Combining silicon nanoparticles (Si NPs) with graphite is considered as a promising strategy to develop commercial anodes for high‐energy lithium-ion batteries (LIBs). Nevertheless, the challenge lies in achieving homogeneous dispersion while ensuring the Si NPs make effective electrical contact within the graphite matrix. Herein, a scalable double-roll milling process is developed to uniformly disperse and embed Si NPs within graphite sheets (GS), yielding the E-Si-GS composite. The mechanical rolling force enables effective interlayer confinement of Si NPs, which are firmly anchored to the GS via van der Waals interactions and amorphous carbon bridging. Meanwhile, the preconstructed internal voids between GS and Si NPs efficiently accommodate the volume expansion of Si NPs and promote electrolyte infiltration. Benefiting from these structural merits, the E-Si-GS anode delivers excellent rate capability and long-term cycling stability, achieving a capacity retention of 89.3% over 800 cycles at 3 C. When matched with a LiFePO4 cathode, the assembled full cell exhibits a high-capacity retention of 95.7% after 100 cycles at 1 C. Furthermore, high-mass-loading testing, pouch cell fabrication, and LED lighting demonstrations further verify the promising practical applicability of the E-Si-GS anode.

Biomass-derived carbons are promising sodium-ion battery anodes because they combine renewable feedstocks, tunable pore structures, and adjustable surface chemistry. However, many biomass carbons still show limited specific capacity and unsatisfactory initial coulombic efficiency. Here, corn silk was used as the carbon precursor, and potassium-sulfate-assisted carbothermal reduction was applied to produce sulfur-enriched porous carbon. Sulfur incorporation introduced C-S-related active sites and high-voltage redox features near 2.1/1.5 V. The optimized SC1400 electrode delivered an initial discharge capacity of 365.94 mAh g-1 at 0.1 A g-1 and an initial coulombic efficiency of 84.52%. It retained 342 mAh g-1 after 500 cycles at 1 A g-1, corresponding to more than 93% capacity retention. The improved cycling stability originates from the coupled effects of a defect-rich framework, enlarged interlayer spacing, and sulfur-containing surface species. Density functional theory calculations are consistent with stronger Na adsorption after sulfur incorporation. Density functional theory calculations support that sulfur incorporation enhances sodium-ion adsorption energy. This work provides a practical route for converting agricultural waste into biomass-derived carbon anodes for sodium-ion batteries.

Biomass-derived carbon materials present significant economic advantages alongside environmental sustainability, owing to their renewable nature and distinctive structure. They have been extensively studied for applications in energy storage. However, the low specific capacity over prolonged cycling periods impedes their progress. Activation of salt templates and heteroatom doping have been proven to be effective methods for enhancing the electrochemical properties of Biomass-derived carbon materials. This study focuses on utilizing waste corn straw as a precursor to develop nitrogen-doped poly porous carbon, which is employed as a negative electrode material for lithium-ion batteries (LIBs). The synergistic effects arising from heteroatom doping coupled with a dual-defect porous carbon structure resulted in exceptional electrochemical performance exhibited by nitrogen-doped corn stover-based porous carbon, achieving a reversible capacity of 425 mAh g(-1) after 600 cycles at a current density of 1 A g(-1). Density functional theory (DFT) calculations corroborate that the incorporation of nitrogen significantly enhances lithium-ion adsorption energies. Through element doping and structural adjustments made within this research, overall electrochemical performances for biomass-derived carbon materials were improved while proposing an economically viable solution for pollution-free sustainable anode materials suitable for industrial-scale production.

