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Tin‐based hybrid flow batteries have demonstrated dendrite‐free morphology and superior performance in terms of cycle life and energy density. However, the quick accumulation of electrodeposits near the electrode/membrane interface blocks the ion transport pathway during the charging of the battery, resulting to a very limited areal capacity (especially at high current density) that significantly hinders its deployment in long‐duration storage applications. Herein, a conductivity‐activity dual‐gradient design is disclosed by electrically passivating the carbon felt near the membrane/electrode interface and chemically activating the carbon felt near the electrode/current collector interface. In consequence, the tin metals are preferentially plated at the region near electrode/current collector, preventing the ion transport pathway from being easily blocked. The resultant gradient electrode demonstrated an unprecedentedly high areal capacity of 268 mAh cm−2 at a current density of as high as 80 mA cm−2. Numerical modeling and experimental characterizations show that the dual‐gradient electrode differs from conventional electrodes with regard to their reaction current density distribution and electrodeposit distribution during charging. This work demonstrates a new design strategy of 3D electrodes for hybrid flow batteries to induce a desirable distribution of electrodeposits and achieve a high areal capacity at commercially relevant current densities. [ABSTRACT FROM AUTHOR]

The accelerated oxidative degradation observed in all‐solid‐state batteries (ASSBs), particularly focusing on the argyrodite solid electrolyte in conjunction with Ni‐rich positive electrode surfaces is demonstrated. The formation of oxidative intermediates of the solid electrolyte oxidation process increases the amount of oxidation on the NCM surface with conductive carbon. The introduction of high‐weight‐composition conductive carbon additives results in a reduction of solid electrolytes within the positive electrode and the amount of solid electrolytes retained after formation. Consequently, cells with high concentrations of carbon additives demonstrate a decrease in both the cycle and power performances of ASSBs. The energy density of ASSBs is significantly limited by the fundamental failure mechanism induced by conductive carbon, particularly pronounced in cells with high active material contents. Consequently, this study provides pivotal insights for the design of high‐energy‐density ASSBs with NCM electrodes and high active material contents. To mitigate failure induced by high‐volumetric‐occupied carbon additives, carbon fiber‐type additives are further utilized to interconnect the NCMs by decreasing the occupation of the solid electrolyte domain by carbon. Morphological alteration of the carbon additive significantly improves the electrochemical performance of ASSBs by preventing the deterioration of the electrode structure even after prolonged cycling and suppressing electrolyte degradation. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable zinc‐sulfur (Zn‐S) batteries are a promising, cost‐effective, and high‐capacity energy storage technology. Still, they are challenged by the poor reversibility of S cathodes, sluggish redox kinetics, low S utilization, and unsatisfactory areal capacity. This work develops a facile strategy to achieve an appealing high‐areal‐capacity (above 5 mAh cm−2) Zn‐S battery by molecular‐level regulation between S and high‐electrical‐conductivity tellurium (Te). The incorporation of Te as a dopant allows for manipulation of the Zn‐S electrochemistry, resulting in accelerated redox conversion, and enhanced S utilization. Meanwhile, accompanied by the S‐ZnS conversion, Te is converted to zinc telluride during the discharge process, as revealed by ex‐situ characterizations. This additional redox reaction contributes to the S cathode's total excellent discharge capacity. With this unique cathode structure design, the carbon‐confined TeS cathode (denoted as Te1S7/C) delivers a high reversible capacity of 1335.0 mAh g−1 at 0.1 A g−1 with a mass loading of 4.22 mg cm−2, corresponding to a remarkable areal capacity of 5.64 mAh cm−2. Notably, a hybrid electrolyte design uplifts discharge plateau, reduces overpotential, suppresses Zn dendrites growth, and extends the calendar life of Zn‐Te1S7 batteries. This study provides a rational S cathode structure to realize high‐capacity Zn‐S batteries for practical applications. [ABSTRACT FROM AUTHOR]

