Metal–Sulfur Battery Cathodes Based on PAN–Sulfur Composites

Aminomethyl-Functionalized Carbon Nanotubes as a Host of Small Sulfur Clusters for High-Performance Lithium-Sulfur Batteries

Here we propose an effective strategy to stabilize small sulfur species by using aminomethyl-functionalized carbon nanotubes (AM-CNT) without impairing the conductive channel of the carbon nanotube (CNT) cathode. The linear S_n clusters can be anchored strongly to the AM-CNT for the favorable size of n=5 and the maximum size of n=6 in the production of the cathode, which depresses the mass loss of active sulfur effectively and eliminates the formation of high-order polysulfides completely during the discharge process. The most stable 3 D cross-linked Inter-S₅ -AM-CNT network shows a fast electron transfer redox reaction through the CNT skeleton that possesses a theoretical capacity of 1337 mA h g^-1 (based on sulfur) or 592 mA h g^-1 (based on the cathode). The discharge products of the linear S₅ cluster tend to form a hyperbranched tight structure through N⋅⋅⋅S⋅⋅⋅Li bridges that are fully impregnated in the AM-CNT bundles, and thus stabilize the entire system. Importantly, this study provides vital guidance into how to design cathodes based on small sulfur clusters for Li-S batteries to depress the shuttle effect intrinsically during charge-discharge cycles, which can be extended to the other small-sulfur-cluster-based batteries.

Remedies for Polysulfide Dissolution in Room-Temperature Sodium-Sulfur Batteries

Rechargeable room-temperature sodium-sulfur (RT-NaS) batteries represent one of the most attractive technologies for future stationary energy storage due to their high energy density and low cost. The S cathodes can react with Na ions via two-electron conversion reactions, thus achieving ultrahigh theoretical capacity (1672 mAh g^-1 ) and specific energy (1273 Wh kg^-1 ). Unfortunately, the sluggish reaction kinetics of the nonconductive S, severe polysulfide dissolution, and the use of metallic Na are causing enormous challenges for the development of RT-NaS batteries. Fatal polysulfide dissolution is highlighted, important studies toward polysulfide immobilization and conversion are presented, and the reported remedies in terms of intact physical confinement, strong chemical interaction, blocking layers, and optimization of electrolytes are summarized. Future research directions toward practical RT-NaS batteries are summarized.

Polysulfide Regulation by the Zwitterionic Barrier toward Durable Lithium-Sulfur Batteries

Rational regulation on polysulfide behaviors is of great significance in pursuit of reliable solution-based lithium-sulfur (Li-S) battery chemistry. Herein, we develop a unique polymeric zwitterion (PZI) to establish a smart polysulfide regulation in Li-S batteries. The zwitterionic nature of PZI integrates sulfophilicity and lithiophilicity in the matrix, fostering an ionic environment for selective ion transfer through the chemical interactions with lithium polysulfides (LiPS). When implemented as a functional interlayer in the cell configuration, PZI empowers strong obstruction against polysulfide permeation but simultaneously allows fast Li⁺ conduction, thus contributing to significant shuttle inhibition as well as the resultant facile and stable sulfur electrochemistry. The PZI-based cells realize excellent cyclability over 1000 cycles with a minimum capacity fading rate of 0.012% per cycle and favorable rate capability up to 5 C. Moreover, a high areal capacity retention of 5.3 mAh cm^-2 after 300 cycles can be also obtained under raised sulfur loading and limited electrolyte, demonstrating great promise in developing high-efficiency and long-lasting Li-S batteries.

A High-Kinetics Sulfur Cathode with a Highly Efficient Mechanism for Superior Room-Temperature Na-S Batteries

Applications of room-temperature-sodium sulfur (RT-Na/S) batteries are currently impeded by the insulating nature of sulfur, the slow redox kinetics of sulfur with sodium, and the dissolution and migration of sodium polysulfides. Herein, a novel micrometer-sized hierarchical S cathode supported by FeS₂ electrocatalyst, which is grown in situ in well-confined carbon nanocage assemblies, is presented. The hierarchical carbon matrix can provide multiple physical entrapment to polysulfides, and the FeS₂ nanograins exhibit a low Na-ion diffusion barrier, strong binding energy, and high affinity for sodium polysulfides. Their combination makes it an ideal sulfur host to immobilize the polysulfides and achieve reversible conversion of polysulfides toward Na₂ S. Importantly, the hierarchical S cathode is suitable for large-scale production via the inexpensive and green spray-drying method. The porous hierarchical S cathode offers a high sulfur content of 65.5 wt%, and can deliver high reversible capacity (524 mAh g^-1 over 300 cycles at 0.1 A g^-1 ) and outstanding rate capability (395 mAh g^-1 at 1 A g^-1 for 850 cycles), holding great promise for both scientific research and real application.

