Rare Metals最新文献

Nickel-rich single-crystal cathode materials are considered optimal candidates for next-generation lithium-ion batteries (LIBs) due to their combination of high-energy density and crack-resistant, grain boundary-free structures. However, cyclic stress induces repetitive surface slip in single crystals, promoting the propagation of microcracks and exposing fresh crystal planes to the electrolyte. This accelerates interfacial reactions and corrosion, increasing charge transfer resistance and active material loss, ultimately degrading electrochemical performance. To address the slip-related issues in single-crystal materials, we have synthesized a single-crystal quaternary cathode: LiNi_0.8Co_0.08Mn_0.06Al_0.06O₂ (SC-NCMA), via a molten salt method. The effects of Al incorporation on suppressing lamellar slip and enhancing electrochemical performance are systematically investigated by comparing the characteristics of SC-NCMA and ternary SC-NCM. The experimental results show that SC-NCMA retains 83.0% of its capacity after 200 cycles (2.7–4.3 V), significantly higher than the 66.5% capacity retention observed for SC-NCM. In situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses reveal that Al incorporation expands the (003) layer spacing, suppresses Li⁺/Ni²⁺ mixing, and mitigates lattice distortion induced by the H2–H3 phase transition by reinforcing the Al–O bonds. Furthermore, Al³⁺ not only optimizes Li⁺ diffusion kinetics and reduces surface lattice oxygen loss but also facilitates the formation of a moderate-thickness cathode-electrolyte interphase (CEI) layer, enabling the pouch cell to achieve 89.1% capacity retention after 400 cycles. Overall, this work validates molten salt synthesis as a viable route for producing single-crystal quaternary cathodes and elucidates Al’s dual stabilization mechanism—through both crystal structure modulation and interfacial passivation—offering strategic insights into the development of advanced nickel-rich cathode systems.

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Transition metal fluorides hold promise for high-energy lithium-ion batteries but suffer from irreversible regeneration and sluggish kinetics. Here, an amorphous composite cathode strategy to overcome these limitations is proposed. In the fabricated amorphous LiF–Co–Mo (a-LCM) composite cathodes, LiF nanoclusters are embedded in a disordered Co/Mo matrix. This unique Schottky heterojunction enables reversible order–disorder transitions during cycling, bypassing crystalline lattice constraints. The a-LCM cathode delivers an initial discharge capacity of 602 mAh g⁻¹ with 75% retention after 100 cycles, achieving a high energy density of 918 Wh kg⁻¹ and energy efficiency of 70.6%. Structural analyses reveal surface-dominated conversion mechanisms, where the amorphous matrix promotes LiF regeneration while suppressing bulk degradation. Unlike conventional composites requiring excessive conductive additives, the additive-free a-LCM leverages intrinsic metallic conductivity and interfacial Li⁺ transport pathways. This work establishes amorphous engineering as a transformative approach to reconcile energy density and cyclability in conversion-type cathodes, offering new design principles for high-performance fluoride-based lithium-ion batteries.

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The global energy crisis and the growing demand for sustainable energy sources have driven considerable interest in green hydrogen production via water electrolysis. Among non-noble metal catalysts, nickel-based materials have emerged as promising candidates for the hydrogen evolution reaction (HER) in alkaline media, owing to their natural abundance and intrinsic catalytic activity. However, their practical application remains hindered by poor stability under high current densities, challenges in regulating active site distribution, and obstacles to large-scale implementation. This review systematically explores the fundamental principles of alkaline water electrolysis (AWE) and alkaline anion exchange membrane water electrolysis (AEMWE), critically assesses the key barriers to commercialization of nickel-based catalysts, and discusses targeted modification strategies for high-current operation. Emphasis is placed on approaches such as electronic structure modulation, stabilization of active sites, optimization of mass transport, and mitigation of catalyst degradation. Finally, future perspectives are proposed to guide the rational design of durable nickel-based electrocatalysts and promote their integration into industrial-scale alkaline electrolyzers.

