High Areal Sulfur Loading Research Articles

Easy fabrication of flexible and multilayer nanocarbon-based cathodes with a high unreal sulfur loading by electrostatic spraying for lithium-sulfur batteries

A high areal sulfur loading in a carbon-based cathode together with a high cell capacity is key to the design of lithium-sulfur batteries guaranteeing a superior energy density for use. However, a high sulfur loading produced using traditional blade coating techniques results in many technical issues such as sluggish electron/ion transport kinetics and cracking of the electrodes. Here a well designed two-step electrostatic spray deposition (ESD) technique is proposed to prepare a flexible, multilayer carbon electrode with a high sulfur areal loading, in which different carbon components by a careful selection are used for different functions in each layer. The unique "aerosol deposition" in the ESD creates buffer voids in the electrode, ensuring fast infiltration of the electrolyte and releasing the internal stress of the electrode thus avoiding the cracking of thick electrodes. With such an integrated design, the as-prepared cathode exhibits excellent flexibility, a long cyclic stability with a low capacity decay of 0.064% per cycle at 1 C for 500 cycles and a high rate capability of 736 mAh g−1 at 2 C. Moreover, a high areal sulfur loading of 9.4 mg cm−2 with an areal capacity of 6.2 mAh cm−2 at 0.1 C has been achieved.

Enhanced kinetics of polysulfide redox reactions on Mo2C/CNT in lithium–sulfur batteries

Among different energy storage devices, the lithium–sulfur (Li–S) battery is the subject of recent attention. However, the capacity decay caused by polysulfide shuttle leading to sluggish kinetics of polysulfide redox reactions is the main hindrance for its practical application in Li–S batteries. Herein, molybdenum carbide nanoparticles anchored on carbon nanotubes (Mo2C/CNT) are reported to serve as an efficient cathode material to enhance the electrochemical kinetics of polysulfide conversion in Li–S batteries. Mo2C/CNT shows strong adsorption and activation of polar polysulfides and therefore accelerates the redox kinetics of polysulfides, reduces the energy barrier, effectively mitigates the polarization and polysulfide shuttle, thus improving the electrochemical performance. The S-Mo2C/CNT composite with 70 wt% sulfur loading exhibits high specific discharge capacity (1206 mA h g−1 at 0.5 C), excellent high-rate performance, long cycle life (900 cycles), and outstanding Coulombic efficiency (∼100%) at a high rate (2 C) corresponding to a capacity decay of only 0.05%. Remarkably, the S-Mo2C/CNT cathode with high areal sulfur loading of 2.5 mg cm−2 exhibits high-rate capacities and stable cycling performance over 100 cycles, offering the potential for use in high energy Li–S batteries.

3D CNTs/Graphene-S-Al3Ni2 Cathodes for High-Sulfur-Loading and Long-Life Lithium-Sulfur Batteries.

Lithium–sulfur batteries suffer from poor cycling stability at high areal sulfur loadings (ASLs) mainly because of the infamous shuttle problem and the increasing diffusion distance for ions to diffuse along the vertical direction of the cathode plane. Here, a carbon nanotube (CNT)/graphene (Gra)‐S‐Al3Ni2 cathode with 3D network structure is designed and prepared. The 3D network configuration and the Al in the Al3Ni2 provide an efficient channel for fast electron and ion transfer in the three dimensions, especially along the vertical direction of the cathode. The introduction of Ni in the Al3Ni2 is able to suppress the shuttle effect via accelerating reaction kinetics of lithium polysulfide species conversion reactions. The CNT/Gra‐S‐Al3Ni2 cathode exhibits ultrahigh cycle‐ability at 1 C over 800 cycles, with a capacity degradation rate of 0.055% per cycle. Additionally, having high ASLs of 3.3 mg cm−2, the electrode delivers a high reversible areal capacity of 2.05 mA h cm−2 (622 mA h g−1) over 200 cycles at a higher current density of 2.76 mA cm−2 with high capacity retention of 85.9%. The outstanding discharge performance indicates that the design offers a promising avenue to develop long‐life cycle and high‐sulfur‐loading Li–S batteries.