Black phosphorus-modified sulfurized polyacrylonitrile with high C-rate and cycling performance in ether-based electrolyte for lithium sulfur batteries

Black phosphorus modified sulfurized polyacrylonitrile (BP-SPAN) is reported for the first time for Li-S batteries operated in ether electrolyte. The amorphous P2S5+x in BP-SPAN is crucial to suppress the shuttling effect of polysulfides and enhance the reaction kinetics. It delivers an amazing capacity of 1086 mA h g-1 (2C) and capacity retention of 91.1% (0.1C, 100th).

An ester electrolyte for lithium–sulfur batteries capable of ultra-low temperature cycling

Li||SPAN batteries in the lithium bis(fluorosulfonyl)imide methyl propionate/fluoroethylene carbonate (LiFSI MP/FEC) electrolyte system can charge and discharge at −40 °C with over 78% room temperature capacity retention.

MXene-Based Dendrite-Free Potassium Metal Batteries

Potassium metal batteries are considered as attractive alternatives beyond lithium-ion batteries. However, uncontrollable dendrite growth on the potassium metal anode has restrained their practical applications. A high-performance potassium anode achieved by confining potassium metal into a titanium-deficient nitrogen-containing MXene/carbon nanotube freestanding scaffold is reported. The high electronic transport and fast potassium diffusion in this scaffold enable reduced local current density and homogeneous ionic flux during plating/stripping processes. Furthermore, as verified by theoretical calculations and experimental investigations, such "potassium-philic" MXene sheets can induce the nucleation of potassium, and guide potassium to uniformly distribute in the scaffold upon cycling. Consequently, the as-developed potassium metal anodes exhibit a dendrite-free morphology with high Coulombic efficiency and long cycle life during plating/stripping processes. Such anodes also deliver significantly improved electrochemical performances in potassium-sulfur batteries compared with bare potassium metal anodes. This work can provide a new avenue for developing potassium metal-based batteries.

Metal Coated Polypropylene Separator with Enhanced Surface Wettability for High Capacity Lithium Metal Batteries

Lithium metal batteries are among the strong contenders to meet the increasing energy demands of the modern world. Metallic lithium (Li) is light in weight, possesses very low standard negative electrochemical potential and offers an enhanced theoretical capacity (3860 mA h g-1). As a negative electrode Li paves way to explore variety of elements including oxygen, sulfur and various other complex oxides as potential positive electrodes with a promise of much higher energy densities than that of conventional positive electrodes. However, there are technical challenges in utilizing metallic lithium due to its higher reactivity towards liquid electrolytes and higher affinity to form Li dendrites, leading to serious safety concerns. Here, we report on preparation of niobium (Nb) metal-coated binder-free and highly hydrophilic polypropylene separator prepared via radio frequency (RF) magnetron sputtering. Thin layer of niobium metal (Nb) particles were deposited onto the polypropylene (PP) sheet for various time periods to achieve desired coating thickness. The as-prepared separator revealed excellent hydrophilic behaviour due to enhanced surface wettability. Symmetric cells display reduced interface resistance and uniform voltage profiles for 1000 cycles with reduced polarization at higher current densities suggesting smooth stripping and plating of Li and homogeneous current distribution at electrode/electrolyte interface under room temperature conditions. Nb nanolayer protected separator with LiNi0.33M0.33Co0.33O2 (LNMC) and composite sulfur cathodes revealed an enhanced cycling stability.

