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The application of sodium-based batteries in grid-scale energy storage requires electrode materials that facilitate fast and stable charge storage at various temperatures. However, this goal is not entirely achievable in the case of P2-type layered transition-metal oxides because of the sluggish kinetics and unfavorable electrode|electrolyte interphase formation. To circumvent these issues, we propose a P2-type Na 0.78 Ni 0.31 Mn 0.67 Nb 0.02 O 2 (P2-NaMNNb) cathode active material where the niobium doping enables reduction in the electronic band gap and ionic diffusion energy barrier while favoring the Na-ion mobility. Via physicochemical characterizations and theoretical calculations, we demonstrate that the niobium induces atomic scale surface reorganization, hindering metal dissolution from the cathode into the electrolyte. We also report the testing of the cathode material in coin cell configuration using Na metal or hard carbon as anode active materials and ether-based electrolyte solutions. Interestingly, the Na||P2-NaMNNb cell can be cycled up to 9.2 A g −1 (50 C), showing a discharge capacity of approximately 65 mAh g −1 at 25 °C. Furthermore, the Na||P2-NaMNNb cell can also be charged/discharged for 1800 cycles at 368 mA g −1 and −40 °C, demonstrating a capacity retention of approximately 76% and a final discharge capacity of approximately 70 mAh g −1 . The practical application of sodium-ion batteries at subzero temperatures is hindered by the slow Na-ion transfer kinetics. Here, the authors reported the niobium doping of P2-type cathode active material capable of efficient battery cycling at low temperatures such as −40 °C.

Aqueous zinc-ion batteries offer sustainable large-scale storage potential with inherent safety and low cost, yet suffer from limited energy density and cycle life due to aqueous electrolyte constraints. Here, we introduce affordable, stable electrolyte (0.33 $·kg −1 ) incorporating minimal multi-halogen anions (Cl − , Br − , and I − ) to create a high-entropy solvation structure enabling high-performance zinc batteries. Despite the small amount, the diversified mono-halogenated contact ion pair and multi-halogenated aggregate solvation structures create the unique high-entropy solvation structure, to form the lean-water halogenated interfacial environment, suppressing the hydrogen evolution reaction, while facilitating cascade desolvation. Multi-halogen additives generate diverse contact ion pairs (Zn-X, X = Cl/Br/I) with compact solvation shells accelerating ion transport. In this way, the high-entropy solvation structure breaks the trade-off between plating overpotential (energy efficiency) and plating/stripping reversibility (Coulombic efficiency). As a result, the high-entropy solvation-based electrolyte enables practical zinc metal battery with 152.2 Wh kg − 1 electrode for 120 cycles at lean electrolyte of 2.4 μL mg − 1 and an Ah-level pouch cell is validated with high Coulombic efficiency of over 99.90% for over 250 cycles. Our findings emphasize the importance of electrolyte design for the precise control of anion-cation interactions for stable Zn/electrolyte interface and enable practical zinc metal battery with high energy and low cost. Aqueous zinc batteries offer a safe and low-cost energy storage option but have a limited lifespan. Here, authors develop a multi-halogen mediated high entropy electrolyte that restructures ion interactions, enabling high energy batteries with extended cycle life and low electrolyte cost.

Considering that the low recovery efficiency and the massive loss of valuable metals by the traditional pyrometallurgical process smelting low‒nickel matte. Therefore, this paper focuses on studying the optimal process parameters and the mechanism of sulphation roasting followed by water leaching achieving efficient synchronous extraction of nickel (Ni), copper (Cu), and cobalt (Co) from low‒nickel matte with sodium sulfate as the sulfating addictive. Under optimal conditions, the recovery efficiency of Ni, Cu, and Co metals can achieve 95%, 99%, and 94%, respectively, whereas the recovery efficiency of Fe metal is less than 1%. The results revealed that the mechanism of the sulfating roasting pretreatment could form a liquidus eutectic compound sulfates [Na 2 Me(SO 4 ) 2 ] (Me = Ni, Cu, Co) at the solid–solid interface, which plays a significant role in promoting the leaching efficiency of valuable metals. Not only enhance the reaction kinetics of sulfation, but improve the utilization efficiency of SO 2 /SO 3 . Thus, the sulfation roasting‒water leaching process developing an efficient and eco-friendly pathway to simultaneous extraction of Ni, Cu, and Co valuable metals from low grade sulfide ores.

