Alloy-Based Anode Materials toward Advanced Sodium-Ion Batteries

Data-Driven Theoretical Design of Anion Cluster-Based Sodium Antiperovskite Superionic Conductors

Sodium antiperovskite materials (APs) are a promising class of solid-state electrolytes owing to their high structural tolerance and good formability. However, few APs have been synthesized experimentally, indicating the necessity of exploring potential chemical spaces with higher ionic conductivities. Herein, through a combined particle swarm optimization algorithm, high-throughput first-principles calculations, ab initio molecular dynamics, and long time-scale machine-learning molecular dynamics simulations, strategies based on site-exchanging and anion clusters are shown to simultaneously enhance the thermal stability and sodium diffusivity in the designed APs. Among these APs, the highest theoretical ionic conductivity of 39.05 mS/cm is achieved with Na3BrSO4 at room temperature due to the strong coupling of cluster rotation and sodium migration. We highlight that not only the rotation dynamics but also its coupling with Na diffusion contribute to the high ionic conductivity, as confirmed by the proposed local difference frequency center to evaluate the coupling degree. Our work designs promising site-exchanging APs and offers insights into the coupling between anion rotation and cation migration, which can effectively guide the design of superionic conductors with cluster rotation dynamics.

Recent Advances in Developing High-Performance Anode for Potassium-Ion Batteries based on Nitrogen-Doped Carbon Materials

Owing to the low potential (vs K/K+), good cycling stability, and sustainability, carbon-based materials stand out as one of the optimal anode materials for potassium-ion batteries (PIBs). However, achieving high-rate performance and excellent capacity with the current carbon-based materials is challenging because of the sluggish reaction kinetics and the low capacity of carbon-based anodes. The doping of nitrogen proves to be an effective way to improve the rate performance and capacity of carbon-based materials as PIB anode. However, a review article is lacking in systematically summarizing the features and functions of nitrogen doping types. In this sense, it is necessary to provide a fundamental understanding of doped nitrogen types in nitrogen-doped(N-doped) carbon materials. The types, functions, and applications of nitrogen-doped carbon-based materials are overviewed in this review. Then, the recent advances in the synthesis, properties, and applications of N-doped carbon as both active and modification materials for PIBs anode are summarized. Finally, doped nitrogen's main features and functions are concluded, and critical perspectives for future research in this field are outlined.

Sulfide electrolytes for all-solid-state sodium batteries: fundamentals and modification strategies

Sulfide solid-state electrolytes (SSSEs) have garnered overwhelming attention as promising candidates for high-energy-density all-solid-state sodium batteries (ASSSBs) due to their high room-temperature ionic conductivity and excellent mechanical properties. However, the poor chemical/electrochemical stability, narrow electrochemical windows, and limited adaptability to cathodes/anodes of SSSEs hinder the performance and application of SSSEs in ASSSBs. Consequently, a comprehensive understanding of the preparation methods, fundamental properties, modification techniques, and compatibility strategies between SSSEs and electrodes is crucial for the advancement of SSSE-based ASSSBs. This review summarizes the SSSEs based on their compositional makeup and crystal structure, aiming to elucidate the Na+ conduction mechanisms. It also provides an overview of modification strategies designed to enhance ionic conductivity, chemical/electrochemical stability, and interfacial compatibility with electrodes. Furthermore, we outline the challenges and strategies related to the interfaces of SSSEs with cathodes/anodes. Finally, we discuss the existing challenges facing SSSEs and propose the future research directions for SSSE-based ASSSBs.

Self-Template Construction of Hierarchical Bi@C Microspheres as Competitive Wide Temperature-Operating Anodes for Superior Sodium-Ion Batteries

Huge volume changes of bismuth (Bi) anode leading to rapid capacity hindered its practical application in sodium-ion batteries (SIBs). Herein, porous Bi@C (P-Bi@C) microspheres consisting of self-assembled Bi nanosheets and carbon shells were constructed via a hydrothermal method combined with a carbothermic reduction. The optimized P-Bi@C-700 (annealed at 700 °C) demonstrates 359.8 mAh g-1 after 1500 cycles at 1 A g-1. In situ/ex situ characterization and density functional theory calculations verified that this P-Bi@C-700 relieves the volume expansion, facilitates Na+/electron transport, and possesses an alloying-type storage mechanism. Notably, P-Bi@C-700 also achieved 360.8 and 370.3 mAh g-1 at 0.05 A g-1 under 0 and 60 °C conditions, respectively. Na3V2(PO4)3//P-Bi@C-700 exhibits a capacity of 359.7 mAh g-1 after 260 cycles at 1 A g-1. These hierarchical microspheres effectively moderate the volume fluctuation, preserving structural reversibility, thereby achieving superior Na+ storage performance. This self-template strategy provides insight into designing high-volumetric capacity alloy-based anodes for SIBs.

Natural Pitch-Derived Carbon Networks Induced Lattice Strain Engineering in Nickel-Based Heterostructures Enables Efficient Anodes for Sodium-Ion Batteries

The development of high-performance sodium-ion batteries (SIBs) relies on enhancing the electrochemical properties of the electrodes, particularly the transition metal compounds (TMCs) through effective carbon coatings. Herein, a straightforward approach using polymerized natural pitch-derived carbon (PNPC) via step-growth polymerization regulates the lattice strain in Ni3S2-NiO heterostructures (NSNO) on nickel foam (NF). This method replaces the complex multistep carbon coatings with a cost-effective liquid-phase application of PNPC, followed by pyrolysis to create PNPC@NSNO/NF. Comparative analysis shows that PNPC effectively modulates lattice strain, achieving 3.50% tensile strain compared to 5.60% for non-polymerized carbon. The optimized PNPC@NSNO/NF electrode exhibits exceptional high areal capacity of 2.72 mAh cm-2@1 mA cm-2, impressive rate capability, and 97.28% capacity retention after 200 cycles. The enhanced contact area and electrical conductivity provided by the PNPC improve charge transfer kinetics and overall performance. Theoretical analyses confirm that the PNPC@NSNO/NF electrode with 3.50% lattice strain lowers the Na⁺ diffusion barrier, enhances charge transfer, and improves charge distribution, boosting the electrode performance. This work establishes a straightforward method for synthesizing lattice-strained SIB anodes, highlighting its potential for advancing SIB technology.

Exploration of electrochemical behavior of Sb-based porous carbon composites anode for sodium-ion batteries

Sb-based materials are considered as promising anode materials for sodium-ion batteries (SIBs) due to their excellent sodium storage capacities and suitable potentials. However, the Sb-based anodes usually suffer from intense volume expansion and severe pulverization during the alloying-dealloying process, resulting in poor cycling performance. Herein, a composite anode with Sb/Sb2O3 nanoparticles embedded in N-doped porous carbon is prepared by the gas-solid dual template method. The volume change of the anode material is mitigated by the carbon layer enwrapping and the confinement of the porous structure. Nitrogen doping provides abundant sodium storage sites, thus enhancing the storage capacity of sodium ion. Furthermore, to gain the accurate kinetic interpretation of the electrochemical process, an ex-situ transmission electron microscope (TEM) characterization combined with distribution of relaxation times (DRT) is conducted. The Sb/Sb2O3@NPC-1.0 demonstrates excellent electrochemical performance, achieving 340.3 mAh g-1 at 1A g-1, and maintains a capacity of 86.7 % after 1000 cycles. This work paves the way for the practical application of SIBs with high-performance and long-life Sb-based anodes.

