Dielectric capacitors, which store electrical energy in the form of electrostatic field via dielectric polarization, can be used in pulsed power electronics, due to their high power density and ultrashort discharge time. However, the energy density of dielectric capacitors is relatively low (<2 J/cm³), which has limited their further development. Therefore, it is necessary to develop dielectric energy storage materials with high energy density. In this paper, the history and performance characteristics of dielectric energy storage materials will be briefly described, while the research progress of different dielectric energy storage materials will be summarized. Besides, some of the unsolved problems related to dielectric energy storage materials will be touched and the future development of this research topic will be forecasted.

Solid state lithium metal batteries have extremely high safety, due to the non-flammable and non-volatile characteristics, which makes it possible to use high energy density lithium metal as negative electrode. However, there are still several challenges in the industrialization of solid state lithium metal batteries, such as high interface impedance, poor solid electrolyte/electrode compatibility, low electrolyte ionic conductivity and narrow electrochemical window. Therefore, the development of flexible solid electrolytes with high performance has become an important research topic, in terms of accelerating the development of solid state lithium metal batteries. Here, the latest research progress of composite solid electrolytes in solid state lithium metal batteries and the interface problems and solutions of composite solid electrolyte matching electrode materials will be comprehensively described.

In recent years, rechargeable batteries based on multivalent cations (Al³⁺, Mg²⁺, Ca²⁺, Zn²⁺, etc.) have attracted extensive attention due to their high natural abundance, low cost and good chemical safety. In this review, some achievements and breakthrough progress in the study of multivalent ion batteries, both from home and abroad research teams were summarized. It is found that most researches are focused on the development of anode and cathode materials and the optimization of electrolyte components in aluminum-ion and magnesium-ion batteries. However, there are still some tricky problems to be solved in the rapid development of multivalent ion batteries, such as the structural instability of the cathode materials, the slow migration of ions, the passivation and dendrite problems of the anodes, and the corrosion of the electrolytes. Finally, the future perspective of multivalent ion batteries is prospected. In the later study, looking for multivalent ion battery model with high energy density is the main research direction, in which we could make some explorations and experiments on the modification to the cathode and anode structures to improve corresponding performance, as well as the optimization and matching of multicomponent electrolytes to obtain high-performance multivalent ion batteries.

Thermoelectric materials (TE), which enable the direct energy conversion between heat and electricity, have attracted global attention in both academic and industrial sections, due to their significant applications in power generation and refrigeration. In this review, the research background of thermoelectrics will be introduced first, while the recent progress on several widely studied thermoelectric materials will be overviewed according to their working temperatures. In particular, their crystal structure characteristics and performance optimization strategies will be highlighted. The difficulties and challenges faced in thermoelectric technology, in terms of materials development, device fabrication and R&D modes, will be discussed. Finally, the prospect and expectation for the further development of thermoelectrics will be put forward.

Organic-inorganic hybrid perovskites exhibit excellent optoelectronic properties, such as high absorption coefficients, long carrier diffusion lengths and lifetimes, low-temperature solution processibility and so on. The highest recorded power conversion efficiency (PCE) of perovskite solar cells (PSCs) has reached 25.5%, displaying huge potential for their commercialization. Here, the definition and classification of perovskite semiconductors are first summarized. Subsequently, strategies to enhance the PCE and stability, development of lead-free perovskite alternatives and recent advances in the fabrication of large area devices are highlighted. Last but not the least, the economic feasibility of PSCs and the future prospects for commercialization are also discussed, which could be used as a reference for the future study and development of PSCs.

As a new type of secondary ion battery, aqueous zinc-ion batteries (AZIBs) showed a promising application prospect in the field of large-scale energy storage, due to their low cost, high safety, environmental friendliness and high-power density. In this article, the research progress of AZIBs will be summarized from three aspects, including cathode materials, anode materials and electrolytes. Furthermore, the bottlenecks such as the short cycle life of batteries in this research area will be identified, while the respective possible solutions such as "single-phase reaction mechanism" will be proposed. Finally, an outlook on future research and development directions for AZIBs with high energy density, high safety and long cycle life will be offered as a conclusion.

