Controllable Synthesis of Peapod-like Sb@C and Corn-like C@Sb Nanotubes for Sodium Storage

Chloride-Ion-Enriched Solid Electrolyte Interphase with Rapid Na+ Migration toward High-Performance Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have emerged as potential alternatives to lithium-ion batteries (LIBs), particularly for large-scale applications. Alloy-type anode materials for sodium-ion batteries are esteemed as prospective candidate materials for sodium-ion anodes, owing to their elevated theoretical capacity, heightened utilization efficiency, and minimal production of insulating byproducts. However, the severe volume changes and sluggish ion diffusion kinetics can lead to irreversible particle fragmentation and reaggregation phenomena, ultimately resulting in electrode degradation. Additionally, repetitive volume changes can cause an unstable solid electrolyte interphase (SEI). This study presents the synthesis of chloride-ion-modulated bimetallic SnSb/C nanoparticle anode materials, highlighting the following advantages: (i) Designing a bimetallic SnSb alloy structure serves to buffer the structural stresses generated during sodium insertion/extraction processes, effectively mitigating particle fracture phenomena induced by electrode material expansion/contraction. (ii) Nanostructuring both alloy materials enables the full utilization of active materials and shortens diffusion pathways, thereby significantly enhancing the diffusion rate of sodium ions. (iii) Introducing a carbonaceous matrix serves to alleviate self-agglomeration phenomena of the material during charge/discharge cycles, enhancing the material's conductivity and structural stability. (iv) Utilizing chloride-ion interface modification to achieve a chloride-rich solid-electrolyte interphase (SEI) enhances battery performance.

Fast-Charging Anode Materials for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have undergone rapid development as a complementary technology to lithium-ion batteries due to abundant sodium resources. However, the extended charging time and low energy density pose a significant challenge to the widespread use of SIBs in electric vehicles. To overcome this hurdle, there is considerable focus on developing fast-charging anode materials with rapid Na⁺ diffusion and superior reaction kinetics. Here, the key factors that limit the fast charging of anode materials are examined, which provides a comprehensive overview of the major advances and fast-charging characteristics across various anode materials. Specifically, it systematically dissects considerations to enhance the rate performance of anode materials, encompassing aspects such as porous engineering, electrolyte desolvation strategies, electrode/electrolyte interphase, electronic conductivity/ion diffusivity, and pseudocapacitive ion storage. Finally, the direction and prospects for developing fast-charging anode materials of SIBs are also proposed, aiming to provide a valuable reference for the further advancement of high-power SIBs.

Ultrafast and Durable Sodium-Ion Storage of Pseudocapacitive VN@C Hybrid Nanorods from Metal-Organic Framework

Vanadium nitride (VN) is a promising electrode material for sodium-ion storage due to its multivalent states and high electrical conductivity. However, its electrochemical performance has not been fully explored and the storage mechanism remains to be clarified up to date. Here, the possibility of VN/carbon hybrid nanorods synthesized from a metal-organic framework for ultrafast and durable sodium-ion storage is demonstrated. The VN/carbon electrode delivers a high specific capacity (352 mA h g-1), fast-charging capability (within 47.5 s), and ultralong cycling stability (10 000 cycles) for sodium-ion storage. In situ XRD characterization and density functional theory (DFT) calculations reveal that surface-redox reactions at vanadium sites are the dominant sodium-ion storage mechanism. An energy-power balanced hybrid capacitor device is verified by assembling the VN/carbon anode and active carbon cathode, and it shows a maximum energy density of 103 Wh kg-1 at a power density of 113 W kg-1.

Al Doped into Si/P Sites of Na3Zr2Si2PO12 with Conducted Na3PO4 Impurities for Enhanced Ionic Conductivity

Natrium superionic conductor (NASICON) is a promising solid-state electrolyte because of its high stability under air as well as its safety. Doping is an effective way to improve its ionic conductivity, but there is limited information about the explanation of the doping sites. In this work, Al-doped NASICONs are designed. When Al doping is 0.3 (NAl0.3ZSP), the ionic conductivity is the highest and is 5.08 × 10-5 S cm-1 at 30 °C, which is 3.3 times that of undoped NASICON. NAl0.3ZSP consists of a NASICON structure (monoclinic and rhombohedral phases), an amorphous glassy phase, and Na3PO4 impurities. After Al doping, more Si/P sites are occupied by Al; thus, the ratio of Na3PO4 impurities increases. Na3PO4 at the grain boundary is beneficial for grain boundary resistance decrease, contributing to the decrease of the total resistance. Our work first provides a detailed explanation of doped-Al sites and interprets their effects on ionic conductivity.

