Graphitic Carbon Nitride (g‐C3N4)‐Derived N‐Rich Graphene with Tuneable Interlayer Distance as a High‐Rate Anode for Sodium‐Ion Batteries

Heteroatom‐doped carbon materials with expanded interlayer distance have been widely studied as anodes for sodium‐ion batteries (SIBs). However, it remains unexplored to further enlarge the interlayer spacing and reveal the influence of heteroatom doping on carbon nanostructures for developing more efficient SIB anode materials. Here, a series of N‐rich few‐layer graphene (N‐FLG) with tuneable interlayer distance ranging from 0.45 to 0.51 nm is successfully synthesized by annealing graphitic carbon nitride (g‐C₃N₄) under zinc catalysis and selected temperature (T = 700, 800, and 900 °C). More significantly, the correlation between N dopants and interlayer distance of resultant N‐FLG‐T highlights the effect of pyrrolic N on the enlargement of graphene interlayer spacing, due to its stronger electrostatic repulsion. As a consequence, N‐FLG‐800 achieves the optimal properties in terms of interlayer spacing, nitrogen configuration and electronic conductivity. When used as an anode for SIBs, N‐FLG‐800 shows remarkable Na⁺ storage performance with ultrahigh rate capability (56.6 mAh g^?1 at 40 A g^?1) and excellent long‐term stability (211.3 mAh g^?1 at 0.5 A g^?1 after 2000 cycles), demonstrating the effectiveness of material design.     

A Flexible Sulfur‐Enriched Nitrogen Doped Multichannel Hollow Carbon Nanofibers Film for High Performance Sodium Storage

Heteroatom doping is regarded as a promising method to enhance the sodium storage performance of carbon materials. In this work, a sulfur‐enriched N‐doped multichannel hollow carbon nanofiber (denoted as S‐NCNF) film is prepared through electrospinning technology and heat treatment with sublimed sulfur as the flexible anode for sodium ion batteries (NIBs). The S‐NCNF film displays outstanding electrochemical performance, particularly with a high rate capacity (132 mA h g^?1 at the current density of 10 A g^?1) and remarkable long cycling stability (reversible specific capacity of 187 mA h g^?1 at 2 A g^?1 over 2000 cycles). The improved sodium storage performance results from the unique 3D structure, abundant defects, and increased interlayer spacing of S‐NCNFs. The density functional theory calculations demonstrate that nitrogenous carbon nanofibers doping with sulfur could not only promote the adsorption of sodium but also favor electrons' transfer. This strategy has been demonstrated as a general process to design free‐standing carbon‐based thin film with other heteroatom doping.     

Glucose‐Induced Synthesis of 1T‐MoS2/C Hybrid for High‐Rate Lithium‐Ion Batteries

1T phase MoS₂ possesses higher conductivity than the 2H phase, which is a key parameter of electrochemical performance for lithium ion batteries (LIBs). Herein, a 1T‐MoS₂/C hybrid is successfully synthesized through facile hydrothermal method with a proper glucose additive. The synthesized hybrid material is composed of smaller and fewer‐layer 1T‐MoS₂ nanosheets covered by thin carbon layers with an enlarged interlayer spacing of 0.94 nm. When it is used as an anode material for LIBs, the enlarged interlayer spacing facilitates rapid intercalating and deintercalating of lithium ions and accommodates volume change during cycling. The high intrinsic conductivity of 1T‐MoS₂ also contributes to a faster transfer of lithium ions and electrons. Moreover, much smaller and fewer‐layer nanosheets can shorten the diffusion path of lithium ions and accelerate reaction kinetics, leading to an improved electrochemical performance. It delivers a high initial capacity of 920.6 mAh g^?1 at 1 A g^?1 and the capacity can maintain 870 mAh g^?1 even after 300 cycles, showing a superior cycling stability. The electrode presents a high rate performance as well with a reversible capacity of 600 mAh g^?1 at 10 A g^?1. These results show that the 1T‐MoS₂/C hybrid shows potential for use in high‐performance lithium‐ion batteries.     

