A Hollow‐Shell Structured V2O5 Electrode‐Based Symmetric Full Li‐Ion Battery with Highest Capacity

The symmetric batteries with an electrode material possessing dual cathodic and anodic properties are regarded as an ideal battery configuration because of their distinctive advantages over the asymmetric batteries in terms of fabrication process, cost, and safety concerns. However, the development of high‐performance symmetric batteries is highly challenging due to the limited availability of suitable symmetric electrode materials with such properties of highly reversible capacity. Herein, a triple‐hollow‐shell structured V₂O₅ (THS‐V₂O₅) symmetric electrode material with a reversible capacity of >400 mAh g^?1 between 1.5 and 4.0 V and >600 mAh g^?1 between 0.1 and 3.0 V, respectively, when used as the cathode and anode, is reported. The THS‐V₂O₅ electrodes assembled symmetric full lithium‐ion battery (LIB) exhibits a reversible capacity of ≈290 mAh g^?1 between 2 and 4.0 V, the best performed symmetric energy storage systems reported to date. The unique triple‐shell structured electrode makes the symmetric LIB possessing very high initial coulombic efficiency (94.2%), outstanding cycling stability (with 94% capacity retained after 1000 cycles), and excellent rate performance (over 140 mAh g^?1 at 1000 mA g^?1). The demonstrated approach in this work leaps forward the symmetric LIB performance and paves a way to develop high‐performance symmetric battery electrode materials.     

Covalent Encapsulation of Sulfur in a MOF‐Derived S,N‐Doped Porous Carbon Host Realized via the Vapor‐Infiltration Method Results in Enhanced Sodium–Sulfur Battery Performance

Practical applications of room temperature sodium–sulfur batteries are still inhibited by the poor conductivity and slow reaction kinetics of sulfur, and dissolution of intermediate polysulfides in the commonly used electrolytes. To address these issues, starting from a novel 3D Zn‐based metal–organic framework with 2,5‐thiophenedicarboxylic acid and 1,4‐bis(pyrid‐4‐yl) benzene as ligands, a S, N‐doped porous carbon host with 3D tubular holes for sulfur storage is fabricated. In contrast to the commonly used melt‐diffusion method to confine sulfur physically, a vapor‐infiltration method is utilized to achieve sulfur/carbon composite with covalent bonds, which can join electrochemical reaction without low voltage activation. A polydopamine derived N‐doped carbon layer is further coated on the composite to confine the high‐temperature‐induced gas‐phase sulfur inside the host. S and N dopants increase the polarity of the carbon host to restrict diffusion of sulfur, and its 3D porous structure provides a large storage area for sulfur. As a result, the obtained composite shows outstanding electrochemical performance with 467 mAh g^?1 (1262 mAh g^?1_(sulfur)) at 0.1 A g^?1, 270 mAh g^?1 (730 mAh g^?1_(sulfur)) after 1000 cycles at 1 A g^?1 and 201 mAh g^?1 (543 mAh g^?1_(sulfur)) at 5.0 A g^?1.     

Direct Growth of Flower‐Like δ‐MnO2 on Three‐Dimensional Graphene for High‐Performance Rechargeable Li‐O2 Batteries

A challenge still remains to develop high‐performance and cost‐effective air electrode for Li‐O₂ batteries with high capacity, enhanced rate capability and long cycle life (100 times or above) despite recent advances in this field. In this work, a new design of binder‐free air electrode composed of three‐dimensional (3D) graphene (G) and flower‐like δ‐MnO₂ (3D‐G‐MnO₂) has been proposed. In this design, graphene and δ‐MnO₂ grow directly on the skeleton of Ni foam that inherits the interconnected 3D scaffold of Ni foam. Li‐O₂ batteries with 3D‐G‐MnO₂ electrode can yield a high discharge capacity of 3660 mAh g^?1 at 0.083 mA cm^?2. The battery can sustain 132 cycles at a capacity of 492 mAh g^?1 (1000 mAh g_carbon ^?1) with low overpotentials under a high current density of 0.333 mA cm^?2. A high average energy density of 1350 Wh Kg^?1 is maintained over 110 cycles at this high current density. The excellent catalytic activity of 3D‐G‐MnO₂ makes it an attractive air electrode for high‐performance Li‐O₂ batteries.     