Achieving Stable and Ultrafast Potassium Storage of Antimony Anode via Dual Confinement of MXene@Carbon Framework

Antimony-based anode materials are recognized for their high potassium storage capacities and appropriate operating potentials. However, the large volume expansion of Sb during the potassiation/depotassiation process, which results in a quick capacity decay, severely limits its practical application in potassium-ion batteries (PIBs). Here, a carbon-coated Sb/MXene heterostructure composite (CSM) is synthesized by adsorption of Sb3+ on MXene nanosheets via Sb-O-Ti bonds followed by carbothermic reduction to construct dual-confined MXene@carbon conductive framework capable of withstanding high volume expansion of Sb and conducive to enabling accelerated electron transfer kinetics. The CSM composite, particularly CSM-700, when configured as an anode for PIBs, realized high capacity (484.4 mAh g-1 at 0.1 A g-1 ), an ultra-stable cycling performance with a high reversible capacity of 435.9 mAh g-1 at 0.1 A g-1 after 100 cycles corresponding to a capacity retention rate of 90.0%, and superior rate performance of 323.0 mAh g-1 at 1 A g-1 . The proposed strategy offers a simple route to construct high-performance Sb-based anodes for advanced PIBs.

Nitrogen-Rich WN Clusters with Atomic Disorders and Non-Grain Boundaries Confined in Carbon Nanosheets Boosting Sodium-Ion Storage

Sodium-ion batteries (SIBs) as economic candidates have received considerable attention for large-scale energy storage applications. However, crystalline metal compounds with specific transport routes and rigid structures restrict their practical applications. Herein, the atomically dispersed N-rich amorphous WN clusters confined in the carbon nanosheets (WN/CNSs) are reported. Through advanced tests and calculations, the structural advantages, reaction mechanisms, and kinetic behaviors of the clusters are systematically analyzed. Compared with the crystalline W₂ N with low theoretical capacity (only 209.3 mAh g^-1 ), the amorphous WN clusters have the advantages of atomic disorders and non-grain boundaries and can afford abundant active sites (unsaturated dangling bonds) and isotropic charge transfer channels, which can be further enhanced by the N-rich characteristics and high electronegativity of the clusters. The encapsulation of CNSs has high conductivity and structural stability, which promotes electron transfer and effectively buffers volume expansions. As a SIB anode, the reversible capacity of WN/CNSs reaches 421.2 mAh g^-1 at 0.1 A g^-1 . Even at 20 A g^-1 , the reversible capacity of 170.7 mAh g^-1 is maintained after 8000 cycles. This study focuses on the advantages of amorphous nitrides, which have important guiding significance for the design of atomic clusters for high-performance metal ion batteries.

High-Capacity Sb/Fe2S3 Sodium-Ion Battery Anodes Fabricated by a One-Step Redox Reaction, Followed by Ball Milling with Graphite

Antimony (Sb) has been considered a promising anode for sodium-ion batteries (SIBs) owing to its high theoretical capacity (660 mA h g^-1) and low redox voltage (0.2-0.9 V vs Na⁺/Na). However, the capacity degradation caused by the volumetric variation during battery discharge/charge hinders the practical application. Herein, guided by the DFT calculation, Sb/Fe₂S₃ was fabricated by annealing Fe and Sb₂S₃ mixed powder. Next, Sb/Fe₂S₃ was blended with 15 wt % graphite by ball milling, yielding nano-Sb/Fe₂S₃ anchored on an exfoliated graphite composite (denoted as Sb/Fe₂S₃-15%). When applied as an anode of SIBs, Sb/Fe₂S₃-15% delivered reversible capacities of 565, 542, 467, 366, 285, and 236 mA h g^-1 at current rates of 1, 2, 4, 6, 8, and 10 A g^-1, respectively, surpassing most of the Sb-based anodes. The co-existence of highly conductive Fe₂S₃ and Sb minimizes the polarization of the anode. Our experiments proved that the Sb and Fe₂S₃ phases were reversible during discharge/charge cycling, and the exfoliated graphite can accelerate the Na⁺ diffusion and e^- conduction. The proposed synthesis method of this work can also be applicable to synthesize various antimony/transition metal sulfide heterostructures (Sb/M_1-xS), which may be applied in a series of fields.