The development of low‐cost and high‐performance iron (Fe)‐based anode materials is of great significance for rechargeable aqueous batteries. Herein, a FeS@Fe foam anode with crosslinked nanoflake array structure is fabricated. Being adopted as alkaline anode, FeS@Fe foam delivers enhanced areal capacity of 31.1 mAh cm−2 (at 50 mA cm−2), which is ≈1.5 times that of the‐state‐of‐the‐art literatures. The scaled‐up tests further reveal the higher capacity (800.7 mAh) and current density (1.25 A) with the area of 25 cm2. The FeS@Fe foam anode sustains intact after 270‐day cycles, demonstrating excellent durability. The assembled FeS//NiO single battery provides a superior areal energy density of 300.7 Wh m−2 at 500 W m−2. The reaction mechanism and electrode kinetics are revealed by combining in/ex situ techniques and DFT calculations. Experimental results and in/ex situ characterizations validate that excellent structural stability and high areal capacity are attributed to effective interface regulation and improved energy storage mechanism, respectively. This work pushes the advanced Fe‐based electrode to a superior level among these available alkaline solid‐state batteries. [ABSTRACT FROM AUTHOR]

The design of supercapacitor materials with both high mass loading and high areal capacity is a major strategy to overcome relatively low energy density of supercapacitors. Herein, NiCo‐layered double hydroxide (NiCo‐LDH)/NiCoOOH composite films with both ultrahigh mass loading and high areal capacity are prepared by a two‐step cyclic voltammetry method. The films consist of NiCo‐LDH/NiCoOOH microspheres assembled with ultrafine nanosheets with highly ordered pore distribution from macropores to micropores and abundant defect active sites, which are conducive to the transport of electrolyte ions, increasing the reaction kinetics, and greatly improving the utilization of active material. The optimal film with hierarchical microstructure featuring an ultrahigh mass loading of 80 mg cm−2 not only exhibits a state‐of‐the‐art high areal capacity of 14.7 mAh cm−2, but also shows a record‐high energy density of 10.7 mWh cm−2 , as well as presents remarkable mechanical stabilityand superior capacity retention of 99% after 20000 galvanostatic charge‐discharge cycles. Moreover, by combining the experimental analysis and theoretical calculations, the mechanism of preferential conversion of the NiCo‐LDH in the subtle defect region to NiCoOOH by electrochemistry and the synergistic effect in electrochemical energy storage of the NiCo‐LDH and NiCoOOH phases is proposed. [ABSTRACT FROM AUTHOR]

The development of sodium ion batteries will require high‐performance electrodes with very large areal capacity and reasonable rate performance. Although red phosphorus is a very promising electrode material, it has not yet fulfilled these requirements. Here, liquid phase exfoliation is used to convert solid red phosphorus into amorphous, quasi‐2D nanoplatelets. These nanoplatelets have lateral sizes of hundreds of nanometers, thickness of 10s of nanometers and are quite stable in ambient conditions, displaying only low levels of oxidation on the nanosheet surface. By solution mixing with carbon nanotubes, these nanoplatelets can be fabricated into nanocomposite battery anodes. After employing an extended activation process, good cycling stability over 1000 cycles and low‐rate capacitances >2000 mAh gP−1 is achieved. Because of the high conductivity and mechanical robustness provided by the nanotube network, it is possible to fabricate very thick electrodes. These electrodes display extremely high areal capacities approaching 10 mAh cm−2 at currents of ≈1 mA cm−2. Detailed analysis shows these electrodes to be limited by solid‐state diffusion such that the thickest electrodes have state‐of‐the‐art rate performance and a near‐optimized combination of capacity and rate performance. [ABSTRACT FROM AUTHOR]

High mass loading and high areal capacity are essential for lithium‐ion batteries (LIBs) with high energy density, but they usually suffer from the sluggish charge‐transfer kinetic of thick electrodes, especially at low temperature. Here, organic molecule perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) has been investigated as a feasible cathode for high areal capacity rechargeable LIBs operated at low temperature. Specifically, the charge storage process mainly occurs on the surface redox‐active groups of PTCDA, resulting in a fast kinetics of charge storage. Meanwhile, the delocalization of electrons in the π‐conjugated systems of PTCDA could enhance the electron transportation prominently. Consequently, the Li‐PTCDA battery with a high mass loading of 14.35 mg cm−2 delivers a high reversible areal capacity of 1.06 mAh cm−2 at −40 °C. This work demonstrates a great potential of π‐conjugated organic materials for low temperature and high‐areal‐capacity rechargeable LIBs. [ABSTRACT FROM AUTHOR]

