The demand for lithium-ion batteries (LIBs) is increasing with a rapid development of new energy vehicles. Massive waste LIBs pollute the environment and have a risk of insufficient supply of lithium resources. Recycling metal lithium from waste LIBs thus becomes a recent research hotspot. Effective battery recycling can alleviate the shortage of resources and realize resource utilization, as well as reduce environmental pollution and promote the sustainable development of the industry. Also, research work on recovering lithium by preferential extraction and step-by-step separation has attracted much attentions to realize the efficient recovery of lithium metal in waste LIBs. This review represented the existing situation and methods of recycling waste LIBs, described recent research work on pyrometallurgy, hydrometallurgy, bio metallurgy and electrochemical methods in the process of selective lithium recovery, and analyzed the technical features of electrode electric field drive and membrane electrodialysis in the field of selective lithium recovery. Also, the advantages and disadvantages of each recovery process were summarized, and the problems faced by lithium recovery were analyzed in combination with economic benefits and environmental impact. In addition, the challenges and limitations of LIBs recycling were given, and the future development on LIBs recycling was prospected. This review thus provides a reference for the research and development of more energy-saving, environment-friendly and efficient recycling process of lithium metal in waste LIBs.

The acetaldehyde vapor produced in industrial production and life needs to be monitored in real time and efficiently, WO₃ nanoplates and a series of Ti₃C₂T_x-WO₃ composite materials were synthesized by a hydrothermal method. The structure and morphology of the as-prepared materials were investigated by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The gas sensing properties of materials were analyzed. The results show that the addition of Ti₃C₂T_x can enhance the gas sensing performance of WO₃ nanoplates. The optimized gas sensing operation temperature is 80 ℃ for 7%(mass fraction) Ti₃C₂T_x-WO₃ composite material. The sensitivity of 7% Ti₃C₂T_x-WO₃ composite material to 100 μL/L acetaldehyde vapor at 80 ℃ is 32.9 within a low detection limit of 0.1 μL/L.

To obtain materials with superior antibacterial properties, Ag-ZnO/Talc ternary composite was prepared by a water-bath heating method with black talc (from Guangfeng, Jiangxi) as a matrix material. The composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, respectively. Escherichia coli and staphylococcus aureus were used as the experimental strains. The antibacterial properties of the composite were examined by a plate counting method and a bacteriostatic zone method. The results show that the layered structure of talc sheet promotes the dispersion of nanoparticles and increases the contact area between the composite and bacteria. The Ag-ZnO/Talc composite displays a high antibacterial activity, and the antibacterial rate against escherichia coli and staphylococcus aureus reaches more than 99%.

To clarify the mechanism of water transport in mortar, a three-phase model consisting of fine aggregate-interfacial transition zone (ITZ) -cement paste was developed to represent mortar, and then the water transport process in mortar was simulated by a partial bounce-back lattice Boltzmann method (PBB-LBM). The influences of aggregate volume fraction, the ITZ's thickness and pore structure on the water permeability of mortar were evaluated. The results show that mortar's water permeability declines at an increased aggregate content and it is always below cement paste's water permeability at a thin thickness of ITZ and a low porosity. Once the thickness of ITZ exceeds 150 μm or its effective porosity is two times greater than that of cement paste, the permeability of mortar is close to or even above the matrix's water permeability. This is attributed to the competitions among the ITZ effect, aggregate dilution effect and tortuous transport path in mortar.

The calcium leaching resistance of bonding interface between engineered cementitious composite (ECC) and existing concrete is a key issue in reinforcement engineering. A nitric acid solution of 0.5 mol/L was used to carry out the accelerated leaching test, and the time-dependent influences of interface treatment methods (i.e., roughening, wet saturation and interfacial agent) were investigated via indications of bonding strength, leaching depth and cumulative leached calcium ion. The improvement mechanism in micro scale was analyzed by scanning electron microscopy. The results show that the three interface treatment methods can effectively improve the bonding quality, and their time-dependent influences are similar. The bonding strength before leaching can be used to evaluate the leaching resistance of bonding interface. Roughening is more effective to improve the initial bonding strength, while interfacial agent is helpful to slow down the deterioration rate of interface treatment effect in the leaching process. The improvement effect of combined treatment methods is better than that of single treatment method.

Lithium metal batteries are considered as one of the most promising energy storage batteries due to their high energy density. However, the growth of lithium dendrites in the lithium metal anode can lead to the capacity degradation and even safety problems. In this paper, attapulgite was loaded on fiber membrane for the application of lithium metal anode protection, assembling them into symmetrical cells and lithium iron phosphate full cells for electrochemical testing. The results show that the growth of lithium dendrites can be effectively inhibited due to the addition of attapulgite to the fibrous membrane. The polarization voltage of the symmetric cell is only 83.2 mV at a current density of 2 mA/cm² and deposition capacity of 1 mA·h/cm² for 500 h. The specific capacity of the full cell with attapulgite added to the fibrous membrane remains 84.92 mA·h/g after 1 000 cycles at 1 C. The inhibition of lithium dendrites by attapulgite provides an approach for the protection of lithium metal batteries with negative electrodes.

