Fabrication of van der Waals Heterostructured FePSe3/Carbon Hybrid Nanosheets for Sodium Storage with High Performance

Se-Regulated MnS Porous Nanocubes Encapsulated in Carbon Nanofibers as High-Performance Anode for Sodium-Ion Batteries

Manganese-based chalcogenides have significant potential as anodes for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, abundant natural reserves, and environmental friendliness. However, their application is hindered by poor cycling stability, resulting from severe volume changes during cycling and slow reaction kinetics due to their complex crystal structure. Here, an efficient and straightforward strategy was employed to in-situ encapsulate single-phase porous nanocubic MnS0.5Se0.5 into carbon nanofibers using electrospinning and the hard template method, thus forming a necklace-like porous MnS0.5Se0.5-carbon nanofiber composite (MnS0.5Se0.5@N-CNF). The introduction of Se significantly impacts both the composition and microstructure of MnS0.5Se0.5, including lattice distortion that generates additional defects, optimization of chemical bonds, and a nano-spatially confined design. In situ/ex-situ characterization and density functional theory calculations verified that this MnS0.5Se0.5@N-CNF alleviates the volume expansion and facilitates the transfer of Na+/electron. As expected, MnS0.5Se0.5@N-CNF anode demonstrates excellent sodium storage performance, characterized by high initial Coulombic efficiency (90.8%), high-rate capability (370.5 mAh g-1 at 10 A g-1) and long durability (over 5000 cycles at 5 A g-1). The MnS0.5Se0.5@N-CNF //NVP@C full cell, assembled with MnS0.5Se0.5@N-CNF as anode and Na3V2(PO4)3@C as cathode, exhibits a high energy density of 254 Wh kg-1 can be provided. This work presents a novel strategy to optimize the design of anode materials through structural engineering and Se substitution, while also elucidating the underlying reaction mechanisms.

Long-Lasting Lithium-Ion Batteries Enabled by Advanced Anode Design of a Hydrangea-like FeP/SnP@C Heterostructure

Transition metal phosphide (TMP)-based anode materials for lithium-ion batteries (LIBs) have garnered significant attention due to their high theoretical specific capacity and cost-effectiveness, yet they suffer from volume changes and pulverization during cycling. Herein, an advanced heterostructural FeP/SnP@C material was synthesized and applied as the anode material for tackling the key issues. The FeP/SnP@C composite comprises ultrathin nanosheets arranged in a hydrangea-like morphology, boasting a substantial specific surface area toward electrolyte penetration. Moreover, the heterogeneous interface between FeP and SnP creates a self-generated electric field, thereby improving electrochemical reaction kinetics and furnishing additional active sites for lithium storage performance. Electrochemical measurements reveal an initial discharge specific capacity of 1140.7 mAh g-1 at a current density of 0.2 A g-1, which remains at 756.1 mAh g-1 after 200 cycles. Even at a high current density of 2 A g-1, the electrode material exhibits a reversible specific capacity of 284.2 mAh g-1 after 1000 cycles, showcasing its excellent long-life cyclic stability. When assembled into full cells with commercial LiFePO4, FeP/SnP@C shows high discharge capacity and exceptional cyclic stability with a high value of 101.2 mAh g-1 after 100 cycles. This work provides new insights for rational design of TMP-based anodes for advanced LIBs.

Hierarchical Architecture Engineering of Branch-Leaf-Shaped Cobalt Phosphosulfide Quantum Dots: Enabling Multi-Dimensional Ion-Transport Channels for High-Efficiency Sodium Storage

New-fashioned electrode hosts for sodium-ion batteries (SIBs) are elaborately engineered to involve multifunctional active components that can synergistically conquer the critical issues of severe volume deformation and sluggish reaction kinetics of electrodes toward immensely enhanced battery performance. Herein, it is first reported that single-phase CoPS, a new metal phosphosulfide for SIBs, in the form of quantum dots, is successfully introduced into a leaf-shaped conductive carbon nanosheet, which can be further in situ anchored on a 3D interconnected branch-like N-doped carbon nanofiber (N-CNF) to construct a hierarchical branch-leaf-shaped CoPS@C@N-CNF architecture. Both double carbon decorations and ultrafine crystal of the CoPS in-this exquisite architecture hold many significant superiorities, such as favorable train-relaxation, fast interfacial ion-migration, multi-directional migration pathways, and sufficiently exposed Na+ -storage sites. In consequence, the CoPS@C@N-CNF affords remarkable long-cycle durability over 10 000 cycles at 20.0 A g-1 and superior rate capability. Meanwhile, the CoPS@C@N-CNF-based sodium-ion full cell renders the potential proof-of-feasibility for practical applications in consideration of its high durability over a long-term cyclic lifespan with remarkable reversible capacity. Moreover, the phase transformation mechanism of the CoPS@C@N-CNF and fundamental springhead of the enhanced performance are disclosed by in situ X-ray diffraction, ex situ high-resolution TEM, and theoretical calculations.