Yolk–Shell NiS2 Nanoparticle‐Embedded Carbon Fibers for Flexible Fiber‐Shaped Sodium Battery

Fiber‐shaped rechargeable batteries hold promise as the next‐generation energy storage devices for wearable electronics. However, their application is severely hindered by the difficulty in fabrication of robust fiber‐like electrodes with promising electrochemical performance. Herein, yolk–shell NiS₂ nanoparticles embedded in porous carbon fibers (NiS₂?PCF) are successfully fabricated and developed as high‐performance fiber electrodes for sodium storage. Benefiting from the robust embedded structure, 3D porous and conductive carbon network, and yolk–shell NiS₂ nanoparticles, the as‐prepared NiS₂?PCF fiber electrode achieves a high reversible capacity of about 679 mA h g^?1 at 0.1 C, outstanding rate capability (245 mA h g^?1 at 10 C), and ultrastable cycle performance with 76% capacity retention over 5000 cycles at 5 C. Notably, a flexible fiber‐shaped sodium battery is assembled, and high reversible capacity is kept at different bending states. This work offers a new electrode‐design paradigm toward novel carbon fiber electrodes embedded with transition metal oxides/sulfides/phosphides for application in flexible energy storage devices.     

Toward a High‐Performance All‐Plastic Full Battery with a'Single Organic Polymer as Both Cathode and Anode

The design and fabrication of high‐performance all‐plastic batteries is essentially important to achieve future flexible electronics. A major challenge in this field is the lack of stable and reliable soft organic electrodes with satisfactory performance. Here, a novel all‐plastic‐electrode based Li‐ion battery with a single flexible bi‐functional ladderized heterocyclic poly(quinone), (C₆O₂S₂)_n, as both cathode and anode is demonstrated. Benefiting from its unique ladder‐like quinone and dithioether structure, the as‐prepared polymer cathode shows a high energy density of 624 Wh kg^?1 (vs lithium anode) and a stable battery life of 1000 cycles. Moreover, the as‐fabricated symmetric full‐battery delivers a large capacity of 249 mAh g^?1 (at 20 mA g^?1), a good capacity retention of 119 mAh g^?1 after 250 cycles (at 1.0 A g^?1) and a noteworthy energy density up to 276 Wh kg^?1. The superior performance of poly(2,3‐dithiino‐1,4‐benzoquinone)‐based electrode rivals most of the state‐of‐the‐art demonstrations on organic‐based metal‐ion shuttling batteries. The study provides an effective strategy to develop stable bi‐functional electrode materials toward the next‐generation of high performance all‐plastic batteries.     

Low‐Temperature Reduction Strategy Synthesized Si/Ti3C2 MXene Composite Anodes for High‐Performance Li‐Ion Batteries

Silicon is attracting enormous attention due to its theoretical capacity of 4200 mAh g^?1 as an anode for Li‐ion batteries (LIBs). It is of fundamental importance and challenge to develop low‐temperature reaction route to controllably synthesize Si/Ti₃C₂ MXene LIBs anodes. Herein, a novel and efficient strategy integrating in situ orthosilicate hydrolysis and a low‐temperature reduction process to synthesize Si/Ti₃C₂ MXene composites is reported. The hydrolysis of tetraethyl orthosilicate leads to homogenous nucleation and growth of SiO₂ nanoparticles on the surface of Ti₃C₂ MXene. Subsequently, SiO₂ nanoparticles are reduced to Si via a low‐temperature (200 °C) reduction route. Importantly, Ti₃C₂ MXene not only provides fast transfer channels for Li⁺ and electrons, but also relieves volume expansion of Si during cycling. Moreover, the characteristics of excellent pseudocapacitive performance and high conductivity of Ti₃C₂ MXene can synergistically contribute to the enhancement of energy storage performance. As expected, Ti₃C₂/Si anode exhibits an outstanding specific capacity of 1849 mAh g^?1 at 100 mA g^?1, even retaining 956 mAh g^?1 at 1 A g^?1. The low‐temperature synthetic route to Si/Ti₃C₂ MXene electrodes and involved battery‐capacitive dual‐model energy storage mechanism has potential in the design of novel high‐performance electrodes for energy storage devices.     