Co-sputtering strategy to construct robust sodiophilic interfaces for anode-less sodium metal batteries

A copper-bismuth composite coating was fabricated by a facile co-sputtering strategy to enhance the sodiophilicity and structural stability of the substrate. The composite coating with lower bismuth content can maintain the sodiophilicity and form a thin and dense SEI during cycling, thus improving the reversibility of the anode-less sodium metal batteries.

Pb nanospheres encapsulated in metal-organic frameworks-derived porous carbon as anode for high-performance sodium-ion batteries

Alloying-type anode materials are considered promising candidates for sodium-ion batteries (SIBs) due to their high theoretical capacities. However, their application is limited by the severe capacity decay stemming from dramatic volume changes during Na+ insertion/extraction processes. Here, Pb nanospheres encapsulated in a carbon skeleton (Pb@C) were successfully synthesized via a facile metal-organic frameworks (MOFs)-derived method and used as anodes for SIBs. The nanosized Pb particles are uniformly incorporated into the porous carbon framework, effectively mitigating volume changes and enhancing Na+ ion transport during discharging/charging. Benefiting from this unique architecture, a reversible capacity of 334.2 mAh g-1 at 2 A g-1 is achieved after 6000 cycles corresponding to an impressive 88.2 % capacity retention and a minimal capacity loss of 0.00748 % per cycle. Furthermore, a high-performance full sodium-ion battery of Pb@C//NVPF was constructed, demonstrating a high energy density of 291 Wh kg-1 and power density of 175 W kg-1. This facile MOFs-derived method offers insights into the design of high-capacity alloy-type anode materials using Pb sources, opening up new possibilities for innovative approaches to Pb recycling and pollution prevention.

Constructing hierarchical MoS2/WS2 heterostructures in dual carbon layer for enhanced sodium ions batteries performance

The escalating global demand for clean energy has spurred substantial interest in sodium-ion batteries (SIBs) as a promising solution for large-scale energy storage systems. However, the insufficient reaction kinetics and considerable volume changes inherent to anode materials present significant hurdles to enhancing the electrochemical performance of SIBs. In this study, hierarchical MoS2/WS2 heterostructures were constructed into dual carbon layers (HC@MoS2/WS2@NC) and assessed their suitability as anodes for SIBs. The internal hard carbon core (HC) and outer nitrogen-doped carbon shell (NC) effectively anchor MoS2/WS2, thereby significantly improving its structural stability. Moreover, the conductive carbon components expedite electron transport during charge-discharge processes. Critically, the intelligently engineered interface between MoS2 and WS2 modulates the interfacial energy barrier and electric field distribution, promoting faster ion transport rates. Capitalizing on these advantageous features, the HC@MoS2/WS2@NC nanocomposite exhibits outstanding electrochemical performance when utilized as an anode in SIBs. Specifically, it delivers a high capacity of 415 mAh/g at a current density of 0.2 A/g after 100 cycles. At a larger current density of 2 A/g, it maintains a commendable capacity of 333 mAh/g even after 1000 cycles. Additionally, when integrated into a full battery configuration with a Na3V2(PO4)3 cathode, the Na3V2(PO4)3//HC@MoS2/WS2@NC full cell delivers a high capacity of 120 mAh/g after 300 cycles at 1 A/g. This work emphasizes the substantial improvement in battery performance that can be attained through the implementation of dual carbon confinement, offering a constructive approach to guide the design and development of next-generation anode materials for SIBs.

Challenges and Breakthroughs in Enhancing Temperature Tolerance of Sodium-Ion Batteries

Lithium-based batteries (LBBs) have been highly researched and recognized as a mature electrochemical energy storage (EES) system in recent years. However, their stability and effectiveness are primarily confined to room temperature conditions. At temperatures significantly below 0 °C or above 60 °C, LBBs experience substantial performance degradation. Under such challenging extreme contexts, sodium-ion batteries (SIBs) emerge as a promising complementary technology, distinguished by their fast dynamics at low-temperature regions and superior safety under elevated temperatures. Notably, developing SIBs suitable for wide-temperature usage still presents significant challenges, particularly for specific applications such as electric vehicles, renewable energy storage, and deep-space/polar explorations, which requires a thorough understanding of how SIBs perform under different temperature conditions. By reviewing the development of wide-temperature SIBs, the influence of temperature on the parameters related to battery performance, such as reaction constant, charge transfer resistance, etc., is systematically and comprehensively analyzed. The review emphasizes challenges encountered by SIBs in both low and high temperatures while exploring recent advancements in SIB materials, specifically focusing on strategies to enhance battery performance across diverse temperature ranges. Overall, insights gained from these studies will drive the development of SIBs that can handle the challenges posed by diverse and harsh climates.

Unleashing the Power of Sn2S3 Quantum Dots: Advancing Ultrafast and Ultrastable Sodium/Potassium-Ion Batteries with N, S Co-Doped Carbon Fiber Network

Tin sulfide (Sn2S3) has been recognized as a potential anode material for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to its high theoretical capacities. However, the sluggish ion diffusion kinetics, low conductivity, and severe volume changes during cycling have limited its practical application. In this study, Sn2S3 quantum dots (QDs) (≈1.6 nm) homogeneously embedded in an N, S co-doped carbon fiber network (Sn2S3-CFN) are successfully fabricated by sequential freeze-drying, carbonization, and sulfidation strategies. As anode materials, the Sn2S3-CFN delivers high reversible capacities and excellent rate capability (300.0 mAh g-1 at 10 A g-1 and 250.0 mAh g-1 at 20 A g-1 for SIBs; 165.3 mAh g-1 at 5 A g-1 and 100.0 mAh g-1 at 10 A g-1 for PIBs) and superior long-life cycling capability (279.6 mAh g-1 after 10 000 cycles at 5 A g-1 for SIBs; 166.3 mAh g-1 after 5 000 cycles at 2 A g-1 for PIBs). According to experimental analysis and theoretical calculations, the exceptional performance of the Sn2S3-CFN composite can be attributed to the synergistic effect of the conductive carbon fiber network and the Sn2S3 quantum dots, which contribute to the structural stability, reversible electrochemical reactions, and superior electron transportation and ions diffusion.

Bi Nanospheres Embedded in N-Doped Carbon Nanowires Facilitate Ultrafast and Ultrastable Sodium Storage

Sodium ion batteries (SIBs) are considered as the ideal candidates for the next generation of electrochemical energy storage devices. The major challenges of anode lie in poor cycling stability and the sluggish kinetics attributed to the inherent large Na+ size. In this work, Bi nanosphere encapsulated in N-doped carbon nanowires (Bi@N-C) is assembled by facile electrospinning and carbonization. N-doped carbon mitigates the structure stress/strain during alloying/dealloying, optimizes the ionic/electronic diffusion, and provides fast electron transfer and structural stability. Due to the excellent structure, Bi@N-C shows excellent Na storage performance in SIBs in terms of good cycling stability and rate capacity in half cells and full cells. The fundamental mechanism of the outstanding electrochemical performance of Bi@N-C has been demonstrated through synchrotron in-situ XRD, atomic force microscopy, ex-situ scanning electron microscopy (SEM) and density functional theory (DFT) calculation. Importantly, a deeper understanding of the underlying reasons of the performance improvement is elucidated, which is vital for providing the theoretical basis for application of SIBs.

