In this report, the applications for National Natural Science Foundation of China programs on inorganic nonmetallic materials in 2020 were summarized and statistically analyzed. A pilot classified evaluation measure according to the scientific attributes of individual project was introduced in the evaluation process and the new-methodology-based trial results were revealed and objectively interpreted.

The crystal defects structure, thermal expansion coefficients, electrical transport property, redox cycling stability, and electrochemical performance of Sr₂FeMo_0.6Mg_0.25Al_0.15O₆(SFMMA) double perovskite material as a high-performance anode for solid oxide fuel cells (SOFCs) were investigated. The SFMMA has a tetragonal structure of I 4/m at room temperature, but transforms into a cubic structure of at 400℃. The real structure of SFMMA should be in the form of Sr₂(Fe_0.75Mg_0.25)(Mo_0.6Fe_0.25Al_0.15)·O_6-δ, generating a plenty amount of anti-site defects Fe_B' and -Fe_B-O-Fe_B'-bonds formed in the crystal lattice, which are beneficial to the formation of oxygen vacancies and migration of oxygen ions. The thermal expansion coefficients of SFMMA anode are 13.0×10^-6 K^-1 and 17.6×10^-6 K^-1 at 25-400℃ and 400-900℃, respectively. The electrical conductivity of SFMMA is greater than 35 S/cm in the operating temperature range of 600-900℃. The SFMMA anode shows a fast oxygen surface exchange kinetic and an excellent redox cycling stability. The area specific resistances of SFMMA/La_0.4Ce_0.6O₂(LDC)/La_0.8S_r0.2Ga_0.8Mg_0.2O₃(LSGM)/LDC/SFMMA symmetrical half-cell are 0.096, 0.142, 0.239 Ω·cm² and 0.447 Ω·cm² at 900, 850, 800℃ and 750℃ in wet H₂(3% H₂O, 50 mL/min), respectively. The electrolyte supported single cell with the configuration of SFMMA/LDC/LSGM (300 μm)/PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ can deliver a maximum power density of 886 mW·cm^-2 at 850℃.

La_0.4Sr_0.6Co_0.2F_e0.7Nb_0.1O_3-δ (LSCFN) anode structure, electrochemical performance and operating stability are characterized using CO-CO₂ mixed as fuel. Results show that, the ABO₃ perovskite structure of LSCFN is reduced to A₂BO₄ Ruddlesden-popper structure in CO fuel. While, the addition of CO₂ can shift the structure of LSCFN back to single perovskite, and inhibit coking effectively. The maximum output power density of single cell using pure CO fuel is 0.6 W/cm² at 850℃. And the cell operates for more than 100 hours when using CO∶CO₂ mixed gas as fuel in molar ratio of 5∶1.

Al₂O₃-SiO₂-CaO-based sealing material was developed. The properties of high-temperature crystallization/softening, thermal behavior and interfacial bonding of the sealing material were observed in situ. The results show that the sealing material begins to soften at 850℃, spheroidizes at 900-1 000℃ and keeps amorphous at <1 100℃. In addition, the sealing material has a slight mass loss according to the thermal analysis, and it is bonded with the interconnect and the cell tightly, which is conducive to the application in solid oxide fuel cell (SOFC) stack. Two 5-cell solid oxide fuel cell (SOFC) stacks were assembled by the sealing material. The cycling and stability performance of SOFC stacks were tested. The results indicate that the open circuit voltage (OCV) of the stack reaches 6.0 V, showing an average OCV of 1.2 V for single cells. The stack 1 is operated under cycling conditions, showing no degradation before and after cycling. The stack 2 is operated under stability conditions, exhibiting no degradation for 300 h operation.