This paper investigates the kinetic characteristics of sponge iron powder reoxidation under two different oxidation atmospheres by examining the reoxidation process from thermodynamic, microstructural, and kinetic perspectives. It reveals the changes in the surface microstructure and oxide content of sponge iron under different oxidation conditions. The results indicate that the thermodynamic conditions for the formation of Fe2O3 were more relaxed than those for Fe3O4. As the oxidation time increased, the surface microstructure of the sponge iron transitioned from a porous granular form (Fe) to a dense blocky structure (Fe3O4), eventually forming a rod-like product (Fe2O3). Under an atmosphere of O2/Ar = 21/79, the oxide content was significantly higher compared to an atmosphere of O2/Ar = 11/89. Under an atmosphere of O2/Ar = 11/89, the oxidation rate index (n) remained at 0.68 throughout all stages, indicating a consistently higher oxidation rate. Conversely, under an atmosphere of O2/Ar = 21/79, the initial oxidation rate index (n1) was 1.17, reflecting a slower initial oxidation rate, while in the final stage, the oxidation rate index (n2) dripped to 0.33, indicating a substantial increase in the oxidation rate. The research results provide basic research ideas and references for an in-depth study of the antioxidant storage of sponge iron.

Sodium ion batteries (SIBs) have attracted great interest as candidates in stationary energy storage systems relying on low cost, high abundance and outstanding electrochemical properties. The foremost challenge in advanced NIBs lies in developing high-performance and low-cost electrode materials. To accelerate the commercialization of sodium ion batteries, various types of materials are being developed to meet the increasing energy demand. O3-type layered oxide cathode materials show great potential for commercial applications due to their high reversible capacity, moderate operating voltage and easy synthesis, while allowing direct matching of the negative electrode to assemble a full battery. Here, representative progress for Ni/Fe/Mn based O3-type cathode materials have been summarized, and existing problems, challenges and solutions are presented. In addition, the effects of irreversible phase transitions, air stability, structural distortion and ion migration on electrochemical performance are systematically discussed. We hope to provide new design ideas or solutions to advance the commercialization of sodium ion batteries.

A molten-metal catalyst exhibits strong resistance to carbon encapsulation and deactivation, due to its unique physical and chemical properties, demonstrating excellent catalytic activity and stability. This paper overviews recent developments in molten-metal catalysts for methane cracking and hydrogen production. It thoroughly examines the stability of reactors, carbon products, and catalysts for each molten-metal system. The kinetics and mechanism of the catalysts in each system have also been analyzed. Finally, for future development, several recommendations for hydrogen production via methane cracking have been proposed, addressing the following research challenges: (1) gaining a deeper understanding of the active sites and methane conversion process, which can provide crucial guidance for designing high-performance catalysts; (2) fostering the advancement of new reaction interfaces; and (3) attempting to develop a low-eutectic-point molten salt system for chemical vapor deposition reactions. The molten-metal catalyst exhibits strong resistance to carbon encapsulation and deactivation due to its unique physical and chemical properties, demonstrating excellent catalytic activity and stability.