Heterogeneous engineering and carbon confinement strategy to synergistically boost the sodium storage performance of transition metal selenides

Transition metal selenides (TMSs) stand out as a promising anode material for sodium-ion batteries (SIBs) owing to their natural resources and exceptional sodium storage capacity. Despite these advantages, their practical application faces challenges, such as poor electronic conductivity, sluggish reaction kinetics and severe agglomeration during electrochemical reactions, hindering their effective utilization. Herein, the dual-carbon-confined CoSe2/FeSe2@NC@C nanocubes with heterogeneous structure are synthesized using ZIF-67 as the template by ion exchange, resorcin-formaldehyde (RF) coating, and subsequent in situ carbonization and selenidation. The N-doped porous carbon promotes rapid electrolyte penetration and minimizes the agglomeration of active materials during charging and discharging, while the RF-derived carbon framework reduces the cycling stress and keeps the integrity of the material structure. More importantly, the built-in electric field at the heterogeneous boundary layer drives electron redistribution, optimizing the electronic structure and enhancing the reaction kinetics of the anode material. Based on this, the nanocubes of CoSe2/FeSe2@NC@C exhibits superb sodium storage performance, delivering a high discharge capacity of 512.6 mA h g-1 at 0.5 A g-1 after 150 cycles and giving a discharge capacity of 298.2 mA h g-1 at 10 A g-1 with a CE close to 100.0 % even after 1000 cycles. This study proposes a viable method to synthesize advanced anodes for SIBs by a synergy effect of heterogeneous interfacial engineering and a carbon confinement strategy.

Cobalt-Mediated Defect Engineering Endows High Reversible Amorphous VS4 Anode for Advanced Sodium-Ion Storage

Metal sulfides are promising anode materials for sodium-ion batteries (SIBs) due to their structural diversity and high theoretical capacity, but the severe capacity decay and inferior rate capability caused by poor structural stability and sluggish kinetics impede their practical applications. Herein, a cobalt-doped amorphous VS4 wrapped by reduced graphene oxide (i.e., Co0.5-VS4/rGO) is developed through a Co-induced defect engineering strategy to boost the kinetics performances. The as-prepared Co0.5-VS4/rGO demonstrates excellent rate capacities over 10 A g-1 and superior cycling stability at 5 A g-1 over 1600 cycles, which is attributed to the defects formed by Co doping, the formed amorphous structure and the robust rGO substrate. The great features of Co0.5-VS4/rGO anode are further confirmed in sodium-ion capacitors when the active carbon cathode is used. Additionally, the relationships between metal doping, the derived defects, the amorphous structure, and the sodium storage of VS4 are uncovered. This work provides deep insights into preparing amorphous functional materials and also probes the potential applications of metal sulfide-based electrode materials for advanced batteries.

Low-Surface-Area Nitrogen-Doped Carbon Submicrospheres as High-Coulombic-Efficiency and High-Capacity Anodes for Practical Sodium-Ion Batteries

Nitrogen-doped carbon submicrospheres (NCSMs) are synthesized via an efficient and environmentally friendly one-pot polymerization reaction at room temperature, in which dopamine hydrochloride serves as the source for both carbon and nitrogen. Through leverage of its distinctive structure characterized by minimal surface area, fewer oxygen-containing functional groups, and a heightened presence of active nitrogen-doping sites, the synthesized NCSM showcases a noteworthy initial Coulombic efficiency (ICE) of 84.8%, a remarkable sodium storage capacity of 384 mAh g-1, an impressive rate capability of 215 mAh g-1 at 10 A g-1, and a superior cyclic performance, maintaining 83.0% of its capacity after 2000 cycles. The submicron spherical structure, with its limited surface area and scarce oxygen-containing moieties, effectively curtails the irreversible sodium-ion loss in solid-electrolyte interphase film formation, resulting in heightened ICE. The abundant nitrogen doping can expand carbon-layer spacing as well as improve the electron/ion-transport dynamics, guaranteeing a high sodium storage capacity and a strong rate capability. Crucially, the synthesis method presented here is straightforward, effective, and amenable to scaling, offering a novel avenue for the commercialization of sodium-ion batteries.

MXene-based anode materials for high performance sodium-ion batteries

As an emerging class of layered transition metal carbides/nitrides/carbon-nitrides, MXenes have been one of the most investigated anode subcategories for sodium ion batteries (SIBs), due to their unique layered structure, metal-like conductivity, large specific surface area and tunable surface groups. In particular, different MAX precursors and synthetic routes will lead to MXenes with different structural and electrochemical properties, which actually gives MXenes unlimited scope for development. In this feature article, we systematically present the recent advances in the methods and synthetic routes of MXenes, together with their impact on the properties of MXenes and also the advantages and disadvantages. Subsequently, the sodium storage mechanisms of MXenes are summarized, as well as the recent research progress and strategies to improve the sodium storage performance. Finally, the main challenges currently facing MXenes and the opportunities in improving the performance of SIBs are pointed out.

Resolving the Origins of Superior Cycling Performance of Antimony Anode in Sodium-ion Batteries: A Comparison with Lithium-ion Batteries

Alloying-type antimony (Sb) with high theoretical capacity is a promising anode candidate for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Given the larger radius of Na+ (1.02 Å) than Li+ (0.76 Å), it was generally believed that the Sb anode would experience even worse capacity degradation in SIBs due to more substantial volumetric variations during cycling when compared to LIBs. However, the Sb anode in SIBs unexpectedly exhibited both better electrochemical and structural stability than in LIBs, and the mechanistic reasons that underlie this performance discrepancy remain undiscovered. Here, using substantial in situ transmission electron microscopy, X-ray diffraction, and Raman techniques complemented by theoretical simulations, we explicitly reveal that compared to the lithiation/delithiation process, sodiation/desodiation process of Sb anode displays a previously unexplored two-stage alloying/dealloying mechanism with polycrystalline and amorphous phases as the intermediates featuring improved resilience to mechanical damage, contributing to superior cycling stability in SIBs. Additionally, the better mechanical properties and weaker atomic interaction of Na-Sb alloys than Li-Sb alloys favor enabling mitigated mechanical stress, accounting for enhanced structural stability as unveiled by theoretical simulations. Our finding delineates the mechanistic origins of enhanced cycling stability of Sb anode in SIBs with potential implications for other large-volume-change electrode materials.

