by the fluid extraction process. [ABSTRACT FROM AUTHOR]

Safe and harmless treatment of electrolyte is a critical environment issue for spent lithium‐ion battery recycling; the effective separation of cathode materials from aluminum foil is a key technology for resource utilization. Previous studies have never considered the two as a whole. This study introduced supercritical CO2 technology to realize the integrated treatment of electrolyte removal and cathode material exfoliation. The results indicated that the optimum parameter was obtained at a temperature of 38 °C, a time of 15 min and a pressure of 10 MPa. The peeling efficiency of cathode material from Al foil reached 98.86 wt.%. Mechanism analysis confirmed that the separation of Al foil and cathode material was the result of the weakened adhesion of electrode interface, which can be attributed to the removal of the organic component including carbonate‐based organic solution and organic binder caused by the fluid extraction process. [ABSTRACT FROM AUTHOR]

Regeneration of cathode materials from spent lithium‐ion batteries (LIBs), as an efficient short‐range recycling strategy, is gradually becoming a research hotspot. However, due to the unavoidable influence of impurities in the recycling process, the regenerated material suffers from severe performance degradation during the recycling process. Surface coating is an effective routine to improve cycling stability. Here, regenerated Li(Ni0.8Co0.1Mn0.1)O2 cathode material is successfully wet‐coated by an appropriate amount of MoO3. The study finds the material loading 2.0 wt% MoO3 exhibits even better properties. After 100 cycles, the capacity retention efficiency is significantly improved from 70 % to 86.5 % in the range of 2.8∼4.3 V. It is confirmed that the MoO3 coating effectively stabilized the cathode/electrolyte interface, thus reducing the occurrence of side reactions and improving the electrochemical stability of the battery. In addition, the MoO3 had great electrical conductivity, keeping the lithium diffusion even at a stable level upon cycling. To sum up, our work provides a simple and available modification strategy for nickel‐rich cathode materials recovered from spent LIBs. [ABSTRACT FROM AUTHOR]

Cubic zinc titanate (ZTO) rods were synthesized via a simple liquid precipitation method. Reduced graphene oxide/zinc titanate (rGO/ZTO) composites were prepared by using the synthesized ZTO rods and graphene oxide as precursors. The composites were characterized by thermogravimetry and differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (UV-vis). The photocatalytic activity of the synthesized photocatalysts was evaluated by the degradation of rhodamine B (RhB) in water under sunlight irradiation. The results revealed that the rGO/ZTO composites exhibited higher photocatalytic activity than pristine ZTO. The rGO in rGO/ZTO composites preferentially accepted the photo-generated electrons as an electron reservoir, significantly reduced the chances of recombination, and effectively prolonged the lifetime of holes in rGO/ZTO, thereby greatly enhancing the efficiency of hole-induced decomposition of dyes. [ABSTRACT FROM AUTHOR]

Electrolyte solutions have a vital function in lithium-ion batteries. In consideration of their toxic and harmful characteristics and widespread applications in the EVs, the treatment or recovery of the electrolyte is of concern and accurate analysis is needed for the resource and environment benefits. In this work, we present a highly-selective electrolyte recovery method―transcritical CO2 extraction―that combined the extraction and separation processes together. The use of response surface methodology helps in obtaining a simplified and optimized extraction protocol at room temperature and low pressure saving time and reagents. In order to evaluate these extracts, various techniques like GC-MS, GC-FID, FITR and NMR were applied. The GC-FID quantitative analysis and calculation formula may help with realizing the oriented control of the extraction process, and hexafluorophosphate (PF6−), fluoride (F−) and difluorophosphate (PO2F2−) detected by both 19F and 31P spectra imply the degradation pathway. [ABSTRACT FROM AUTHOR]