Encapsulating Sulfur into Magnéli Phase Ti4O7 Nanotube Array for Lithium Sulfur Battery Cathode

Lithium sulfur (Li-S) battery is considered the next generation lithium ion batteries for energy storage. However, several issues have to be addressed before the full potential of Li-S battery can be realized. The intrinsically low electronic conductivity of sulfur renders incomplete material utilization; the dissolution of charge/discharge intermediates, lithium polysulfides, results in the shuttle phenomenon that leads to low a coulombic efficiency and fast capacity fading upon cycling; the 80% volume expansion of sulfur upon full lithiation changes the electrode structure and shortens battery cycle life. Magnéli phase Ti4O7 is known for its high electronic conductivity, which is as high as that of metal, and the polar nature of the compound allows strong chemisorption of lithium polysulfides onto Ti4O7 surface. In this study, Magnéli phase Ti4O7 nanotube array (Ti4O7 NTA) grown on a titanium nitride mesh is synthesized via anodization of titanium mesh followed by high-temperature reduction under a hydrogen atmosphere. The effect of the duration of the reduction reaction is investigated, and from X-ray diffraction patterns, a 45-minute reaction time generates a product that most closely resembles pure Magnéli phase Ti4O7. Sulfur is introduced inside the Ti4O7 NTA via electrodeposition followed by melt-infusion under vacuum. The electrodeposition of sulfur onto the free-standing Ti4O7 NTA electrode allows a precise control of the areal loading of sulfur, simply via adjusting the duration of electrodeposition under a constant current density of 20mA/cm2. A conductive carbon coating is applied onto the sulfur-incorporated Ti4O7 NTA mesh to further confine sulfur inside the Ti4O7 nanotubes. This produces a composite material of C-S-Ti4O7 The Ti4O7 NTA provides sulfur with a large electronically conductive and strong polysulfide-absorbing surface that facilitates the redox chemistry of sulfur. The NTA structure promises ample access of electrolyte to sulfur, and allows a high areal sulfur loading in the cathode. Excellent battery performance is obtained using this composite as the cathode material. Under a moderate sulfur loading in the range of 1.3~2.8mg/cm2, a high initial specific capacity (1604mAh/g at 0.05C), ultra-low capacity decay rates (0.0322% per cycle, Figure (a)) for 1800 cycles, and good rate capability (660mAh/g at 2C and 500mAh/g and 4C, Figure (b)) are achieved. Under a higher sulfur loading in the range of 3.5~4.8mg/cm2, stable cycling (capacity decay rates below 0.10% per cycle, Figure (c)) with very high values areal capacity (4.97mAh/cm2 at 0.05C, 3.82mAh/cm2 0.1C, and 2.74 mAh/cm2 at 0.2C) are obtained, making a high-volumetric-energy-density Li-S battery more practical. The low capacity decay rate and the high areal capacity in this study are among the best reported polar sulfur hosts such as graphitic carbon nitride C3N4, α-MnO2, MXene phase Ti2C, Co9S8, and Magnéli phase Ti4O7 nanoparticles. The interaction between Magnéli phase Ti4O7 and lithium polysulfides is investigated via X-ray photoelectron spectroscopy. It is discovered that the interaction is of a redox nature, where titanium atoms on Ti4O7 NTA are partially reduced while sulfur atoms in lithium polysulfides are partially oxidized with peaks corresponding to sulfate and sulfite becoming more dominant when lithium polysulfides are in contact with Ti4O7 NTA. The positive effects of Ti4O7 NTA and those of carbon coating are studied via cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the Ti4O7 NTA decreases the charge transfer resistance of the Li-S cell, and that the carbon coating produces a stable cycling performance through gradually decreasing polarization as reflected by a lowering of overpotential during charge and discharge. Figure 1

Free-Standing Mn3O4@CNF/S Paper Cathodes with High Sulfur Loading for Lithium-Sulfur Batteries.

Free-standing paper cathodes with layer-by-layer structure are synthesized for high-loading lithium-sulfur (Li-S) battery. Sulfur is loaded in a three-dimensional (3D) interconnected nitrogen-doped carbon nanofiber (CNF) framework impregnated with Mn3O4 nanoparticles. The 3D interconnected CNF framework creates an architecture with outstanding mechanical properties. Synergetic effects generated from physical and chemical entrapment could effectively suppress the dissolution and diffusion of the polysulfides. Electrochemical measurements suggest that the rationally designed structure endows the electrode with high utilization of sulfur and good cycle performance. Specifically, the cathode with a high areal sulfur loading of 11 mg cm-2 exhibits a reversible areal capacity over 8 mAh cm-2. The fabrication procedure is of low cost and readily scalable. We believe that this work will provide a promising choice for potential practical applications.