A new type of graphite carbon nitride (g-C₃N₄)/kaolinite composites with abundant nitrogen vacancies was prepared by using a facile thermal reduction method. The composites were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometer(FTIR), UV-Vis absorption spectroscopy and X-ray photoelectron spectrometry (XPS). Bisphenol A (BPA) was used as the target pollutant to evaluate the catalytic activity of the composites through photocatalysis coupled with persulfate oxidation. It was observed that the degradation rate of NGK-10:1 was 9.98 and 5.72 times higher than those of g-C₃N₄ and nitrogen vacancies modified g-C₃N₄, respectively. On one hand, the large specific surface area and high porosity provided with more reactive site and hence promoted the adsorption capacity of pollutants on the composites. On the other hand, the formation of nitrogen vacancies acted as the photo-generated electron trap centers and thus inhibited the recombination of electron-hole pairs. In addition, there would be more electrons to activate PMS, thus promoting the formation of SO₄^•- and ·OH. Quenching experimental results showed that the non-radical pathway played the major role in the removal of BPA.

Systematic studying the relationship between microstructure and properties of clay mineral materials at the atomic and electronic scales has become an important trend. In this paper, the research progress in computational simulation of surface/interface of mineral materials is reviewed, covering three directions, i.e., interface recombination, surface modification and structural modification. The relevant contents about atomic and electronic micromechanisms are summarized, while the challenges and future development direction of mineral material functional design are prospected.

A tripolyphosphate-intercalated layered double hydroxide compound (LDH-P) was prepared by using exchange method, with flame retardant and structural characteristics. Then, sodium oleate was used to modify the hydroxide, thus forming LDH-P composite (LDH-P-S), by using a water bath method. The synergistic flame retardant behavior of the LDH-P-S with the combination of decabromodiphenyl ethane (DBDPE) on polypropylene (PP) was evaluated. When the content of LDH-P-S was 25% and the total loading of the flame regardant component was 30% in the system, the oxygen index of PP was increased from 24.2% to 24.9%, the total amount of smoke released was decreased by 10.3%, the peak heat release was decreased by 38%, and the vertical combustion performance reached V-0 level. Owing to the synergistic flame retardant effect of LDH-P-S and DBDPE, the amount of DBDPE could be reduced, while the comprehensive flame retardant performance could be effectively improved.

A new two-dimensional layered mesoporous kaolinite based photocatalysis composite with strong visible light response and high photocatalytic efficiency was successfully prepared by acid-base etching and thermal polymerization, using mesoporous kaolinite (PK) as carrier and dicyandiamide as precursor. The crystal structure, molecular composition, microstructure, specific surface area, pore structure, and photochemical properties of the photocatalytic composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area test, UV-Vis absorption spectroscopy, electrochemical impedance spectroscopy and other detection methods. The results show that when the mass ratio of PK to g-C₃N₄ (GCN) is 1∶3, the prepared PK/GCN-3 composite has a larger specific surface area (25.9 m²/g) and a wider visible light absorption threshold (517 nm). The apparent reaction rate constant of PK/GCN-3 in terms of the degradation of Rhodamine B dye was 5 times that of pure GCN after 6 h visible light irradiation.

Noting the extensive application of minerals in catalysts and the urgent solution to address the global greenhouse problem caused by the too fast release of CO₂, TiO₂-attapulgite (ATP) was prepared by using a sol-gel method, on which Ni-Ru catalyst was loaded through impregnation for CO₂ methanation. Performances of the samples with different contents of Ru and Ni were compared, while the influence of CO₂ intake rate was especially studied and the reaction mechanism was explored by using in-situ IR spectroscopy. It was found that the bimetallic catalyst had excellent low temperature activities, whereas the effect of Ru was more pronounced. Among the catalysts prepared, 5Ni-1Ru-TiO₂-ATP has the best catalytic effect, with the CO₂ conversion rate reaching 47.9% at 350℃ and the highest (59.6%) at 400℃. Compared with the catalyst without Ru prepared under the same conditions, the conversion rate at 350℃ was increased by 31.8%, and at 400℃ by 26.5%. Excessive intake rate leads to insufficient gas-solid contact and poor catalytic effect. The composite catalyst followed a reaction path with CO* radicals as the intermediate.