Interfacial-Confined Isochronous Conversion to Biphasic Selenide Heterostructure with Enhanced Adsorption Behaviors for Robust High-Rate Na-Ion Storage

Sodium-ion batteries (SIBs) have gradually become one of the most promising energy storage techniques in the current era of post-lithium-ion batteries. For anodes, transitional metal selenides (TMSe) based materials are welcomed choices , owing to relatively higher specific capacities and enriched redox active sites. Nevertheless, current bottlenecks are blamed for their poor intrinsic electronic conductivities, and uncontrollable volume expansion during redox reactions. Given that, an interfacial-confined isochronous conversion strategy is proposed, to prepare orthorhombic/cubic biphasic TMSe heterostructure, namely CuSe/Cu3 VSe4 , through using MXene as the precursor, followed by Cu/Se dual anchorage. As-designed biphasic TMSe heterostructure endows unique hierarchical structure, which contains adequate insertion sites and diffusion spacing for Na ions, besides, the surficial pseudocapacitive storage behaviors can be also proceeded like 2D MXene. By further investigation on electronic structure, the theoretical calculations indicate that biphasic CuSe/Cu3 VSe4 anode exhibits well-enhanced properties, with smaller bandgap and thus greatly improves intrinsic poor conductivities. In addition, the dual redox centers can enhance the electrochemical Na ions storage abilities. As a result, the as-designed biphasic TMSe anode can deliver a reversible specific capacity of 576.8 mAh g-1 at 0.1 A g-1 , favorable Na affinity, and reduced diffusion barriers. This work discloses a synchronous solution toward demerits in conductivities and lifespan, which is inspiring for TMSe-based anode development in SIBs systems.

Inorganic All-Solid-State Sodium Batteries: Electrolyte Designing and Interface Engineering

Inorganic all-solid-state sodium batteries (IASSSBs) are emerged as promising candidates to replace commercial lithium-ion batteries in large-scale energy storage systems due to their potential advantages, such as abundant raw materials, robust safety, low price, high-energy density, favorable reliability and stability. Inorganic sodium solid electrolytes (ISSEs) are an indispensable component of IASSSBs, gaining significant attention. Herein, this review begins by discussing the fundamentals of ISSEs, including their ionic conductivity, mechanical property, chemical and electrochemical stabilities. It then presents the crystal structures of advanced ISSEs (e.g., β/β''-alumina, NASICON, sulfides, complex hydride and halide electrolytes) and the related issues, along with corresponding modification strategies. The review also outlines effective approaches for forming intimate interfaces between ISSEs and working electrodes. Finally, current challenges and critical perspectives for the potential developments and possible directions to improve interfacial contacts for future practical applications of ISSEs are highlighted. This comprehensive review aims to advance the understanding and development of next-generation rechargeable IASSSBs.

Unleashing the Potential of MXene-Based Flexible Materials for High-Performance Energy Storage Devices

Since the initial discovery of Ti3 C2 a decade ago, there has been a significant surge of interest in 2D MXenes and MXene-based composites. This can be attributed to the remarkable intrinsic properties exhibited by MXenes, including metallic conductivity, abundant functional groups, unique layered microstructure, and the ability to control interlayer spacing. These properties contribute to the exceptional electrical and mechanical performance of MXenes, rendering them highly suitable for implementation as candidate materials in flexible and wearable energy storage devices. Recently, a substantial number of novel research has been dedicated to exploring MXene-based flexible materials with diverse functionalities and specifically designed structures, aiming to enhance the efficiency of energy storage systems. In this review, a comprehensive overview of the synthesis and fabrication strategies employed in the development of these diverse MXene-based materials is provided. Furthermore, an in-depth analysis of the energy storage applications exhibited by these innovative flexible materials, encompassing supercapacitors, Li-ion batteries, Li-S batteries, and other potential avenues, is conducted. In addition to presenting the current state of the field, the challenges encountered in the implementation of MXene-based flexible materials are also highlighted and insights are provided into future research directions and prospects.

2D MXenes Nanosheets for Advanced Energy Conversion and Storage Devices: Recent Advances and Future Prospects

Since the initial MXenes were discovered in 2011, several MXene compositions constructed using combinations of various transition metals have been developed. MXenes are ideal candidates for different applications in energy conversion and storage, because of their unique and interesting characteristics, which included good electrical conductivity, hydrophilicity, and simplicity of large-scale synthesis. Herein, we study the current developments in two-dimensional (2D) MXene nanosheets for energy storage and conversion technologies. First, we discuss the introduction to energy storage and conversion devices. Later, we emphasized on 2D MXenes and some specific properties of MXenes. Subsequently, research advances in MXene-based electrode materials for energy storage such as supercapacitors and rechargeable batteries is summarized. We provide the relevant energy storage processes, common challenges, and potential approaches to an acceptable solution for 2D MXene-based energy storage. In addition, recent advances for MXenes used in energy conversion devices like solar cells, fuel cells and catalysis is also summarized. Finally, the future prospective of growing MXene-based energy conversion and storage are highlighted.

Recent Advances in Laser-Induced Synthesis of MOF Derivatives

Metal-organic frameworks (MOFs) are crystalline materials with permanent pores constructed by the self-assembly of organic ligands and metal clusters through coordination bonds. Due to their diversity and tunability, MOFs are used as precursors to be converted into other types of functional materials by pyrolytic recrystallization. Laser-induced synthesis is proven to be a powerful pyrolytic processing technique with fast and accurate laser irradiation, low loss, high efficiency, selectivity, and programmability, which endow MOF derivatives with new features. Laser-induced MOF derivatives exhibit high versatility in multidisciplinary research fields. In this review, first, the basic principles of laser smelting and the types of materials for laser preparation of MOF derivatives are briefly introduced. Subsequently, it is focused on the peculiarity of the engineering of structural defects and their applications in catalysis, environmental protection, and energy fields. Finally, the challenges and opportunities at the current stage are highlighted with the aim of elucidating the future direction of the rapidly growing field of laser-induced synthesis of MOF derivatives.

A Universal Method for Regulating Carbon Microcrystalline Structure for High-Capacity Sodium Storage: Binding Energy As Descriptor

Sodium-ion batteries (SIBs) are attracting worldwide attention due to their multiple merits including abundant reserve and safety. However, industrialization is challenged by the scarcity of high-performance carbon anodes with high specific capacities. Here, we report the metal-assisted microcrystalline structure regulation of carbon materials to achieve high-capacity sodium storage. Systematic investigations of in situ thermal-treatment X-ray diffraction and multiple spectroscopies uncover the regulation mechanism of constructing steric hindrance (C-O-C bonds) to restrain the aromatic polycondensation reaction. The carbon precursor of polycyclic aromatic hydrocarbon-type pitch contributes to a high carbon yield rate (40%) compared with those of resin and biomass precursors. The as-synthesized carbon materials deliver high capacities of up to 390 mAh g-1, surpassing many reported carbon anodes for SIBs. Through correlating specific capacity with ID/IG values in Raman spectra and theoretical calculation of carbon materials regulated by different metal elements (Mn, Nb, Ce, Cr, and V), we identify and propose the binding energy as the descriptor for characterizing the capability of regulating the carbon microcrystalline structure to promote sodium storage. This work provides a universal method for regulating the carbon structure, which may lead to the controlled design and fabrication of carbon materials for energy storage and conversion and beyond.