Effects of temperature, fuel composition and flow rate on the performance of an anode-supported cell and a stack were studied. The results show that in the complex impedance spectrum, the activation energy corresponding to high frequency arc is the highest; that of the Ohmic loss is lower, which indicates that not only the ionic conductivity resistance, but also the surface resistance and possible contact resistance are included. With dry hydrogen as fuel, the results show that the activation polarization near the open circuit voltage is large and the activation energy is very small, which indicates that the rate control step of the activation polarization is not a charge transfer process, but a surface diffusion process. For simulated reforming gas fuels, the results show the activation polarization is small, but the open circuit voltage is lower, so that the performance is worse than that of hydrogen fuel. With the increase of the stack current, the temperature of the fuel exhaust gas increases, showing obvious thermal effect.

A cobalt-free double-perovskite cathode SmBaFeNiO_5+δ (SBFN) was synthesized by a modified sol-gel process, and SmBaFeNiO_5+δ-Sm_0.2Ce_0.8O_1.9 (SBFN-SDC) composite cathodes were applied to reduce the thermal expansion coefficient (TEC) and improve the electrochemical performance. The average TEC of SBFN is 14.1×10^-6K^-1 in air at 30-900℃, while the SBFN-SDC15 (the mass ratio is 85∶15) composite cathode shows the lowest average TEC of 12.0×10^-6K^-1. The maximum conductivity of SBFN is 48 S/cm at 425℃. The polarization resistance (R_p) of SBFN is 0.386 Ω·cm² at 700℃ on SDC electrolyte. Introducing SDC to SBFN can increase the electrochemical catalytic activity of the cathode materials. SBFN-SDC10 (the mass ratio is 90∶10) composite cathode has the lowest R_p, which is 0.224 Ω·cm² at 700℃. The maximum power densities of Ni-SDC|SDC|SBFN and Ni-SDC|SDC|SBFN-SDC10 single cells are 367.6 mW/cm² and 507.8 mW/cm² at 800℃, respectively.

The response of a large area single cell and a kW class stack against step current change, hot start-up and thermal cycling (cold start-up) were systematically investigated when the current change, gas composition, flow rate and operating temperature were fixed. The results show that the voltage and power of the stack can quickly track the corresponding current changes in the small current area. The on-off of current test results show that SOFC stack is sufficiently tolerant, and a certain amount of on-off of current test cannot cause the significant degradation of the stack performance. However, the thermal cycling will lead to stress release and changes in contact resistance, thus result in the degradation of the stack performance. The more than 5 heat cycles can ease the stress release to a modest way.

A solid oxide fuel cell cathode material La_0.6Sr_0.4Co_0.2Fe_0.8O₃-_δ (LSCF) powder was prepared by a citric acid-EDTA complex method. Sm_0.2Ce_0.8O_1.9 (SDC) was used as an electrolyte to prepare LSCF/SDC/LSCF symmetric electrode cells. The mixed solution of La(NO₃)₃、Ni(NO₃)₂ and Fe(NO₃)₃ was impregnated on both electrodes of LSCF/SDC/LSCF, and the surface-modified cathodes were obtained after sintering at 850℃. The phase structure characteristics, electrochemical AC impedance, electrochemical catalytic activity and single cell output performance of the surface-modified cathode material after impregnation were investigated. The results show that La_0.62Sr_0.38Ni_0.03Co_0.19Fe_0.78O₃-_δ solid solution with the similar structure to LSCF is formed by the impregnation method. The nanoparticles generated on the surface enhances the ability of the cathode material to adsorb and dissociate O₂, and exhibits a lower polarization resistance. The polarization resistance of LSNCF cathode material is 0.083 Ω·cm² at 800℃, the polarization impedance of LSNCF cathode material is 0.117 Ω·cm² at 800℃ after 7 200-min continuous operation. For assemble anode-supported cells with Ni-SDC as an anode, SDC as an electrolyte and LSNCF as a cathode, the maximum power density is 693 mW/cm² at 750℃.