Ultrahigh Rate Performance of Hollow Antimony Nanoparticles Impregnated in Open Carbon Boxes for Sodium‐Ion Battery under Elevated Temperature

Antimony is a competitive and promising anode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, the poor rate capability and fast capacity fading greatly restrict its practical application. To address the above issues, a facile and eco‐friendly sacrificial template method is developed to synthesize hollow Sb nanoparticles impregnated in open carbon boxes (Sb HPs@OCB). The as‐obtained Sb HPs@OCB composite exhibits excellent sodium storage properties even when operated at an elevated temperature of 50 °C, delivering a robust rate capability of 345 mAh g^?1 at 16 A g^?1 and rendering an outstanding reversible capacity of 187 mAh g^?1 at a high rate of 10 A g^?1 after 300 cycles. Such superior electrochemical performance of the Sb HPs@OCB can be attributed to the comprehensive characteristics of improved kinetics derived from hollow Sb nanoparticles impregnated into 2D carbon nanowalls, the existence of robust Sb? O? C bond, and enhanced pseudocapacitive behavior. All those factors enable Sb HPs@OCB great potential and distinct merit for large‐scale energy storage of SIBs.     

Rational Design and General Synthesis of S‐Doped Hard Carbon with Tunable Doping Sites toward Excellent Na‐Ion Storage Performance

Heteroatom‐doping is a promising strategy to tuning the microstructure of carbon material toward improved electrochemical storage performance. However, it is a big challenge to control the doping sites for heteroatom‐doping and the rational design of doping is urgently needed. Herein, S doping sites and the influence of interlayer spacing for two kinds of hard carbon, perfect structure and vacancy defect structure, are explored by the first‐principles method. S prefers doping in the interlayer for the former with interlayer distance of 3.997 Å, while S is doped on the carbon layer for the latter with interlayer distance of 3.695 Å. More importantly, one step molten salts method is developed as a universal synthetic strategy to fabricate hard carbon with tunable microstructure. It is demonstrated by the experimental results that S‐doping hard carbon with fewer pores exhibits a larger interlayer spacing than that of porous carbon, agreeing well with the theoretical prediction. Furthermore, the S‐doping carbon with larger interlayer distance and fewer pores exhibits remarkably large reversible capacity, excellent rate performance, and long‐term cycling stability for Na‐ion storage. A stable and reversible capacity of ≈200 mAh g^?1 is steadily kept even after 4000 cycles at 1 A g^?1.     

Strong Surface‐Bound Sulfur in Carbon Nanotube Bridged Hierarchical Mo2C‐Based MXene Nanosheets for Lithium–Sulfur Batteries

In this work, hydroxyl‐functionalized Mo₂C‐based MXene nanosheets are synthesized by facilely removing the Sn layer of Mo₂SnC. The hydroxyl‐functionalized surface of Mo₂C suppresses the shuttle effect of lithium polysulfides (LiPSs) through strong interaction between Mo atoms on the MXenes surface and LiPSs. Carbon nanotubes (CNTs) are further introduced into Mo₂C phase to enlarge the specific surface area of the composite, improve its electronic conductivity, and alleviate the volume change during discharging/charging. The strong surface‐bound sulfur in the hierarchical Mo₂C‐CNTs host can lead to a superior electrochemical performance in lithium–sulfur batteries. A large reversible capacity of ≈925 mAh g ^{? 1} is observed after 250 cycles at a current density of 0.1 C (1 C = 1675 mAh g^?1) with good rate capability. Notably, the electrodes with high loading amounts of sulfur can also deliver good electrochemical performances, i.e., initial reversible capacities of ≈1314 mAh g^?1 (2.4 mAh cm^?2), ≈1068 mAh g^?1 (3.7 mAh cm^?2), and ≈959 mAh g^?1 (5.3 mAh cm^?2) at various areal loading amounts of sulfur (1.8, 3.5, and 5.6 mg cm^?2) are also observed, respectively.     

