Structural Transformation by Crystal Engineering Endows Aqueous Zinc-Ion Batteries with Ultra-long Cyclability

Manganese oxide is a promising cathode material for aqueous zinc batteries. However, its weak structural stability, low electrical conductivity, and sluggish reaction kinetics lead to rapid capacity fading. Herein, a crystal engineering strategy is proposed to construct a novel MnO₂ cathode material. Both experimental results and theoretical calculations demonstrate that Al-doping plays a crucial role in phase transition and doping-superlattice structure construction, which stabilizes the structure of MnO₂ cathode materials, improves conductivity, and accelerates ion diffusion dynamics. As a result, 1.98% Al-doping MnO₂ (AlMO) cathode shows an incredible 15 000 cycle stability with a low capacity decay rate of 0.0014% per cycle at 4 A g⁻¹. Additionally, it provides superior specific capacity of 311.2 mAh g⁻¹ at 0.1 A g⁻¹ and excellent rate performance (145.2 mAh g⁻¹ at 5.0 A g⁻¹). To illustrate the potential of 1.98%AlMO to be applied in actual practice, flexible energy storage devices are fabricated and measured. These discoveries provide a new insight for structural transformation via crystal engineering, as well as a new avenue for the rational design of electrode material in other battery systems.     

Isostructural and Multivalent Anion Substitution toward Improved Phosphate Cathode Materials for Sodium‐Ion Batteries

Polyanion‐type phosphate materials are highly promising cathode candidates for next‐generation batteries due to their excellent structural stability during cycling; however, their poor conductivity has impeded their development. Isostructural and multivalent anion substitution combined with carbon coating is proposed to greatly improve the electrochemical properties of phosphate cathode in sodium‐ion batteries (SIBs). Specifically, multivalent tetrahedral SiO₄^4? substitute for PO₄^3? in Na₃V₂(PO₄)₃ (NVP) lattice, preparing the optimal Na_3.1V₂(PO₄)_2.9(SiO₄)_0.1 with high‐rate capability (delivering a high capacity of 82.5 mAh g^?1 even at 20 C) and outstanding cyclic stability (≈98% capacity retention after 500 cycles at 1 C). Theoretical calculation and experimental analyses reveal that the anion‐substituted Na_3.1V₂(PO₄)_2.9(SiO₄)_0.1 reduces the bandgap of NVP lattice and enhanced its structural stability, Na⁺‐diffusion kinetics and electronic conductivity. This strategy of multivalent and isostructural anion substitution chemistry provides a new insight to develop advanced phosphate cathodes.     

Triggering High Capacity and Superior Reversibility of Manganese Oxides Cathode via Magnesium Modulation for Zn//MnO2 Batteries

Aqueous zinc-ion batteries (ZIBs) have attracted extensive attention in recent years because of its high volumetric energy density, the abundance of zinc resources, and safety. However, ZIBs still suffer from poor reversibility and sluggish kinetics derived from the unstable cathodic structure and the strong electrostatic interactions between bivalent Zn²⁺ and cathodes. Herein, magnesium doping into layered manganese dioxide (Mg–MnO₂) via a simple hydrothermal method as cathode materials for ZIBs is proposed. The interconnected nanoflakes of Mg–MnO₂ possess a larger specific surface area compared to pristine δ-MnO₂, providing more electroactive sites and boosting the capacity of batteries. The ion diffusion coefficients of Mg–MnO₂ can be enhanced due to the improved electrical conductivity by doped cations and oxygen vacancies in MnO₂ lattices. The assembled Zn//Mg–MnO₂ battery delivers a high specific capacity of 370 mAh g⁻¹ at a current density of 0.6 A g⁻¹. Furthermore, the reaction mechanism confirms that Zn²⁺ insertion occurred after a few cycles of activation reactions. Most important, the reversible redox reaction between Zn²⁺ and MnOOH is found after several charge–discharge processes, promoting capacity and stability. It believes that this systematic research enlightens the design of high-performance of ZIBs and facilitates the practical application of Zn//MnO₂ batteries.     