In recent decades, extensive nanomaterials and related techniques have been proposed to achieve high capacities surpassing conventional battery electrodes. Nevertheless, most of them show low mass loadings and areal capacities, which deteriorates the cell‐level energy densities and increases cost after the consideration of inactive components in batteries. Achieving high‐areal‐capacity is essential for those advanced materials to move out of laboratories and into practical applications, yet remains challenging due to the decreased mechanical properties and sluggish electrochemical kinetics at elevated mass loadings. In this paper, the previously reported strategies for promoting areal lithium storage performance, including material‐level designs, electrode‐level architecture optimization, and novel manufacturing techniques are reviewed. Sodium‐ion battery electrodes are discussed subsequently, emphatically on its difference with those for lithium storage. Pouch‐cell‐level energy densities based on high‐areal‐capacity electrodes with different thicknesses are also estimated. For each category of these strategies, working principles, advantages, and possible problems are analyzed, with typical examples presented in detail and a summary table comparing the structures and achieved performance. Finally, the features of the high‐areal‐capacity electrodes demonstrated in this review are concluded, and overlooked issues and potential research directions in this field are summarized. [ABSTRACT FROM AUTHOR]

The practical application of rechargeable aqueous zinc batteries is impeded by dendrite growth, especially at high areal capacities and high current densities. Here, this challenge is addressed by proposing zinc perfluoro(2‐ethoxyethane)sulfonic (Zn(PES)2) as a zinc battery electrolyte. This new amphipathic zinc salt, with a hydrophobic perfluorinated tail, can form an anode protecting layer, in situ, with a biomimetic lipid‐bilayer structure. The layer limits the anode contact with free H2O and offers fast Zn2+ transport pathways, thereby effectively suppressing dendrite growth while maintaining high rate capability. A stable, Zn2+‐conductive fluorinated solid electrolyte interphase (SEI) is also formed, further enhancing zinc reversibility. The electrolyte enables unprecedented cycling stability with dendrite‐free zinc plating/stripping over 1600 h at 1 mA cm−2 at 2 mAh cm−2, and over 380 h under an even harsher condition of 2.5 mA cm−2 and 5 mAh cm−2. Full cell tests with a high‐loading VS2 cathode demonstrate good capacity retention of 78% after 1000 cycles at 1.5 mA cm−2. The idea of in situ formation of a biomimetic lipid‐bilayer anode protecting layer and fluorinated SEI opens a new route for engineering the electrode–electrolyte interface toward next‐generation aqueous zinc batteries with long lifetime and high areal capacities. [ABSTRACT FROM AUTHOR]

The fabrication, by an electrochemical process, of a new battery‐type electrode material, is presented. Such materials are fabricated by direct current electrodeposition of Ni(OH)2 on lamellar Ni3Si. Microstructure and morphology of Ni(OH)2/Ni3Si electrodes were characterised. Cyclic voltammetry and galvanostatic charge–discharge results revealed that they are battery‐type electrodes. Increasing deposition time or decreasing discharge current can significantly increase the areal capacity. The areal capacity of Ni(OH)2/Ni3Si‐20 with a discharge current of 20 mA is only 2.8% of that with 1 mA. However, the increasing deposition time will reduce the cyclic stability of the electrodes. The initial areal capacity of Ni(OH)2/Ni3Si‐20 is twice that of Ni(OH)2/Ni3Si‐10 with a discharge current of 10 mA, but after 1000 cycles, it can only maintain 59.3% of the initial value. This Letter is expected to provide a powerful reference and guidance for the preparation of electrodes with large areal capacity and cycle stability. [ABSTRACT FROM AUTHOR]