Acid leaching, alkali leaching and alkali leaching combined with hydrothermal process were used to control the pore structure of stellerite, while the pore structure characteristics, phase composition, micro morphology, chemical composition and humidity controlling performance of stellerite samples were systematically evaluated. The acid treatment led to an increase in the number of micropores and mesopores of 2-10 nm, while the alkali treatment resulted in an increment in the number of mesopores of 2-50 nm. The combined process of alkali leaching and hydrothermal allowed the pore structure regulation of stellerite at lower alkali concentrations. The moisture absorption capacity of the stellerite was increased as the number of micropores was increased, while the moisture release behavior was enhanced if the number of the 10-50 nm mesopore and macropore was raised. In the relative humidity range of 33-75%, the balance of moisture absorption and desorption of the alkali treated samples was better than that of those the acid treated ones. After leaching with 3 mol/L hydrochloric acid solution, 5 mol/L sodium hydroxide solution and 0.6 mol/L sodium hydroxide solution hydrothermal reaction, the 12 h moisture control capacities reached 4.44%, 5.41% and 3.72% respectively, which were 4.62 times, 5.84 times and 3.71 times respectively higher than that of the untreated stellerite.

Diatomite samples were prepared at different calcination temperatures, with Linjiang diatomite as raw material. Pore structures of the diatomite and calcined samples were characterized by using the low-temperature nitrogen adsorption and the mercury intrusion technologies. With these experimental data, fractal characteristics of the diatomite and the calcined samples were analyzed with FHH model, Menger sponge model and thermodynamic relations model. It was found that the diatomite contained mainly mesoporous and macropores. With increasing calcination temperature, specific surface area and mesoporous volume of the diatomite samples were decreased, while the proportion of the macropores was increased. At the same time, the sample surface roughness was reduced or the surface became smoother and smoother. When the calcination temperature was lower than 600℃, fractal dimension of the mesopore volume and heterogeneity of the mesoporous structure were decreased with increasing calcination temperature. The deformation of the mesoporous structure and the mesoporous volume fractal dimension was seriously accelerated after calcining at 1000℃. When the calcination temperature was higher than 600℃, the fractal dimension of the macroporous pores was reduced, while the roughness and inhomogeneity of macropore surface of the samples were decreased.

Monoclinic pyrrhotite (M-Pyr) was derived from pyrite through thermal decomposition in nitrogen atmosphere with controlled temperature and time, which was used to activate sodium persulfate (PDS) for the degradation of oxytetracycline (OTC). The effects of initial concentration of OTC, initial solution pH value, contents of PDS and M-Pyr on OTC degradation were studied. The contents of PDS and M-Pyr had a positive effect on the OTC removal rate, while the effect of the initial OTC concentration was negative. Specifically, 99% of OTC was degraded in the M-Pyr/PDS system with pH=6-7, ρ (M-Pyr) =0.1 g/L and c(PDS)=1.0 mmol/L. The removal rate of OTC was 86.5% after recycling for two times, where the relatively poor recyclability might be attributed to the corrosion of M-Pyr and the formation of intermediate product to occupy the active sites. Sulfate radical and hydroxyl radical were the main active species in the M-Pyr/PDS system.

Organic silicon waste residue was used as silicon source to prepare MCM-41 mesoporous silica by using alkali fusion and hydrothermal reaction method. The effect of alkali fusion time and liquid-solid ratio on extraction rate of the silicon source was evaluated, while the effect of CTAB/SiO₂ molar ratio on structure of the mesoporous silica was detailly explored. Besides, adsorption performance of the MCM-41 toward Rhodamine B (RhB) was comprehensively studied. It was found that the MCM-41 possessed highest degree of ordered mesoporous structure, after calcining for 2 h, with the liquid-solid ratio of 50∶1 mL/g, and CTAB/SiO₂ molar ratio of 1∶0.3. Accordingly, the specific surface area, pore size and pore volume of the sample were 783.23 m²/g, 2.529 nm and 0.7479 cm³/g, respectively. In addition, the RhB could be effectively removed with MCM-41, with the maximum efficiency to be 295.23 mg/g. Isotherm and kinetic studies revealed that the RhB removal process could be well fitted with Langmuir and pseudo-second-order kinetic models. Meanwhile, owing to its spontaneous and exothermic adsorption, MCM-41 exhibited a high recyclability.