Protective NaSICON Interlayer between a Sodium-Tin Alloy Anode and Sulfide-Based Solid Electrolytes for All-Solid-State Sodium Batteries

This paper presents a suitable combination of different sodium solid electrolytes to surpass the challenge of highly reactive cell components in sodium batteries. The focus is laid on the introduction of ceramic Na3.4Zr2Si2.4P0.6O12 serving as a protective layer for sulfide-based separator electrolytes to avoid the high reactivity with the sodium metal anode. The chemical instability of the anode|sulfide solid electrolyte interface is demonstrated by impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The Na3.4Zr2Si2.4P0.6O12 disk shows chemical stability with the sodium metal anode as well as the sulfide solid electrolyte. Impedance analysis suggests an electrochemically stable interface. Electron microscopy points to a reaction at the Na3.4Zr2Si2.4P0.6O12 surface toward the sulfide solid electrolyte, which does not seem to affect the performance negatively. The results presented prove the chemical stabilization of the anode-separator interface using a Na3.4Zr2Si2.4P0.6O12 interlayer, which is an important step toward a sodium all-solid-state battery. Due to the applied pressure that is mandatory for battery cells with sulfide-based cathode composite, the use of a brittle ceramic in such cells remains challenging.

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.

Increasing the Sodium Metal Electrode Compatibility with the Na3 PS4 Solid-State Electrolyte through Heteroatom Substitution

Rechargeable batteries are essential to the global shift towards renewable energy sources and their storage. At present, improvements in their safety and sustainability are of great importance as part of global sustainable development goals. A major contender in this shift are rechargeable solid-state sodium batteries, as a low-cost, safe, and sustainable alternative to conventional lithium-ion batteries. Recently, solid-state electrolytes with a high ionic conductivity and low flammability have been developed. However, these still face challenges with the highly reactive sodium metal electrode. The study of these electrolyte-electrode interfaces is challenging from a computational and experimental point of view, but recent advances in molecular dynamics neural-network potentials are finally enabling access to these environments compared to more computationally expensive conventional ab-initio techniques. In this study, heteroatom-substituted Na3 PS3 X1 analogues, where X is sulfur, oxygen, selenium, tellurium, nitrogen, chlorine, and fluorine, are investigated using total-trajectory analysis and neural-network molecular dynamics. It was found that inductive electron-withdrawing and electron-donating effects, alongside differences in heteroatom atomic radius, electronegativity, and valency, influenced the electrolyte reactivity. The Na3 PS3 O1 oxygen analogue was found to have superior chemical stability against the sodium metal electrode, paving the way towards high-performance, long lifetime and reliable rechargeable solid-state sodium batteries.

Improving the Initial Coulombic Efficiency of Sodium-Storage Antimony Anodes via Electrochemically Alloying Bismuth

Improving cycling stability while maintaining a high initial Coulombic efficiency (ICE) of the antimony (Sb) anode is always a trade-off for the design of electrodes of sodium-ion batteries (SIBs). Herein, we prepare a carbon-free Sb8Bi1 anode with an ICE of 87.1% at 0.1 A g-1 by a one-step electrochemical reduction of Sb2O3 and Bi2O3 in alkaline solutions. The improved ICE of the Sb8Bi1 anode is due to the alloying of bismuth (Bi) that prevents irreversible interfacial reactions during the sodiation process. Unlike carbon buffers, the use of Bi will reduce the number of side reactions between the carbon buffer and sodium. Moreover, Bi2O3 can promote the reduction of Sb2O3 and reduce the particle size of Sb from ∼20 μm to below 300 nm. The electrolytic products can be modulated by controlling the cell voltages and electrolysis time. The electrolytic Sb8Bi1 anode delivered a capacity of 625 mAh g-1 after 200 cycles with an ICE of 87.1% at 0.1 A g-1 and even 625 mAh g-1 at 1 A g-1 over 100 cycles. Hence, alloying Bi into Sb is an effective way to make a long-lasting Sb anode while maintaining a high Coulombic efficiency.

SnSe Nanosheet Array on Carbon Cloth as a High-Capacity Anode for Sodium-Ion Batteries

Binder-free electrodes offer a great opportunity for developing high-performance sodium-ion batteries (SIBs) aiming at the application in energy storage devices. Tin selenide (SnSe) is considered to be a promising anode material for SIBs owing to its high theoretical capacity (780 mA h g-1). In this work, a SnSe nanosheet array (SnSe NS) on a carbon cloth is prepared using a vacuum thermal evaporation method. The as-prepared SnSe NS electrode does not have metal current collectors, binders, or any conductive additives. In comparison with the electrode of SnSe blocky particles (SnSe BP), the SnSe NS electrode delivers a higher initial charge capacity of 713 mA h g-1 at a current density of 0.1C and maintains a higher charge capacity of 410 mA h g-1 after 50 cycles. Furthermore, the electrochemical behaviors of the SnSe NS electrode are determined via pseudocapacitance and electrochemical impedance spectroscopy measurements, indicating a faster kinetic process of the SnSe NS electrode compared to that of the SnSe BP. Operando X-ray diffraction measurements prove that the SnSe NS exhibits better phase reversibility than the SnSe BP. After the cycles, the SnSe NS electrode still maintains its particular structure. This work provides a feasible method to prepare SnSe nanostructures with high capacity and improved sodium ion diffusion ability.

Machine learning search for stable binary Sn alloys with Na, Ca, Cu, Pd, and Ag

We present our findings of a large-scale screening for new synthesizable materials in five M-Sn binaries, M = Na, Ca, Cu, Pd, and Ag. The focus on these systems was motivated by the known richness of M-Sn properties with potential applications in energy storage, electronics packaging, and superconductivity. For the systematic exploration of the large configuration space, we relied on our recently developed MAISE-NET framework that constructs accurate neural network interatomic potentials and utilizes them to accelerate ab initio global structure searches. The scan of over two million candidate phases at a fraction of the typical ab initio calculation cost has uncovered 29 possible intermetallics thermodynamically stable at different temperatures and pressures (1 bar and 20 GPa). Notable predictions of ambient-pressure materials include a simple hP6-NaSn2 phase, fcc-based Pd-rich alloys, tI36-PdSn2 with a new prototype, and several high-temperature Sn-rich ground states in the Na-Sn, Cu-Sn, and Ag-Sn systems. Our modeling work also involved ab initio (re)examination of previously observed M-Sn compounds that helped explain the entropy-driven stabilization of known Cu-Sn phases. The study demonstrates the benefits of guiding structure searches with machine learning potentials and significantly expands the number of predicted thermodynamically stable crystalline intermetallics achieved with this strategy so far.

Renaissance of elemental phosphorus materials: properties, synthesis, and applications in sustainable energy and environment

The polymorphism of phosphorus-based materials has garnered much research interest, and the variable chemical bonding structures give rise to a variety of micro and nanostructures. Among the different types of materials containing phosphorus, elemental phosphorus materials (EPMs) constitute the foundation for the synthesis of related compounds. EPMs are experiencing a renaissance in the post-graphene era, thanks to recent advancements in the scaling-down of black phosphorus, amorphous red phosphorus, violet phosphorus, and fibrous phosphorus and consequently, diverse classes of low-dimensional sheets, ribbons, and dots of EPMs with intriguing properties have been produced. The nanostructured EPMs featuring tunable bandgaps, moderate carrier mobility, and excellent optical absorption have shown great potential in energy conversion, energy storage, and environmental remediation. It is thus important to have a good understanding of the differences and interrelationships among diverse EPMs, their intrinsic physical and chemical properties, the synthesis of specific structures, and the selection of suitable nanostructures of EPMs for particular applications. In this comprehensive review, we aim to provide an in-depth analysis and discussion of the fundamental physicochemical properties, synthesis, and applications of EPMs in the areas of energy conversion, energy storage, and environmental remediation. Our evaluations are based on recent literature on well-established phosphorus allotropes and theoretical predictions of new EPMs. The objective of this review is to enhance our comprehension of the characteristics of EPMs, keep abreast of recent advances, and provide guidance for future research of EPMs in the fields of chemistry and materials science.