High areal capacity electrodes are essential to practical energy storage devices to achieve high volumetric capacity with compacted size. However, high loading of active materials remains a fundamental challenge for most metal‐ion batteries (e.g., Li+, Na+, K+) due to sluggish mass transfer kinetics and poor processability. Here, an ultrahigh areal capacity MoO3 electrode based on high loading for hydrogen‐ion battery is shown. Hydrogen ions can rapidly intercalate/deintercalate into/from MoO3‐nanofibers anode with a high specific capacity of 235 mAh g−1 at 5 C and superior rate capability up to 200 C at a low loading (≈1 mg cm−2). Attributed to the ultrafast H+ diffusion in thick MoO3 electrode, an areal capacity of 22.4 mAh cm−2 is achieved at the loading over 90.48 mg cm−2, which is the highest areal capacity ever reported for electrodes of rechargeable batteries, to the best of the authors' knowledge. This study paves the way toward high areal capacity batteries with high‐loading active materials. [ABSTRACT FROM AUTHOR]

High areal capacity electrodes are essential to practical energy storage devices to achieve high volumetric capacity with compacted size. However, high loading of active materials remains a fundamental challenge for most metal‐ion batteries (e.g., Li+, Na+, K+) due to sluggish mass transfer kinetics and poor processability. Here, an ultrahigh areal capacity MoO3 electrode based on high loading for hydrogen‐ion battery is shown. Hydrogen ions can rapidly intercalate/deintercalate into/from MoO3‐nanofibers anode with a high specific capacity of 235 mAh g−1 at 5 C and superior rate capability up to 200 C at a low loading (≈1 mg cm−2). Attributed to the ultrafast H+ diffusion in thick MoO3 electrode, an areal capacity of 22.4 mAh cm−2 is achieved at the loading over 90.48 mg cm−2, which is the highest areal capacity ever reported for electrodes of rechargeable batteries, to the best of the authors' knowledge. This study paves the way toward high areal capacity batteries with high‐loading active materials. [ABSTRACT FROM AUTHOR]

Silicon nanowires (Si NWs) have been identified as an excellent candidate material for the replacement of graphite in anodes, allowing for a significant boost in the capacity of lithium‐ion batteries (LIBs). Herein, high‐density Si NWs are grown on a novel 3D interconnected network of binary‐phase Cu‐silicide nanofoam (3D CuxSiy NF) substrate. The nanofoam facilitates the uniform distribution of well‐segregated and small‐sized catalyst seeds, leading to high‐density/single‐phase Si NW growth with an areal‐loading in excess of 1.0 mg cm−2 and a stable areal capacity of ≈2.0 mAh cm−2 after 550 cycles. The use of the 3D CuxSiy NF as a substrate is further extended for Al, Bi, Cu, In, Mn, Ni, Sb, Sn, and Zn mediated Si NW growth, demonstrating the general applicability of the anode architecture. [ABSTRACT FROM AUTHOR]

Silicon has been considered as a promising anode material for lithium‐ion batteries owing to its extraordinarily high capacity. However, the huge volume expansion during cycling results in severe pulverization and disintegration of active materials, especially when the particle size is in microscale. This challenge can be addressed by highly stretchable polymer binders engineered with helical polysaccharides. The elaborately designed binder presents excellent stretchability and adhesive property, which can buffer the strain caused by the large volume change and coalesce the pulverized silicon fragments without disintegration. As a result, the microsized silicon electrode exhibits high initial Coulombic efficiency of 91.8 % and excellent cycling stability for 300 cycles. Importantly, when paired with a commercial LiCoO2 cathode, the full cell manifests a high areal capacity of 3.02 mAh cm−2 and superior stability for 100 cycles. Our contribution paves the way to the practical application of microsized silicon for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

It remains a great challenge to simultaneously guarantee the conductivity and high areal loading of active materials for integrated electrode of supercapacitors. Herein, we designed a hierarchical structure with cores of NiSe single‐crystal nanorods and sheaths of 2‐nm‐thick NiCo thin sheets grown on nickel foam (NiCo LDH@NiSe/NF) as integrated electrode. It reaches a high areal capacity of 1131 μAh cm−2 at a current density of 5 mA cm−2, which is 2.2 times of NiSe/NF (522 μAh cm−2) and 6.0 times of NiCo LDH/NF (189 μAh cm−2), superior to most reported integrated electrodes. The enhanced areal capacity can be ascribed to the high active material loading of 6.5 mg cm−2 (twice more than other reported values) and considerable conductivity of single‐crystal NiSe nanorods of 2630 S cm−1. The fabricated hierarchical integrated electrode of NiCo LDH@NiSe/NF assembled with activated carbon shows a maximum energy density of 0.454 mWh cm−2 and a maximum power density of 80 mW cm−2. This work presents supports of single‐crystal nanorods for thin LDH sheets to fabricate high‐density hierarchical structure for integrated electrode, which improves the conductivity and structural stability of active materials especially the LDHs, resulting in excellent electrochemical performance. It offers a promising approach to engineer and fabricate advanced supercapacitors with enhanced areal capacity. [ABSTRACT FROM AUTHOR]