Boosting High Energy Density Lithium-Ion Storage via the Rational Design of an FeS-Incorporated Sulfurized Polyacrylonitrile Fiber Hybrid Cathode

In order to satisfy the escalating energy demands, it is inevitable to improve the energy density of current Li-ion batteries. As the development of high-capacity cathode materials is of paramount significance compared to anode materials, here we have designed for the first time a unique synergistic hybrid cathode material with enhanced specific capacity, incorporating cost-effective iron sulfide (FeS) nanoparticles in a sulfurized polyacrylonitrile (SPAN) nanofiber matrix through a rational in situ synthesis strategy. Previous reports on FeS cathodes are scarce and consist of an amorphous carbon matrix to accommodate the volume changes encountered during the cycling process. However, this inactive buffering matrix eventually increases the weight of the cell, reducing the overall energy density. By the rational design of this hybrid composite cathode, we ensure that the presence of covalently bonded sulfur in SPAN guarantees high sulfur utilization, while effectively buffering the volume changes in FeS. Meanwhile, FeS can compensate for the conductivity issues in the SPAN, thereby realizing a synergistically driven dual-active cathode material improving the overall energy density of the composite. Simultaneous in situ generation of FeS nanoparticles within the SPAN fiber matrix was carried out via electrospinning followed by a one-step heating procedure. The developed hybrid cathode material displays enhanced lithium-ion storage, retaining 688.6 mA h g_{(FeS@SPAN composite)}^-1 at the end of 500 cycles at 1 A g^-1 even within a narrow voltage range of 1-3.0 V. A high discharge energy density > 900 W h kg_{(FeS@SPAN composite)}^-1, much higher than the theoretical energy density of the commercial LiCoO₂ cathode, was also achieved, revealing the promising prospects of this hybrid cathode material for high energy density applications.

One-Step In Situ Preparation of Polymeric Selenium Sulfide Composite as a Cathode Material for Enhanced Sodium/Potassium Storage

Alkali metal-sulfur/selenium batteries have attracted much attention because they offer promising high energy density. However, the shuttle effect of the polysulfide dissolutions, poor electrical conductivity, and relatively large volume variations greatly hinder their potential applications. Herein, a novel organic carbon/selenium sulfide (OC/SeS₂) composite has been prepared by a one-step in situ method by heating the mixture of commercial polyacrylonitrile (PAN) with selenium sulfide powder in vacuum. The carbonized PAN matrix with an N-doped carbon ring structure could effectively confine SeS₂ in the form of small molecules and regulate its electronic structure. The superior sodium/potassium storage performance of the OC/SeS₂ composite electrodes stems from their rational chemical structure design, including high electrical conductivity of the N-doped organic carbon network and chemical binding with SeS₂ molecules. As a result, the OC/SeS₂ cathode delivers a reversible capacity of 416 mAh g^-1 after 700 cycles for sodium-ion batteries and 216 mAh g^-1 after 500 cycles for potassium-ion batteries at 0.5 A g^-1, respectively. These findings could open a new window to develop selenium sulfide cathode for metal-sulfur/selenium batteries.

Synergy of Sulfur/Polyacrylonitrile Composite and Gel Polymer Electrolyte Promises Heat-Resistant Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries with high theoretical energy density attract great research attention. Although tremendous efforts have been made, heat tolerance capability of Li-S batteries is a topic rarely touched, although it is essential for practical application. At high temperatures, the dissolution of the polysulfides is aggravated, and the safety issue becomes severe. Herein, by using sulfur/polyacrylonitrile (SPAN) composites as positive electrode materials and a gel polymer membrane with carbonate electrolyte, we successfully realized a Li-S battery with remarkable heat-resistant performance at 50°C and 60°C. The SPAN-positive materials allow the Li-S battery operated in safer carbonate-containing electrolyte. The gel polymer electrolyte enhances the charge transfer, maintains the morphology of Li metal during cycling, and suppresses the migration of the soluble polysulfides, which is also observed when SPAN is used as positive electrode material. This contribution would bring new opportunity to extend the application of lithium batteries at high temperatures.

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A Li-S battery with remarkable heat-resistant performance is obtained

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Sulfur/polyacrylonitrile nanocomposites is used as positive electrode materials

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Migration of polysulfides is observed during the cycling of the assembled battery

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Gel polymer electrolyte is crucial for enhancing the performance at high temperature