Construction of the Fast Potassiation Path in Sbx Bi1-x @NC Anode with Ultrahigh Cycling Stability for Potassium-Ion Batteries

Due to the scarce of lithium resources, potassium-ion batteries (PIBs) have attracted extensive attention due to their similar electrochemical properties to lithium-ion batteries (LIBs) and more abundant potassium resources. Even though there is considerable progress in SbBi alloy anode for LIBs and PIBs, most studies are focused on the morphology/structure tuning, while the inherent physical features of alloy composition's effect on the electrochemical performance are rarely investigated. Herein, combined the nanonization, carbon compounding, and alloying with composition regulation, the anode of nitrogen-doped carbon-coated Sbx Bi1-x (Sbx Bi1-x @NC) with a series of tuned chemical compositions is designed as an ideal model. The density functional theory (DFT) calculation and experimental investigation results show that the K+ diffusion barrier is lower and the path is easier to carry out when element Bi dominates the potassiation reaction, which is also the reason for better circulation. The optimized Sb0.25 Bi0.75 @NC shows an excellent cycling performance with a reversible specific capacity of 301.9 mA h g-1 after 500 cycles at 0.1 A g-1 . Meanwhile, the charge-discharge mechanism is intuitively invetigated and analyzed by in situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) in detail. Such an alloy-type anode synthesis approach and in situ observation method provide an adjustable strategy for the designing and investigating of PIB anodes.

Bi nanoparticles confined in N,S co-doped carbon nanoribbons with excellent rate performance for sodium-ion batteries

Bismuth (Bi) has emerged as a promising candidate for sodium-ion battery anodes because of its unique layered crystal structure, superior volumetric capacity, and high theoretical gravimetric capacity. However, the large volume expansion and severe aggregation of Bi during the alloying/dealloying reactions are extremely detrimental to cycling stability, which seriously hinders its practical application. To overcome these issues, we propose an effective synthesis of composite materials, encapsulating Bi nanoparticles in N,S co-doped carbon nanoribbons and composites with carbon nanotubes (N,S-C@Bi/CNT), using Bi₂S₃ nanobelts as templates. The uniform distribution of Bi nanoparticles and the structure of carbon nanoribbons can reduce the diffusion path of ions/electrons, efficiently buffer the large volume change and prevent Bi from aggregating during cycles. As expected, the N,S-C@Bi/CNT electrode shows superior sodium storage performance in half cells, including a high specific capacity (345.3 mA h g^-1 at 1.0 A g^-1), long cycling stability (1000 cycles), and superior rate capability (336.0 mA h g^-1 at 10.0 A g^-1).

Advanced Anode Materials for Rechargeable Sodium-Ion Batteries

Rechargeable sodium-ion batteries (SIBs) have been considered as promising energy storage devices owing to the similar "rocking chair" working mechanism as lithium-ion batteries and abundant and low-cost sodium resource. However, the large ionic radius of the Na-ion (1.07 Å) brings a key scientific challenge, restricting the development of electrode materials for SIBs, and the infeasibility of graphite and silicon in reversible Na-ion storage further promotes the investigation of advanced anode materials. Currently, the key issues facing anode materials include sluggish electrochemical kinetics and a large volume expansion. Despite these challenges, substantial conceptual and experimental progress has been made in the past. Herein, we present a brief review of the recent development of intercalation, conversion, alloying, conversion-alloying, and organic anode materials for SIBs. Starting from the historical research progress of anode electrodes, the detailed Na-ion storage mechanism is analyzed. Various optimization strategies to improve the electrochemical properties of anodes are summarized, including phase state adjustment, defect introduction, molecular engineering, nanostructure design, composite construction, heterostructure synthesis, and heteroatom doping. Furthermore, the associated merits and drawbacks of each class of material are outlined, and the challenges and possible future directions for high-performance anode materials are discussed.

Recent Progress on Honeycomb Layered Oxides as a Durable Cathode Material for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are becoming promising candidates for energy storage devices due to the low cost, abundant reserves, and excellent electrochemical performance. As the most important unit, layered cathodes attract much attention, where honeycomb-layered-oxides (HLOs) manifest outstanding structural stability, high redox potential, and long-life electrochemistry. Here, recent progress on HLOs as well as Na₃ Ni₂ SbO₆ and Na₃ Ni₂ BiO₆ as two representative materials are introduced, and the crystal and electronic structure, electrochemical performance, and modification strategies are summarized. The advanced high nickel HLOs are highlighted toward development of state-of-the-art sodium-ion batteries. This review would deepen the understanding of superstructure in layered oxides, as well as structure-property relationship, and inspire more interest in high output voltage, long lifespan sodium-ion batteries.

Hexaindium Heptasulfide/Nitrogen and Sulfur Co-Doped Carbon Hollow Microspindles with Ultrahigh-Rate Sodium Storage through Stable Conversion and Alloying Reactions

Group IIIA-VA metal sulfides (GMSs) have attracted increasing attention because of their unique Na-storage mechanisms through combined conversion and alloying reactions, thus delivering large theoretical capacities and low working potentials. However, Na⁺ diffusion within GMSs anodes leads to severe volume change, generally representing a fundamental limitation to rate capability and cycling stability. Here, monodispersed In₆ S₇ /nitrogen and sulfur co-doped carbon hollow microspindles (In₆ S₇ /NSC HMS) are produced by morphology-preserved thermal sulfurization of spindle-like and porous indium-based metal organic frameworks. The resulting In₆ S₇ /NSC HMS anode exhibits theoretical-value-close specific capacity (546.2 mAh g^-1 at 0.1 A g^-1 ), ultrahigh rate capability (267.5 mAh g^-1 at 30.0 A g^-1 ), high initial coulombic efficiency (≈93.5%), and ≈92.6% capacity retention after 4000 cycles. This kinetically favored In₆ S₇ /NSC HMS anode fills up the kinetics gap with a capacitive porous carbon cathode, enabling a sodium-ion capacitor to deliver an ultrahigh energy density of 136.3 Wh kg^-1 and a maximum power density of 47.5 kW kg^-1 . The in situ/ex situ analytical techniques and theoretical calculation both show that the robust and fast Na⁺ charge storage of In₆ S₇ /NSC HMS arises from the multi-electron redox mechanism, buffered volume expansion, negligible morphological change, and surface-controlled solid-state Na⁺ transport.