Confined Fe2VO4⊂Nitrogen‐Doped Carbon Nanowires with Internal Void Space for High‐Rate and Ultrastable Potassium‐Ion Storage

Developing low‐cost, high‐capacity, high‐rate, and robust earth‐abundant electrode materials for energy storage is critical for the practical and scalable application of advanced battery technologies. Herein, the first example of synthesizing 1D peapod‐like bimetallic Fe₂VO₄ nanorods confined in N‐doped carbon porous nanowires with internal void space (Fe₂VO₄?NC nanopeapods) as a high‐capacity and stable anode material for potassium‐ion batteries (KIBs) is reported. The peapod‐like Fe₂VO₄?NC nanopeapod heterostructures with interior void space and external carbon shell efficiently prevent the aggregation of the active materials, facilitate fast transportation of electrons and ions, and accommodate volume variation during the cycling process, which substantially boosts the rate and cycling performance of Fe₂VO₄. The Fe₂VO₄?NC electrode exhibits high reversible specific depotassiation capacity of 380 mAh g^?1 at 100 mA g^?1 after 60 cycles and remarkable rate capability as well as long cycling stability with a high capacity of 196 mAh g^?1 at 4 A g^?1 after 2300 cycles. The first‐principles calculations reveal that Fe₂VO₄?NC nanopeapods have high ionic/electronic conductivity characteristics and low diffusion barriers for K⁺‐intercalation. This study opens up new way for investigating high‐capacity metal oxide as high‐rate and robust electrode materials for KIBs.     

K‐Ion Storage Enhancement in Sb2O3/Reduced Graphene Oxide Using Ether‐Based Electrolyte

In this work, an ether‐based electrolyte is adopted instead of conventional ester‐based electrolyte for an Sb₂O₃‐based anode and its enhancement mechanism is unveiled for K‐ion storage. The anode is fabricated by anchoring Sb₂O₃ onto reduced graphene oxide (Sb₂O₃‐RGO) and it exhibits better electrochemical performance using an ether‐based electrolyte than that using a conventional ester‐based electrolyte. By optimizing the concentration of the electrolyte, the Sb₂O₃‐RGO composite delivers a reversible specific capacity of 309 mAh g^?1 after 100 cycles at 100 mA g^?1. A high specific capacity of 201 mAh g^?1 still remains after 3300 cycles (111 days) at 500 mA g^?1 with almost no decay, exhibiting a longer cycle life compared with other metallic oxides. In order to further reveal the intrinsic mechanism, the energy changes for K atom migrating from surface into the sublayer of Sb₂O₃ are explored by density functional theory calculations. According to the result, the battery using the ether‐based electrolyte exhibits a lower energy change and migration barrier than those using other electrolytes for K‐ion, which is helpful to improve the K‐ion storage performance. It is believed that the work can provide deep understanding and new insight to enhance electrochemical performance using ether‐based electrolytes for KIBs.     

Intermixed Cation–Anion Aqueous Battery Based on an Extremely Fast and Long‐Cycling Di‐Block Bipyridinium–Naphthalene Diimide Oligomer