A metal-organic skeleton (MOF) -derived bimetallic sulfide catalyst, FeCoS2/Fe0.95S1.05, is proposed here for electrochemical ammonia production, which offers a sustainable and energy-saving technical solution for nitrate removal and green NH3 synthesis under environmental conditions. The catalyst benefits from the excellent conductivity and effective synergistic effect of bimetallic sulfides, and it has a NH3 yield of 2.705 mg h- 1 mgcat. - 1 , a maximum Faraday efficiency of 94.79 %, an ammonium selectivity of 96.88 %, and it also maintains good catalytic stability over 12 consecutive cycles. Theoretical and experimental results demonstrate that the incorporation of Fe into the Co site changes the electron configuration of the atoms, resulting in a more pronounced Fe-to-*NO3 electron transfer, and NO3 - can be effectively activated at the surface Fe-Co sites, thereby facilitating the NO3-RR process and realizing efficient NH3 production. Therefore, this study provides a strategy for the design of electrochemical nitrate reduction electrocatalysts.

Compared with the original Discrete Element Method, the coarse-grained DEM significantly improves simulation efficiency. In CG DEM, the coarse-grained ratio is defined as the diameter of the coarse-grained particle divided by the diameter of the original particle. When the upper limit of coarse-grained ratio is used, the simulation is the most efficient. The upper value for simulating mixing process of spherical fuel particles was determined using a multi-level methodology. The adequacy of the upper value of the coarse-grained ratio was assessed by comparing the mixing characteristics and kinetic prop-erties of the coarse-grained particle systems with those of the original particle systems in a rotating drum with blades. The impact of rotation speed and particle number on the upper value was examined and dis-cussed. It was observed that the kinetic energy increases with an increase in the coarse-grained ratio, lim-iting the efficiency improvement. To ensure kinetic energy conservation, a scaling law for the restitution coefficient was proposed. Combined with the Reduced Particle Stiffness method, the simulation time of the coarse-grained case is only 1/3030 that of the original case (with a particle number of 2.3 million) when the upper limit of the coarse-grained ratio was used (12.0).(c) 2023 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved.

A set of overcoating equipment with a single batch output of 80-100 kg overcoated particles was developed. The experimental results obtained by using the optimized process validated that the equipment and process can not only maintain a high yield within a wide range of process parameters, but also be suitable for producing in a wide range of batch size. By studying the particle size distributions (PSDs) of different batches of overcoated particles and the transformations of PSDs and sphericity during a single batch production, combined with the movement law of particles in the overcoating drum, the reasons for the transformation of PSDs from near normal to positive skewness to negative skewness during the overcoating process was revealed. The origin of the formation of abnormal particles with different shapes was explained by analyzing the details of the defects of odd-shaped particles. The technology in this study can effectively improve the productivity, production efficiency and quality of overcoated particles, which can meet the demand of mass manufacture of fuel elements for HTR.

Matrix graphite (MG) constitutes a major component of the fuel element in high-temperature gas-cooled reactors (HTRs), and its performance directly affects the economy and safety of HTRs. A3-3 MG, developed in Germany in the last century, is still used today without significant changes. However, with the successful commercialization of HTR, there is an urgent need to develop MG that is suitable for the characteristics of each country. In this paper, comparative studies on the powder processing of natural flake graphite were carried out based on the raw materials from Inner Mongolia. First, the influence of the sequence of purification and pulverization on the basic properties of graphite powder was studied. Second, the influence of the degree of spheroidization of the natural flake graphite powder on the properties of the MG was further investigated, and the controlling mechanism of the spheroidization process on the microstructure and physical properties of the MG was revealed. The results of this study provide important insights for optimizing the preparation process of HTR fuel element MG.

The anisotropy of graphitic matrix in fuel elements for high-temperature gas-cooled reactors (HTR) has an important effect on the distribution of thermal stress and irradiation stress, which should be strictly controlled. In this study, the graphitic matrix spheres were prepared through quasi-isostatic pressing and dry-bag isostatic pressing. The anisotropy was compared from the elastic modulus, crushing load, coefficient of thermal expansion (CTE) and thermal conductivity in different directions. The causes of anisotropy were investigated from the aspects of raw material microstructure, charging, pressing, as well as heat treatment. The graphite microstructure and the preferred orientation of graphite particles in the production process were found as the main reasons for the anisotropy of thermal and mechanical properties. The dry-bag isostatic pressing method can effectively reduce anisotropy and increase the production capacity compared with the quasi-isostatic method, which is consistent with the development trends of high quality and low cost fuel elements. (C) 2022 Elsevier B.V. All rights reserved.