Cobalt-Doped Vanadium Nitride Yolk-Shell Nanospheres @ Carbon with Physical and Chemical Synergistic Effects for Advanced Li-S Batteries.

Lithium-sulfur (Li-S) battery has been attracting increasing attention because of its high energy density and the presence of abundance of sulfur. However, its commercialization is still restricted owing to the low conductivity of sulfur, large volume expansion, and a severe polysulfide-shuttle effect. To address these problems, here, we have reported for the first time a simple template-free solvothermal method combined with a subsequent calcination method to prepare cobalt-doped vanadium nitride (VN) yolk-shell nanospheres, encapsulated in a thin layer of a nitrogen-doped carbon (Co-VN@C) composite as an ideal sulfur host. Benefiting from the unique structural advantages and the synergistic effect of conductive VN, cobalt, and nitrogen-doped carbon (NC), the obtained composite could not only facilitate the kinetics of polysulfide conversion as a functional catalyst but also physically confine and chemically absorb the polysulfides effectively. With these advantages, the batteries present a high initial discharge capacity of 1379.2 mAh g-1 at 0.1 C (1 C is defined as 1675 mA g-1), good rate performance, and excellent cycling performances (∼715 mAh g-1 at 0.5 C after 200 cycles and ∼600 mAh g-1 at 1 C after 300 cycles, respectively), even with a high areal sulfur loading of 4.07 mg cm-2 (∼830 mAh g-1 at 0.2 C after 100 cycles). These results demonstrate that the rationally designed multifunctional sulfur host material Co-VN@C has great potential for application in Li-S batteries.

Three-Dimensional Carbon Current Collector Promises Small Sulfur Molecule Cathode with High Areal Loading for Lithium-Sulfur Batteries.

With the high energy density of 2600 W h kg-1, lithium-sulfur (Li-S) batteries have been considered as one of the most promising energy storage systems. However, the serious capacity fading resulting from the shuttle effect hinders its commercial application. Encapsulating small S2-4 molecules into the pores of ultramicroporous carbon (UMC) can eliminate the dissolved polysulfides, thus completely inhibiting the shuttle effect. Nevertheless, the sulfur loading of S2-4/UMC is usually not higher than 1 mg cm-2 because of the limited pore volume of UMC, which is a great challenge for small sulfur cathode. In this paper, by applying ultralight 3D melamine formaldehyde-based carbon foam (MFC) as a current collector, we dramatically enhanced the areal sulfur loading of the S2-4 electrode with good electrochemical performances. The 3D skeleton of MFC can hold massive S2-4/UMC composites and act as a conductive network for the fast transfer of electrons and Li+ ions. Furthermore, it can serve as an electrolyte reservoir to make a sufficient contact between S2-4 and electrolyte, enhancing the utilization of S2-4. With the MFC current collector, the S2-4 electrode reaches an areal sulfur loading of 4.2 mg cm-2 and performs a capacity of 839.8 mA h g-1 as well as a capacity retention of 82.5% after 100 cycles. The 3D MFC current collector provides a new insight for the application of Li-S batteries with high areal small sulfur loading and excellent cycle stability.

Self-standing sulfur cathodes enabled by 3D hierarchically porous titanium monoxide-graphene composite film for high-performance lithium-sulfur batteries

Although lithium-sulfur batteries show great promise for next-generation energy storage due to their high energy density, the practical implementation of lithium-sulfur batteries has been largely impeded by the shuttle effect of lithium polysulfides and low areal capacity (< 2 mAh cm−2). Here we rationally design a new self-standing host enabled by a 3D hierarchically-porous titanium monoxide-graphene composite film to overcome the two issues at once. The hierarchically porous graphene scaffold not only can facilitate rapid lithium ion and electron transport, but also provide sufficient spaces to accommodate sulfur and buffer the volume expansion during the lithiation process. In addition, the ultrafine and polar titanium monoxide nanoparticles embedded in the three-dimensional graphene networks show strong chemical anchoring for polysulfides as evidenced by ex-situ X-ray photoelectron spectroscopy analysis, and their inherent metallic conductivity accelerates the redox reaction kinetics. Benefiting from this attractive architecture, the freestanding titanium monoxide-graphene/sulfur cathode delivered a high initial capacity of 1350 mAh g−1 at 0.1 C, a Coulombic efficiency approaching 100%, and a high-rate capacity of 832 mAh g−1 at 2 C. Moreover, when the areal sulfur loading was increased to 5.2 mg cm−2, the titanium monoxide-graphene/sulfur electrode delivered a high areal capacity of 3.2 mAh cm−2 after 300 cycles at 0.2 C, demonstrating excellent cycling performance compared with other recently reported sulfur cathodes with high areal sulfur loadings.