Sulfur-Grafted Hollow Carbon Spheres for Potassium-Ion Battery Anodes

Sulfur-rich carbons are minimally explored for potassium-ion batteries (KIBs). Here, a large amount of S (38 wt%) is chemically incorporated into a carbon host, creating sulfur-grafted hollow carbon spheres (SHCS) for KIB anodes. The SHCS architecture provides a combination of nanoscale (≈40 nm) diffusion distances and CS chemical bonding to minimize cycling capacity decay and Coulombic efficiency (CE) loss. The SHCS exhibit a reversible capacity of 581 mAh g^-1 (at 0.025 A g^-1 ), which is the highest reversible capacity reported for any carbon-based KIB anode. Electrochemical analysis of S-free carbon spheres baseline demonstrates that both the carbon matrix and the sulfur species are highly electrochemically active. SHCS also show excellent rate capability, achieving 202, 160, and 110 mAh g^-1 at 1.5, 3, and 5 A g^-1 , respectively. The electrode maintains 93% of the capacity from the 5th to 1000th cycle at 3 A g^-1 , with steady-state CE being near 100%. Raman analysis indicates reversible breakage of CS and SS bonds upon potassiation to 0.01 V versus K/K⁺ . The galvanostatic intermittent titration technique (GITT) analysis provides voltage-dependent K⁺ diffusion coefficients that range from 10^-10 to 10^-12 cm² s^-1 upon potassiation and depotassiation, with approximately five times higher coefficient for the former.

Current Status and Future Prospects of Metal-Sulfur Batteries

Lithium-sulfur batteries are a major focus of academic and industrial energy-storage research due to their high theoretical energy density and the use of low-cost materials. The high energy density results from the conversion mechanism that lithium-sulfur cells utilize. The sulfur cathode, being naturally abundant and environmentally friendly, makes lithium-sulfur batteries a potential next-generation energy-storage technology. The current state of the research indicates that lithium-sulfur cells are now at the point of transitioning from laboratory-scale devices to a more practical energy-storage application. Based on similar electrochemical conversion reactions, the low-cost sulfur cathode can be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum. These new "metal-sulfur" systems exhibit great potential in either lowering the production cost or producing high energy density. Inspired by the rapid development of lithium-sulfur batteries and the prospect of metal-sulfur cells, here, over 450 research articles are summarized to analyze the research progress and explore the electrochemical characteristics, cell-assembly parameters, cell-testing conditions, and materials design. In addition to highlighting the current research progress, the possible future areas of research which are needed to bring conversion-type lithium-sulfur and other metal-sulfur batteries into the market are also discussed.

Immobilized Single Molecular Molybdenum Disulfide on Carbonized Polyacrylonitrile for Hydrogen Evolution Reaction

Designing a MoS₂ catalyst having a large number of active sites and high site activity enables the catalytic activity toward the hydrogen evolution reaction to be improved. Herein, we report the synthesis of a low-cost and catalytically active immobilized single molecular molybdenum disulfide on carbonized polyacrylonitrile (MoS₂-cPAN) electrocatalyst. From the extended X-ray absorption fine structure spectra analysis, we found that the as-prepared material has no metal-metal scattering and it resembles MoS₂ with a molecular state. Meanwhile, the size of the molecular MoS₂ has been estimated to be about 1.31 nm by high-angle annular dark-field scanning transmission electron microscopy. A low coordination number and maximum utilization of the single molecular MoS₂ surface enable MoS₂-cPAN to demonstrate electrochemical performance significantly better than that of bulk MoS₂ by two orders of exchange current density ( j_o) and turnover frequency to the hydrogen evolution.

Recent Progress on Organic Electrodes Materials for Rechargeable Batteries and Supercapacitors

Rechargeable batteries are essential elements for many applications, ranging from portable use up to electric vehicles. Among them, lithium-ion batteries have taken an increasing importance in the day life. However, they suffer of several limitations: safety concerns and risks of thermal runaway, cost, and high carbon footprint, starting with the extraction of the transition metals in ores with low metal content. These limitations were the motivation for an intensive research to replace the inorganic electrodes by organic electrodes. Subsequently, the disadvantages that are mentioned above are overcome, but are replaced by new ones, including the solubility of the organic molecules in the electrolytes and lower operational voltage. However, recent progress has been made. The lower voltage, even though it is partly compensated by a larger capacity density, may preclude the use of organic electrodes for electric vehicles, but the very long cycling lives and the fast kinetics reached recently suggest their use in grid storage and regulation, and possibly in hybrid electric vehicles (HEVs). The purpose of this work is to review the different results and strategies that are currently being used to obtain organic electrodes that make them competitive with lithium-ion batteries for such applications.