The steady development of high-temperature gas-cooled reactors(HTRs) has increased the requirements for the production cost and quality of fuel elements. Green fuel element pressing is one of the key steps to increase the production capacity. This paper proposes a proprietary vacuum dry-bag isostatic pressing(DIP) apparatus. The structural change of the matrix graphite powder during the DIP process was examined by analyzing the density change of the matrix graphite spheres with pressure. The soft molding process was simulated using the finite element method. The dimensional changes in the spheres during the pressing, carbonization, and purification stages were explored. The performance of the fuel matrix produced by the DIP method was comprehensively examined. The fuel matrix met the technical requirements and its anisotropy was significantly reduced. The DIP method can significantly improve both the production efficiency and quality of fuel elements. This will play a key role in meeting the huge demand for fuel elements of HTRs and molten salt reactors.

Separation of complete TRISO-coated fuel particles from matrix graphite is challenging but important for the post-irradiation examination (PIE) of high-temperature gas-cooled reactor (HTGR) fuel elements. Electrochemical technology is considered one of the most promising and effective approaches in this regard. Herein, to explore the influence of HNO3 concentration on galvanostatic deconsolidation, 4%-68% HNO3 were taken as examples. The matrix graphite anodes gradually exfoliated to fragments in 34% HNO3, while expanding in other concentrations. The characterization results of deconsolidated fragments and galvanostatic curves identified the highest oxygen content was reached in 34% HNO3 due to the combined effect of intercalation, hydrolysis and oxygen evolution. In higher HNO3 concentrations like 68%, the intercalating agent predominates and therefore the intercalation and following hydrolysis reactions are the main causes of matrix graphite deconsolidation, with no oxygen evolution occurring. In contrast, in lower HNO3 concentrations like 4%, the violent oxygen evolution reaction hinders the intercalation and hydrolysis reactions. In short, only the combined interaction of intercalation, hydrolysis and oxygen evolution can deconsolidate the bulk matrix graphite into a more homogeneous powder. This work will provide more insights into the electrochemical deconsolidation mechanism and process of both HTGR fuel elements and other graphite materials. (C) 2022 Elsevier Ltd. All rights reserved.

The anisotropy of graphitic matrix in fuel element for high-temperature gas-cooled reactor (HTR) has an important effect on the distribution of thermal stress and irradiation stress under normal operating conditions, which should be strictly controlled. In this study, the graphitic matrix spheres were prepared through quasi-isostatic pressing and dry-bag isostatic pressing. The anisotropy was compared from the elastic modulus, breaking loading, coefficient of thermal expansion (CTE) and thermal conductivity in different directions. The causes of anisotropy were investigated from the aspects of raw material microstructure, charging, pressing, as well as heat treatment. The graphite microstructure and the preferred orientation of graphite particles in the production process were found as the main reasons for the anisotropy of thermal and mechanical properties. From the performance of cold-state characteristics, the anisotropy of the graphitic matrix spheres prepared through dry-bag isostatic pressing was significantly better than that of quasi-isostatic pressing, consistent with the development trends of high quality and low cost of fuel elements.