Vapor-phase derived ultra-fine Bismuth nanoparticles embedded in carbon nanotube networks as anodes for sodium and potassium ion batteries

Bismuth (Bi) is a promising material as the anode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to its characteristics such as reasonable price and high theoretical volumetric capacity (3800 mAh cm^-3). Nevertheless, considerable drawbacks have hindered the practical applications of Bi, including its relatively low electrical conductivity and inevitable volumetric change during the alloying/dealloying processes. To solve these problems, we proposed a novel design:Bi nanoparticles were synthesized via a single-step low-pressure vapor-phase reaction and embedded onto the surfaces of multi-walled carbon nanotubes (MWCNTs). After being vaporized at 650℃ and 10^-5 Pa, Bi nanoparticles less than 10 nm were uniformly distributed in the three-dimensional (3D) MWCNT networks to form a Bi/MWNTs composite. In this unique design, the nanostructured Bi can reduce the risk of structural rupture during cycling, and the structure of the MWCMT network is beneficial in shortening the electron/ion transport path. In addition, MWCNTs can improve the overall conductivity of the Bi/MWCNTs composite and prevent particle aggregation, thus improving the cycling stability and rate performance. As an anode material for SIB, the Bi/MWCNTs composite has demonstrated excellent fast charging performance with a reversible capacity of 254 mAh/g at 20 A/g. A capacity of 221mAhg^-1 after cycling at 10 A/g for 8000 cycles has also been achieved for SIB. As an anode material for PIB, the Bi/MWCNTs composite has delivered excellent rate performances with a reversible capacity of 251 mAh/g at 20 A/g. A specific capacity of 270mAhg^-1 after cycling at 1Ag^-1 for 5000 cycles has also been achieved for PIB.

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.

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.

Interface Engineering Enables High-Performance Sb Anode for Sodium Storage

Heterointerface engineering has been verified to be an effective approach to enhance the energy density of alkali-ion batteries by resolving inherent shortcomings of single materials. However, the rational construction of heterogeneous composite with abundant heterogeneous interfaces for sodium-ion batteries (SIBs) is still a significant challenge. Herein, inspired by density functional theory calculations, interface engineering can greatly decrease the energy bandgap and migration barrier of Na ions in Sb and Na₃Sb phases, as well as enhance the mechanical properties. A porous heterointerface MOFC-Sb is fabricated by utilizing MOF-C as a support and buffer, exhibiting excellent electrochemical performances for sodium storage. The MOF-C-Sb anode with its rich heterointerface presents an improved electrochemical performance of 540.5 mAh g^-1 after 100 cycles at 0.1 A g^-1, and 515.9 mAh g^-1 at 1.6 A g^-1 in term of sodium storage, efficiently resolving the serious volume expansion issues of metal Sb. These results indicate the structural superiority of heterointerface-engineered structure and afford valuable information for the rational design and construction of Sb-based anode materials for high-performance electrochemical energy storage.

Iodine-Ion-Assisted Galvanic Replacement Synthesis of Bismuth Nanotubes for Ultrafast and Ultrastable Sodium Storage