Untying thioether bond structures enabled by "voltage-scissors" for stable room temperature sodium-sulfur batteries

A steady sulfur cathode is central to realizing stable room temperature sodium-sulfur (RT Na-S) batteries. Here, sulfur atoms are incorporated into carbon to form thioether bond functionalized carbon (SC) as a cathode material for sodium storage, which is capable of the complete elimination or great suppression of the shuttle effect of soluble poly-sulfides by the generation of insoluble sulfides in RT Na-S batteries using an ordinary carbonate electrolyte. This thioether bond structure (C-S-C) in sulfur-doped carbon can be disassembled by the assistance of "voltage-scissors" in the low voltage range of 0.01-0.50 V vs. Na/Na+. The small sulfur species derived from the thioether bond structure react with the sodium anode to form insoluble sulfides. Moreover, the insoluble sulfides Na2S2 and Na2S are confined in the carbon defects induced by the cleaved sulfur to prevent them from degrading the long-chain poly-sulfides. The distinctive electrochemical performance of SC enriches our understanding of the sulfur cathode, and could provide novel insights for constructing stable sulfur cathode materials for specific energy storage devices.

Ether-compatible sulfurized polyacrylonitrile cathode with excellent performance enabled by fast kinetics via selenium doping

Sulfurized polyacrylonitrile is suggested to contain Sn (n ≤ 4) and shows good electrochemical performance in carbonate electrolytes for lithium sulfur batteries. However inferior results in ether electrolytes suggest that high solubility of Li2Sn (n ≤ 4) trumps the limited redox conversion, leading to dissolution and shuttling. Here, we introduce a small amount of selenium in sulfurized polyacrylonitrile to accelerate the redox conversion, delivering excellent performance in both carbonate and ether electrolytes, including high reversible capacity (1300 mA h g-1 at 0.2 A g-1), 84% active material utilization and high rate (capacity up to 900 mA h g-1 at 10 A g-1). These cathodes can undergo 800 cycles with nearly 100% Coulombic efficiency and ultralow 0.029% capacity decay per cycle. Polysulfide dissolution is successfully suppressed by enhanced reaction kinetics. This work demonstrates an ether compatible sulfur cathode involving intermediate Li2Sn (n ≤ 4), attractive rate and cycling performance, and a promising solution towards applicable lithium-sulfur batteries.

Influence of morphology of monolithic sulfur-poly(acrylonitrile) composites used as cathode materials in lithium-sulfur batteries on electrochemical performance

Solvent-induced phase separation (SIPS) and thermally-induced phase separation (TIPS) derived poly(acrylonitrile) (PAN) based monoliths with different morphology and specific surface area were prepared and thermally converted into monolithic sulfur-poly(acrylonitrile) (SPAN) materials for use as active cathode materials in lithium-sulfur batteries. During thermal processing, the macroscopic monolithic structure fully prevailed while significant changes in porosity were observed. Both the monomer content in the precursor PAN-based monoliths and the tortuosity of the final monolithic SPAN materials correlate with the electrochemical performance of the SPAN-based cathodes. Overall, percolation issues predominate. In percolating SPAN-based cathode materials, the specific capacity of the SPAN-based cells increases with decreasing tortuosity. All monolithic SPAN materials provided highly reversible and cycle stable cathodes reaching reversible discharge capacities up to 1330 mA h gsulfur -1 @ 0.25C, 900 mA h gsulfur -1 @ 2C and 420 mA h gsulfur -1 @ 8C.

Rationally Designed High-Sulfur-Content Polymeric Cathode Material for Lithium-Sulfur Batteries

Polyethylene hexasulfide (PEHS) is investigated as a cathode material in lithium batteries. By utilizing a condensation reaction, ethylene groups are inserted between six linear sulfurs in a chain to obtain PEHS while simultaneously exercising control over the polysulfur chain length. Additionally, by selecting a low-molecular-weight organic group, PEHS contains 87 wt % sulfur, thus maximizing the material-level specific capacity to 1217 mA h g^-1. Furthermore, this synthesis method is validated using a host of materials characterization techniques. In a battery, PEHS prevents the formation of soluble long-chain intermediates that plague traditional sulfur cathodes. This enables a high material-level capacity of 774 mA h g^-1 at 1C-rate alongside a stable performance over 350 cycles with a capacity fade rate of only 0.083% per cycle. We also elucidate the unique reaction pathway of our short-chain polysulfur material and provide a useful foundation for further development of sulfur-containing polymer-based cathode materials.