Two typical montmorillonite samples, with layer charge densities of 0.342 and 0.439, measured by using alkylammonium method, were selected in this study. The effects of layer charge density on the two-dimensional (2D) exfoliation of montmorillonite and the surface electrical properties of the nanosheets after exfoliation were studied. The mechanisms of the exfoliation and hydration swelling ability of montmorillonite were explained using molecular dynamics simulation. It was found that montmorillonite with relatively low layer charge density exhibited stronger hydration and swelling ability and thus was easier to be exfoliated into 2D nanosheets. The exfoliated 2D nanosheets from the montmorillonite with higher layer charge density had larger electronegativity per unit area. The lower layer charge density of montmorillonite, the weaker adsorption of water molecules on the surface of montmorillonite crystal layer, the stronger interlayer cation hydration and greater hydration swelling ability, could be used to explain the fact that the montmorillonite with low layer charge density was more easily exfoliated into 2D nanosheets.

4A zeolite was prepared by using calcination and hydrothermal method with weathered granite sand tail mud as silicon and aluminum sources. The optimal calcination temperature was determined to be 600℃. Based on the single-factor experiment, in terms of cation exchange capacity, according to the experimental design principle of central composite, NaO₂/SiO₂, H₂O/NaO₂, crystallization temperature and crystallization time were all optimized. The optimum parameters were determined to be Na₂O/SiO₂=1.42, H₂O/Na₂O=61.00, crystallization temperature of 90.89℃, and crystallization time of 8.16 h. The corresponding optimum was 198.50 mmol/100 g. The as-obtained 4A zeolite was characterized by using scanning electron microscopy and X-ray diffraction, indicating that it was highly crystallized. The removal mechanism of NH₄⁺-N from the solutions with the 4A zeolite was attributed to the ion exchange and NH₄⁺-N adsorption on the 4A zeolite, which could be well described with the pseudo-second-order kinetic model and the Langmuir model. In addition, the maximum adsorption capacity to NH₄⁺-N was calculated to be 102.04 mg/g. Therefore, this 4A zeolite could be used as highly efficient adsorbents to remove NH₄⁺-N from water.

Si₃N₄/BaAl₂Si₂O₈(BAS) composite ceramics were prepared by a novel freeze gelation method. The flexural strength, flexural modulus, flexural fracture and microstructures of Si₃N₄/BAS composite ceramics were investigated at different temperatures (i.e., 25-1 400℃) and BAS contents (i.e., 7.5%-40.0%, in mass fraction). The results show that the high-temperature mechanical properties of Si₃N₄/BAS composite ceramics can be improved via the increasing of BAS content. At 1 400℃ and 40% BAS, the flexural strength and flexural modulus of Si₃N₄/BAS composite ceramics are 241 MPa and 92 GPa, respectively. At 25-1 400℃ and 30%-40% BAS, Si₃N₄/BAS composite ceramics become a rigid fracture mode, and the sintered body is mainly composed of β-Si₃N₄ and BAS without Si₂N₂O. In air, the testing samples show a surface oxidation phenomenon at 1 500℃, but the samples are not oxidized at <1 400℃.

As the ideal candidate materials for high-temperature structure parts in aeronautics and astronautics domain, SiC/SiC composites possess some advantages, e.g., heat-resistant, oxidation resistance, ablation resistance and heat shock resistance. Interphase is one of critical factors affecting the performances of SiC/SiC composites. According to the interphase design philosophy of ceramics matrix composites, the interphases of SiC/SiC composites are divided into four kinds, i.e., layered structure, refractory oxide, rare metal salts and multiple components ceramics. In this review, the species and styles of interphase, modifying effects on mechanical and oxidation resistance properties, influence factors on the properties and mechanisms and some existing problems were represented, and the proper perspectives were proposed.

Natural halloysite was used as precursor and template to prepare silicon nanotubes through low temperature aluminothermic reduction. The mechanism of variation in morphology during the reduction process and the lithium storage performance of the silicon nanotube were studied. It was found that the alumina octahedron in the natural halloysite was helpful to maintain the one-dimensional nanotube structure of the products during the low temperature aluminothermic reduction process, leading to the formation of silicon nanotubes. The silicon nanotubes had excellent electrochemical performance when used as anode of lithium-ion batteries, with an initial specific capacity of 3 150 mA·h/g. After 50 cycles, the specific capacity was still 1 977 mA·h/g, which is more than twice the value of commercial silicon anode. At a current density of 2 A/g, the capacity was maintained to be 913 mA·h/g after 200 cycles, which is also much higher than that of commercial silicon anode.