The problem of the decrease in cycling stability of Li3(V0.9Mg0.1)2(PO4)3/C limits its practical application in a broad electrochemical window. However, the cause of the cycling stability decrease in Li3(V0.9Mg0.1)2(PO4)3/C has not been studied in previous research. In this paper, to illustrate the cause of the decreased cycling stability of the Li3(V0.9Mg0.1)2(PO4)3/C samples, we investigated the crystal structure changes in the cathode materials in a broad electrochemical window. The structure of the Li3(V0.9Mg0.1)2(PO4)3/C samples was analyzed by XRD refinement, SEM and TEM. The results indicate that the higher the charge cut-off voltage is, the worse the cycling stability of the sample is. It was concluded that the cell volume of the Li3(V0.9Mg0.1)2(PO4)3/C samples expands irreversibly after cycling in different voltage ranges, and the bond lengths of Li(3)–O become longer while those of Li(2)–O and Li(1)–O become shorter. This means that the bond energy of the Li(3) ion increased, and the bond energy of the Li(1) and Li(2) ions decreased. This is not beneficial to the intercalation/deintercalation of Li ions with the increase in the charge cut-off voltage. The TEM test shows that the carbon layer of the samples is destroyed with the increase in the charge cut-off voltage. It is reasonably inferred that the crystal structure change in the Li3(V0.9Mg0.1)2(PO4)3/C samples causes poor cycling stability with the increase in the charge cut-off voltage. [ABSTRACT FROM AUTHOR]

The composite photocatalyst FeOOH/g-C 3 N 4 was prepared through thermal polycondensation and co-precipitation methods, followed by XRD, SEM and UV-vis characterization. The stability of FeOOH/g-C 3 N 4 was explored by the recycling test. The active species in the reaction system were investigated by the capture experiment. The results indicated that the optimal preparation condition for g-C 3 N 4 involved calcination at 600 °C for 4 h. XRD analysis revealed that g-C 3 N 4 exhibits a high-purity phase, and Fe in FeOOH/g-C 3 N 4 exists in a highly dispersed amorphous state. SEM analysis showed that FeOOH/g-C 3 N 4 has a rough surface with an irregular layered structure. Element composition analysis confirmed that the content of elements in the prepared catalyst is consistent with the theoretical calculation. FeOOH/g-C 3 N 4 possesses the largest specific surface area of 143.2 m 2 /g and a suitable pore distribution. UV-vis DRS analysis showed that the absorption intensity of FeOOH/g-C 3 N 4 is stronger than that of g-C 3 N 4 . When the catalyst dosage was 1.0 g/L, the H 2 O 2 dosage was 4 mmol/L, the PNP initial concentration was 10 mg/L and the initial pH value was 5, the PNP removal could reach 92% in 120 min. Even after 5 cycles, the efficiency of PNP removal by FeOOH/g-C 3 N 4 remains nearly 80%. The capture experiment indicated that both •OH and •O 2 - play roles in the photocatalytic degradation of PNP, with •OH being more significant. These findings affirm that FeOOH has been successfully incorporated into g-C 3 N 4 , resulting in a conspicuous catalytic effect on the degradation of PNP in the visible light-assisted Fenton-like reaction.

An aerobic moving bed biofilm reactor (MBBR) was applied to treat landfill leachate generated from a domestic waste incineration plant. Pollutant removal efficiency of this reactor under stable operating condition was studied. The biomass, bacteria species, and microbial metabolism in this reactor were investigated. These results showed that the average removal efficiency of chemical oxygen demand (COD) and ammonia nitrogen in the aerobic MBBR achieved 64% and 97% in the optimum conditions, respectively. The three-dimensional fluorescence spectrum revealed that the content of soluble microbial byproducts from extracellular polymeric substances extraction in suspended sludge was much higher than that on biofilm, and the types of pollutants were various in different regions of the reactor. It also indicated that the MBBR system had a stable, rich and regular microorganism community, including large amounts of nitrifying bacteria and denitrifying bacteria. Scanning electron microscopy suggested that biofilm attached to the packing provided a good anoxic-aerobic micro environment system to achieve a high metabolic activity, which favored COD and ammonia removal.