High‐Lithium‐Affinity Chemically Exfoliated 2D Covalent Organic Frameworks

Covalent organic frameworks (COFs) with reversible redox behaviors are potential electrode materials for lithium‐ion batteries (LIBs). However, the sluggish lithium diffusion kinetics, poor electronic conductivity, low reversible capacities, and poor rate performance for most reported COF materials limit their further application. Herein, a new 2D COF (TFPB‐COF) with six unsaturated benzene rings per repeating unit and ordered mesoporous pores (≈2.1 nm) is designed. A chemical stripping strategy is developed to obtain exfoliated few‐layered COF nanosheets (E‐TFPB‐COF), whose restacking is prevented by the in situ formed MnO₂ nanoparticles. Compared with the bulk TFPB‐COF, the exfoliated TFPB‐COF exhibits new active Li‐storage sites associated with conjugated aromatic π electrons by facilitating faster ion/electron kinetics. The E‐TFPB‐COF/MnO₂ and E‐TFPB‐COF electrodes exhibit large reversible capacities of 1359 and 968 mAh g^?1 after 300 cycles with good high‐rate capability.     

Recent Advances and Perspectives on the Promising High-Voltage Cathode Material of Na3(VO)2(PO4)2F

Na₃(VO)₂(PO₄)₂F (NVOPF) has emerged as one of the most promising cathode materials for sodium-ion batteries (SIBs) attributed to its high specific capacity (130 mAh g⁻¹), high operation voltage (>3.9 V vs Na⁺/Na), and excellent structural stability (<2% volume change). However, the comparatively low intrinsic electronic conductivity (≈10⁻⁷ S cm⁻¹) of NVOPF leads to unsatisfactory electrochemical performance, especially at high rates, limiting its practical applications. To improve the conductivity and enhance Na storage performance, many efforts have been devoted to designing NVOPF, including morphology optimization, hybridization with conductive materials, metal-ion doping, Na-site regulation, and F/O ratio adjustment. These attempts have shown some encouraging achievements and shed light on the practical application of NVOPF cathodes. This work aims to provide a general introduction, synthetic methods, and rational design of NVOPF to give a deeper understanding of the recent progress. Additionally, the unique microstructure of NVOPF and its relationship with Na storage properties are also described in detail. The current status, as well as the advances and limitations of such SIB cathode material, are reported. Finally, future perspectives and guidance for advancing high-performance NVOPF cathodes toward practical applications are presented.     

Nitrogen-doped porous carbon as cathodes for aluminum-ion batteries

Abstract

Aluminum-ion batteries are favorable for the next generation of rechargeable batteries by virtue of their high theoretical energy density, high safety and low cost. Graphite with excellent electronic conductivity and large surface area is likely to be the most pleasurable cathode material for aluminum-ion batteries. However, due to the lack of high-performance cathodes and cost-effective electrolytes, aluminum-ion batteries are greatly hindered. Herein, a nitrogen doped three-dimensional porous carbon material cathode (N-3PC) with controlled porous and disordered structures is synthesized via a facile heating reaction in oil bath combined with sintering method. Moreover, the controlled porous structures by the Zn(NO₃)₂ pore-forming agent method support a very large specific surface area, which is beneficial to a relatively high initial Coulombic efficiency. In terms of open porous structures of N-3PC, the increased disordered structures can not only benefit the diffusion of Al³⁺ ions but also enlarge the reversible capacity of Al storage. When applied as cathode materials for aluminum-ion batteries, N-3PC cathode showcases rosy rate capability (33?mA h g^?1 at 500?mA g^?1) and perfect reversible capacity (13?mA h g^?1 at a high current density of 2000?mA g^?1). Furthermore, the high-performance N-3PC cathode material is prepared via a green approach stemming from low-cost and Zn(NO₃)₂ template, demonstrating a feasible development of carbon cathode materials for aluminum-ion batteries.     