The reversible solid oxide cell (RSOC) is an all-solid-state electrochemical energy conversion device that can achieve an efficient and clean reversible conversion of chemical energy and electrical energy. In anticipation, the RSOCs can be applied in the field of the intelligent electric grid for peak shaving, as well as the conversion and storage of large-scale renewable energy. As the key components of RSOCs, the electrode materials are expected to exhibit great performance and stability since the RSOC works in a reversible cycle both in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes. There is an impetration to improve the catalytic activity and the redox stability of electrode materials. This paper briefly introduced the working principles of RSOCs, discussed the recent progress of electrode materials for RSOCs and the application of symmetrical electrode materials and prospected the future development direction for RSOC.

The development of efficient, stable and inexpensive electrode materials is a key to the further commercialization of solid oxide fuel cells (SOFC). This should solve some problems of anode carbon deposition, sulfur toxicity and poor low-temperature performance of cathode oxygen reduction reaction (ORR). Recent studies indicate that some reducible transition metal element dopants could in situ exsolved from perovskite lattice in reducing atmosphere, and pinning on the surface to form a "nanometal/perovskite" composite structure. The material prepared by this method has some advantages of high performance, strong carbon deposition resistance, good stability, and good regeneration. This review represented recent work on the construction of nano-(in situ exsolved metal particles) micron-(perovskite oxide parent) heterostructure (collectively referred to as nano-and micron-isomerisms) perovskite oxide composite electrode with a nanofiber morphology from the perovskite parent selection, A/B site doping, defect manipulation, topological ion exchange, and phase transition trigger. The affecting factors on the SOFC performance and stability were also summarized. In addition, the advantages, disadvantages, and prospects of the nano-and micron-isomer materials were also discussed.

Proton-conducting solid oxide fuel cells (P-SOFCs/PCFCs) are all-solid-state, ecofriendly, and economic power generation devices for proton conduction in oxide lattices. This review represented the proton conduction mechanism, the typical electrolyte and electrode materials used in PCFCs, and the efficient construction of the internal proton conduction pathways based on the development of low-temperature working SOFCs. The principles of designing these materials were analyzed and some possible problems in this aspect were discussed. This review also indicated the future work on PCFCs to develop some novel electrolytes and electrode materials with an improved proton conductivity.

Liquid metal anode direct carbon solid oxide fuel cells have attracted recent attention due to the extremely high theoretical conversion efficiency. However, the corrosion of liquid metal electrodes to electrolytes is one of the key factors to degrade their performance and limit their life. This review represented the results on the chemical and electrochemical corrosion of liquid metal and oxides, i.e., mainly liquid antimony (Sb) and antimony oxide (Sb₂O₃), to the most frequently used ZrO₂ and CeO₂ based electrolytes in solid oxide fuel cells. The possible methods of reducing the degree of corrosion were discussed.

As a novel sintering technology, flash sintering has attracted extensive attention because of its unique characteristics rather than conventional sintering, such as lower temperature, lower power consumption, and much shorter holding time. The corresponding work focuses on the construction of experimental equipment, phenomenon of different ceramic materials, optimization and control of the parameters, etc. since 2010, leading to rapid development of flash sintering technology. The parameters and mechanisms were summarized, and the application of flash sintering in solid oxide fuel cells was introduced.

The performance of solid oxide fuel cell (SOFC) as a clean and efficient energy conversion device is often restricted due to the oxygen reduction reaction at cathode. As a potential cathode electrocatalyst, cobalt based double perovskite oxide, namely PrBaCo₂O_5+δ, has a high oxygen surface exchange coefficient and a great bulk diffusion coefficient. However, the physical and chemical properties (i.e., thermal expansion behavior) should be optimized to improve the electrochemical activity and durability as applying PrBaCo₂O_5+δ into SOFC. Therefore, recent work is devoted to modifying PrBaCo₂O_5+δ by element doping. This review summarized various element doping approaches, i.e., doping to the Pr site, Ba site, Co site, and O site. In addition, the doping effect on the PrBaCo₂O_5+δ properties (i.e., phase structure, oxygen nonstoichiometry δ, electronic conductivity, oxygen transport properties and electrochemical performances) was also discussed.