Monolithic 3D graphene frameworks (GFs) electrode materials have exhibited the great potential for energy storage devices. However, most approaches for fabricating 3D GF require expensive and sophisticated drying techniques, and the current achieved 3D GF electrodes usually hold a relatively low mass loadings of the active materials with low areal capacity, which is not satisfactory for practical application. Herein, a convenient, economic, and scalable drying approach is developed to fabricate 3D holey GFs (HGFs) by a vacuum‐induced drying (VID) process for the first time. This binder‐free 3D HGF electrode with high mass loading can obtain extraordinary electrochemical performance for lithium‐ion batteries (LIBs) due to the 3D holey graphene network owning a highly interconnected hierarchical porous structure for fast charge and ion transport. The HGF electrode with high mass loading of 4 mg cm−2 exhibits superior rate performance and delivers an areal capacity as high as 5 mAh cm−2 under the current density of 8 mA cm−2 even after 2000 cycles, considerably outperforming those of state‐of‐the‐art commercial anodes and some representative anodes in other studies. This facile drying approach and robust realization of high areal capacity represent a critical step for 3D graphene‐based electrode materials toward practical electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

We present a new interlayer concept for the realization of high‐energy‐density LiS batteries. Disordered mesoporous carbons replicated by silica nanoparticles were partially filled with sulfur via a melt‐diffusion method. Sulfur‐impregnated disordered mesoporous carbon (DMC‐S) composites were used as an interlayer between a cathode and anode to provide additional active materials for a LiS cell. The LiS cell with the DMC‐S interlayer exhibited an approximately two‐fold increase in areal capacity compared with the control cell without an interlayer. DMC‐S composites offer the unique advantage of acting as a porous framework to accommodate active materials and suppress polysulfide diffusion. We propose that this new approach provides a viable path for the development of LiS batteries with a high‐energy density and excellent cycling stability. [ABSTRACT FROM AUTHOR]

Low‐cost and scalable processes to fabricate Si‐based anodes with high areal capacity and excellent cycling performance remain a challenge, thereby limiting their widespread application. Herein, we report Si nanoparticles@conductive carbon framework@polymer (Si@C@P) composite electrodes, in which Si nanoparticles are homogeneously immobilized within a three‐dimensional network of conductive carbon nanofibers bound by a high‐viscosity polymer. When used as anodes for lithium‐ion batteries, the obtained Si@C@P composite electrodes deliver an initial coulombic efficiency of 83.5 % and an areal capacity of 2.0 mAh cm−2 (1152 mAh gelectrode-1), with a capacity retention about 0.8 mAh cm−2 (466 mAh gelectrode-1) after 150 discharge–charge cycles at 0.1 C. This work provides a low‐cost route for the large‐scale manufacture of Si‐based anodes with high areal capacity, which may be very significant for the development of lithium‐ion batteries with high energy density. Battery confinement: During the process of lithiation, the electrode structure can be well maintained, because the well dispersed Si nanoparticles swell within the three‐dimensional cross‐linked framework of the carbon nanofibers (CNFs). During the process of delithiation, the Si nanoparticles shrink in situ within the CNF framework. Importantly, only when Si and CNF are formed in the well‐balanced structure can the volumetric expansion of Si particles during alloying be accommodated and the interparticle electrical contact be maintained. [ABSTRACT FROM AUTHOR]