The hydration activity of ternesite is crucial for the development of the mechanical properties of the new Belite-ye'elimite-ternesite cement. To explore a suitable sintering procedure for improving the hydration activity of ternesite, ternesite was synthesized by different sintering procedures with analytical reagents. The effect of sintering procedure on the microstructure, crystal structure, hydration activity and mechanical properties of ternesite was investigated by scanning electron microscopy, X-ray powder diffraction with Rietveld refinement, ²⁹Si solid-state nuclear magnetic resonance, comprehensive thermal analysis and isothermal calorimetry. The results show that ternesite grains obtained by a single-stage sintering process are irregular in shape and generally larger in size (~10 μm), while the shape of ternesite grains obtained by a two-stage sintering process are regular as granular, and the size of the grains decreases to approximately 5 μm. Air quenching can reduce the crystallinity of ternesite, thereby improving its early hydration activity and promoting the rapid development of its early mechanical properties. Among them, ternesite obtained by a single-stage sintering process and air quenching has the minimum degree of crystal structure development, but has the maximum early hydration activity and development strength. Ternesite obtained by cooling in a furnace has a higher crystallinity and a lower hydration activity in the early period, but its mechanical properties can develop rapidly in the middle and later periods.

The effective joining between silicon nitride ceramics and metals is crucial for making full use of their excellent properties and meeting the service requirements of materials or components in complex environments. The gradient joining of silicon nitride ceramic (Si₃N₄) and molybdenum (Mo) with large physical properties difference was realized by a powder metallurgy gradient composite technology. The reaction mechanism of Si₃N₄ and Mo in each gradient layer under different sintering temperatures and Si₃N₄ additions was investigated. The transition layer structure of Si₃N₄/Mo_xSi_y/Mo gradient material was optimized based on the reaction mechanism and the concentration distribution index p, obtaining the gradient connection of Si₃N₄ to Mo and improving the mechanical properties. The results show that Si₃N₄ and Mo mainly form molybdenum-silicon compounds through the diffusion reaction between Mo and Si. The reaction process follows (Mo+Si)→(Mo₃Si/MoSi₂+Si)→(Mo₅Si₃). The bending strength of Si₃N₄/Mo_xSi_y/Mo gradient material reaches the maximum value of 371.42 MPa, the shear strength reaches the maximum value of 30.58 MPa, and the elements in the transition layer appear a quasi-continuous gradient distribution when p=1.5.

Iron oxide dry desulphurization is an effective method for H₂S removal. In this paper, three limonite materials from Yeshan, Xinqiao and Shao jilao iron mines were selected as desulfurizers for hydrogen sulfide removal. The effects of calcination temperature and reaction temperature on the desulfurization performance of limonite were investigated at medium-high temperatures, and a desulfurization cycle regeneration experiment was conducted. The removal mechanism of hydrogen sulfide was analyzed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that SJL-300 as an effective desulfurizer has a total desulfurization capacity of 1 525.7mg/g after seven cycles. In the evolution process of the reaction between limonite and hydrogen sulfide, pyrite and pyrrhotite are the desulfurization products at 300-400 ℃, while only pyrrhotite appears at > 500 ℃.

In order to construct a high-efficiency paper catalysts for soot removal, it is very important to design different active elements and realize the synergistic effects with the matrix fibers. A series of La_1-xK_xMnO₃ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) nanofiber catalysts were prepared via electrospinning. The oxidation performance of the catalyst for soot particles was examined by temperature programmed oxidation reaction. The defect effects induced by doping K⁺ ions in the LaMnO₃ lattice on their catalytic performance evaluated by soot temperature-programmed oxidation were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and temperature programmed reduction analysis. The results show that all the nanofiber catalysts have a perovskite structure, while K₂Mn₄O₈ as a new phase appears in the samples as x ≥ 0.3. The amount of active oxygen in the sample is affected by K⁺ ions replacing La³⁺ ions and Mn³⁺ ions transferring into Mn⁴⁺ ions. The replacement of A-site ions increases the degree of oxygen defects in the system, while the transformation of Mn³⁺ ions into Mn⁴⁺ ions determining the number of oxygen vacancies as a new phase can occur at a great content of K⁺ ions doped in the system. The sample La_0.6K_0.4MnO₃ has an optimum catalytic activity at T₅₀ of 347 ℃. The paper-structured catalyst prepared with a nanofiber to matrix fiber ratio of 1∶1 has a good catalytic activity at T₅₀ of 478 ℃.