Progress in Natural Science: Materials International最新文献

Sodium-ion batteries (SIBs) are considered potential successors to lithium-ion batteries in the fields of energy storage and low-speed vehicles, thanks to their advantages such as abundant raw material sources, high energy density, and a wide operational temperature range. However, several scientific and engineering challenges still require attention in the development of sodium-ion batteries. Electrolyte salts, as a key component of sodium-ion battery electrolytes, play a critical role in battery performance. This paper provides a brief overview of the research progress on different electrolyte salt systems in sodium-ion batteries. It discusses characteristics such as ionic conductivity, electrochemical windows, electrochemical performance, and thermal safety in various solvent systems. Furthermore, the paper summarizes a series of strategies for controlling electrolyte and electrode interfaces, offering references for addressing the challenges in the mass production and application of sodium-ion batteries.

Clay minerals represent a class of hydrated phyllosilicates making up the fine-grained portions of rocks, sediments, and soils. Due to the advantages of abundant reserves, low prices, and wide applications, the development and utilization of clay minerals have received increasing attention in recent years. Isomorphic replacement is a common phenomenon in clay minerals, which is one of the main causes of changes in mineral chemical composition and physical and chemical properties. This article briefly describes the crystal structure of several clay minerals such as montmorillonite, vermiculite, palygorskite, kaolinite, and halloysite. It summarized the research status of the effect of isomorphic replacement on their structure and application performance. The research results can provide theoretical basis for the structural research and efficient resource utilization of clay minerals.

Thermal conductivity measurement of high-temperature heat transfer fluids provides a crucial basis for designing utility-scale thermal systems. Molten salts are promising heat transfer and thermal storage fluids in high-temperature thermal energy storage systems, while the molten salt thermal conductivity obtained in existing studies exhibits large deviations due to the high experimental complexity and unstandardized test procedures. In this work, we improve the conventional laser flash analysis method by proposing a theoretical heat transfer model for multi-layer heat conduction and providing a near-optimal molten salt container design. With water as a test sample, the relative error of thermal conductivity measurement using the improved method is 6.3%. The thermal conductivity of Solar Salt from 250 to 400 ​°C, and of Hitec Salt from 160 to 250 ​°C are measured and compared with the previous work. Both results show that the thermal conductivity increases with the temperature rising. This work will promote the technology standardization for accurately acquiring the thermal conductivity of molten salts or other similar high-temperature heat transfer fluids.

Using nanocatalysts to catalyze water electrolysis for hydrogen production is an ideal solution to address the energy crisis. The most well-adopted fabrication methods for nanocatalysts are tube furnace annealing, Hydrothermal method, etc., hardly satisfying the trade-off among coarsening, dispersity, and particle size due to mutual restrictions. Herein, a universal, ultrafast and facile cellulose nanometer whiskers-high temperature shock (CNW-HTS) method was reported for fabricating a library of ultrafine metal nanoparticles with uniform dispersion and narrow size distribution. The metal-anchor functional groups in CNW (i.e., –OH and –COOH) and the characteristics of the HTS method for ultrafast heating and powerful quenching synergistically contribute to the successful synthesis of metal nanoparticles. As an initial demonstration, the as-prepared Pt nanocatalyst (η10 ​mA ​cm⁻² ​= ​51.8 ​mV) shows more excellent catalytic hydrogen evolution reaction (HER) performance than the Pt catalyst prepared in the tubular furnace (η10 ​mA ​cm⁻² ​= ​169.4 ​mV). This rapid and universal CNW-HTS method can pave the way for nanomanufacturing to produce high-quality metal nanoparticles, thereby expanding applications of energy conversion and electrocatalysis.

Metal-organic frameworks (MOFs) are a large class of crystalline porous materials that composed of organic ligands and metal ions, of which zeolitic imidazolate frameworks (ZIFs) are a broad classification. The most well-known ZIF-like material is ZIF-8 crystals, which have been the subject of extensive research for decades. ZIF-8 crystals have been synthesized under various conditions for application in the fields of sensing, drug delivery, and catalysis. This paper provides a brief introduction to the preparation methods, formation processes, and formation mechanisms of ZIF-8 crystals in different media, and then explains the effects of different precursor conditions (type of Zn²⁺, ratio of raw materials, and type of solvent) on ZIF-8 crystals in terms of formation mechanisms. Subsequently, current reports on the application of ZIF-8-based chemiresistive gas sensors, electrochemical, fluorescent and colorimetric sensors are also summarized. Hopefully, ZIF-8 crystals with good catalytic properties will be obtained based on rational design for promoting the application in different fields of the sensors.

Layered LiNi_xCo_yMn_zO₂ (NCM) cathode materials have emerged as the best choice for high-energy-density lithium-ion batteries for powering electric vehicles. Despite significant research efforts, the understanding of complex structural dynamics during lithium (de-) intercalation still remains a subject of debate, especially in scenarios where morphology and composition vary. In this study, we carried out in situ high-energy synchrotron X-ray diffraction experiments on commercial NCM523 cathode materials in both single crystal and polycrystalline forms to probe the structural changes during charging and discharging in detail. Our findings reveal that both single crystal and polycrystalline materials exhibit typical H1–H2–H3 phase transitions. However, in polycrystalline NCM532, a monoclinic intermediate phase emerges between the H1 and H2 phases. During this process, symmetry reduces from R-3m to C2/m, which is attributed to a shear distortion along the ab plane. In contrast, for single crystal materials, the H1 phase directly transforms into the H2 phase without the monoclinic phase. The observed monoclinic distortion significantly impacts structural stability and material cycling performance. This study provides new insight into the structural dynamics in NCM532 cathode materials, particularly concerning morphology-dependent behaviors, which could deepen our understanding of the relationship between NCM material structures and their performance.