Birnessite Nanosheet Arrays with High K Content as a High‐Capacity and Ultrastable Cathode for K‐Ion Batteries

Potassium‐ion batteries (PIBs) are one of the emerging energy‐storage technologies due to the low cost of potassium and theoretically high energy density. However, the development of PIBs is hindered by the poor K⁺ transport kinetics and the structural instability of the cathode materials during K⁺ intercalation/deintercalation. In this work, birnessite nanosheet arrays with high K content (K_0.77MnO₂?0.23H₂O) are prepared by “hydrothermal potassiation” as a potential cathode for PIBs, demonstrating ultrahigh reversible specific capacity of about 134 mAh g^?1 at a current density of 100 mA g^?1, as well as great rate capability (77 mAh g^?1 at 1000 mA g^?1) and superior cycling stability (80.5% capacity retention after 1000 cycles at 1000 mA g^?1). With the introduction of adequate K⁺ ions in the interlayer, the K‐birnessite exhibits highly stabilized layered structure with highly reversible structure variation upon K⁺ intercalation/deintercalation. The practical feasibility of the K‐birnessite cathode in PIBs is further demonstrated by constructing full cells with a hard–soft composite carbon anode. This study highlights effective K⁺‐intercalation for birnessite to achieve superior K‐storage performance for PIBs, making it a general strategy for developing high‐performance cathodes in rechargeable batteries beyond lithium‐ion batteries.     

High-Entropy Doping Boosts Ion/Electronic Transport of Na4Fe3(PO4)2(P2O7)/C Cathode for Superior Performance Sodium-Ion Batteries

Fe-based mixed phosphate cathodes for Na-ion batteries usually possess weak rate capacity and cycle stability challenges resulting from sluggish diffusion kinetics and poor conductivity under the relatively low preparation temperature. Here, the excellent sodium storage capability of this system is obtained by introducing the high-entropy doping to enhance the electronic and ionic conductivity. As designed high-entropy doping Na₄Fe_2.85(Ni,Co,Mn,Cu,Mg)_0.03(PO₄)₂P₂O₇ (NFPP-HE) cathode can release 122 mAh g⁻¹ at 0.1 C, even 85 mAh g⁻¹ at ultrahigh rate of 50 C, and keep a high retention of 82.3% after 1500 cycles at 10 C. Besides, the cathode also exhibits outstanding fast charge capacity in terms of the cyclability and capacity with 105 mAh g⁻¹ at 5 C/1 C, corresponding 94.3% retention after 500 cycles. The combination of in situ X-ray diffraction, density functional theory, conductive-atomic force microscopy, and galvanostatic intermittent titration technique tests reveal that the reversible structure evolution with optimized Na⁺ migration path and energy barrier boost the Na⁺ kinetics and improve the interfacial electronic transfer, thus improving performance.     

Structural insights into composition design of Li-rich layered cathode materials for high-energy rechargeable battery

The Li-rich layered oxide is considered as one of the most promising cathode materials for high energy density batteries, due to its ultrahigh capacity derived from oxygen redox. Although incorporating over-stoichiometric Li into layered structure can generate Li₂MnO₃-like domain and enhance the oxygen redox activity thermodynamically, the fast and complete activation of the Li₂MnO₃-like domain remains challenging. Herein, we performed a systematic study on structural characteristics of Li-rich cathode materials to decipher the factors accounting for activation of oxygen redox. We reveal that the activation of Li-rich cathode materials is susceptible to local Co coordination environments. The Co ions can intrude into Li₂MnO₃-like domain and modulate the electronic structure, thereby facilitating the activation of Li-rich layered cathode materials upon first charging, leading to higher reversible capacity. In contrast, Li₂MnO₃-like domain hardly contains any Ni ions which contribute little to the activation process. The optimum composition design of this class of materials is discussed and we demonstrate a small amount of Co/Mn exchange in Li₂MnO₃-like domain can significantly promote the oxygen redox activation. Our findings highlight the vital role of Co ions in the activation of oxygen redox Li-rich layered cathode materials and provide new insights into the pathway toward achieving high-capacity Li-rich layered cathode materials.     