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Promising energy storage devices, lithium-ion capacitors (LICs), integrate the high energy density characteristic of lithium-ion batteries with the superior power density found in supercapacitors. A key challenge impeding their practical deployment, however, is the kinetic disparity between the cathode’s rapid charge acceptance and the anode’s sluggish reaction rates. Herein, we present a cost-effective strategy to address this limitation through the rational design of pitch-derived soft carbon anodes. By precisely controlling the carbonization process of pitch, the pitch-based soft carbon material (PC800) synthesized at a carbonization temperature of 800 °C exhibits a unique hybrid structure consisting of an amorphous carbon matrix embedded with graphitic nanodomains. This hierarchical structure not only provides abundant active sites and efficient ion diffusion pathways, but also ensures rapid electron transport, thereby enabling excellent rate capability. The PC800 electrode delivers a remarkable reversible capacity of 319.2 mAh g⁻¹ at 0.1 A g⁻¹ and maintains 131.6 mAh g⁻¹ even at 5 A g⁻¹. When assembled into a full-cell LIC with activated carbon cathode, the device achieves a high energy density of 159.4 Wh kg⁻¹ at 246.7 W kg⁻¹ and retains 42.8 Wh kg⁻¹ under a high power density of 11 kW kg⁻¹ (based on the total mass of active materials). Notably, the scaled-up production of PC800 demonstrates excellent structural stability and electrochemical consistency in pouch-type LICs, achieving an energy density of 30 Wh kg⁻¹ based on the overall device mass. This work highlights the feasibility of transforming low-cost pitch precursors into high-performance carbon anodes through structural engineering, thereby enabling the industrial development of advanced LICs with balanced energy and power characteristics.

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Two-dimensional (2D) layered materials have attracted considerable research attention due to their exceptional electronic and optical properties. Among these emerging materials, a novel 2D fullerene (C₆₀) network-composed of C₆₀ structural units has gained prominence, exhibiting remarkable characteristics that arise from its unique conjugated carbon structure. Despite the increasing interest in 2D fullerene networks, there is a notable lack of comprehensive reviews since the groundbreaking synthesis of these materials in 2022. This review intends to fill this gap by offering a thorough analysis of the recent advancements in the study of the 2D fullerene network, encompassing the synthesis methods, theoretical investigations revealing the physical properties and potential applications, as well as versatile applications ranging from photo-electrochemical catalysis to organic solvent separation. By providing a thorough overview of the current state of research on 2D fullerene networks, this review aims to equip researchers with a valuable resource, enabling them to further investigate the vast potential of this innovative material.

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Exploring high-performance electrode materials are indispensable for the commercialization of potassium-ion batteries (PIBs). Nickel thiophosphate (NPS), a representative ternary metal thiophosphate, holds great promise as an anode due to its high theoretical capacity and distinctive layered structure, yet still facing critical challenges such as rapid capacity decay and sluggish rate performance. Herein, we developed a flexible, self-supporting composite film anode by integrating high-purity NPS nanosheets within a three-dimensional (3D) conductive scaffold composed of nitrogen-doped graphene (NG) and single-wall carbon nanotube (SWNT) via simple vacuum filtration method. The resulting hybrid film features abundant heterointerfaces, which enhance electron/ion transport, accommodate volume changes, and stabilize the electrode structure. As a result, the anode delivers high potassium storage capacity of 643.5 mAh g⁻¹ at 0.1 A g⁻¹ and maintains 163.9 mAh g⁻¹ at 10 A g⁻¹, showcasing excellent rate performance. Full cell assemblies exhibit stable cycling performance with a reversible capacity of 207.8 mAh g⁻¹ after 100 cycles. Combined crystallography and valence state analyses reveal a disordered phase transition in crystalline NPS during potassiation, indicating a dual mechanism involving both conversion and alloying reactions. This study offers valuable insights into the rational design of advanced anode materials for next-generation PIBs.

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This work presents a novel approach to enhance the specific energy of supercapacitors by developing Bi₂O₃/Mn₃O₄/Mn₂AlO₄(O_V)/rGO multiphase oxygen vacancy heterostructures via dealloying and hydrothermal self-growth strategy. The synergy between reduced graphene oxide (rGO) heterostructures and oxygen vacancy defects generates an internal polarized electric field that accelerates ion transport and enhances electrochemical response through an interconnected conductive network. This innovation extends the operating voltage from 0.6 to 0.8 V, significantly improving material energy storage. An asymmetric supercapacitor assembled with Bi₂O₃/Mn₃O₄/Mn₂AlO₄(O_V)/rGO//rGO delivers a specific energy of 333 Wh kg⁻¹ and a specific power of 6.3 kW kg⁻¹ at a cell voltage of 4.9 V. At the highest specific power (31 kW kg⁻¹), the specific energy remains at 204 Wh kg⁻¹. Density functional theory (DFT) simulations further validate that the synergy of oxygen vacancies and heterostructures enhances conductivity, narrows the bandgap, and improves surface properties, unveiling novel theoretical perspectives on ion transport dynamics within oxygen vacancy heterostructures.