Metal Phosphorous Chalcogenide: A Promising Material for Advanced Energy Storage Systems

The development of efficient and affordable electrode materials is crucial for clean energy storage systems, which are considered a promising strategy for addressing energy crises and environmental issues. Metal phosphorous chalcogenides (MPX3 ) are a fascinating class of two-dimensional materials with a tunable layered structure and high ion conductivity, making them particularly attractive for energy storage applications. This review article aims to comprehensively summarize the latest research progress on MPX3 materials, with a focus on their preparation methods and modulation strategies. Additionally, the diverse applications of these novel materials in alkali metal ion batteries, metal-air batteries, and all-solid-state batteries are highlighted. Finally, the challenges and opportunities of MPX3 materials are presented to inspire their better potential in energy storage applications. This review provides valuable insights into the promising future of MPX3 materials in clean energy storage systems.

A novel exfoliated manganese phosphoselenide as a high-performance anode material for lithium ions storage

Layered manganese phosphoselenide (MnPSe3) is expected to be a potential anode for Li ions storage due to it combines the merits of phosphorus with metal selenide. It promotes charge transfer and ensures a high theoretical capacity of up to 746 mA h g−1. In this work, a comprehensive study clearly demonstrated that bulk MnPSe3 electrode is the inability to maintain the integrity of the structure with severe detectable fracture or pulverization after full lithiation/delithiation, resulting in poor rate capability and cycling stability. Additionally, exfoliated few-layered MnPSe3 nanoflakes by the ultrasonic method show enhanced electrical conductivity and resistance to volume expansion. It has a high initial discharge/charge capacity reaching to 524/796 mA h g−1 and outstanding cycling stability with charge capacities of 709 mA h g−1 after 100 cycles at 0.2 A g−1 within the potential window of 0.005–3 V vs. Li+/Li. While further improving the cycles, the retention rate was still held at ∼72% after 350 cycles. This work provides new insights into exploiting new novel layered materials, such as MnPSe3 as anodes for lithium-ion batteries.

Achieving Ultrahigh-Rate and Low-Temperature Sodium Storage of FePS3 via In Situ Construction of Graphitized Porous N-Doped Carbon

Sodium-ion batteries (SIBs) have become an important supplementation to lithium-ion batteries. Unfortunately, the low capacity and inferior low-temperature performance of traditional hard carbon led to limited energy density and a range of applications of SIBs. Herein, we present high-performance SIBs via embedding FePS₃ in graphitized porous N-doped carbon (FPS/GPNC) using coordination polymerization reaction. Such unique graphitized pores are in situ-constructed by the self-aggregation of Fe nanoparticles with high surface energy at high temperatures, which affords a three-dimensional open channel and a graphitized conductive network for fast transportation of Na⁺ and electrons. Moreover, an ingenious buffer barrier composed of graphitized pores is constructed for FePS₃ to withstand volume fluctuation during cycling. Consequently, a superior capacity of 354.2 mAh g^-1 is delivered even when the rate increases to 50 A g^-1. The impressing cycling lifespan up to 4700 cycles is achieved at 30 A g^-1 with excellent retention of 84.4%. Interestingly, the low-temperature performance (-20 °C) of FePS₃ is explored for the first time, and excellent stability (502.6 mAh g^-1 maintained after 100 cycles at 0.1 A g^-1) is obtained, indicating huge potential of practical application. This work provides insights into designing high-rate, high-capacity, and low-temperature SIBs.

Ultrahigh Rate and Ultralong Life Span Sodium Storage of FePS3 Enabled by the Space Confinement Effect of Layered Expanded Graphite

Metal phosphorus trichalcogenides have been regarded as promising high-capacity anode materials for sodium-ion batteries (SIBs) owing to their high reversible capacity. Nevertheless, their practical application is plagued by poor diffusion kinetics and dramatic volume fluctuations during the charge-discharge process, resulting in no satisfactory rate and life span so far. Herein, we propose a space-confinement strategy to remarkably promote the cycling stability and rate capacity by embedding FePS₃ particles in the interlayer of expanded graphite (EG), which are derived from in situ transformation of graphite intercalation compounds. The layered EG not only greatly alleviates the volume fluctuations of FePS₃ by the space confinement effect so as to maintain the stability of the electrode microstructure, but it also ensures rapid Na⁺ and electron transfer during cycling. When acting as an anode for SIBs, the hybrid electrode delivers a highly reversible capacity of 312.5 mAh g^-1 at an ultrahigh rate of 50 A g^-1 while retaining an ultralong life span of 1300 cycles with a retention of 82.4% at 10 A g^-1. Moreover, the excellent performance of the assembled full battery indicates the practical application potential of FPS/EG.

