The sodium metal anode as an ideal candidate material beyond lithium-ion battery technology has a high theoretical specific capacity (i.e., 1 165 mA·h·g^-1), a low redox potential (i.e., -2.71 V vs. standard hydrogen electrode), and low cost. However, the practical application of sodium metal anode involves sodium dendrite growth and infinite volume expansion, leading to a low Coulombic efficiency and a short cycle life, and affecting its development. Recent work have dedicated much effort to solving these problems. This review represented some effective strategies in enhancing the cycling stability of sodium metal anodes, i.e., reducing the local current density of sodium metal electrodes, increasing sodium nucleation sites, and creating appropriate pores in current collectors to alleviate volume expansion. This review also discussed the main problems of sodium metal anodes and summarized the modification strategies of current collectors of electrodeposited sodium metal anodes, i.e., three-dimensional current collector design, doping or defect engineering, introduction of crystal seeds, and buffer layer modification. In addition, the future development aspects of high-safety and high-energy-density sodium metal batteries were also prospected.

Carbon-based materials is considered as the most effective candidate for noble metal oxygen reduction reaction (ORR) catalysts. Among them, graphdiyne as a new type of carbon allotrope is composed by both sp and sp² hybrid carbon atoms and a two-dimensional network structure with a single atomic layer thickness. Therefore, graphdiyne-based materials exhibit a greater intrinsic electrochemical activity due to the inherent conductivity and stability. This review represented the latest progress and achievements on the synthesis of various graphdiyne-based materials and their composites used in the ORR catalysis, and analyzed the advantages of graphdiyne-based carbon materials in the oxygen reduction catalysis from the perspective of electronic structure and catalytic activity. In addition, the prospects and challenges of graphdiyne-based carbon materials in the ORR catalysis were also summarized, thus providing some future research aspects for the design and synthesis of high-quality graphdiyne-based inorganic nonmetal ORR catalysts.

It is essential for the adhesion mechanism of the cement-asphalt interface to evaluate the performance of cement-asphalt composite material in a micro-scale. The interface molding experiment was designed in laboratory according to the actual formation process. The influences of environmental temperature, grouting type and asphalt type on the cement-asphalt interfacial bonding characteristics were investigated. The microstructures and features of the cement-asphalt interfacial transition zone were analyzed by scanning electronic microscopy, energy dispersive spectroscopy, and Fourier transformed infrared spectroscopy. The hydrophilia of grouting and asphalt was evaluated by contact angle analysis. The adhesion mechanism of the cement-asphalt interface was investigated. The results show that the bonding strength of the cement-asphalt interface decreases with increasing the temperature. The interfacial bonding strength of sulphoaluminate cement-asphalt is 1.03-1.98 N/mm² at 25-35 ℃, which is more than 10% greater than that of the Portland cement-asphalt. The interfacial bonding strength of sulphoaluminate cement-asphalt is 0.32-0.38 N/mm² at 60 ℃, which is increased by >80%, compared with that of Portland cement-asphalt. Grouting has a slight emulsification effect on the asphalt interface region, reflecting that the more free asphalt changes to structural asphalt and increases the bond strength. The cement-asphalt interfacial adhesion is due to the physical force. The adhesion failure is the damage between the structural asphalt and free asphalts. Based on the adhesion mechanism, the asphalt-cement composite material can be improved to reduce the crack risk of cement grouting asphalt composite pavement.

It is important for the further improvement of lithium-ion battery energy densities to develop high-specific-capacity cathode materials. Li₃V₂O₅ has attracted much attention due to its high specific capacity, even exceeding 240 mA·h/g. However, its low electrochemical cycling stability induced by the low Li⁺ transport dynamics and irreversible phase transition restricts the application of Li₃V₂O₅ cathode materials in lithium-ion batteries. In this paper, co-doped Li₃V₂O₅ nanorod cathode materials were prepared. The one-dimensional structure can relieve the accumulation of strain during charging and discharging process. Also, Co³⁺ doping can stabilize the structure of Li₃V₂O₅ by forming the more intense Co—O bonds. Furthermore, Co³⁺ doping expands the cell volume and ratio of V⁴⁺ in Li₃V₂O₅. These collectively result in the improved Li⁺ diffusion coefficient and cycling stability of Li₃V₂O₅. The 1% Co-doped Li₃V₂O₅ (i.e., 1%Co-LVO sample) has a specific discharge capacity of 256.43 mA·h/g at a current density of 50 mA/g and a capacity retention rate of 77.3% after 100 cycles, which is 28% greater than that of the pristine Li₃V₂O₅. 1%Co-LVO sample shows a superior capacity fading (i.e., 0.23%/cycle). This paper can provide an effective method for the preparation and performance regulation of high-energy-density lithium-ion cathode material (i.e., Li₃V₂O₅).

Silicon has attracted wide attention due to its high theoretical specific capacity. However, the huge volume change and poor reaction kinetics in the lithiation process lead to a serious deterioration of its structure, a continuous capacity attenuation and a poor magnification performance, thus restricting its practical application. To solve these problems, silicon/reduced graphene oxide (Si/rGO) nanocomposites with a three-dimensional cage-like conductive structure were designed by an in-situ electrostatic self-assembly and hydrothermal reduction method with commercial Si nano-particles with the size of 60 nm and natural flake graphite. The lithium ion storage performance and energy storage mechanism of Si/rGO nanocomposite were investigated. The results show that Si nano-particles are uniformly encapsulated into a three-dimensional cage-like conductive network structure of rGO, effectively limiting the volume expansion of nano-Si particles and providing the more ion transport channels in the process of lithium ion intercalation/detachment. The specific capacity of Si/rGO nanocomposites is 1 246 mA·h/g at 0.1 A/g. The Coulomb efficiency is 98.2% and the capacity retention is 95.5% from fifth cycle, indicating that the nanocomposite has a fast stability behavior. The reversible capacity remains 852 mA·h/g, the Coulomb efficiency is 99.9%, and the capacity retention is 68.4% after 200 cycles.