Bismuth (Bi) has emerged as a promising anode material for fast-charging and long-cycling sodium-ion batteries (SIBs). However, its dramatically volumetric variations during cycling will undesirably cause the pulverization of active materials, severely limiting the electrochemical performance of Bi-based electrodes. Constructing hollow nanostructures is recognized as an effective way to resolve the volume expansion issues of alloy-type anodes but remains a great challenge for metallic bismuth. Here, we report a facile iodine-ion-assisted galvanic replacement approach for the synthesis of Bi nanotubes (NTs) for high-rate, long-term and high-capacity sodium storage. The hollow tubular structure effectively alleviates the structural strain during sodiation/desodiation processes, resulting in excellent structural stability; the thin wall and large surface area enable ultrafast sodium ion transport. Benefiting from the structural merits, the Bi NT electrode exhibits extraordinary rate capability (84% capacity retention at 150 A g^-1) and outstanding cycling stability (74% capacity retention for 65,000 cycles at 50 A g^-1), which represent the best rate performance and longest cycle life among all reported anodes for SIBs. Moreover, when coupled with the Na₃(VOPO₄)₂F cathode in full cells, this electrode also demonstrates excellent cycling performance, showing the great promise of Bi NTs for practical application. A combination of advanced research techniques reveals that the excellent performance originates from the structural robustness of the Bi NTs and the fast electrochemical kinetics during cycling.

2D Bismuth@N-Doped Carbon Sheets for Ultrahigh Rate and Stable Potassium Storage

Metallic Bi, as an alloying-type anode material, has demonstrated tremendous potential for practical application of potassium-ion batteries. However, the giant volume expansion, severe structure pulverization, and sluggish dynamics of Bi-based materials result in unsatisfied rate performance and unstable cycling stability. Here, 2D bismuth@N-doped carbon sheets with BiOC bond and internal void space (2D Bi@NOC) are successfully fabricated via a self-template strategy to address these issues, which own ultrafast electrochemical kinetics and impressive long-term cycling stability for delivering an admirable capacity of 341.7 mAh g^-1 after 1000 cycles at 10 A g^-1 and impressive rate capability of 220.6 mAh g^-1 at 50 A g^-1 . Particularly, the in situ transmission electron microscopy observations visualize the real-time alloying/dealloying process and reveal that plastic carbon shell and void space can availably relieve dramatic volume stress and powerfully maintain structural integrity. Density functional theory calculation and ultraviolet photoelectron spectroscopy test certify that the robust BiOC bond is thermodynamically and kinetically beneficial for adsorption/diffusion of K⁺ . This work will light on designing advanced high-performance energy materials and provide important evidence for understanding the energy storage mechanism of alloy-based materials.

Green and Scalable Template-Free Strategy to Fabricate Honeycomb-Like Interconnected Porous Micro-Sized Layered Sb for High-Performance Potassium Storage

The tremendous volume change and severe pulverization of micro-sized Sb anode generate no stable capacity in potassium-ion batteries (PIBs). The honeycomb-like porous structure provides free spaces to accommodate its volume expansion and offers efficient ion transport, yet complex synthesis and low yield limits its large-scale application. Here, a green, scalable template-free method for designing a 3D honeycomb-like interconnected porous micro-sized Sb (porous-Sb) is proposed. Its honeycomb-like porous formation mechanism is also verified. Under hydrothermal conditions, Sb reacts with water and dissolved oxygen in water, undergoing non-homogeneous and continuous corrosion at grain boundaries, and producing soluble H₂ Sb₂ O₆ (H₂ O), which regulates the porous structure of Sb by controlling reaction time. Benefiting from its porous structure and micron size, porous-Sb anode displays large gravimetric and volumetric capacities with 655.5 mAh g^-1 and 2,001.9 mAh cm^-3 at 0.05 A g^-1 and superior rate performance of 441.9 mAh g^-1 at 2.0 A g^-1 in PIBs. Furthermore, ex situ characterization and kinetic analysis uncover the small volume expansion and fast K⁺ reaction kinetics of porous Sb during potassiation/depotassiation, originating from its large electrolyte contact area and internal expansion mechanism. It verifies a green, scalable template-free strategy to construct honeycomb-like porous metals for energy storage and conversion.

Innovative Materials for Energy Storage and Conversion

The metal chalcogenides (MCs) for sodium-ion batteries (SIBs) have gained increasing attention owing to their low cost and high theoretical capacity. However, the poor electrochemical stability and slow kinetic behaviors hinder its practical application as anodes for SIBs. Hence, various strategies have been used to solve the above problems, such as dimensions reduction, composition formation, doping functionalization, morphology control, coating encapsulation, electrolyte modification, etc. In this work, the recent progress of MCs as electrodes for SIBs has been comprehensively reviewed. Moreover, the summarization of metal chalcogenides contains the synthesis methods, modification strategies and corresponding basic reaction mechanisms of MCs with layered and non-layered structures. Finally, the challenges, potential solutions and future prospects of metal chalcogenides as SIBs anode materials are also proposed.