All-solid-state lithium batteries become popular due to their high energy density, high safety, and wide electrochemical window. However, there are also some problems in the practical applications, such as the rigid contact between solid electrolyte and electrode material, side reactions occurring readily in contact with electrolyte because of active lithium metal causing the interface to be unstable, sulfide solid electrolyte being unstable to air and high production costs. This review summarized some research work on the interface between electrode material and oxide solid electrolyte, sulfide solid electrolyte, and polymer solid electrolyte, analyzed the interface problems, and discussed the interface optimization strategies to solve the interface problems of all solid-state lithium batteries in the future.

At intermediate and low temperatures, the increase in electrolyte resistance and the decrease in the catalytic activity of electrodes can restrict solid oxide fuel cells (SOFCs) performance. The oxidation of the interconnects leads to the degradation in the output performance of SOFCs. Therefore, various thin film technologies are used to reduce the internal resistance of SOFCs, improve the electrode activity, and enhance the oxidation resistance of interconnects. Among these technologies, pulsed laser deposition (PLD) is widely used in the fabrication of the thin films for ILT-SOFCs due to its easily controlled feature, environmental friendliness, uniform composition between target and film, and capability of depositing multilayer films. The research work on PLD technology in the preparation of electrolyte, electrodes and interconnect of ILT-SOFCs were reviewed comprehensively. The existing research work show that PLD can increase the surface activity of the electrode, significantly reduce the ohmic resistance and effectively block the electron conduction of electrolyte. The protective film deposited by PLD can retard the oxidation of the interconnect. The improvements in these components increase the performance of SOFCs. Finally, the future development of PLD in SOFC manufacture was given.

Ni-YSZ anode supportors with straight pores as well as an integrated Ni-YSZ anode supportor/functional layer were prepared by an alginate ion gel method. A large number of the through-holes are parallelly distributed in the straight-pored Ni-YSZ anode supports with a pore diameter of approximately 80 μm. The thickness of Ni-YSZ anode functional layer fabricated by a spin-coating method is 130 μm. The pores with the diameters of 20-60 μm of the integrated anode support are divergent distributed, and the thickness of the anode functional layer is only 24 μm. Using the integrated method can reduc the time and cost of the preparation procedure. The solid oxide fuel cell supported by the straight-pored Ni-YSZ anode and the single cell based on the integrated substrates possessa maximum power density of 258 mW/cm² and 365 mW/cm² at 800℃, respectively, when using H₂ as a fuel and air as an oxidant.

An Al—In—Mg—Sn—Ce alloy anode was prepared. The effect of annealing condition on the electrochemistry properties of the alloy anode was analyzed via the measurements of hydrogen evolution rate, polarization curve, electrochemical impedance and constant current discharge. The microstructure and corrosion morphology of the alloy anode were determined by electron probe microanalyzer and scanning electron microscopy. The results show that the annealing treatment has a certain effect on the number and size of precipitates on the alloy surface, thus improving the electrochemical activity and corrosion resistance of the alloy anode. Also, the Al—In—Mg—Sn—Ce alloy anode material has an excellent discharge performance in an actual use process when the annealing condition is 350℃ and 6 h. Tthe energy density is the maximum value, and its energy density is 4 837.64 W·h/kg and 3 283.62 W·h/kg when the aluminum alloy anode is discharged at the current density of 40 mA/cm² and 100 mA/cm², respectively.

Chopped carbon fiber (CF) was used as a conductive material to prepare alkali-activated slag/fly ash conductive mortar. The effects of carbon fiber content, stress loading amplitude and loading rate on the conductivity, mechanical properties and self-sensing properties of carbon fiber-alkali-activated conductive mortar were investigated. The results show that the alkali-activated conductive mortar reaches the percolation threshold and forms a conductive path when the volume fraction of carbon fiber is 0.2%. The mixture has a stable self-sensing performance with a high gauge factor at different loading rates and stress amplitudes. The self-sensing performance of alkali-activated slag/fly ash is the optimum with a gauge factor of 175, which is one order of magnitude greater than that of carbon fiber-cement mortar, when the stress amplitude is 12 MPa and the loading rate is 2.0 kN/s.