Aqueous zinc-ion batteries (ZIBs) are considered to be prospective candidates in energy storage devices because of their excellent safety, crustal abundance, low cost and environmental benignity. Whereas, the design of a satisfied cathode material with a large specific capacity, superior rate performance and long-cycle life is still a significant challenge for ZIBs. Herein, a new strategy is proposed to use W doped V₂O₅ as cathode material for aqueous ZIBs. The W doping can effectively enlarge the lattice spacing and ion migration efficiency of V₂O₅, and the formation of W—O bond can obviously alleviate the capacity decay problem caused by structural damage and low intrinsic conductivity in the cycling process. As a result, the V₂O₅-W cathode exhibits an excellent capacity of 195.0 mA·h/g after 100 cycles at 0.1 A/g, and an impressive rate capability of 243.0 mA·h/g at the high current density of 1 A/g after 1 000 cycles. This work provides a simple, efficient and feasible strategy for designing high-performance cathode materials in ZIBs.

In order to improve the electrochemical performance of cathodes for low-temperature solid oxide fuel cells, two kinds of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ/Ce_0.9Gd_0.1O_2-δ (LSCF/GDC) cathodes with a multifunctional hierarchical scaffold structure were prepared. The microstructure and electrochemical properties of the cathodes were investigated. The results show that the GDC primary scaffold with a porosity of 80.5% fully ensure the construction of LSCF or GDC secondary scaffold, subsequent loading and oxygen diffusion in the working state. Based on the analyses of distribution of relaxation times for the electrochemical impedance spectra, the cathode with LSCF nanoparticles as a secondary scaffold has a total polarization resistance of only 0.236 Ω·cm² at 600 ℃ due to the abundant reactive sites and unobstructed electronic conduction, and the GDC nanoparticles loading promotes the adsorption/dissociation of oxygen. The hierarchical scaffold cathode has a simple process and excellent oxygen reduction performance, which can promote the further development of low-temperature solid oxide fuel cells.

The study of weathering alteration of phyllosilicate minerals is of great significance for understanding the chemical cycle of the earth surface, soil formation and environmental changes. A phlogopite from Xinjiang, China was used as a raw material to control the oxidation environment, pH value, ion species and concentration of sulfuric acid solution in the process of phlogopite vermiculization. The phase, composition release law, spectroscopic properties and thermal properties were characterized by X-ray diffraction, inductive coupled plasma emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetry-differential scanning calorimetry, respectively. The results show that the degree of vermiculite increases with the increase of Mg²⁺ ions concentration in the solution, but the less conversion effect exists at a certain H₂O₂ content in the solution. The conversion effect can be enhanced after the use of sulfuric acid to adjust the solution pH value, because the acidic environment can improve the oxidation capacity of hydrogen peroxide and the increase of SO₄^2- ions concentration. The more jarosite substances are formed, thus accelerating the process of vermiculization.

It is of great significance for the improvement and utilization of fly ash to reduce the accumulation pollution of coal based solid waste. In this work, a porous high-content iron fly ash sorbent named KIFA was obtained via CaO hydration, addition of pore-making agent and binder, and oxidation modification by NaClO. This sorbent KIFA with an optimized pore structure can promote the formation of K₂FeO₄. The fixed-bed evaluation results show that the KIFA has the maximum SO₂ removal ability at 700 ℃, 5% O₂ and 500 mg/m³ SO₂, and the breakthrough time and sulfur capacity of the removal efficiency of > 93% are 111.8 min and 93.58 mg/g, respectively, having the ultra-low emission standard of 35 mg/m³. According to the characterization results of fresh and used KIFA, K₂FeO₄ is a main active component in removing SO₂ by KIFA, and Fe(VI) provides the oxidation site, which oxidizes SO₂ to SO₄^2-. NO can promote the forward desulfurization reaction. NO, SO₂ and CaO can form an intermediate product of NO₃SO₃Ca, which can be converted into SO₄^2-, thus improving the removal efficiency of SO₂.

To obtain easily recycled photocatalyst and improve the reusing practicability for waste water treatment, Bi₂O₃ films were prepared by a plasma spray-chemical vapor deposition method , and the effects of deposition temperature and heat-treatment temperature on the morphology and phase composition of Bi₂O₃ films were investigated. The morphology and composition of the films were characterized by field-emission scanning electron microscopy, X-ray diffraction and high-resolution transmission electron microscopy. The band gaps of α/β-Bi₂O₃ at different heat treatment temperatures were determined by ultraviolet-visable diffuse reflectance spectrometry. The results show that the deposition temperature and heat-treatment temperature affect the microstructure of Bi₂O₃ films and the proportion of α and β phases, while the influence of deposition temperature is more dominant rather than that of heat-treatment temperature. The proportion of β phase gradually converts to α phase and the band gap of α-Bi₂O₃ and β-Bi₂O₃ increases when the heat-treatment temperature increases. The Bi₂O₃ films exhibit a good photocatalytic degradation performance for Methyl Orange and Bisphenol A.