Defect Promoted Capacity and Durability of N‐MnO2–x Branch Arrays via Low‐Temperature NH3 Treatment for Advanced Aqueous Zinc Ion Batteries

Defect engineering (doping and vacancy) has emerged as a positive strategy to boost the intrinsic electrochemical reactivity and structural stability of MnO₂‐based cathodes of rechargeable aqueous zinc ion batteries (RAZIBs). Currently, there is no report on the nonmetal element doped MnO₂ cathode with concomitant oxygen vacancies, because of its low thermal stability with easy phase transformation from MnO₂ to Mn₃O₄ (≥300 °C). Herein, for the first time, novel N‐doped MnO_2–x (N‐MnO_2–x) branch arrays with abundant oxygen vacancies fabricated by a facile low‐temperature (200 °C) NH₃ treatment technology are reported. Meanwhile, to further enhance the high‐rate capability, highly conductive TiC/C nanorods are used as the core support for a N‐MnO_2–x branch, forming high‐quality N‐MnO_2–x@TiC/C core/branch arrays. The introduced N dopants and oxygen vacancies in MnO₂ are demonstrated by synchrotron radiation technology. By virtue of an integrated conductive framework, enhanced electron density, and increased surface capacitive contribution, the designed N‐MnO_2–x@TiC/C arrays are endowed with faster reaction kinetics, higher capacity (285 mAh g^?1 at 0.2 A g^?1) and better long‐term cycles (85.7% retention after 1000 cycles at 1 A g^?1) than other MnO₂‐based counterparts (55.6%). The low‐temperature defect engineering sheds light on construction of advanced cathodes for aqueous RAZIBs.     

A High-Nickel Layered Double Hydroxides Cathode Boosting the Rate Capability for Chloride Ion Batteries with Ultralong Cycling Life

Chloride-ion batteries (CIBs) have drawn growing attention in large-scale energy storage applications owing to their comprehensive merits of high theoretical energy density, dendrite-free characteristic, and abundance of chloride-containing materials. Nonetheless, cathodes for CIBs are plagued by distinct volume effect and sluggish Cl⁻ diffusion kinetics, leading to inferior rate capability and short cycling life. Herein, an unconventional Ni₅Ti-Cl LDH is reported with a high nickel ratio as a cathode material for CIB. The reversible capacity of Ni₅Ti-Cl LDH retains 127.9 mAh g⁻¹ over 1000 cycles at a large current density of 1000 mA g⁻¹, which exceeds that of ever reported CIBs, with extraordinary low volume change of 1.006% during a whole charge/discharge process. Such superior Cl-storage performance is attributed to synergetic contributions consisting of high redox activity from Ni²⁺/Ni³⁺ and pinning Ti that restrains local structural distortion of LDH host layers and enhances adsorption intensity of chloride atoms during the reversible Cl⁻ intercalation/de-intercalation in LDH gallery, which are revealed by a comprehensive study including X-ray photoelectron spectroscopy, kinetic investigations, and DFT calculations. This work provides an effective strategy to design low-cost LDHs materials for high-performance CIBs, which are also applicable to other types of halide-ion batteries (e.g., fluoride-ion and bromide-ion batteries).     