The anode of SOFC is easy to react with sulfur impurities in the cheap hydrocarbon and carbonaceous fuels, which lead to the loss of the SOFC electrochemical performance. This review introduces the electrode reaction mechanism of the SOFC and analysis the rule of the anode sulfur poisoning and activation on the basis of the literature in recent years, in addition, the physical and chemical mechanism of the sulfur poisoning are summarized and some new regeneration methods are also summarized.

Some techniques for fabricating the structural parts of the solid oxide fuel cells were reviewed. These techniques includes dry pressing and tape casting techniques for making planar supports; brush painting, screen printing, centrifugal casting, and spin coating for preparing films on planar supports; slip casting, extrusion, dip coating, hot injection moulding, gel casting, and phase inversion methods for fabricating tubular supports; brush painting, dip coating, suspension spraying, electrochemical vapor deposition, and thermal spraying technique for coating films on tubular supports as well. For each processing technique, the principle and specific process flow were introduced, and some problems regarding the processing parameters were discussed. Some applications of these techniques in preparing solid oxide fuel cells were given.

A SiO_x/C composite with an embedded-structure was prepared by a dual sol-gel one-pot method and subsequent heat treatment. Based on the analysis by scanning electron microscopy, SiO_x nanoparticles are fully embedded in an amorphous carbon matrix. The results by electrochemical test indicate that as anode material for Li-ion battery, the optimized SiO_x/C composite demonstrates a high specific capacity, an excellent cyclic performance and a rate capability. A reversible specific capacity of 710 mA·h/g is achieved without an obvious decline of the capacity for 100 cycles at a current density of 0.1 A/g, and a specific capacity is 380 mA·h/g at a current density of 1.6 A/g. The excellent electrochemical performance is attributed to the well-designed embedded-structure, which can effectively accommodate the volume variation of SiO_x during charge/discharge process and therefore ensure the structural integrity and cyclic stability of SiO_x/C electrode.

Silane additives have attracted recent attention as novel electrolytes for lithium-ion batteries due to their high thermal stability, low flammability, non-toxicity, high conductivity and high decomposition voltage. The role and mechanism of Si—O and Si—N structure in silane electrolyte additives were mainly reviewed. In addition, the further research trends and application prospects of silane additives were also prospected.

CoMn₂O₄ nanoparticles on reduced graphene oxide (CoMn₂O₄/rGO) composites with different graphene contents were synthesized in situ by a coprecipitation method. The effect of graphene content on the morphology, microstructure and electrochemical properties of CoMn₂O₄/rGO materials was investigated. The results show that CoMn₂O₄ nanoparticles are deposited on the surface of graphene nanosheets. The distribution of CoMn₂O₄ nanoparticles on the surface of rGO is gradually uniform, and the particle aggregation disappears as graphene content increases. CoMn₂O₄/rGO exhibits a great specific surface area and an excellent electrochemistry. The optimum capacitance performance of CoMn₂O₄/rGO20 (20% rGO, in mass fraction) can be obtained, and the specific capacitance is 1 420 F/g at 1 A/g. CoMn₂O₄/rGO30 (30% rGO, in mass fraction) has the optimum cyclic stability. The specific capacitance retention rate of CoMn₂O₄/rGO30 is 94% at 5 A/g, while that of CoMn₂O₄ is 78%, after 2 000 cycles of charges and discharges.