Self-assembled nanoflower-like FeSe2/MoSe2 heterojunction anode with enhanced kinetics for superior-performance Na-ion half/full batteries

Transition metal selenides are a research hotspot in sodium-ion batteries (SIBs). However, slow kinetics and rapid capacity decay due to volume changes during cycling limit their commercial applications. Heterostructures have the ability to accelerate charge transport and are widely used in energy storage devices due to their abundant active sites and lattice interfaces. A rational design of heterojunction electrode materials with excellent electrochemical performance is essential for SIBs. Herein, a novel anode material heterostructured FeSe₂/MoSe₂ (FMSe) nanoflower for SIBs was successfully prepared through a facile co-precipitation and hydrothermal route. The as-prepared FMSe heterojunction exhibits excellent electrochemical performance, including a high invertible capacity (493.7 mA h g^-1 after 150 cycles at 0.2 A g^-1), long-term cycling stability (352.2 mA h g^-1 even after 4200 cycles at 5.0 A g^-1) and competitive rate capability (361.2 mA h g^-1 at 20 A g^-1). By matching with a Na₃V₂(PO₄)₃ cathode, it can even exhibit ideal cycling stability (123.5 mA h g^-1 at 0.5 A g^-1 after 200 cycles). Furthermore, the sodium storage mechanism of the FMSe electrodes was systematically determined by ex situ electrochemical techniques. Theoretical calculation also reveals that the heterostructure on the FMSe interface enhances charge transport and promotes reaction kinetics.

Bismuth-Antimony Alloy Embedded in Carbon Matrix for Ultra-Stable Sodium Storage

Alloy-type anodes are the most promising candidates for sodium-ion batteries (SIBs) due to their impressive Na storage capacity and suitable voltage platform. However, the implementation of alloy-type anodes is significantly hindered by their huge volume expansion during the alloying/dealloying processes, which leads to their pulverization and detachment from current collectors for active materials and the unsatisfactory cycling performance. In this work, bimetallic Bi-Sb solid solutions in a porous carbon matrix are synthesized by a pyrolysis method as anode material for SIBs. Adjustable alloy composition, the introduction of porous carbon matrix, and nanosized bimetallic particles effectively suppress the volume change during cycling and accelerate the electrons/ions transport kinetics. The optimized Bi₁Sb₁@C electrode exhibits an excellent electrochemical performance with an ultralong cycle life (167.2 mAh g^-1 at 1 A g^-1 over 8000 cycles). In situ X-ray diffraction investigation is conducted to reveal the reversible and synchronous sodium storage pathway of the Bi₁Sb₁@C electrode: (Bi,Sb) Na(Bi,Sb) Na₃(Bi,Sb). Furthermore, online electrochemical mass spectrometry unveils the evolution of gas products of the Bi₁Sb₁@C electrode during the cell operation.

Understanding the Configurational Entropy Evolution in Metal-Phosphorus Solid Solution for Highly Reversible Li-Ion Batteries

The high-entropy materials (HEM) have attracted increasing attention in catalysis and energy storage due to their large configurational entropy and multiunique properties. However, it is failed in alloying-type anode due to their Li-inactive transition-metal compositions. Herein, inspired by high-entropy concept, the Li-active elements instead of transition-metal ones are introduced for metal-phosphorus synthesis. Interestingly, a new Znx Gey Cuz Siw P2 solid solution is successfully synthesized as proof of concept, which is first verified to cubic system in F-43m. More specially, such Znx Gey Cuz Siw P2 possesses wide-range tunable region from 9911 to 4466, in which the Zn0.5 Ge0.5 Cu0.5 Si0.5 P2 accounts for the highest configurational entropy. When served as anode, Znx Gey Cuz Siw P2 delivers large capacity (>1500 mAh g-1 ) and suitable plateau (≈0.5 V) for energy storage, breaking the conventional view that HEM is helpless for alloying anode due to its transition-metal compositions. Among them, the Zn0.5 Ge0.5 Cu0.5 Si0.5 P2 exhibits the highest initial coulombic efficiency (ICE) (93%), Li-diffusivity (1.11 × 10-10 ), lowest volume-expansion (34.5%), and best rate performances (551 mAh g-1 at 6400 mA g-1 ) owing to its largest configurational entropy. Possible mechanism reveals the high entropy stabilization enables good accommodation of volume change and fast electronic transportation, thus supporting superior cyclability and rate performances. This large configurational entropy strategy in metal-phosphorus solid solution may open new avenues to develop other high-entropy materials for advanced energy storage.

Yolk-Shell Sb@Void@Graphdiyne Nanoboxes for High-Rate and Long Cycle Life Sodium-Ion Batteries

Antimony (Sb) has been pursued as a promising anode material for sodium-ion batteries (SIBs). However, it suffers from severe volume expansion during the sodiation-desodiation process. Encapsulating Sb into a carbon matrix can effectively buffer the volume change of Sb. However, the sluggish Na⁺ diffusion kinetics in traditional carbon shells is still a bottleneck for achieving high-rate performance in Sb/C composite materials. Here we design and synthesize a yolk-shell Sb@Void@graphdiyne (GDY) nanobox (Sb@Void@GDY NB) anode for high-rate and long cycle life SIBs. The intrinsic in-plane cavities in GDY shells offer three-dimensional Na⁺ transporting channels, enabling fast Na⁺ diffusion through the GDY shells. Electrochemical kinetics analyses show that the Sb@Void@GDY NBs exhibit faster Na⁺ transport kinetics than traditional Sb@C NBs. In situ transmission electron microscopy analysis reveals that the hollow structure and the void space between Sb and GDY successfully accommodate the volume change of Sb during cycling, and the plastic GDY shell maintains the structural integrity of NBs. Benefiting from the above structural merits, the Sb@Void@GDY NBs exhibit excellent rate capability and extraordinary cycling stability.

Adjusting Crystal Orientation to Promote Sodium-Ion Transport in V5 S8 @Graphene Anode Materials for High-Performance Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have inspired the potential for widespread use in energy storage owing to the advantages of abundant resources and low cost. Benefiting from the layered structure, 2D-layered materials enable fast interlayer transport of sodium ions and thus are considered promising candidates as anodes for SIBs. Herein, a strategy of adjusting crystal orientation is proposed via a solvothermal method to improve sodium-ion transport at the edge of the interlayers in 2D-layered materials. By introducing surfactants and templates, the 2D-layered V₅ S₈ nanosheets are controlled to align the interlayer diffusion channels vertically to the surface, which promotes the fast transport of Na⁺ at the edge of the interlayers as revealed by experimental methods and ab initio calculations. Benefiting from the aligned crystal orientation and rGO coating, the vertical-V₅ S₈ @rGO hybrid delivers a high initial discharge capacity of 350.6 mAh g^-1 at a high current density of 15 A g^-1 . This work provides a strategy for the structural design of 2D-layered anode materials by adjusting crystal orientation, which demonstrates the promise for applications in fast-charging alkaline-ion batteries.

Novel Preoxidation-Assisted Mechanism to Preciously Form and Disperse Bi2O3 Nanodots in Carbon Nanofibers for Ultralong-Life and High-Rate Sodium Storage

Metal oxides, as promising electrode materials for sodium-ion batteries, usually need to be formed by exposure to oxygen, which usually thermally corrodes the carbon material with which they are compounded, reducing their flexibility and electrical conductivity. Herein, we present for the first time a preoxidation-assisted mechanism to prepare bismuth oxide and carbon nanofibers (Bi₂O₃@C-NFs) by electrospinning, using Bi₂S₃ nanorods as multifunctional templates. The bismuth could be oxidized by C═O bonds formed through the cyclization reaction in the high-temperature calcination process, effectively avoiding thermal corrosion of carbon in oxygen atmosphere at high temperature. More importantly, the uniformly distributed Bi₂O₃ nanodots and longitudinal tunnels are formed inside the S- and N-doped carbon nanofibers with the continuous diffusion of Bi generated from the decomposition of Bi₂S₃ nanorods and the conversion to Bi─O bonds with C═O bonds being broken. Benefiting from the structural and composition merits arising from preoxidation, Bi₂O₃@C-NFs self-supporting anodes show high specific capacity (439 mAh g^-1 at 0.05 A g^-1), superior rate performance (243 mAh g^-1 at a current density of 20 A g^-1), and outstanding cycling stability (211 mAh g^-1 after 2000 cycles at 5 A g^-1). The effective combination of the well-established electrospinning technology and the preoxidation assisted mechanism provides a new way for the preparation of metal oxide and carbon composites.