In Situ Nitrogen Retention of Carbon Anode for Enhancing the Electrochemical Performance for Sodium-Ion Battery

Retaining nitrogen for polyacrylonitrile (PAN) based carbon anode is a cost-effective way to make full use of the advantages of PAN for sodium-ion batteries (SIBs). Here, a simple strategy has been successfully adopted to retain N atoms in situ and increase production yield of a novel composite PAZ by mixing 3 wt % of zinc borate (ZB) with poly (acrylonitrile-co-itaconic acid) (PANIA). Among the prepared carbonised fibre (CF) samples, PAZ-CF-700 maintains the highest N content, retaining 90 % of the original N from PANIA. It represents the highest capacity storage contribution (80.55 %) and the lowest impedance R_ct (117 Ω). Consequently, the specific capacity increases from 60 mAh g^-1 of PANIA-CF-700 to 190 mAh g^-1 of PAZ-CF-700 at a current density of 100 mA g^-1 . At the same time, PAZ-CF-700 exhibits a good rate performance and excellent long-term cycling stability with a specific capacity of 94 mAh g^-1 after 4000 cycles at 1.6 A g^-1 .

Rock-Salt MnS0.5Se0.5 Nanocubes Assembled on N-Doped Graphene Forming van der Waals Heterostructured Hybrids as High-Performance Anode for Lithium- and Sodium-Ion Batteries

Manganese-based chalcogenides would be of latent capacity in serving as anodes for assembling lithium- and/or sodium-ion batteries (LIBs/SIBs) due to their large theoretical capacity, low price, and low-toxicity functionality, while the low electroconductivity and easy agglomeration behavior may impede their technical applications. Here, a solid-state solution of MnS_0.5Se_0.5 nanocubes in rock-salt phase has been synthesized for the first time at a relatively low temperature from the precursors of Mn(II) acetylacetonate with dibenzyl dichalcogens in oleylamine with octadecene, and the MnS_0.5Se_0.5 nanocubes have been assembled with N-doped graphene to form a new kind of heterostructured nanohybrids (shortened as MnS_0.5Se_0.5/N-G hybrids), which are very potential for the fabrication of metal-ion batteries including LIBs and/or SIBs. Investigations revealed that there have been dense vacancies generated and active sites increased via nonequilibrium alloying of MnS and MnSe into the solid-solution MnS_0.5Se_0.5 nanocubes with segregation and defects achieved in the low-temperature solution synthetic route. Meanwhile, the introduction of N-doped graphene forming heterojunction interfaces between MnS_0.5Se_0.5 and N-doped graphene would efficiently enhance their electroconductivity and avoid agglomeration of the active MnS_0.5Se_0.5 nanocubes with considerably improved electrochemical properties. As a result, the MnS_0.5Se_0.5/N-G hybrids delivered superior Li/Na storage capacities with outstanding rate performance as well as satisfactorily lasting stability (1039/457 mA h g^-1 at 0.1 A g^-1 for LIBs/SIBs). Additionally, full-cell LIBs of the anodic MnS_0.5Se_0.5/N-G constructed with cathodic LiFePO₄ (LFP) further confirmed the promising future for their practical application.

Design of 2D materials - MSi2CxN4-x (M = Cr, Mo, and W; x = 1 and 2) - with tunable electronic and magnetic properties

Two-dimensional (2D) materials have attracted increasing interest in the past decades due to their unique physical and chemical properties for diverse applications. In this work, we present a first-principles design on a novel 2D family, MSi₂C_xN_4-x (M = Cr, Mo, and W; x = 1 and 2), based on density-functional theory (DFT). We find that all MSi₂C_xN_4-x monolayers are stable by investigating their mechanic, dynamic, and thermodynamic properties. Interestingly, we see that the alignment of magnetic moments can be tuned to achieve non-magnetism (NM), ferromagnetism (FM), anti-ferromagnetism (AFM) or paramagnetism (PM) by arranging the positions of carbon atoms in the 2D systems. Accordingly, their electronic properties can be controlled to obtain semiconductor, half-metal, or metal. The FM states in half-metallic 2D systems are contributed to the hole-mediated double exchange, while the AFM states are induced by super-exchange. Our findings show that the physical properties of 2D systems can be tuned by compositional and structural engineering, especially the layer of C atoms, which may provide guidance on the design and fabrication of novel 2D materials with projected properties for multi-functional applications.

Co-Vacancy, Co1−xS@C flower-like nanosheets derived from MOFs for high current density cycle performance and stable sodium-ion storage

A non-stoichiometric cobalt–sulfur compound anode material with excellent electrochemical properties was prepared, and the first principles simulation described the effect of Co-vacancy on electrode reaction.