The homogeneous Ca(Mg_1/3Ta_2/3)O₃ (CMT), CaTiO₃ (CT) dielectric thin films and heterogeneous CMT/CT films with different stacking sequences and different mole ratios of CMT and CT were deposited on Pt/Ti/SiO₂/Si(100) substrates by a Pechini method, respectively. The results show that the hetero-layered CMT/CT films with CT film as the first layer have single perovskite phase. However, a secondary phase diffraction peaks appear in the hetero-layered CMT/CT films with CMT film as the first layer. Meanwhile, the CT peak gradually weakens and finally disappears with increasing CMT mole ratio in the hetero-layered CMT/CT films with CT film as the first layer, indicating CT favored the CMT forming perovskite phase. The dielectric property characterizations show that the dielectric constant is highly dependent upon the mole ratio of CMT in hetero-layered CMT/CT films. However, the dielectric loss is not only dependent on the mole ratio of CMT, but also the interface number of CMT/CT thin films. The optimized dielectric constant and loss were found to be 56 and 0.038 under the mole ratio of 1∶1 for CMT to CT, respectively.

The threading dislocation density (TDD) in Si-based Ge films prepared via the epitaxial growth is rather high due to 4.2% lattice mismatch between Si and Ge, leading to a large dark current of the device. However, the low-temperature Ge/Si wafer bonding can lower the TDD in Ge film by restraining the propagation of the misfit dislocations, exhibiting an enormous potential in the fabrication of high-quality large-misfit film. The oxide layer at Ge/Si bonded interface produced via hydrophilic reaction could affect the performance of Ge/Si heterojunction. In this work, a carrier non-local quantum tunneling model was proposed at Ge/Si bonded interface based on the carrier basic equation. The effect of the oxide layer thickness (d_O) at Ge/Si bonded interface on the dark current, total current, spectrum response, and bandwidth was investigated and the influencing mechanism of heterojunction performance was clarified by the introduction of the semi-classical approximate solution. It is indicated that the carrier blocking effect of the oxide layer becomes serious as the d_O increases, leading to the decrease of the dark current, total current, and spectrum response. In addition, the d_O in Ge layer decreases due to the increase of the electric field in the oxide layer, leading to the decrease of the carrier velocity and the high-frequency characteristic. In order to ensure the excellent photoelectric property of Ge/Si heterojunction, the d_O should be limited to be <0.50 nm.

High-temperature electrolysis via a solid oxide electrolysis cell (SOEC) is considered as one of the most potential energy conversion and storage technologies due to its high energy conversion efficiency, modularization and easy assembly, and flexible application. Methane-assisted SOEC mode, which combines the state-of-the-art SOEC system with partial oxidation of methane (POM) reaction, was used to effectively reduce the energy consumption and produce a high-quality synthesized gas (i.e., a mixture of CO and H₂). This novel SOEC mode can utilize different energy networks including electricity, heat and gas, which can efficiently and flexibly transform different energies and realize the optimal utilization of energies and resources. This review represented recent developments on methane-assisted SOEC mode. The thermodynamic parameters, the Nernst potential, electrochemical performance, products compositions as well as energy structure and efficiency of methane-assisted SOEC mode were summarized. In addition, the research status of the electrode system for methane-assisted SOEC mode was also reviewed, and the future prospects of methane-assisted SOEC mode were discussed.

AgBr/ZnO composite photocatalyst was prepared by a simple one-step hydrothermal method. The composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and photoluminescence spectroscopy. The effect of AgBr/ZnO system synthesis on the photocatalytic properties of the materials was analyzed. The photocatalytic activity of the composite catalyst was investigated with rhodamine B solution as a target pollutant. The results show that an optimum AgBr/ZnO-2 composite with a molar ratio of AgBr to ZnO of 1∶5 has a degradation rate of rhodamine B of 98.98% for 60 min under visible light irradiation. Compared to ZnO, the photocatalytic activity is improved and the degradation rate constant is increased by 11.08 times. Compared to commercial TiO₂(P25), the degradation rate constant is increased by 10.14 times. That is mainly since AgBr/ZnO has a lower electron-hole recombination ratio than ZnO, and the optical absorption band edge of the composite catalyst is red-shifted, thereby enhancing the absorption of visible light.