Interfacial Coupling SnSe2 /SnSe Heterostructures as Long Cyclic Anodes of Lithium-Ion Battery

Tin selenide (SnSe2 ) is considered a promising anode of the lithium-ion battery because of its tunable interlayer space, abundant active sites, and high theoretical capacity. However, the low electronic conductivity and large volume variation during the charging/discharging processes inevitably result in inadequate specific capacity and inferior cyclic stability. Herein, a high-throughput wet chemical method to synthesize SnSe2 /SnSe heterostructures is designed and used as anodes of lithium-ion batteries. The hierarchical nanoflower morphology of such heterostructures buffers the volume expansion, while the built-in electric field and metallic feature increase the charge transport capability. As expected, the superb specific capacity (≈911.4 mAh g-1 at 0.1 A g-1 ), high-rate performance, and outstanding cyclic stability are obtained in the lithium-ion batteries composed of SnSe2 /SnSe anodes. More intriguingly, a reversible specific capacity (≈374.7 mAh g-1 at 2.5 A g-1 ) is maintained after 1000 cycles. The internal lithium storage mechanism is clarified by density functional theory (DFT) calculations and in situ characterizations. This work hereby provides a new paradigm for enhancing lithium-ion battery performances by constructing heterostructures.

Metal Selenides Anode Materials for Sodium Ion Batteries: Synthesis, Modification, and Application

The powerful and rapid development of lithium-ion batteries (LIBs) in secondary batteries field makes lithium resources in short supply, leading to rising battery costs. Under the circumstances, sodium-ion batteries (SIBs) with low cost, inexhaustible sodium reserves, and analogous work principle to LIBs, have evolved as one of the most anticipated candidates for large-scale energy storage devices. Thereinto, the applicable electrode is a core element for the smooth development of SIBs. Among various anode materials, metal selenides (MSe_x ) with relatively high theoretical capacity and unique structures have aroused extensive interest. Regrettably, MSe_x suffers from large volume expansion and unwished side reactions, which result in poor electrochemistry performance. Thus, strategies such as carbon modification, structural design, voltage control as well as electrolyte and binder optimization are adopted to alleviate these issues. In this review, the synthesis methods and main reaction mechanisms of MSe_x are systematically summarized. Meanwhile, the major challenges of MSe_x and the corresponding available strategies are proposed. Furthermore, the recent research progress on layered and nonlayered MSe_x for application in SIBs is presented and discussed in detail. Finally, the future development focuses of MSe_x in the field of rechargeable ion batteries are highlighted.

Highly Stable Sb/C Anode for K+ and Na+ Energy Storage Enabled by Pulsed Laser Ablation and Polydopamine Coating

Potassium- and sodium-ion batteries (PIBs and SIBs) have great potential as the next-generation energy application owing to the natural abundance of K and Na. Antimony (Sb) is a suitable alloying-type anode for PIBs and SIBs due to its high theoretical capacity and proper operation voltage; yet, the severe volume variation remains a challenge. Herein, a preparation of N-doped carbon-wrapped Sb nanoparticles (L-Sb/NC) using pulsed laser ablation and polydopamine coating techniques, is reported. As the anode for PIB and SIB, the L-Sb/NC delivers superior rate capabilities and excellent cycle stabilities (442.2 and 390.5 mA h g^-1 after 250 cycles with the capacity decay of 0.037% and 0.038% per cycle) at the current densities of 0.5 and 1.0 A g^-1 , respectively. Operando X-ray diffraction reveals the facilitated and stable potassiation and sodiation mechanisms of L-Sb/NC enabled by its optimal core-shell structure. Furthermore, the SIB full cell fabricated with L-Sb/NC and Na₃ V₂ (PO₄ )₂ F₃ shows outstanding electrochemical performances, demonstrating its practical energy storage application.

Alloy-Type Lithium Anode Prepared by Laser Microcladding and Dealloying for Improved Cycling/Rate Performance

Nanosized alloy-type materials (Si, Ge, Sn, etc.) present superior electrochemical performance in rechargeable batteries. However, they fail to guarantee cycling capacity and stability under high mass loading required by industrial applications due to low electric contact and adhesive strength, which has long been a challenge. This work proposes a rational design for an alloy-type anode via facile and versatile laser microcladding and dealloying. The proposed anode features a large-area porous network composed of continuous nano-ligaments, which consist of evenly distributed nanosized alloy-type material metallurgically bonded with conductive material. The fabrication of the structure is validated using Ge-Cu and Sn-Cu anodes, both exhibiting enhanced cycling stability at high areal capacity and rate performance in lithium-ion batteries. The enhancement is attributed to the structural features, which contribute to lithiation-delithiation stability and intact electron/Li ion transference path, as verified by in situ and ex situ transmission electron microscopy observations. More importantly, the critical solidification conditions of laser microcladding are provided by a multiphysics simulation, allowing for a thorough understanding of the structural formation mechanism. The study provides a possible approach to improve mass loading and performance of an alloy-type anode for practical application.

Tin nanoparticle in-situ decorated on nitrogen-deficient carbon nitride with excellent sodium storage performance

Tin (Sn)-based electrodes, featuring high electrochemical activity and suitable voltage plateau, gain tremendous attention as promising anode materials for sodium-ion batteries. However, the application of Sn-based electrodes has been largely restricted by the serious pulverization upon repeated cycling due to their large volume expansion, especially at high current densities. Herein, a unique three-dimensional decorated structure was designed, containing ultrafine Sn nanoparticles and nitrogen-deficient carbon nitride (Sn/D-C₃N₄), to efficiently alleviate the expansion stress and prevent the aggregation of Sn nanoparticles. Furthermore, the density functional theory calculations have proved the high sodium adsorption ability and improved diffusion kinetics through the hybridization of D-C₃N₄ with Sn nanoparticles. Further combining the high electronic/ionic conductivity provided by the porous C₃N₄ matrix, high charge contribution from capacitive behavior, and high sodium storage activity of ultrafine Sn nanoparticles, the resultant Sn/D-C₃N₄ can achieve an ultrahigh reversible capacity of 518.3 mA g^-1 after 300 cycles at 1.0 A g^-1, and even maintaining a reversible capacity of 436.1 mAh g^-1 up to 500 cycles (5.0 A g^-1). What's more, the optimized Sn/D-C₃N₄∥Na₃V₂(PO₄)₃/C full cell can keep a high capacity retention of 87.1% at 1.0 A g^-1 even after 5000 cycles, manifesting excellent sodium storage performance.