Abstract: Metal‐organic frameworks (MOFs) hybridized with a conductive matrix could potentially serve as a sulfur host for lithium‐sulfur (Li‐S) battery electrodes; so far most of the previously studied hybrid structures are in the powder form or thin compact films. This study reports 3D porous MOF@carbon nanotube (CNT) networks by grafting MOFs with tailored particle size uniformly throughout a CNT sponge skeleton. Growing larger‐size MOF particles to entrap the conductive CNT network yields a mutually embedded structure with high stability, and after sulfur encapsulation, it shows an initial discharge capacity of ≈1380 mA h g−1 (at 0.1 C) and excellent cycling stability with a very low fading rate. Furthermore, owing to the 3D porous network that is suitable for enhanced sulfur loading, a remarkable areal capacity of ≈11 mA h cm−2 (at 0.1 C) is obtained, which is much higher than other MOF‐based hybrid electrodes. The mutually embedded MOF@CNTs with simultaneously high specific capacity, areal capacity, and cycling stability represent an advanced candidate for developing high‐performance Li‐S batteries and other energy storage systems. [ABSTRACT FROM AUTHOR]

Abstract: Achieving a high areal capacity is essential for the transfer of outstanding laboratory electrode results to commercial applications and also to ensure there exists a capacity matched cathode and anode for a properly tuned battery. Despite intensive efforts, most electrode materials exhibit areal capacities lower than that of the graphite anodes (4 mA h cm−2). An effective and low‐cost approach is reported to attain a high areal capacity via an intense densification by compacting a porous carbon nanotube sponge grafted with Co3O4 nanoparticles. The hybrid sponge can be compacted to a large degree (up to a tenfold densification) while still keeping its structural integrity and the 3D porous network. This method allows achieving a mass loading of up ‑to 14.3 mg cm−2 and an areal capacity of 12 mA h cm−2 (at a current density of 200 mA g−1) together with a gravimetric capacity of >800 mA h g−1. This densification by compaction approach offers an effective and low‐cost strategy to develop high mass loading and areal capacity electrodes for practical energy storage systems. [ABSTRACT FROM AUTHOR]

Silicon, because of its high specific capacity, is intensively pursued as one of the most promising anode material for next-generation lithium-ion batteries. In the past decade, various nanostructures are successfully demonstrated to address major challenges for reversible Si anodes related to pulverization and solid-electrolyte interphase. However, the electrochemical performance is still limited by challenges that stem from the use of nanomaterials. In this progress report, the focus is on the challenges and recent progress in the development of Si anodes for lithium-ion battery, including initial Coulombic efficiency, areal capacity, and material cost, which call for more research effort and provide a bright prospect for the widespread applications of silicon anodes in the future lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Freestanding nanofiber mat Li-ion battery anodes containing Si nanoparticles, carbon black, and poly(acrylic acid) (Si/C/PAA) are prepared using electrospinning. The mats are compacted to a high fiber volume fraction (≈0.85), and interfiber contacts are welded by exposing the mat to methanol vapor. A compacted+welded fiber mat anode containing 40 wt % Si exhibits high capacities of 1484 mA h g−1 (3500 mA h g [ABSTRACT FROM AUTHOR]

The search for earth-abundant and high-performance electrode materials for sodium-ion batteries represents an important challenge to current battery research. 2D transition metal dichalcogenides, particularly MoS2, have attracted increasing attention recently, but few of them so far have been able to meet expectations. In this study, it is demonstrated that another phase of molybdenum sulfide-amorphous chain-like MoS3-can be a better choice as the anode material of sodium-ion batteries. Highly compact MoS3 particles infiltrated with carbon nanotubes are prepared via the facile acid precipitation method in ethylene glycol. Compared to crystalline MoS2, the resultant amorphous MoS3 not only exhibits impressive gravimetric performance-featuring excellent specific capacity (≈615 mA h g−1), rate capability (235 mA h g−1 at 20 A g−1), and cycling stability but also shows exceptional volumetric capacity of ≈1000 mA h cm−3 and an areal capacity of >6.0 mA h cm−2 at very high areal loadings of active materials (up to 12 mg cm−2). The experimental results are supported by density functional theory simulations showing that the 1D chains of MoS3 can facilitate the adsorption and diffusion of Na+ ions. At last, it is demonstrated that the MoS3 anode can be paired with an Na3V2(PO4)3 cathode to afford full cells with great capacity and cycling performance. [ABSTRACT FROM AUTHOR]