Aqueous batteries, particularly those integrating organic active materials functioning in a neutral pH environment, stand out as highly promising contenders in the stationary electrochemical storage domain, owing to their unparalleled safety, sustainability, and low‐cost materials. Herein, a novel di‐block oligomer, serving as the negative electrode of an all‐organic aqueous battery, is shown to offer exceptional output capabilities. The battery's performance is further enhanced by a unique intermixed p/n‐type storage mechanism, which is able to simultaneously exchange light and naturally abundant Na⁺, Mg²⁺, and Cl^?. Reaching up to 105 mAh g^?1, this system shows remarkable capacity retention for several thousand cycles (6500 cycles, ≈40 days) in various neutral electrolytes, including raw ocean water (≈3000 cycles, ≈75 days). The surprisingly fast kinetics of this di‐block oligomer allow to attain an unmatched specific capacity of near to 60 mAh g^?1_electrode while entirely devoid of conducting additives, and more than 80 mAh g^?1_electrode with 10% carbon additive, as well as displaying an areal capacity as high as 3.4 mAh cm^?2 at C rate. Full cell validation was demonstrated over 1600 cycles by virtue of a commercial 2,2,6,6‐tétraméthylpipéridin‐1‐yl)oxyl (TEMPO) molecule, which permitted an energy density of close to 40 Wh kg^?1_materials at C rate in a self‐pH‐buffered and inexpensive aqueous electrolyte.     

All‐Printed MnHCF‐MnOx‐Based High‐Performance Flexible Supercapacitors

Here, a simple active materials synthesis method is presented that boosts electrode performance and utilizes a facile screen‐printing technique to prepare scalable patterned flexible supercapacitors based on manganese hexacyanoferrate‐manganese oxide and electrochemically reduced graphene oxide electrode materials (MnHCF‐MnO_x/ErGO). A very simple in situ self‐reaction method is developed to introduce MnO_x pseudocapacitor material into the MnHCF system by using NH₄F. This MnHCF‐MnO_x electrode materials can deliver excellent capacitance of 467 F g^?1 at a current density of 1 A g^?1, which is a 2.4 times capacitance increase compared to MnHCF. In addition a printed, patterned, flexible MnHCF‐MnO_x/ErGO supercapacitor is fabricated, showing a remarkable areal capacitance of 16.8 mF cm^?2 and considerable energy and power density of 0.5 mWh cm^?2 and 0.0023 mW cm^?2, respectively. Furthermore, the printed patterned flexible supercapacitors also exhibit exceptional flexibility, and the capacitance remains stable, even while bending to various angles (60°, 90°, and 180°) and for 100 cycles. The flexible supercapacitor arrays integrated by multiple prepared single supercapacitors can power various LEDs even in the bent states. This approach offers promising opportunities for the development of printable energy storage materials and devices with high energy density, large scalability, and excellent flexibility.     

Template‐Free Construction of Self‐Supported Sb Prisms with Stable Sodium Storage

Antimony (Sb) is a promising anode material for sodium‐ion batteries owing to its large capacity of 660 mAh g^?1. However, its practical application is restricted by the rapid capacity decay resulted from a large volume expansion up to 390% upon Na alloying. Herein, construction of a self‐supported Sb array that has enough space allowing for effective accommodation of the volume change is reported. The array of Sb prisms is directly grown on a Cu substrate via a template‐free electrodeposition, followed by mild heating to consolidate the structural integrity between Sb and Cu. The resulting 3D architecture endows the Sb array with excellent sodium storage performance, exhibiting a reversible capacity of 578 mAh g^?1 and retaining 531 mAh g^?1 over 100 cycles at 0.5 C. The potential of Sb array in sodium‐ion full cells by pairing it with a Na_0.67(Ni_0.23Mg_0.1Mn_0.67)O₂ cathode is further demonstrated. This full cell affords a specific energy of 197 Wh kg^?1 at 0.2 C and a specific power of 1280 W kg^?1 at 5 C. Considering its low cost and scale‐up capability, the template‐free route may find extensive applications in designing electrode architectures.     