The matrix graphite (MG) of pebble fuel elements for a High Temperature Gas-cooled Reactor (HTGR), composed of 71wt% natural graphite, 18 wt% artificial graphite and 11 wt% phenolic resin-derived carbon, was purified by high temperature treatment (HTT), and its properties and microstructure were analyzed to investigate the effect of different HTT temperatures and optimize the purification temperature. Results showed that with increasing HTT temperature, its density and thermal conductivity gradually increased, but pore size and d002 gradually decreased. The rate of erosion caused by friction as the fuel pebbles move in the reactor also decreased. The ash content decreased significantly from to 18.2×10−6to 12.3×10−6 after HTT at 1600 °C, but changed little when the HTT temperature was further increased to 1900 °C, especially for catalytic metals such as Fe, Ni and Ca that are related to its corrosion rate. The microstructure improvement and ash content reduction at high temperatures jointly contributed to the increase in the anti-corrosion performance of MG. Based on properties such as crushing strength, erosion resistance, and corrosion rate, a HTT of 1600 °C is adequate although the MG gradually became more ordered with a further increase of HTT temperature from 1600 to 1900 °C. This determination of an appropriate HTT temperature for the production of MG for the fuel elements of an HTGR should improve the production efficiency and reduce the mass production cost of this material for a commercial HTGR.

利用自行设计的大型氧化实验装置,研究了不同空气流量条件下A3-3基体石墨的氧化特性随温度的变化情况,分别计算和拟合了氧化速率和Arrhenius方程,并结合密度分析、扫描电镜等对氧化机理进行分析.结果 表明:氧化速率在不同空气流量下均随温度的升高而增大.在相对较低的温度范围(600～675℃),氧化速率较低,空气流量对氧化速率的影响程度基本相同,受化学反应速率控制;在相对较高的温度范围(800～900℃),氧化速率较高,空气流量的影响程度基本相同且较低温更大,属边界层控制区.通过拟合Arrhenius方程发现,A3-3基体石墨在不同空气流量下的氧化均呈现3个区:化学区、净扩散区和边界层控制区,化学区和净扩散区的转变温度随空气流量的增大而提高,并在密度分析结果中得到进一步验证,但空气流量不影响化学区的活化能.

As the main components of the matrix graphite of pebble fuel elements for HTR-PM, the natural flake graphite powder (NFGP) and artificial graphite powder (AGP) must present suitable microstructural features such as specific surface area (SSA), particle size distribution (PSD), and ash contents. As a regular method, the graphite powders are purified at high temperature of similar to 2500 degrees C with the purge of halogens to obtain their high purity prior to the powder treatments such as pulverizing, shaping, and particle classification, which may introduce impurities into the graphite powders during the powder treatment process. Therefore, the purification of NFGP and AGP should be carried out after the powder treatment to prevent the graphite powders from being contaminated and reduce the cost. In this manuscript, the microstructural features of NFGP and AGP before and after purification were comparatively analyzed to figure out the effects of purification process on the microstructures of NFGP and AGP. Results showed that purification had great influences on the ash contents and the contents of impurity elements, SSA, and degree of graphitization of graphite powders. However, the purification had little influence on the PSD of graphite powders. The significant decrease of SSA of graphite powders through the purification was due to the reduction of BJH adsorption cumulative volume and porosity. Comparing with those of the NFGP, the properties and microstructure of the AGP changed more through the purification process, which was probably due to the original un-graphitized coke of AGP before purification.

In High-Temperature Gas-cooled Reactor (HTGR)s, coated fuel particles are dispersed in a graphite matrix, which forms both compact and spherical fuel elements. As for the post irradiation examination (PIE) of HTGR irradiated fuels, the electrochemical deconsolidation method in which graphite matrix is disintegrated into graphite powder is one of the feasible processing methods. The graphite matrix is composed of natural graphite, artificial graphite and glassy carbon from carbonized resin, which have different effects on electrochemical deconsolidation. In this work, synthesized graphite matrix specimens were produced by intentionally varying the resin binder content in the graphite matrix raw materials from 5% to 50%, in order to investigate the electrochemical deconsolidation mechanism of graphite matrix in HTGR fuel elements. The results showed that increasing the glassy carbon content increased the degree of chemical oxidation, with more pronounced production of graphite oxide. The driving force for graphite matrix deconsolidation is proposed to be a synergetic effect of the expansion stress around closed- and through-hole microstructure originating from oxidatively destroyed graphite layers. This work will not only help to more thoroughly understand the electrochemical deconsolidation procedure of HTGR fuels, but also contribute to the development of a feasible method to manage radioactive graphite waste.