Bean Pod-Like SbSn/N-Doped Carbon Fibers toward a Binder Free, Free-Standing, and High-Performance Anode for Sodium-Ion Batteries

Bimetallic SbSn alloy stands out among the anode materials for sodium-ion batteries (SIBs) because of its high theoretical specific capacity (752 mAh g^-1 ) and good electrical conductivity. However, the major challenge is the large volume change during cycling processes, bringing about rapid capacity decay. Herein, to cope with this issue, through electrostatic spinning and high temperature calcination reduction, the unique bean pod-like free-standing membrane is designed initially, filling SbSn dots into integrated carbon matrix including hollow carbon spheres and nitrogen-doped carbon fibers (B-SbSn/NCFs). Significantly, the synergistic carbon matrix not only improves the conductivity and flexibility, but provides enough buffer space to alleviate the large volume change of metal particles. More importantly, the B-SbSn/NCFs free-standing membrane can be directly used as the anode without polymer binder and conductive agent, which improves the energy density and reaction kinetics. Satisfyingly, the free-standing BSbSn/NCFs membrane anode shows excellent electrochemical performance in SIB. The specific capacity of the membrane electrode can maintain 486.9 mAh g^-1 and the coulombic efficiency is close to 100% after 400 cycles at 100 mA g^-1 . Furthermore, the full cell based on B-SbSn/NCFs anode also exhibits the good electrochemical performance.

Bi@C Nanospheres with the Unique Petaloid Core-Shell Structure Anchored on Porous Graphene Nanosheets as an Anode for Stable Sodium- and Potassium-Ion Batteries

Bismuth (Bi) has emerged as a prospective candidate as Na-ion and potassium-ion battery anodes because of its unique advantages of low cost, high theoretical gravimetric capacity (386 mAh g^-1), and superior volumetric capacity (3800 mAh cm^-3). However, the low electronic conductivity and the huge volume expansion of Bi during the alloying/dealloying reactions are extremely detrimental to cycling stability, which seriously hinder its practical application. To overcome these issues, we propose a rational design: Bi@C nanospheres with the unique petaloid core-shell structure are synthesized in one step for the first time and then combined with different contents of graphene (GR) nanosheets to form the composites Bi@C@GR. The Bi@C nanospheres with a core-shell structure are beneficial to shortening the transmission path of electrons/ions and reducing the risk from structural rupture of the particles during cycling. In addition, the combination of Bi@C nanospheres and porous GR could greatly improve the conductivity and prevent the aggregation of particles, which is conducive to better cycling stability and rate performance. Consequently, Bi@C@GR-2 presents a superior reversible capacity for sodium storage (300 mAh g^-1 over 80 cycles) and potassium storage (200 mAh g^-1 over 70 cycles) at 0.1 A g^-1. Furthermore, in situ electrochemical impedance spectroscopy and ex situ transmission electron microscopy are carried out to analyze and reflect the kinetic reaction mechanism and the phase change of the Bi@C@GR-2 electrode during the charge/discharge processes.

Photoelectrochemical aptasensor based on La2Ti2O7/Sb2S3 and V2O5 for effectively signal change strategy for cancer marker detection

In this item, a high-efficiency signal "on-off-on" strategy photoelectrochemical (PEC) apatsensor was resoundingly developed for target ultrasensitive analysis. Primarily, the heterojunction formation between Cd: Sb₂S₃ and La₂Ti₂O₇ was contributed to the first "signal-on" state to improve the stability of the PEC platform. Secondly, V₂O₅ nanosphere act as a catalyst for H₂O₂ was used to label on aptamer DNA to consume electron donor for achieving "signal-off" state. Then target analyte was modified on the surface of the PEC platform, and part of V₂O₅ with aptamer DNA would be released from the aptasensor surface, thus, the "signal-on" state was realized again. In this signal "on-off-on" strategy, the PEC performance of perovskite La₂Ti₂O₇ was effectively perfected with Cd: Sb₂S₃ sensitization, and broaden the application of perovskite in PEC sensor field. And the signal attenuation and recovery strategy were distinctly elevated the sensitivity of the aptasensor. In the preferred detection conditions, the proposed PEC sensor for analyte (PSA as an example) analysis revealed a wide sensing range from 1.000 × 10^-5 to 500.0 ng/mL, own a low detection limit of 4.300 fg/mL. This smart response change mode also provide prospect for other target detection, and offer a reference to signal transform for other electrochemical method.