Achieving Ultralong-Cycle Zinc-Ion Battery via Synergistically Electronic and Structural Regulation of a MnO2 Nanocrystal–Carbon Hybrid Framework

Aqueous rechargeable zinc-ion batteries (ZIBs) have attracted burgeoning interests owing to the prospect in large-scale and safe energy storage application. Although manganese oxides are one of the typical cathodes of ZIBs, their practical usage is still hindered by poor service life and rate performance. Here, a MnO₂–carbon hybrid framework is reported, which is obtained in a reaction between the dimethylimidazole ligand from a rational designed MOF array and potassium permanganate, achieving ultralong-cycle-life ZIBs. The unique structural feature of uniform MnO₂ nanocrystals which are well-distributed in the carbon matrix leads to a 90.4% capacity retention after 50 000 cycles. In situ characterization and theoretical calculations verify the co-ions intercalation with boosted reaction kinetics. The hybridization between MnO₂ and carbon endows the hybrid with enhanced electrons/ions transport kinetics and robust structural stability. This work provides a facile strategy to enhance the battery performance of manganese oxide-based ZIBs.     

Joint Charge Storage for High‐Rate Aqueous Zinc–Manganese Dioxide Batteries

Aqueous rechargeable zinc–manganese dioxide batteries show great promise for large‐scale energy storage due to their use of environmentally friendly, abundant, and rechargeable Zn metal anodes and MnO₂ cathodes. In the literature various intercalation and conversion reaction mechanisms in MnO₂ have been reported, but it is not clear how these mechanisms can be simultaneously manipulated to improve the charge storage and transport properties. A systematical study to understand the charge storage mechanisms in a layered δ‐MnO₂ cathode is reported. An electrolyte‐dependent reaction mechanism in δ‐MnO₂ is identified. Nondiffusion controlled Zn²⁺ intercalation in bulky δ‐MnO₂ and control of H⁺ conversion reaction pathways over a wide C‐rate charge–discharge range facilitate high rate performance of the δ‐MnO₂ cathode without sacrificing the energy density in optimal electrolytes. The Zn‐δ‐MnO₂ system delivers a discharge capacity of 136.9 mAh g^?1 at 20 C and capacity retention of 93% over 4000 cycles with this joint charge storage mechanism. This study opens a new gateway for the design of high‐rate electrode materials by manipulating the effective redox reactions in electrode materials for rechargeable batteries.     

Highly Flexible K-Intercalated MnO2/Carbon Membrane for High-Performance Aqueous Zinc-Ion Battery Cathode

The layered MnO₂ is intensively investigated as one of the most promising cathode materials for aqueous zinc-ion batteries (AZIBs), but its commercialization is severely impeded by the challenging issues of the inferior intrinsic electronic conductivity and undesirable structural stability during the charge–discharge cycles. Herein, the lab-prepared flexible carbon membrane with highly electrical conductivity is first used as the matrix to generate ultrathin δ-MnO₂ with an enlarged interlayer spacing induced by the K⁺-intercalation to potentially alleviate the structural damage caused by H⁺/Zn²⁺ co-intercalation, resulting in a high reversible capacity of 190 mAh g⁻¹ at 3 A g⁻¹ over 1000 cycles. The in situ/ex-situ characterizations and electrochemical analysis confirm that the enlarged interlayer spacing can provide free space for the reversible deintercalation/intercalation of H⁺/Zn²⁺ in the structure of δ-MnO₂, and H⁺/Zn²⁺ co-intercalation mechanism contributes to the enhanced charge storage in the layered K⁺-intercalated δ-MnO₂. This work provides a plausible way to construct a flexible carbon membrane-based cathode for high-performance AZIBs.     