Electrospun nanofiber mats containing carbon nanoparticles in a poly(vinylidene fluoride) binder were prepared and characterized as Li-ion battery anodes. The mats exhibited an initial capacity of 161 mAh g−1 with 91.7 % capacity retention after 510 cycles at 0.1 C (1 C=372 mA gcarbon−1). Whereas many nanoscale electrodes are limited to low areal and/or volumetric capacities, the particle/polymer nanofiber anodes can be made thick with a high fiber volume fraction while maintaining good rate capabilities. Thus, a nanofiber anode with a fiber volume fraction of 0.79 exhibits a volumetric capacity of 55 mAh cm−3 at 2 C, which is twice that of a typical graphite anode. Similarly, thick nanofiber mats with a high areal capacity of 4.3 mAh cm−2 were prepared and characterized. The excellent performance of electrospun anodes is attributed to electrolyte intrusion throughout the interfiber void space and efficient Li+ transport between the electrolyte and carbon nanoparticles in the radial fiber direction. [ABSTRACT FROM AUTHOR]

As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium-sulfur (Li-S) batteries. In this paper, a mesoporous nitrogen-doped carbon (MPNC)-sulfur nanocomposite is reported as a novel cathode for advanced Li-S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verified by X-ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables the behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC-sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh cm-2 with a high sulfur loading (4.2 mg S cm-2) and a sulfur content (70 wt%). A high areal capacity (≈3.3 mAh cm-2) is demonstrated by using the novel cathode, which is crucial for the practical application of Li-S batteries. It is believed that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon-sulfur composite cathodes for Li-S batteries. [ABSTRACT FROM AUTHOR]

Exploring advanced electrode materials with superb energy/power densities and long lifetime as well as low cost is the recent focus of hybrid solid‐state supercapacitor (HSSC). This study reports a novel hierarchical bimetallic hydroxide (Ni1Co1‐OH) built by nanowire‐lapped bonfire‐like bundles through a facile and scalable method, and provides thorough insights into possible formation mechanism and structural merits of the interesting hierarchical architecture. Benefiting from multistep redox reactions, high accessible surface area and fast kinetics contributed by the unique structure, Ni1Co1‐OH using 2 m KOH electrolyte can achieve highly improved gravimetric capacity/capacitance of 876.8 C g−1/1753.6 F g−1 at active mass loading of 3 mg cm−2 at 1 A g−1, and especially deliver a record‐high areal capacity of 7.6 C cm−2 at 1 A g−1 under a commercial loading of 15 mg cm−2. 1.5 V Ni1Co1‐OH based HSSC with the poly(vinyl alcohol)/KOH gel electrolyte verifies the intriguing performance including high energy/power densities of 27.9 Wh kg−1/13812.9 W kg−1, a long life over 10 000 cycles, and a low self‐discharge rate with a voltage decline of 20% after 24 h. The findings identify the scalable production of high‐performance bimetal compounds, which will boost the development of highly demanding HSSC devices. [ABSTRACT FROM AUTHOR]

Among other things, battery electrodes need to display large absolute capacities coupled with high rate performance. However, enhancing areal capacity, for example via increased electrode thickness, results in reductions in rate performance. The basis for this negative correlation has not been studied in a quantitative fashion. Here, a semiempirical model is used to analyze capacity versus rate data for electrodes fabricated from a number of materials, each measured at various thicknesses. Fitting the model to the data outputs the low‐rate areal capacity, QA, and the characteristic time associated with charge/discharge, τ, fit parameters which quantify absolute capacity and rate performance respectively. A clear correlation is found between QA and τ, with all data siting close to a mastercurve approximately defined by constant τ/QA. This data is consistent with a simple model based on the timescales associated with rate‐limiting processes. This model implies that the capacity‐rate trade‐off can be improved for high areal capacity electrodes by increasing the volumetric capacity, electrical conductivity, and porosity of the electrode. Conversely, solid‐state diffusion and reaction kinetics are only important for low areal capacity electrodes. [ABSTRACT FROM AUTHOR]