Engineering Nanostructured Antimony-Based Anode Materials for Sodium Ion Batteries

Sodium-ion batteries (SIBs) are considered a potential alternative to lithium-ion batteries (LIBs) for energy storage due to their low cost and the large abundance of sodium resources. The search for new anode materials for SIBs has become a vital approach to satisfying the ever-growing demands for better performance with higher energy/power densities, improved safety and a longer cycle life. Recently, antimony (Sb) has been extensively researched as a promising candidate due to its high specific capacity through an alloying/dealloying process. In this review article, we will focus on different categories of the emerging Sb based anode materials with distinct sodium storage mechanisms including Sb, two-dimensional antimonene and antimony chalcogenide (Sb2S3 and Sb2Se3). For each part, we emphasize that the novel construction of an advanced nanostructured anode with unique structures could effectively improve sodium storage properties. We also highlight that sodium storage capability can be enhanced through designing advanced nanocomposite materials containing Sb based materials and other carbonaceous modification or metal supports. Moreover, the recent advances in operando/in-situ investigation of its sodium storage mechanism are also summarized. By providing such a systematic probe, we aim to stress the significance of novel nanostructures and advanced compositing that would contribute to enhanced sodium storage performance, thus making Sb based materials as promising anodes for next-generation high-performance SIBs.

Metal-Organic Framework Derived Ultrafine Sb@Porous Carbon Octahedron via In Situ Substitution for High-Performance Sodium-Ion Batteries

Alloying-type anode materials are regarded as promising alternatives beyond intercalation-type carbonaceous materials for sodium storage owing to the high specific capacities. The rapid capacity decay arising from the huge volume change during Na⁺-ion insertion/extraction, however, impedes the practical application. Herein, we report an ultrafine antimony embedded in a porous carbon nanocomposite (Sb@PC) synthesized via facile in situ substitution of the Cu nanoparticles in a metal-organic framework (MOF)-derived octahedron carbon framework for sodium storage. The Sb@PC composite displays an appropriate redox potential (0.5-0.8 V vs Na/Na⁺) and excellent specific capacities of 634.6, 474.5, and 451.9 mAh g^-1 at 0.1, 0.2, and 0.5 A g^-1 after 200, 500, and 250 cycles, respectively. Such superior sodium storage performance is primarily ascribed to the MOF-derived three-dimensional porous carbon framework and ultrafine Sb nanoparticles, which not only provides a penetrating network for rapid transfer of charge carriers but also alleviates the agglomeration and volume expansion of Sb during cycling. Ex situ X-ray diffraction and in situ Raman analysis clearly reveal a five-stage reaction mechanism during sodiation and desodiation and demonstrate the excellent reversibility of Sb@PC for sodium storage. Furthermore, post-mortem analysis reveals that the robust structural integrity of Sb@PC can withstand continuous Na⁺-ion insertion/extraction. This work may provide insight into the effective design of high-capacity alloying-type anode materials for advanced secondary batteries.

Bimetallic Sulfide SnS2/FeS2 Nanosheets as High-Performance Anode Materials for Sodium-Ion Batteries