KTi2(PO4)3 with Large Ion Diffusion Channel for High‐Efficiency Sodium Storage

To accommodate the decreasing lithium resource and ensure continuous development of energy storage industry, sodium‐based batteries are widely studied to inherit the next generation of energy storage devices. In this work, a novel Na super ionic conductor type KTi₂(PO₄)₃/carbon nanocomposite is designed and fabricated as sodium storage electrode materials, which exhibits considerable reversible capacity (104 mAh g^?1 under the rate of 1 C with flat voltage plateaus at ≈2.1 V), high‐rate cycling stability (74.2% capacity retention after 5000 cycles at 20 C), and ultrahigh rate capability (76 mAh g^?1 at 100 C) in sodium ion batteries. Besides, the maximum ability for sodium storage is deeply excavated by further investigations about different voltage windows in half and full sodium ion cells. Meanwhile, as cathode material in sodium‐magnesium hybrid batteries, the KTi₂(PO₄)₃/carbon nanocomposite also displays good electrochemical performances (63 mAh g^?1 at the 230th cycle under the voltage window of 1.0–1.9 V). The results demonstrate that the KTi₂(PO₄)₃/carbon nanocomposite is a promising electrode material for sodium ion storage, and lay theoretical foundations for the development of new type of batteries.     

2D Amorphous V2O5/Graphene Heterostructures for High‐Safety Aqueous Zn‐Ion Batteries with Unprecedented Capacity and Ultrahigh Rate Capability

Rechargeable aqueous zinc‐ion batteries (ZIBs) are appealing due to their high safety, zinc abundance, and low cost. However, developing suitable cathode materials remains a great challenge. Herein, a novel 2D heterostructure of ultrathin amorphous vanadium pentoxide uniformly grown on graphene (A‐V₂O₅/G) with a very short ion diffusion pathway, abundant active sites, high electrical conductivity, and exceptional structural stability, is demonstrated for highly reversible aqueous ZIBs (A‐V₂O₅/G‐ZIBs), coupling with unprecedented high capacity, rate capability, long‐term cyclability, and excellent safety. As a result, 2D A‐V₂O₅/G heterostructures for stacked ZIBs at 0.1 A g^?1 display an ultrahigh capacity of 489 mAh g^?1, outperforming all reported ZIBs, with an admirable rate capability of 123 mAh g^?1 even at 70 A g^?1. Furthermore, the new‐concept prototype planar miniaturized zinc‐ion microbatteries (A‐V₂O₅/G‐ZIMBs), demonstrate a high volumetric capacity of 20 mAh cm^?3 at 1 mA cm^?2, long cyclability; holding high capacity retention of 80% after 3500 cycles, and in‐series integration, demonstrative of great potential for highly‐safe microsized power sources. Therefore, the exploration of such 2D heterostructure materials with strong synergy is a reliable strategy for developing safe and high‐performance energy storage devices.     

Achieving High‐Voltage and High‐Capacity Aqueous Rechargeable Zinc Ion Battery by Incorporating Two‐Species Redox Reaction

Herein, a two‐species redox reaction of Co(II)/Co(III) and Fe(II)/Fe(III) incorporated in cobalt hexacyanoferrate (CoFe(CN)6) is proposed as a breakthrough to achieve jointly high‐capacity and high‐voltage aqueous Zn‐ion battery. The Zn/CoFe(CN)₆ battery provides a highly operational voltage plateau of 1.75 V (vs metallic Zn) and a high capacity of 173.4 mAh g^?1 at current density of 0.3 A g^?1, taking advantage of the two‐species redox reaction of Co(II)/Co(III) and Fe(II)/Fe(III) couples. Even under extremely fast charge/discharge rate of 6 A g^?1, the battery delivers a sufficiently high discharge capacity of 109.5 mAh g^?1 with its 3D opened structure framework. This is the highest capacity delivered among all the batteries using Prussian blue analogs (PBAs) cathode up to now. Furthermore, Zn/CoFe(CN)₆ battery achieves an excellent cycling performance of 2200 cycles without any capacity decay at coulombic efficiency of nearly 100%. One further step, a sol–gel transition strategy for hydrogel electrolyte is developed to construct high‐performance flexible cable‐type battery. With the strategy, the active materials can adequately contact with electrolyte, resulting in improved electrochemical performance (≈18.73% capacity increase) and mechanical robustness of the solid‐state device. It is believed that this study optimizes electrodes by incorporating multi redox reaction species for high‐voltage and high‐capacity batteries.     