Na2Ti6O13 Nanorods with Dominant Large Interlayer Spacing Exposed Facet for High‐Performance Na‐Ion Batteries

As the delegate of tunnel structure sodium titanates, Na₂Ti₆O₁₃ nanorods with dominant large interlayer spacing exposed facet are prepared. The exposed large interlayers provide facile channels for Na⁺ insertion and extraction when this material is used as anode for Na‐ion batteries (NIBs). After an activation process, this NIB anode achieves a high specific capacity (a capacity of 172 mAh g^?1 at 0.1 A g^?1) and outstanding cycling stability (a capacity of 109 mAh g^?1 after 2800 cycles at 1 A g^?1), showing its promising application on large‐scale energy storage systems. Furthermore, the electrochemical and structural characterization reveals that the expanded interlayer spacings should be in charge of the activation process, including the enhanced kinetics, the lowered apparent activation energy, and the increased capacity.     

Polyethylenimine Expanded Graphite Oxide Enables High Sulfur Loading and Long‐Term Stability of Lithium–Sulfur Batteries

To realize practical lithium–sulfur batteries (LSBs) with long cycling life, designing cathode hosts with a high specific surface area (SSA) is recognized as an efficient way to trap the soluble polysulfides. However, it is also blamed for diminishing the volumetric energy density and being susceptible to side reactions. Herein, polyethylenimine intercalated graphite oxide (PEI‐GO) with a low SSA of 4.6 m² g^?1 and enlarged interlayer spacing of 13 Å is proposed as a superior sulfur host, which enables homogeneous distribution of high sulfur content (73%) and facilitates Li⁺ transfer in thick sulfur electrode. LSBs with a moderate sulfur loading (3.4 mg S cm^?2) achieve an initial capacity of 1157 and 668 mAh g^?1 after 500 cycles at 0.5 C. Even when the sulfur loading is increased to 7.3 mg cm^?2, the electrode still delivers a high areal capacity of 4.7 mAh cm^?2 (641 mAh g^?1) after 200 cycles at 0.2 C. The excellent electrochemical properties of PEI‐GO are mainly attributed to the homogeneous distribution of sulfur in PEI‐GO and the strong chemical interactions between polysulfides and amine groups, which can mitigate the loss of active phases and contribute to the better cycling stability.     

Superresilient Hard Carbon Nanofabrics for Sodium‐Ion Batteries

Developing supermechanically resilient hard carbon materials that can quickly accommodate sodium ions is highly demanded in fabricating durable anodes for wearable sodium‐ion batteries. Here, an interconnected spiral nanofibrous hard carbon fabric with both remarkable resiliency (e.g., recovery rate as high as 1200 mm s^?1) and high Young's modulus is reported. The hard carbon nanofabrics are prepared by spinning and then carbonizing the reaction product of polyacrylonitrile and polar molecules (melamine). The resulting unique hard carbon possesses a highly disordered carbonaceous structure with enlarged interlayer spacing contributed from the strong electrostatic repulsion of dense pyrrolic nitrogen atoms. Its excellent resiliency remains after intercalation/deintercalation of sodium ions. The outstanding sodium‐storage performance of the derived anode includes excellent gravimetric capacity, high‐power capability, and long‐term cyclic stability. More significantly, with a high loading mass, the hard carbon anode displays a high‐power capacity (1.05 mAh cm^?2 at 2 A g^?1) and excellent cyclic stability. This study provides a unique strategy for the design and fabrication of new hard carbon materials for advanced wearable energy storage systems.     