3D Honeycomb Architecture Enables a High‐Rate and Long‐Life Iron (III) Fluoride–Lithium Battery

Metal fluoride–lithium batteries with potentially high energy densities, even higher than lithium–sulfur batteries, are viewed as very promising candidates for next‐generation lightweight and low‐cost rechargeable batteries. However, so far, metal fluoride cathodes have suffered from poor electronic conductivity, sluggish reaction kinetics and side reactions causing high voltage hysteresis, poor rate capability, and rapid capacity degradation upon cycling. Herein, it is reported that an FeF₃@C composite having a 3D honeycomb architecture synthesized by a simple method may overcome these issues. The FeF₃ nanoparticles (10–50 nm) are uniformly embedded in the 3D honeycomb carbon framework where the honeycomb walls and hexagonal‐like channels provide sufficient pathways for the fast electron and Li‐ion diffusion, respectively. As a result, the as‐produced 3D honeycomb FeF₃@C composite cathodes even with high areal FeF₃ loadings of 2.2 and 5.3 mg cm^?2 offer unprecedented rate capability up to 100 C and remarkable cycle stability within 1000 cycles, displaying capacity retentions of 95%–100% within 200 cycles at various C rates, and ≈85% at 2C within 1000 cycles. The reported results demonstrate that the 3D honeycomb architecture is a powerful composite design for conversion‐type metal fluorides to achieve excellent electrochemical performance in metal fluoride–lithium batteries.     

Electrophoretic deposition of Y2O3-stabilized ZrO2 nanoparticles on the surface of dense La0.7Sr0.3MnO3−δ cathodes produced by pyrolysis and solid-state reaction

La_0.7Sr_0.3MnO_3?δ (LSM) cathode materials have been prepared through pyrolysis of liquid precursors and by solid-state reaction. We examined the effect of the cathode material synthesis procedure on the growth of thin films of a solid electrolyte based on Y₂O₃-stabilized ZrO₂ (YSZ) nanopowder with an average geometric size of 10.9 nm on a dense surface of model cathodes by electrophoretic deposition. Using electron microscopy, BET surface area measurements, X-ray diffraction, thermal analysis, and dilatometry, we investigated the structure, specific surface area, phase composition, thermal properties, and sintering-induced volume changes of cathode materials differing in prior history. The results demonstrate that the starting cathode materials differed markedly in properties, but the cathodes produced by sintering them were identical in phase composition: they consisted entirely of a rhombohedral phase. The room-temperature electrical conductivity of the cathodes produced by solid-state reaction was 0.231 ± 0.01 S/cm, exceeding that of the cathodes produced through pyrolysis by an order of magnitude.     

Robust,Ultra‐Tough Flexible Cathodes for High‐Energy Li–S Batteries

Sulfur cathodes have become appealing for rechargeable batteries because of their high theoretical capacity (1675 mA h g^?1). However, the conventional cathode configuration borrowed from lithium‐ion batteries may not allow the pure sulfur cathode to put its unique materials chemistry to good use. The solid_(sulfur)–liquid_{(polysulfides)}–solid_(sulfides) phase transitions generate polysulfide intermediates that are soluble in the commonly used organic solvents in Li–S cells. The resulting severe polysulfide diffusion and the irreversible active‐material loss have been hampering the development of Li–S batteries for years. The present study presents a robust, ultra‐tough, flexible cathode with the active‐material fillings encapsulated between two buckypapers (B), designated as buckypaper/sulfur/buckypaper (B/S/B) cathodes, that suppresses the irreversible polysulfide diffusion to the anode and offers excellent electrochemical reversibility with a low capacity fade rate of 0.06% per cycle after 400 cycles. Engineering enhancements demonstrate that the B/S/B cathodes represent a facile approach for the development of high‐performance sulfur electrodes with a high areal capacity of 5.1 mA h cm^?2, which increases further to approach 7 mA h cm^?2 on coupling with carbon‐coated separators.     