An Ultrastable Presodiated Titanium Disulfide Anode for Aqueous “Rocking‐Chair” Zinc Ion Battery

Rechargeable aqueous Zn‐based batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrites, low stripping/plating coulombic efficiency, and inefficient utilization of Zn metal limit the battery reliability and energy density. Herein, for the first time, a novel presodiated TiS₂ (Na_0.14TiS₂) is proposed and investigated as an intercalated anode for aqueous Zn‐ion batteries, showing a capacity of 140 mAh g^?1 with a suitable potential of 0.3 V (vs Zn²⁺/Zn) at 0.05 A g^?1 and superior cyclability of 77% retention over 5000 cycles at 0.5 A g^?1. The remarkable performance originates from the buffer phase formation of Na_0.14TiS₂ after chemically presodiating TiS₂, which not only improves the structural reversibility and stability but also enhances the diffusion coefficient and electronic conductivity, and lowers cation migration barrier, as evidenced by a series of experimental and theoretical studies. Moreover, an aqueous “rocking‐chair” Zn‐ion full battery is successfully demonstrated by this Na_0.14TiS₂ anode and ZnMn₂O₄ cathode, which delivers a capacity of 105 mAh g^?1 (for anode) with an average voltage of 0.95 V at 0.05 A g^?1 and preserves 74% retention after 100 cycles at 0.2 A g^?1, demonstrating the feasibility of Zn‐ion full batteries for energy storage applications.     

Scaling Printable Zn–Ag2O Batteries for Integrated Electronics

Printed batteries are an emerging solution for integrated energy storage using low‐cost, high accuracy fabrication techniques. While several printed batteries have been previously shown, few have designed a battery that can be incorporated into an integrated device. Specifically, a fully printed battery with a small active electrode area (<1 cm²) achieving high areal capacities (>10 mAh cm^?2) at high current densities (1–10 mA cm^?2) has not been demonstrated, which represents the minimum form‐factor and performance requirements for many low‐power device applications. This work addresses these challenges by investigating the scaling limits of a fully printed Zn–Ag₂O battery and determining the electrochemical limitations for a mm²‐scale battery. Processed entirely in air, Zn–Ag₂O batteries are well suited for integration in typical semiconductor packaging flows compared to lithium‐based chemistries. Printed cells with electrodes as small as 1 mm² maintain steady operating voltages above (>1.4 V) at high current densities (1–12 mA cm^?2) and achieve the highest reported areal capacity for a fully printed battery at 11 mAh cm^?2. The findings represent the first demonstration of a small, packaged, fully printed Zn–Ag₂O battery with high areal capacities at high current densities, a crucial step toward realizing chip‐scale energy storage for integrated electronic systems.     

Enhanced Kinetics Harvested in Heteroatom Dual‐Doped Graphitic Hollow Architectures toward High Rate Printable Potassium‐Ion Batteries

Carbonaceous materials have emerged as promising anode candidates for potassium‐ion batteries (PIBs) due to overwhelming advantages including cost‐effectiveness and wide availability of materials. However, further development in this realm is handicapped by the deficiency in their in‐target and large‐scale synthesis, as well as their low specific capacity and huge volume expansion. Herein the precise and scalable synthesis of N/S dual‐doped graphitic hollow architectures (NSG) via direct plasma enhanced chemical vapor deposition is reported. Thus‐fabricated NSG affording uniform nitrogen/sulfur co‐doping, possesses ample potassiophilic surface moieties, effective electron/ion‐transport pathways, and high structural stability, which bestow it with high rate capability (≈100 mAh g^?1 at 20 A g^?1) and a prolonged cycle life (a capacity retention rate of 90.2% at 5 A g^?1 after 5000 cycles), important steps toward high‐performance K‐ion storage. The enhanced kinetics of the NSG anode are systematically probed by theoretical simulations combined with operando Raman spectroscopy, ex situ X‐ray photoelectron spectroscopy, and galvanostatic intermittent titration technique measurements. In further contexts, printed NSG electrodes with tunable mass loading (1.84, 3.64, and 5.65 mg cm^?2) are realized to showcase high areal capacities. This study demonstrates the construction of a printable carbon‐based PIB anode, that holds great promise for next‐generation grid‐scale PIB applications.     