Compared with the long use of carbon materials in human history, the debut of carbon materials in the Chicago Pile-1 nuclear reactor took place only 70 years ago. Since then, carbon materials have played important roles in nuclear reactors, especially in high temperature gas-cooled reactors (HTRs) because of their many excellent properties. As the most promising candidate for Generation IV reactors, a demonstration plant for HTRs, an HTR pebble-bed module (HTR-PM) is currently under construction in China. In the HTR-PM, carbon materials act as the core structural material, reflector, fuel matrix, moderator, and thermal and neutron shields. Because the dimensions and properties of the carbon are generally influenced by the high temperature and neutron irradiation in the HTR-PM, there are rigorous requirements for their performance. Since the precursor materials such as cokes and natural graphite, and the subsequent forming method play a critical role in determining the structure, properties and performance of the material under irradiation, a judicious selection of the raw materials and forming method is required to obtain the desired structure and properties. This paper introduces the detailed property requirements of different carbon materials in the HTR-PM and their fabrication processes. In addition, the current status and future commercialization of the HTR-PM in China and abroad are presented. In order to meet the requirement of full local production in a commercial HTR, long-term considerations such as the sustainable and stable supply of the raw materials, optimization of the manufacturing process in the local production of nuclear graphite for structural graphite and graphite pebbles, and the stable production and reduced cost of the precursor materials are discussed. Finally, current progress and future arrangements for the irradiation testing of Chinese nuclear graphite at the Oak Ridge National Laboratory (USA) are presented. This manuscript is intended to act as a reference for carbon material producers who intend to develop nuclear graphite and carbon materials for use in future commercial HTRs. Meanwhile, a great deal of information introduced in the manuscript is also useful for scientific researchers of carbon materials.

An atomic force microscopy (AFM) scanning head is designed with the probe orthogonal scanning mode for metrological AFM to eliminate the curvature distortion. The AFM probe is driven by piezostage and the scanning trajectory of the probe in 3 directions are orthogonal to reduce the cross coupling. A new optical lever amplification optical path is developed to eliminate the coupling error. The tracing lens and probe tip are moved as an integrated part. The AFM is operated at contacting mode. The step approach process of the probe tip is tested to the sample surface and the noise of the AFM head is analyzed. The response of the probe demonstrates a 0.5 nm resolution of the probe head in the z direction. Finally, the planar scanning performance of the scanning head is demonstrated compared with tube scanning AFM. (C) 2018 Published by Elsevier B.V.

At the beginning, a comparative analysis was made on the oxidation corrosion rate and ash content of A3-3 matrix graphite (MG) pebbles lathed before and after high temperature purification (HTP) treatment. Their oxidation corrosion rate and ash contents were almost identical, which indicated that the HTP process was to purify the entire MG pebbles and not limited on the surfaces. Furthermore, the multiple mechanical and thermal properties of MG treated without and with the treatment of HTP at ~1900°C were compared and their microstructure features were characterized as well. As the crush strength, oxidation corrosion rate, and erosion rate of MG without HTP treatment did not satisfy the specifications, the comprehensive properties and purity of MG with HTP were improved in various degrees through the HTP process so that all performances met the requirements of the A3-3 MG. The improvement of crush strength and erosion rate of MG in the HTP process could be mainly attributed to the upgradation of ordered microstructure and corresponding increase of density. However, the enhancement of oxidation corrosion rate was due to the synergistic effects of microstructural optimization and reduction of impurity elements, especially the transition metal elements of MG in the HTP process.