Multidimensional Integrated Chalcogenides Nanoarchitecture Achieves Highly Stable and Ultrafast Potassium‐Ion Storage

Potassium‐ion batteries (KIBs) have come into the spotlight in large‐scale energy storage systems because of cost‐effective and abundant potassium resources. However, the poor rate performance and problematic cycle life of existing electrode materials are the main bottlenecks to future potential applications. Here, the first example of preparing 3D hierarchical nanoboxes multidimensionally assembled from interlayer‐expanded nano‐2D MoS₂@dot‐like Co₉S₈ embedded into a nitrogen and sulfur codoped porous carbon matrix (Co₉S₈/NSC@MoS₂@NSC) for greatly boosting the electrochemical properties of KIBs in terms of reversible capacity, rate capability, and cycling lifespan, is reported. Benefiting from the synergistic effects, Co₉S₈/NSC@MoS₂@NSC manifest a very high reversible capacity of 403 mAh g^?1 at 100 mA g^?1 after 100 cycles, an unprecedented rate capability of 141 mAh g^?1 at 3000 mA g^?1 over 800 cycles, and a negligible capacity decay of 0.02% cycle^?1, boosting promising applications in high‐performance KIBs. Density functional theory calculations demonstrate that Co₉S₈/NSC@MoS₂@NSC nanoboxes have large adsorption energy and low diffusion barriers during K‐ion storage reactions, implying fast K‐ion diffusion capability. This work may enlighten the design and construction of advanced electrode materials combined with strong chemical bonding and integrated functional advantages for future large‐scale stationary energy storage.     

Novel Structural Design and Adsorption/Insertion Coordinating Quasi-Metallic Na Storage Mechanism toward High-performance Hard Carbon Anode Derived from Carboxymethyl Cellulose

Hard Carbon have become the most promising anode candidates for sodium-ion batteries, but the poor rate performance and cycle life remain key issues. In this work, N-doped hard carbon with abundant defects and expanded interlayer spacing is constructed by using carboxymethyl cellulose sodium as precursor with the assistance of graphitic carbon nitride. The formation of N-doped nanosheet structure is realized by the C N• or C C• radicals generated through the conversion of nitrile intermediates in the pyrolysis process. This greatly enhances the rate capability (192.8 mAh g⁻¹ at 5.0 A g⁻¹) and ultra-long cycle stability (233.3 mAh g⁻¹ after 2000 cycles at 0.5 A g⁻¹). In situ Raman spectroscopy, ex situ X-ray diffraction and X-ray photoelectron spectroscopy analysis in combination with comprehensive electrochemical characterizations, reveal that the interlayer insertion coordinated quasi-metallic sodium storage in the low potential plateau region and adsorption storage in the high potential sloping region. The first-principles density functional theory calculations further demonstrate strong coordination effect on nitrogen defect sites to capture sodium, especially with pyrrolic N, uncovering the formation mechanism of quasi-metallic bond in the sodium storage. This work provides new insights into the sodium storage mechanism of high-performance carbonaceous materials, and offers new opportunities for better design of hard carbon anode.     

Confined Amorphous Red Phosphorus in MOF‐Derived N‐Doped Microporous Carbon as a Superior Anode for Sodium‐Ion Battery

Red phosphorus (P) has attracted intense attention as promising anode material for high‐energy density sodium‐ion batteries (NIBs), owing to its high sodium storage theoretical capacity (2595 mAh g^?1). Nevertheless, natural insulating property and large volume variation of red P during cycling result in extremely low electrochemical activity, leading to poor electrochemical performance. Herein, the authors demonstrate a rational strategy to improve sodium storage performance of red P by confining nanosized amorphous red P into zeolitic imidazolate framework‐8 (ZIF‐8) ‐derived nitrogen‐doped microporous carbon matrix (denoted as P@N‐MPC). When used as anode for NIBs, the P@N‐MPC composite displays a high reversible specific capacity of ≈600 mAh g^?1 at 0.15 A g^?1 and improved rate capacity (≈450 mAh g^?1 at 1 A g^?1 after 1000 cycles with an extremely low capacity fading rate of 0.02% per cycle). The superior sodium storage performance of the P@N‐MPC is mainly attributed to the novel structure. The N‐doped porous carbon with sub‐1 nm micropore facilitates the rapid diffusion of organic electrolyte ions and improves the conductivity of the encapsulated red P. Furthermore, the porous carbon matrix can buffer the volume change of red P during repeat sodiation/desodiation process, keeping the structure intact after long cycle life.     