Novel Synergistic Strategy for Developing High-Performance Lithium Sulfur Batteries of Large Areal Sulfur Loading by SEI Modified Separator

As a crucial energy density determining factor, the areal sulfur loading is still low nowadays for practical applications of Li–S batteries. To address this issue, intensive research efforts have been devoted to development of sulfur-hosting materials with ultrahigh specific surface area. However, design and manufacturing processes for these materials are complicated. Herein, we report a novel and facile strategy for developing a high-performance cathode with high areal sulfur content using conventional sulfur hosts without ultrahigh specific area. This strategy features a dense blocking layer of solid electrolyte interface (SEI) on the separator to ensure cycle stability of the cathode with a high areal sulfur loading. Meanwhile, a nanoarray cathode structure (CNT array on carbon cloth) is adopted to guarantee high sulfur utilization and rate performance. With the synergistic effect of a dense blocking layer and CNT array structure, the cathode with 10 mg/cm2 sulfur (90.9% in CNT/S composite) shows good ...

Facile Synthesis of Crumpled Nitrogen‐Doped MXene Nanosheets as a New Sulfur Host for Lithium–Sulfur Batteries

AbstractCrumpled nitrogen‐doped MXene nanosheets with strong physical and chemical coadsorption of polysulfides are synthesized by a novel one‐step approach and then utilized as a new sulfur host for lithium–sulfur batteries. The nitrogen‐doping strategy enables introduction of heteroatoms into MXene nanosheets and simultaneously induces a well‐defined porous structure, high surface area, and large pore volume. The as‐prepared nitrogen‐doped MXene nanosheets have a strong capability of physical and chemical dual‐adsorption for polysulfides and achieve a high areal sulfur loading of 5.1 mg cm–2. Lithium–sulfur batteries, based on crumpled nitrogen‐doped MXene nanosheets/sulfur composites, demonstrate outstanding electrochemical performances, including a high reversible capacity (1144 mA h g–1 at 0.2C rate) and an extended cycling stability (610 mA h g–1 at 2C after 1000 cycles).

Porous 3D graphene-based biochar materials with high areal sulfur loading for lithium–sulfur batteries

A novel pomelo peel biochar integrated graphene composite was applied as a cathode host for Li–S batteries with high sulfur loading.

Toward Theoretically Cycling-Stable Lithium-Sulfur Battery Using a Foldable and Compositionally Heterogeneous Cathode.

Rechargeable lithium-sulfur (Li-S) batteries have been expected for new-generation electrical energy storages, which are attributed to their high theoretical energy density, cost effectiveness, and eco-friendliness. But Li-S batteries still have some problems for practical application, such as low sulfur utilization and dissatisfactory capacity retention. Herein, we designed and fabricated a foldable and compositionally heterogeneous three-dimensional sulfur cathode with integrated sandwich structure. The electrical conductivity of the cathode is facilitated by three different dimension carbons, in which short-distance and long-distance pathways for electrons are provided by zero-dimensional ketjen black (KB), one-dimensional activated carbon fiber (ACF) and two-dimensional graphene (G). The resultant three-dimensional sulfur cathode (T-AKG/KB@S) with an areal sulfur loading of 2 mg cm-2 exhibits a high initial specific capacity, superior rate performance and a reversible discharge capacity of up to 726 mAh g-1 at 3.6 mA cm-2 with an inappreciable capacity fading rate of 0.0044% per cycle after 500 cycles. Moreover, the cathode with a high areal sulfur loading of 8 mg cm-2 also delivers a reversible discharge capacity of 938 mAh g-1 at 0.71 mA cm-2 with a capacity fading rate of 0.15% per cycle and a Coulombic efficiency of almost 100% after 50 cycles.