Nonlithium Metal-Sulfur Batteries: Steps Toward a Leap

Present mobile devices, transportation tools, and renewable energy technologies are more dependent on newly developed battery chemistries than ever before. Intrinsic properties, such as safety, high energy density, and cheapness, are the main objectives of rechargeable batteries that have driven their overall technological progress over the past several decades. Unfortunately, it is extremely hard to achieve all these merits simultaneously at present. Alternatively, exploration of the most suitable batteries to meet the specific requirements of an individual application tends to be a more reasonable and easier choice now and in the near future. Based on this concept, here, a range of promising alternatives to lithium-sulfur batteries that are constructed with non-Li metal anodes (e.g., Na, K, Mg, Ca, and Al) and sulfur cathodes are discussed. The systems governed by these new chemistries offer high versatility in meeting the specific requirements of various applications, which is directly linked with the broad choice in battery chemistries, materials, and systems. Herein, the operating principles, materials, and remaining issues for each targeted battery characteristics are comprehensively reviewed. By doing so, it is hoped that their design strategies are illustrated and light is shed on the future exploration of new metal-sulfur batteries and advanced materials.

Synthesis of a Macroporous Conjugated Polymer Framework: Iron Doping for Highly Stable, Highly Efficient Lithium-Sulfur Batteries

Porous conjugated polymers offer enormous potential for energy storage because of the combined features of pores and extended π-conjugated structures. However, the drawbacks such as low pore volumes and insolubilities of micro- and mesoporous conjugated polymers restrict the loading of electroactive materials and thus energy storage performance. Herein, we report the synthesis of iron-doped macroporous conjugated polymers for hosting sulfur as the cathode of high-performance lithium-sulfur (Li-S) batteries. The macroporous conjugated polymers are synthesized via in situ growth of poly(3-hexylthiophene) (P3HT) from reduced graphene oxide (RGO) sheets, followed by gelation of the composite (RGO- g-P3HT) in p-xylene and freeze-drying. The network structures of the macroporous materials can be readily tuned by controlling the chain length of P3HT grafted to RGO sheets. The large pore volumes of the macroporous RGO- g-P3HT materials (ca. 34 cm³ g^-1) make them excellent frameworks for hosting sulfur as cathodes of Li-S batteries. Furthermore, incorporation of Fe into the macroporous RGO- g-P3HT cathode results in reduced polarization, enhanced specific capacity (1,288, 1,103, and 907 mA h g^-1 at 0.05, 0.1, and 0.2 C, respectively), and improved cycling stability (765 mA h g^-1 after 100 cycles at 0.2 C). Density functional theory calculations and in situ characterizations suggest that incorporation of Fe enhances the interactions between lithium polysulfides and the P3HT framework.

Covalent bonding of sulfur nanoparticles to unzipped multiwalled carbon nanotubes for high-performance lithium-sulfur batteries

The use of sulfur as a cathode material for lithium-sulfur (Li-S) batteries has attracted significant attention due to its high theoretical specific capacity (1675 mA h g^-1); however, practicality is hindered by a number of obstacles, including the shuttling effect of polysulfides and the low electrical conductivity of sulfur. Herein, ball milling sulfur with unzipped multiwalled carbon nanotubes (UMWNTs) was found to covalently immobilize sulfur nanoparticles to the UMWNTs and resulted in composites (designated as S@UMWNTs) with high electrical conductivity. The unzipping degree of MWNTs was first controlled to optimize the immobilization of sulfur nanoparticles to UMWNTs and the electrochemical performance of the resulting Li-S batteries. The presence of C-S covalent bonds between the UMWNTs and sulfur nanoparticles was verified using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, and the formation of C-S bonds was ascribed to the reactions between the mechanically-induced sulfur radicals and the functional groups of UMWNTs. As a result, when used as a cathode material for Li-S batteries, the S@UMWNTs exhibited excellent electrochemical performance, including a good long-term cycling stability and low capacity decay (e.g., ca. 0.09% per cycle over 500 charge/discharge cycles at 1 C) due to the suppression of the shuttling effect by the C-S covalent bonds.

Iodine-doped sulfurized polyacrylonitrile with enhanced electrochemical performance for room-temperature sodium/potassium sulfur batteries

Iodine-doped sulfurized polyacrylonitrile with high conductivity displays an unprecedented capacity for RT-Na/S and RT-K/S batteries operated in ester-based electrolytes.

Sulfur-anchored azulene as a cathode material for Li–S batteries

A benzene-free and vinyl-free molecule, azulene, is used to polymerize with sulfur for new cathode material based Li–S batteries.

A stable polypyridinopyridine–red phosphorus composite as a superior anode material for long-cycle lifetime lithium-ion batteries

A novel stable polypyridinopyridine–red phosphorus composite as a superior anode material for long-cycle lifetime lithium-ion batteries.