Peapod‐like Li3VO4/N‐Doped Carbon Nanowires with Pseudocapacitive Properties as Advanced Materials for High‐Energy Lithium‐Ion Capacitors

Lithium ion capacitors are new energy storage devices combining the complementary features of both electric double‐layer capacitors and lithium ion batteries. A key limitation to this technology is the kinetic imbalance between the Faradaic insertion electrode and capacitive electrode. Here, we demonstrate that the Li₃VO₄ with low Li‐ion insertion voltage and fast kinetics can be favorably used for lithium ion capacitors. N‐doped carbon‐encapsulated Li₃VO₄ nanowires are synthesized through a morphology‐inheritance route, displaying a low insertion voltage between 0.2 and 1.0 V, a high reversible capacity of ≈400 mAh g^?1 at 0.1 A g^?1, excellent rate capability, and long‐term cycling stability. Benefiting from the small nanoparticles, low energy diffusion barrier and highly localized charge‐transfer, the Li₃VO₄/N‐doped carbon nanowires exhibit a high‐rate pseudocapacitive behavior. A lithium ion capacitor device based on these Li₃VO₄/N‐doped carbon nanowires delivers a high energy density of 136.4 Wh kg^?1 at a power density of 532 W kg^?1, revealing the potential for application in high‐performance and long life energy storage devices.     

N‐Doped Carbon Nanofibers with Interweaved Nanochannels for High‐Performance Sodium‐Ion Storage

Although graphite materials have been applied as commercial anodes in lithium‐ion batteries (LIBs), there still remain abundant spaces in the development of carbon‐based anode materials for sodium‐ion batteries (SIBs). Herein, an electrospinning route is reported to fabricate nitrogen‐doped carbon nanofibers with interweaved nanochannels (NCNFs‐IWNC) that contain robust interconnected 1D porous channels, produced by removal of a Te nanowire template that is coelectrospun within carbon nanofibers during the electrospinning process. The NCNFs‐IWNC features favorable properties, including a conductive 1D interconnected porous structure, a large specific surface area, expanded interlayer graphite‐like spacing, enriched N‐doped defects and active sites, toward rapid access and transport of electrolyte and electron/sodium ions. Systematic electrochemical studies indicate that the NCNFs‐IWNC exhibits an impressively high rate capability, delivering a capacity of 148 mA h g^?1 at current density of as high as 10 A g^?1, and has an attractively stable performance over 5000 cycles. The practical application of the as‐designed NCNFs‐IWNC for a full SIBs cell is further verified by coupling the NCNFs‐IWNC anode with a FeFe(CN)₆ cathode, which displays a desirable cycle performance, maintaining acapacity of 97 mA h g^?1 over 100 cycles.     

Electrolyte‐Dependent Sodium Ion Transport Behaviors in Hard Carbon Anode

A comprehensive study is conducted on hard carbon (HC) series samples by tuning the graphitic local microstructures systematically as an anode for SIBs in both carbonate‐ (CBE) and glyme‐based electrolytes (GBE). The results reveal more detailed charge storage characters of HCs on the LVP section. 1) The LVP capacity is closely related to the prismatic surface area to the basal plane as well as the bulk density, regardless of electrolyte systems. 2) The glyme‐sodium ion complex can facilitate sodium ion delivery into the internal closed pores of the HCs along with not well‐ordered graphitic structures. 3) The glyme‐mediated sodium ion‐storage behavior causes significant decreases in both surface film resistance and charge transfer resistance, leading to enhanced rate capability. 4) The LVP originates from the formation of pseudo‐metallic sodium nanoclusters, which are the same in a CBE and GBE. These results provide insight into the sodium ion‐storage behaviors of HCs, particularly on the interrelationship between graphitic local microstructures and electrolyte systems. In addition, a high‐performance HC anode with a plateau capacity of ≈300 mA h g^?1 is designed based on the information, and its workability is demonstrated in a full‐cell SIB device.     