Single-wall carbon nanotube network enabled ultrahigh sulfur-content electrodes for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are among the most promising candidates for the next-generation energy storage systems. However, challenges regarding the limited sulfur content and areal sulfur loading in the cathode lead to a low areal capacity that cannot even outperform state-of-the-art lithium-ion batteries, which greatly offsets the high-energy advantage of Li-S batteries and further hinders their practical use. Here, we theoretically indicated that the electronic conduction efficiency of the sulfur host nanomaterial plays a crucial role in determining the sulfur content, and a highly efficient single-wall carbon nanotube (SWCNT) conductive network was constructed for our proof-of-concept studies, resulting in an unprecedentedly high sulfur content up to 95wt%. The interwoven SWCNTs not only provide abundant paths for electron and lithium ion transport, but also facilitate polysulfides trapping during sulfur conversion reactions. As a result, a high areal capacity of 8.63mAhcm−2 was obtained with a high areal sulfur loading of 7.2mgcm−2, much higher than that of lithium-ion batteries (4mAhcm−2). Our approach demonstrates a new design concept for the electrode materials of high-energy-density lithium-sulfur batteries and could possibly be extended to other electrochemical energy storage systems.

A High‐Volumetric‐Capacity Cathode Based on Interconnected Close‐Packed N‐Doped Porous Carbon Nanospheres for Long‐Life Lithium–Sulfur Batteries

AbstractThis study reports a Li–S battery cathode of high volumetric capacity enabled by novel micro‐ and mesostructuring. The cathode is based on monodisperse highly porous carbon nanospheres derived from a facile template‐ and surfactant‐free method. At the mesoscale, the nanospheres structure into interconnected close‐packed clusters of a few microns in extent, thus facilitating the fabrication of dense crack‐free high areal sulfur loading (5 mg cm−2) cathodes with high electrical conductivity and low cathode impedance. A combination of the nitrogen doping (5 wt%), high porosity (2.3 cm3 g−1), and surface area (2900 m2 g−1) at the microscale enables high sulfur immobilization and utilization. The cathode delivers among the best reported volumetric capacity to date, above typical Li‐ion areal capacity at 0.2 C over 200 cycles and low capacity fading of 0.1% per cycle at 0.5 C over 500 cycles. The compact cathode structure also ensures a low electrolyte requirement (6 µL mg−1), which aids a low overall cell weight, and further, among the best gravimetric capacities published to date as well.

Robust electrical “highway” network for high mass loading sulfur cathode

High performance cathode with sufficiently high areal sulfur loading is still a major challenge for practical Li/S batteries. Herein, we propose a 3D nanocarbon architecture with robust electrical “highway” network for high sulfur mass loading and efficient sulfur utilization. The structure is constructed by “welding” highly conductive nitrogen-doped graphene (NG) and nitrogen-doped carbon nanotubes (NCNT) together through in-situ polymeric crosslinking and nitrogen-doped carbon shell (NCS) formation. The highly sulfur-absorptive NCS provides strong physical and chemical confinements to sulfur and polysulfides, which is confirmed by in-situ Raman and electrochemical analysis. At a moderate sulfur loading, the NG-NCNT@NCS@S cathode exhibits a high initial discharge capacity of 1421mAhg−1, excellent rate performance of 750mAhg−1 at 2C and 465mAhg−1 at 5C, and a capacity fading rate as low as 0.037% per cycle at 2C for 1400 cycles. At high areal sulfur loading up to 10.2mgcm−2, the cathode retains a high areal capacity of 5.43mAhcm−2 after 150 cycles at a high current rate (1C). A large areal cathode (77 × 50mm2) with sulfur loading of 8.5mgcm−2 delivers a record-high capacity of 9.04mAhcm−2 at 0.1C, demonstrating its great potential for practical application in Li/S batteries.