3D Co-Doping α-Ni(OH)2 Nanosheets for Ultrastable,High-Rate Ni-Zn Battery

The α-Ni(OH)₂ is regarded as one promising cathode for aqueous nickel-zinc batteries due to its high theoretical capacity of ≈480 mAh g⁻¹, its practical deployment however suffers from the poor stability in strong alkaline solution, intrinsic low electrical conductivity as well as the retarded ionic diffusion. Herein, a 3D (three dimensional) macroporous α-Ni(OH)₂ nanosheets with Co doping is designed through a facile and easily scalable electroless plating combined with electrodeposition strategy. The unique micrometer-sized 3D pores come from Ni substrate and rich voids between Co-doping α-Ni(OH)₂ nanosheets can synergistically afford facile, interconnected ionic diffusion channels, sufficient free space for accommodating its volume changes during cycling; meanwhile, the Co-doping can stabilize the structural robustness of the α-Ni(OH)₂ in the alkaline electrolyte during cycling. Thus, the 3D α-Ni(OH)₂ shows a high capacity of 284 mAh g⁻¹ at 0.5 mA cm⁻² with an excellent retention of 78% even at 15 mA cm⁻², and more than 2000 stable cycles at 6 mA cm⁻², as well as the robust cycling upon various flexible batteries. This work provides a simple and efficient pathway to enhance the electrochemical performance of Ni-Zn batteries through improving ionic transport kinetics and stabilizing crystal structure of cathodes.     

3D Hollow α‐MnO2 Framework as an Efficient Electrocatalyst for Lithium–Oxygen Batteries

Lithium–oxygen (Li–O₂) batteries are attracting more attention owing to their superior theoretical energy density compared to conventional Li‐ion battery systems. With regards to the catalytically electrochemical reaction on a cathode, the electrocatalyst plays a key role in determining the performance of Li–O₂ batteries. Herein, a new 3D hollow α‐MnO₂ framework (3D α‐MnO₂) with porous wall assembled by hierarchical α‐MnO₂ nanowires is prepared by a template‐induced hydrothermal reaction and subsequent annealing treatment. Such a distinctive structure provides some essential properties for Li–O₂ batteries including the intrinsic high catalytic activity of α‐MnO₂, more catalytic active sites of hierarchical α‐MnO₂ nanowires on 3D framework, continuous hollow network and rich porosity for the storage of discharge product aggregations, and oxygen diffusion. As a consequence, 3D α‐MnO₂ achieves a high specific capacity of 8583 mA h g^?1 at a current density of 100 mA g^?1, a superior rate capacity of 6311 mA h g^?1 at 300 mA g^?1, and a very good cycling stability of 170 cycles at a current density of 200 mA g^?1 with a fixed capacity of 1000 mA h g^?1. Importantly, the presented design strategy of 3D hollow framework in this work could be extended to other catalytic cathode design for Li–O₂ batteries.     

Yolk–Shelled C@Fe3O4 Nanoboxes as Efficient Sulfur Hosts for High‐Performance Lithium–Sulfur Batteries

Owing to the high theoretical specific capacity (1675 mA h g^?1) and low cost, lithium–sulfur (Li–S) batteries offer advantages for next‐generation energy storage. However, the polysulfide dissolution and low electronic conductivity of sulfur cathodes limit the practical application of Li–S batteries. To address such issues, well‐designed yolk–shelled carbon@Fe₃O₄ (YSC@Fe₃O₄) nanoboxes as highly efficient sulfur hosts for Li–S batteries are reported here. With both physical entrapment by carbon shells and strong chemical interaction with Fe₃O₄ cores, this unique architecture immobilizes the active material and inhibits diffusion of the polysulfide intermediates. Moreover, due to their high conductivity, the carbon shells and the polar Fe₃O₄ cores facilitate fast electron/ion transport and promote continuous reactivation of the active material during the charge/discharge process, resulting in improved electrochemical utilization and reversibility. With these merits, the S/YSC@Fe₃O₄ cathodes support high sulfur content (80 wt%) and loading (5.5 mg cm^?2) and deliver high specific capacity, excellent rate capacity, and long cycling stability. This work provides a new perspective to design a carbon/metal‐oxide‐based yolk–shelled framework as a high sulfur‐loading host for advanced Li–S batteries with superior electrochemical properties.