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Tin–air batteries (TABs) exhibit high safety and low cost, and are expected to be used in electric vehicles and portable electronic devices. However, challenges such as the irregular deposition of tin (Sn) particles on Sn anodes, surface passivation, and significant hydrogen evolution have hindered the development of high-performance TABs. To address these challenges, this study introduces quasi-solid TABs (QSTABs) with satisfactory high-temperature resistance. A conductive metal–organic framework (c-MOF), particularly Ni₃(HITP)₂, was synthesized and deposited onto the Sn anode surface. The porous structure of c-MOF increased the specific surface area of the Sn anode, improved electronic conductivity and facilitated the absorption and release of ions during charge and discharge cycling. Theoretical calculations revealed that Ni₃(HITP)₂ provided more electron donor sites to coordinate with Sn²⁺ and inhibited hydrogen release. Additionally, carboxymethyl cellulose (CMC) was incorporated into the organic gel polymer electrolytes (OGPEs) to significantly enhance their water retention, ensuring stable operation of QSTABs between 25 and 50 °C. Notably, QSTABs assembled with CMC-OGPE/Sn@Ni₃(HITP)₂ exhibited a fine cycle life of over 200 cycles at 50 °C. The electronic c-MOF material effectively inhibited metal shedding and side reactions on the Sn anode. These findings provide valuable guidance for developing QSTABs with high-temperature resistance.

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Yolk–shell structures, defined by their core@void@shell architecture, have garnered considerable interest due to their tunable physical and chemical properties, which make them suitable for applications in nanoreactors, drug delivery, energy storage, biosensing, and surface-enhanced Raman scattering. However, conventional synthesis techniques, such as templating and non-templating liquid-phase methods, are often labor-intensive, time-consuming, and challenging to scale. Recently, spray pyrolysis has gained attention as a rapid, one-pot, and continuous synthesis method offering high scalability and production efficiency. This study presents a novel strategy for synthesizing uniform yolk–shell microspheres via spray pyrolysis, augmented by in situ polymerization and the addition of a drying control agent. By systematically varying carbon sources, including citric acid, ethylene glycol, sucrose, and polyvinylpyrrolidone, their influence on particle size distribution and yolk–shell formation were investigated. A novel formation mechanism involving metal–metal oxide–carbon intermediates was proposed to explain the observed morphologies. This approach led to enhanced spherical uniformity and structural consistency, supported by the use of drying control agents. As a case study, nickel oxide yolk–shell particles were synthesized and subsequently converted into nickel sulfide@C microspheres, which exhibited promising performances as anode materials in potassium-ion batteries. Overall, this method provides a scalable, efficient, and versatile route for fabricating yolk–shell structures with customizable features for advanced technological applications.

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Lithium-sulfur batteries are one of the most promising next-generation energy storage systems, while their real application is largely limited by the shuttle effect of lithium polysulfides (LiPSs). Herein, an interlayer based on a heterostructure consisting of MXene and two-dimensional montmorillonite (MXene@MMT) is developed via an electrostatic self-assembly strategy. Such a heterostructure possesses strong adsorption ability for LiPSs and can accelerate the conversion reaction from liquid LiPSs to solid Li₂S in virtue of its strong adsorption, high conductivity, and good catalytic activity. Furthermore, this heterostructure not only effectively blocks the migration of polysulfides, but also provides low energy barrier and rich pathways for Li⁺ transport. Ultimately, the as-assembled Li–S batteries with the MXene@MMT based interlayer deliver a high initial discharge capacity of 1375.5 mAh g⁻¹ at 0.1C and long-term cycling stability with 500 mAh g⁻¹ remaining over 500 cycles under a high rate of 2C. In a practical demonstration, the as-sembled soft pack battery achieved an initial discharge capacity of 733 mAh g⁻¹ at 0.1C and still retained a high capacity of 402 mAh g⁻¹ after 100 cycles.

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A heterostructure in which two-dimensional (2D) montmorillonite (MMT) nanosheets uniformly inserted between MXene layers is developed. Such a heterostructure possesses strong adsorption ability for polysulfides and rich catalytic sites for the polysulfide conversion, as well as provides low energy barrier and rich pathways for lithium ion transport, which finally enhances the electrochemical reaction kinetics and help realize high-performance lithium-sulfur batteries.