To obtain a high-entropy alloy characterized by high strength and plasticity, (NiCoV)_100-xGa_x (x ​= ​0, 5, 7) was successfully prepared, cold-rolled, and heat-treated. The microstructure was analyzed to correlate Ga content with the performance of the system. The addition of Ga can produce alloying effects, including solid solution strengthening effect, second phase precipitation strengthening effect, and layer misalignment energy reduction effect. The experimental results show adding Ga elements can enrich Ni, Co, V, and Ga above the grain boundaries, causing the alloy to produce annealed twins inside. The alloy is strengthened mainly by precipitation, and the formation of the precipitation phase effectively enhances the strength of the alloy. The low stacking fault energy promotes the toughening of NiCoV but makes the plasticity of the alloy decrease. Still, the formation of annealed twins effectively increases the plasticity, which makes the alloy harder but does not reduce the plasticity too much. By comparing the experimental properties, (NiCoV)₉₃Ga₇ showed the best mechanical properties at the annealing temperature of 900 ​°C, yield strength, tensile strength and elongation of 906 ​MPa, 1321 ​MPa and 21.36 ​%, respectively.

G115 martensitic steel is anticipated to be one of the preferred candidate materials in ultra-super critical (USC) power plants with steam temperatures above 650°C. Microstructure evolutions and mechanical properties of G115 martensitic steel after applying various heat treatment processes were investigated. The results demonstrate that the main precipitate in G115 martensitic steel after applying various heat treatment processes is M₂₃C₆ phase with Cr enrichment. The time required for M₂₃C₆ phase precipitation decreases with increasing secondary normalizing temperature and the extension in holding time according to its precipitation-temperature-time (PTT) curves. Volume fraction of M₂₃C₆ phase increases with increasing secondary normalizing temperature and holding time, which strengthens the inhibitory effect of precipitates on dislocations recovery and laths growth. Therefore, G115 martensitic steel can obtain the best mechanical properties after applying the highest secondary normalizing temperature and the longest holding time. In the current work, the excellent strength of G115 martensitic steel mainly derives from precipitates strengthening and laths strengthening.

Li metal batteries (LMBs) have attracted much attention due to the ultra-high theoretical capacity of the Li metal anode (LMA). However, the uncontrollable dendrites growth and low coulombic efficiency hinder their practical application. Here, we explore 3,5-difluoropyridine (2F-BD) as a novel electrolyte additive to enable high-performance LMBs. The 2F-BD additive participates in and modifies the solvation structure of Li ions by reducing the coordinated number of PF₆⁻ at the electrode surface, leading to the formation of a LiF and Li₃N-rich solid electrolyte interphase (SEI). The LiF component increases the robustness of SEI and suppresses the formation of Li dendrites, while the Li₃N component facilitates the transportation and reaction kinetics of Li ions. As a result, the Li||Li symmetric cell presents a stable cycling performance of up to 500 ​h at a current density of 1 ​mA ​cm⁻². After coupling with LiFePO₄ cathode, the obtained full cell achieves high specific capacities of 106.06 ​mA ​h ​g⁻¹ and 84.98 ​mA ​h ​g⁻¹ at 2.55 ​mA ​cm⁻² and 5.10 ​mA ​cm⁻², respectively, and maintains a high capacity retention of 84.0% after 1000 cycles at 0.13 ​mA ​cm⁻², with an average cycling CE of 99.58%.

Due to the problems of low welding efficiency, large heat-affected zone, and poor welding quality in the process of welding thin-walled titanium tubes by argon arc welding, there are few studies on the use of high-frequency induction welding (HFIW) of thin-walled titanium alloy tubes. The evolution law of weld microstructure and mechanical properties of the thin-walled titanium tube needs to be further studied because of rapid welding speed and the small heat-affected zone of HFIW. Therefore, a novel manufacturing method via high-frequency induction welding is proposed in this paper to solve the existing problems. With an industrial-grade titanium TA2 tube (wall's thickness is 0.5 ​mm) as the research object, a comparative study is conducted in this research to examine the morphology, microstructure, microhardness, and tensile characteristics of welded joints at different welding power. The findings demonstrated a significant efficacy of HFIW in resolving these challenges. The mechanical properties and microstructue of heat-affected zone (HAZ) were characterized. The lowest hardness is measured at 202 HV, while the base material was recorded as 184 HV, when the welding speed of HFIW is set at 50 ​m/min. Meanwhile, the heat-affected zone has the highest hardness at 224 HV, a tensile strength of 446.8 ​MPa and a post-fracture elongation of 16%. The results showed that HFIW can not only greatly improve the welding efficiency, significantly improve the microstructure of weld joint and HAZ, and improve the mechanical properties of thin-walled titanium pipe, but also provide a highly feasible welding method for welding ultra-thin-walled pipes.