Efficient Laser‐Induced Construction of Oxygen‐Vacancy Abundant Nano‐ZnCo2O4/Porous Reduced Graphene Oxide Hybrids toward Exceptional Capacitive Lithium Storage

Recently, binary ZnCo₂O₄ has drawn enormous attention for lithium‐ion batteries (LIBs) as attractive anode owing to its large theoretical capacity and good environmental benignity. However, the modest electrical conductivity and serious volumetric effect/particle agglomeration over cycling hinder its extensive applications. To address the concerns, herein, a rapid laser‐irradiation methodology is firstly devised toward efficient synthesis of oxygen‐vacancy abundant nano‐ZnCo₂O₄/porous reduced graphene oxide (rGO) hybrids as anodes for LIBs. The synergistic contributions from nano‐dimensional ZnCo₂O₄ with rich oxygen vacancies and flexible rGO guarantee abundant active sites, fast electron/ion transport, and robust structural stability, and inhibit the agglomeration of nanoscale ZnCo₂O₄, favoring for superb electrochemical lithium‐storage performance. More encouragingly, the optimal L‐ZCO@rGO‐30 anode exhibits a large reversible capacity of ≈1053 mAh g^?1 at 0.05 A g^?1, excellent cycling stability (≈746 mAh g^?1 at 1.0 A g^?1 after 250 cycles), and preeminent rate capability (≈686 mAh g^?1 at 3.2 A g^?1). Further kinetic analysis corroborates that the capacitive‐controlled process dominates the involved electrochemical reactions of hybrid anodes. More significantly, this rational design holds the promise of being extended for smart fabrication of other oxygen‐vacancy abundant metal oxide/porous rGO hybrids toward advanced LIBs and beyond.     

Hydrothermally Oxidized Single‐Walled Carbon Nanotube Networks for High Volumetric Electrochemical Energy Storage

Improving volumetric energy density is one of the major challenges in nanostructured carbon electrodes for electrochemical energy storage device applications. Herein, a simple hydrothermal oxidation process of single‐walled carbon nanotube (SWNT) networks in dilute nitric acid is reported, enabling simultaneous physical densification and chemical functionalization of the as‐assembled randomly‐packed SWNT films. After the hydrothermal oxidation process, the density of the SWNT films increases from 0.63 to 1.02 g cm^?3 and a considerable amount of redox‐active oxygen functional groups are introduced on the surface of the SWNTs. The functionalized SWNT films are used as positive electrodes against Li metal negative electrodes for potential Li‐ion capacitors or Li‐ion battery applications. The functionalized SWNT electrodes deliver high volumetric as well as gravimetric capacities, 154 Ah L^?1 and 152 mAh g^?1, respectively, owing to the surface redox reactions between the introduced oxygen functional groups and Li ions. In addition, these electrodes exhibit a remarkable rate‐capability by retaining its high capacity of 94 Ah L^?1 (92 mAh g^?1) at a high discharge rate of 10 A g^?1. These results demonstrate the simple hydrothermal oxidation process as an attractive strategy for improving the volumetric performance of nanostructured carbon electrodes.     