To explore the iron coke application in hydrogen-rich blast furnace, which is an effective method to achieve the purpose of low carbon emissions, the initial gasification temperature of iron coke in CO 2 and H 2 O atmosphere and its cogasification reaction mechanism with coke were systematically studied. Iron coke was prepared under laboratory conditions, with a 0–7wt% iron ore powder addition. The properties of iron cokes were tested by coke reactivity index (CRI) and coke strength after reaction (CSR), and their phases and morphology were evolution discussed by scanning electron microscopy and X-ray diffraction analysis. The results indicated that the initial gasification temperature of iron coke decreased with the increase in the iron ore powder content under the CO 2 and H 2 O (g) atmosphere. In the 40vol% H 2 O + 60vol% CO 2 atmosphere, CRI of iron coke with the addition of 3wt% iron ore powder reached 58.7%, and its CSR reached 56.5%. Because of the catalytic action of iron, the reaction capacity of iron coke was greater than that of coke. As iron coke was preferentially gasified, the CRI and CSR of coke were reduced and increased, respectively, when iron coke and coke were cogasified. The results showed that the skeleton function of the coke can be protected by iron coke.

Titanium has excellent all-round performance, but the high cost of its production limits its widespread use. Currently, the Kroll process used to commercially produce titanium sponge is inefficient, energy-intensive, and highly polluting to the environment. Over the past few decades, many new processes have been developed to replace the Kroll process in order to reduce the cost of producing titanium and make it a common metal with as many applications as iron. These new processes can be divided into two categories: thermal reduction and electrolysis. Based on their classification, this paper reviews the current development status of various processes and analyzes the advantages and disadvantages of each process. Finally, the development direction and challenges of titanium production process are put forward.

Molten salt electrodeposition of crystalline silicon (Si) films from silicon dioxide (SiO2) in molten calcium chloride (CaCl2)-calcium oxide (CaO) has been systematically investigated. The dissolution-electrodeposition mechanism was studied by cyclic voltammetry (CV), in situ X-ray diffraction (XRD), and in situ Raman spectroscopy. The results show that different silicate ions, including SiO32−, SiO44−, would be generated in molten salt and could be influenced by the molar ratios of additive SiO2 and CaO, as well as the electrolytic parameters. In particular, with the increase of electrodeposition time, SiO44− increased as the dominated silicate ions in molten salt. Furthermore, different current densities, time and substrates would also have vital influences on the electrodeposition process and the electrodeposited Si products. Si products with tunable morphology have been deposited on different substrates by adjusting the electrodeposition conditions. The deposited crystalline Si films exhibit homogeneous epitaxial structures, in particular, the epitaxial Si film grown on the 110-oriented Si wafer possesses uniform inverted pyramid structure. The ohmic resistivity test and microstructure analysis results show that the electrodeposited epitaxial crystalline Si films have the similar properties and characteristics as their single crystal Si wafer substrates. In general, the investigation of the dissolution-electrodeposition mechanism and its epitaxial growth behavior helps the progress of this one-step CaO-assisted dissolution-electrodeposition process for the production of epitaxial Si films.

Stainless-steel pickling sludge (SSPS) and blast-furnace bag dust (BFBD) contain heavy metals such as Ni and Cr, which are harmful to the environment. A new approach of “using waste to treat waste” is proposed, and the process of using a direct reduction method to synergistically desulfurize and extract Zn from SSPS and BFBD to prepare metalized pellets is investigated. The results show that in the reduction roasting, the Fe, Ni, and Cr oxides can be reduced to metals and exist in the form of alloy phases; the metallization rate was 87.9 pct. ZnFe2O4 can also be reduced to Zn(g) at about 1000 °C and recycled in the flue gas, and the Zn extraction rate was 99.81 pct. Moreover, S was removed in the form of SO2 flue gas, and the desulfurization rate was 45.46 pct; the remaining S was present in the form of CaS, which could be removed in the subsequent blast-furnace smelting process, reducing the SO2 flue-gas pressure during the reduction roasting process. CaF2 was relatively stable and mainly exists in the slag phase. The metalized pellets satisfy the requirements for a blast-furnace charge entering the furnace and can realize efficient resource utilization of SSPS and BFBD.