3D Printing Sulfur Copolymer‐Graphene Architectures for Li‐S Batteries

3D printing is becoming an efficient approach to facilely and accurately fabricate diverse complex architectures with broad applications. However, suitable inks and 3D print favorable architectures with high electrochemical performances for energy storage are still being explored. Here, sulfur copolymer‐graphene architectures with well‐designed periodic microlattices are 3D printed as a cathode for Li‐S batteries using a suitable ink composed of sulfur particles, 1,3‐diisopropenylbenzene (DIB), and condensed graphene oxide dispersion. Using thermal treatment, elemental sulfur can be reacted with DIB to produce sulfur copolymer, which can partially suppress the dissolution of polysulfides. Moreover, graphene in the architecture can provide high electrical conductivity for whole electrode. Hence, 3D printed sulfur copolymer‐graphene architecture exhibits a high reversible capacity of 812.8 mA h g^?1 and good cycle performance. Such a simple 3D printing approach can be further extended to construct many complex architectures for various energy storage devices.     

Frogspawn‐Coral‐Like Hollow Sodium Sulfide Nanostructured Cathode for High‐Rate Performance Sodium–Sulfur Batteries

Room‐temperature (RT) sodium–sulfur (Na–S) batteries are attractive cost‐effective platforms as the next‐generation energy storage systems by using all earth‐abundant resources as electrode materials. However, the slow kinetics of Na–S chemistry makes it hard to achieve high‐rate performance. Herein, a facile and scalable approach has been developed to synthesize hollow sodium sulfide (Na₂S) nanospheres embedded in a highly hierarchical and spongy conductive carbon matrix, forming an intriguing architecture similar to the morphology of frogspawn coral, which has shown great potential as a cathode for high‐rate performance RT Na–S batteries. The shortened Na‐ion diffusion pathway benefits from the hollow structures together with the fast electron transfer from the carbon matrix contributes to high electrochemical reactivity, leading to superior electrochemical performance at various current rates. At high current densities of 1.4 and 2.1 A g^?1, high initial discharge capacities of 980 and 790 mAh g^?1_sulfur can be achieved, respectively, with reversible capacities stabilized at 600 and 400 mAh g^?1_sulfur after 100 cycles. As a proof of concept, a Na‐metal‐free Na–S battery is demonstrated by pairing the hollow Na₂S cathode with tin‐based anode. This work provides guidance on rational materials design towards the success of RT high‐rate Na–S batteries.     

Designing the Charge Storage Properties of Li‐Exchanged Sodium Vanadium Fluorophosphate for Powering Implantable Biomedical Devices

The growing demand for bioelectronics has generated widespread interest in implantable energy storage. These implantable bioelectronic devices, powered by a complementary battery/capacitor system, have faced difficulty in miniaturization without compromising their functionality. This paper reports on the development of a promising high‐rate cathode material for implantable power sources based on Li‐exchanged Na_1.5VOPO₄F_0.5 anchored on reduced graphene oxide (LNVOPF‐rGO). LNVOPF is unique in that it offers dual charge storage mechanisms, which enable it to exhibit mixed battery/capacitor electrochemical behavior. In this work, electrochemical Li‐ion exchange of the LNVOPF structure is characterized by operando X‐ray diffraction. Through designed nanostructuring, the charge storage kinetics of LNVOPF are improved, as reflected in the stored capacity of 107 mAh g^?1 at 20C. A practical full cell device composed of LNVOPF and T‐Nb₂O₅, which serves as a pseudocapacitive anode, is fabricated to demonstrate not only high energy/power density storage (100 Wh kg^?1 at 4000 W kg^?1) but also reliable pulse capability and biocompatibility, a desirable combination for applications in biostimulating devices. This work underscores the potential of miniaturizing biomedical devices by replacing a conventional battery/capacitor couple with a single power source.