Conductive bridging effect of TiN nanoparticles on the electrochemical performance of TiN@CNT-S composite cathode

Improving the reaction kinetics of cathode and preventing the dissolution of polysulfides are two of the key strategies of developing the high-performance lithium-sulfur (Li-S) batteries. Herein, we propose a multi-porous conductive architecture through bridging conductive TiN nanoparticle over the surface of CNT-S composite. The as-prepared TiN@CNT-S composite cathode delivers the superior initial specific capacity of 1269mAhg−1 at 0.05C and as high as 586mAhg−1 at 2C. The reversible capacity of the TiN@CNT-S composite cathode is about two times higher than the bare cathode without TiN conductive bridging at 1C over 400 cycles. A high areal capacity of 4.0mAhcm−2 was realized for the TiN@CNT-S composite cathode with a high areal sulfur loading of 5.4mgcm−2 at a current rate of 0.5C over 50 cycles. The enhancements in the electrochemical performances are mainly ascribed to the TiN bridged highly conductive structure; the formation of the strong chemical interaction of S-N-Ti bond for polysulfides trapping provided by the chemically polar TiN, which is verified by the ultraviolet visible (UV) spectra and X-ray photoelectron spectroscopy (XPS) analyses.

Hierarchically porous carbon derived from banana peel for lithium sulfur battery with high areal and gravimetric sulfur loading

Facile and sustainable route is developed to convert biomass into hierarchically porous carbon matrix cooperating with highly conductive graphene. By tailoring the porosity of the carbon matrix to promote fast mass transfer and cooperating highly conductive interconnected graphene frameworks to accelerate the electron transport, the carbon sulfur cathodes simultaneously achieve high areal and gravimetric sulfur loading/content (6 mg cm−2/67 wt%) and deliver outstanding electrochemical performance. After 100 cyclic discharge-charge test at the current density of 0.2 C, the reversible capacity maintains at 707 mA h g−1.

High areal capacity of Li-S batteries enabled by freestanding CNF/rGO electrode with high loading of lithium polysulfide

Lithium-Sulfur (Li-S) batteries, the most promising next-generation batteries for their high theoretical capacity, are still hindered by several obstacles mainly due to the effect of polysulfide shuttle. Recently, considerable progress has been made to improve the specific capacity and cycling life of the Li-S batteries, but most demonstrations are typically based on thin electrode with limited areal sulfur loading. Herein, we demonstrate a Li-S battery with electrospun carbon nanofiber/reduced graphene oxide (CNF/rGO) as the binder-free and self-standing host for lithium polysulfide-containing liquid active materials in the cathode. The matrix of intertwined long CNF networks with uniformly distributed rGO pieces promotes the long-range high-rate charge transfers in three dimensions, and provides sufficient porous spaces for polysulfide uptake. Plus the mechanical flexibility of the CNF/rGO membrane, thick electrode with high areal sulfur loading (20.3mg/cm2) and high areal specific capacity (15.5mAh/cm2) is demonstrated by a Li-S pouch cell with stable cycling performances.

Freestanding and Sandwich‐Structured Electrode Material with High Areal Mass Loading for Long‐Life Lithium–Sulfur Batteries

Freestanding cathode materials with sandwich‐structured characteristic are synthesized for high‐performance lithium–sulfur battery. Sulfur is impregnated in nitrogen‐doped graphene and constructed as primary active material, which is further welded in the carbon nanotube/nanofibrillated cellulose (CNT/NFC) framework. Interconnected CNT/NFC layers on both sides of active layer are uniquely synthesized to entrap polysulfide species and supply efficient electron transport. The 3D composite network creates a hierarchical architecture with outstanding electrical and mechanical properties. Synergistic effects generated from physical and chemical interaction could effectively alleviate the dissolution and shuttling of the polysulfide ions. Theoretical calculations reveal the hydroxyl functionization exhibits a strong chemical binding with the discharge product (i.e., Li2S). Electrochemical measurements suggest that the rationally designed structure endows the electrode with high specific capacity and excellent rate performance. Specifically, the electrode with high areal sulfur loading of 8.1 mg cm−2 exhibits an areal capacity of ≈8 mA h cm−2 and an ultralow capacity fading of 0.067% per cycle over 1000 discharge/charge cycles at C/2 rate, while the average coulombic efficiency is around 97.3%, indicating good electrochemical reversibility. This novel and low‐cost fabrication procedure is readily scalable and provides a promising avenue for potential industrial applications.

A bifunctional hierarchical porous carbon network integrated with an in situ formed ultrathin graphene shell for stable lithium–sulfur batteries

A bifunctional sulfur host integrating graphene shell and hierarchical porous carbon network is fabricated to enhance conductivity of sulfur and block shuttle of sulfides simultaneously. The resultant cathode possesses high areal sulfur loading, excellent cyclic stability, and improved anti-self-discharge capability.