Flexible 3D Porous MXene Foam for High‐Performance Lithium‐Ion Batteries

2D transition‐metal carbides and nitrides, named MXenes, are promising materials for energy storage, but suffer from aggregation and restacking of the 2D nanosheets, which limits their electrochemical performance. In order to overcome this problem and realize the full potential of MXene nanosheets, a 3D MXene foam with developed porous structure is established via a simple sulfur‐template method, which is freestanding, flexible, and highly conductive, and can be directly used as the electrode in lithium‐ion batteries. The 3D porous architecture of the MXene foam offers massive active sites to enhance the lithium storage capacity. Moreover, its foam structure facilitates electrolyte infiltration for fast Li⁺ transfer. As a result, this flexible 3D porous MXene foam exhibits significantly enhanced capacity of 455.5 mAh g^?1 at 50 mA g^?1, excellent rate performance (101 mAh g^?1 at 18 A g^?1), and superior ultralong‐term cycle stability (220 mAh g^?1 at 1 A g^?1 after 3500 cycles). This work not only demonstrates the great superiority of the 3D porous MXene foam but also proposes the sulfur‐template method for controllable constructing of the 3D foam from 2D nanosheets at a relatively low temperature.     

Hyperporous Sponge Interconnected by Hierarchical Carbon Nanotubes as a High‐Performance Potassium‐Ion Battery Anode

Recently, commercial graphite and other carbon‐based materials have shown promising properties as the anode for potassium‐ion batteries. A fundamental problem related to those carbon electrodes, significant volume expansion, and structural instability/collapsing caused by cyclic K‐ion intercalation, remains unsolved and severely limits further development and applications of K‐ion batteries. Here, a multiwalled hierarchical carbon nanotube (HCNT) is reported to address the issue, and a reversible specific capacity of 232 mAh g^?1, excellent rate capability, and cycling stability for 500 cycles are achieved. The key structure of the HCNTs consists of an inner CNT with dense‐stacked graphitic walls and a loose‐stacked outer CNT with more disordered walls, and individual HCNTs are further interconnected into a hyperporous bulk sponge with huge macropore volume, high conductivity, and tunable modulus. It is discovered that the inner dense‐CNT serves as a robust skeleton, and collectively, the outer loose‐CNT is beneficial for K‐ion accommodation; meanwhile the hyperporous sponge facilitates reaction kinetics and offers stable surface capacitive behavior. The hierarchical carbon nanotube structure has great potential in developing high‐performance and stable‐structure electrodes for next generation K and other metal‐ion batteries.     

Self‐Formed Electronic/Ionic Conductive Fe3S4 @ S @ 0.9Na3SbS4⋅0.1NaI Composite for High‐Performance Room‐Temperature All‐Solid‐State Sodium–Sulfur Battery

Fe₃S₄ @ S @ 0.9Na₃SbS₄?0.1NaI composite cathode is prepared through one‐step wet‐mechanochemical milling procedure. During milling process, ionic conduction pathway is self‐formed in the composite due to the formation of 0.9Na₃SbS₄?0.1NaI electrolyte without further annealing treatment. Meanwhile, the introduction of Fe₃S₄ can increase the electronic conductivity of the composite cathode by one order of magnitude and nearly double enhance the ionic conductivities. Besides, the aggregation of sulfur is effectively suppressed in the obtained Fe₃S₄ @ S @ 0.9Na₃SbS₄?0.1NaI composite, which will enhance the contact between sulfur and 0.9Na₃SbS₄?0.1NaI electrolyte, leading to a decreased interfacial resistance and improving the electrochemical kinetics of sulfur. Therefore, the resultant all‐solid‐state sodium–sulfur battery employing Fe₃S₄ @ S @ 0.9Na₃SbS₄?0.1NaI composite cathode shows discharge capacity of 808.7 mAh g^?1 based on Fe₃S₄@S and a normalized discharge capacity of 1040.5 mAh g^?1 for element S at 100 mA g^?1 for 30 cycles at room temperature. Moreover, the battery also exhibits excellent cycling stability with a reversible capacity of 410 mAh g^?1 at 500 mA g^?1 for 50 cycles, and superior rate capability with capacities of 952.4, 796.7, 513.7, and 445.6 mAh g^?1 at 50, 100, 200, and 500 mA g^?1, respectively. This facile strategy for sulfur‐based composite cathode is attractive for achieving room‐temperature sodium–sulfur batteries with superior electrochemical performance.