Transition-metal sulfide SnS₂ has aroused wide concern due to its high capacity and nanosheet structure, making it an attractive choice as the anode material in sodium-ion batteries. However, the large volume expansion and poor conductivity of SnS₂ lead to inferior cycle stability as well as rate performance. In this work, FeS₂ was in situ introduced to synchronously grow with SnS₂ on rGO to prepare a heterojunction bimetallic sulfide nanosheet SnS₂/FeS₂/rGO composite. The composition and distinctive structure facilitate the rapid diffusion of Na⁺ and improve the charge transfer at the heterogeneous interface, providing sufficient space for volume expansion and improving anode materials' structural stability. SnS₂/FeS₂/rGO bimetallic sulfide electrode boasts a capacity of 768.3 mA h g^-1 at the current density of 0.1 A g^-1, and 541.2 mA h g^-1 at the current density of 1 A g^-1 in sodium-ion batteries, which is superior to that of either single metal sulfide SnS₂ or FeS₂. TDOS calculation further confirms that the binding of FeS₂/SnS₂-Na is more stable than FeS₂ and SnS₂ alone. The superior electrochemical performance of the SnS₂/FeS₂/rGO composite material makes it a promising candidate for sodium storage.

Antimony nanocrystals self-encapsulated within bio-oil derived carbon for ultra-stable sodium storage

Integrating carbon-coating and nanostructuring has been considered as the most promising strategy to accommodate the dramatic volume expansion represented by high-capacity antimony (Sb) upon sodiation. Suitable coating source and synthetic strategy that are both economical and strong are yet to be explored. In this regard, by using renewable bio-oil as carbon source and self-wrapping precursor, robust Sb@C composite anode with Sb nanoparticles homogeneously impregnated into the cross-linked 2D ultrathin carbon nanosheets is developed via a facile NaCl template-assisted self-assembly and followed carbothermal reduction method. Such judiciously crafted interconnected macroporous framework can mitigate of mechanical stress and alleviate the volume change of inner Sb, guaranteeing high-performance sodium-ion battery anode. At a current density of 0.1 A g^-1, ultrahigh reversible capacity of 520 mAh g^-1 can be achieved. Notably, a stable capacity of 391 mAh g^-1 is even retained after 500 cycles at 1 A g^-1. Such a facile and cost-effective synthetic method is promising for high-performance sodium-ion batteries.

Rational Design of Sb@C@TiO2 Triple-Shell Nanoboxes for High-Performance Sodium-Ion Batteries

Antimony is an attractive anode material for sodium-ion batteries (SIBs) owing to its high theoretical capacity and appropriate sodiation potential. However, its practical application is severely impeded by its poor cycling stability caused by dramatic volumetric variations during sodium uptake and release processes. Here, to circumvent this obstacle, Sb@C@TiO₂ triple-shell nanoboxes (TSNBs) are synthesized through a template-engaged galvanic replacement approach. The TSNB structure consists of an inner Sb hollow nanobox protected by a conductive carbon middle shell and a TiO₂ -nanosheet-constructed outer shell. This structure offers dual protection to the inner Sb and enough room to accommodate volume expansion, thus promoting the structural integrity of the electrode and the formation of a stable solid-electrolyte interface film. Benefiting from the rational structural design and synergistic effects of Sb, carbon, and TiO₂ , the Sb@C@TiO₂ electrode exhibits superior rate performance (212 mAh g^-1 at 10 A g^-1 ) and outstanding long-term cycling stability (193 mAh g^-1 at 1 A g^-1 after 4000 cycles). Moreover, a full cell assembled with a configuration of Sb@C@TiO₂ //Na₃ (VOPO₄ )₂ F displays a high output voltage of 2.8 V and a high energy density of 179 Wh kg^-1 , revealing the great promise of Sb@C@TiO₂ TSNBs as the electrode in SIBs.

Cr2P2O7 as a Novel Anode Material for Sodium and Lithium Storage

The development of new appropriate anode material with low cost is still main issue for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs). Here, Cr2P2O7 with an in-situ formed carbon layer has been fabricated through a facile solid-state method and its storage performance in SIBs and LIBs has been reported first. The Cr2P2O7@C delivers 238 mA h g-1 and 717 mA h g-1 at 0.05 A g-1 in SIBs and LIBs, respectively. A capacity of 194 mA h g-1 is achieved in SIBs after 300 cycles at 0.1 A g-1 with a high capacity retention of 92.4%. When tested in LIBs, 351 mA h g-1 is maintained after 600 cycles at 0.1 A g-1. The carbon coating layer improves the conductivity and reduces the side reaction during the electrochemical process, and hence improves the rate performance and enhances the cyclic stability.