Sulfur Host For Lithium-sulfur Batteries Research Articles

Blackberry-like hollow graphene spheres synthesized by spray drying for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries represent one of the most promising battery techniques in 21st century. However, the practical implementation of Li-S batteries is impeded by several intractable obstacles including the poor conductivity of sulfur, shuttling behaviour of polysulfides intermediates, and large volume change during sulfur lithiation. Thus, the rational design and morphological control of sulfur cathode paves the way to Li-S batteries practicalizations. Herein, we develop a blackberry-like hollow graphene sphere through spray drying method as a promising sulfur host for Li-S batteries. Attributed to the uniform sulfur distribution, fast reaction kinetics, and excellent sulfur immobilization, the S-HGS composite electrode achieves a highly reversible capacity of 780 mAh g−1, a great rate capability as well as cyclability without adding additives.

P,O,N-Co Doped Carbon Scaffolds from LiFePO4 Nanoparticles As Sulfur Hosts for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are well knowned as one of the promising energy applications with high specific capacity, such as electric vehicles and energy storage system, owing to their high theoretical capacity of 1672 mA h g−1, eco friendliness, and the abundance all over the world. However, Li-S batteries have some challenge, such as the poor Coulombic efficiency, fast capacity fading, and unstable cycle performance by the dissolution of lithium polysulfides (LiPSs) in the electrolyte by shuttle mechanism during long cycling. To challenge these problems, we suggest that P, O, and N co-doped hollow carbons with graphene from LiFePO4 nanoparticles are very efficient as sulfur hosts for Li-S batteries. This sample from LiFePO4 nanoparticles provides sufficient spaces with the variety of pore sizes for storage of sulfur and various heteroatoms doping to minimize the dissolution of the LiPSs. This sample can block the dissolution of LiPSs due to the efficient hosts and the excellent chemical affinity with LiPSs. Its electrode indicates the very stable cycle performance and high rate capability, as proved by LiPSs adsorption test. We suggest that this sample has high potential as a sulfur host for real application in Li-S batteries with more optimization.

Simultaneous growth of carbon nanotubes on inner/outer surfaces of porous polyhedra: Advanced sulfur hosts for lithium-sulfur batteries

Metal-organic framework (MOF)-derived functional carbon matrices have recently attracted considerable attention as energy-storage materials. However, the development of MOF-derived carbon materials with hierarchical structures, capable of thoroughly preventing the “shuttling᾿of polysulfides, is still a major challenge. Herein, we synthesized cobalt nanoparticle-containing porous carbon polyhedra with in situ grown N-doped carbon nanotube (CNT) backbone (NCCNT-Co), using zeolitic imidazolate framework-67 (ZIF-67) as starting material. The obtained NCCNT-Co, with interconnected N-doped CNTs on both inner and outer surfaces, possesses an integrated conductive network, which can further accelerate the transport of electrons/ions inside the whole sulfur cathode. The mesoporous structure derived from the ZIF-67 matrix and the densely immobilized CNTs, coupled with the homogeneously doped N atoms and Co nanoparticles, can efficiently trap lithium polysulfides (LiPSs) by physical confinement and chemical interactions. Furthermore, the hierarchical structure of the porous carbon polyhedra enables a high sulfur loading of up to 76 wt.% and can also buffer the volume changes of active sulfur during the lithiation process. As a result, the NCCNT-Co-S cathode delivers a high initial specific capacity of 1,300 mAh·g−1 at 0.1 C, along with a high capacity of 860 mAh·g−1 after 500 cycles at 1 C, with an extremely low capacity decay of 0.024% per cycle.

Preparation of Mn3O4-CNTs microspheres as an improved sulfur hosts for lithium-sulfur batteries

A novel, sulfur host, Mn3O4-CNTs microsphere was prepared by ultrasonic spraying with subsequent impregnation methods and appeared to effectively mitigate the dissolution of intermediate polysulfides from the Li-S cathode. Mn3O4-CNTs microspheres are caddice-like balls that are interwoven with CNTs that contains Mn3O4 nanoparticles. These novel Mn3O4-CNTs microspheres were found to exhibit high initial charge and discharge capacities of 1216 and 1227 mAh g−1 at 0.1 C and they exhibited a favorable cycle stability of 1087 mAh g−1 at 0.2 C after 200 cycles. These attributes make this new material a good, potential cathode material for lithium-sulfur batteries.

Mesoporous Mn-Sn bimetallic oxide nanocubes as long cycle life anodes for Li-ion half/full cells and sulfur hosts for Li-S batteries

Mesoporous Mn-Sn bimetallic oxide (BO) nanocubes with sizes of 15–30 nm show outstanding stable and reversible capacities in lithium ion batteries (LIBs), reaching 856.8 mAh·g–1 after 400 cycles at 500 mA·g–1 and 506 mAh·g–1 after 850 cycles at 1,000 mA·g–1. The preliminary investigation of the reaction mechanism, based on X-ray diffraction measurements, indicates the occurrence of both conversion and alloying–dealloying reactions in the Mn-Sn bimetallic oxide electrode. Moreover, Mn-Sn BO//LiCoO2 Li-ion full cells were successfully assembled for the first time, and found to deliver a relatively high energy density of 176.25 Wh·kg–1 at 16.35 W·kg–1 (based on the total weight of anode and cathode materials). The superior long-term stability of these materials might be attributed to their nanoscale size and unique mesoporous nanocubic structure, which provide short Li+ diffusion pathways and a high contact area between electrolyte and active material. In addition, the Mn-Sn BOs could be used as advanced sulfur hosts for lithium-sulfur batteries, owing to their adequate mesoporous structure and relatively strong chemisorption of lithium polysulfide. The present results thus highlight the promising potential of mesoporous Mn-Sn bimetallic oxides for application in Li-ion and Li-S batteries.

Utilizing a metal as a sulfur host for high performance Li-S batteries

Molybdenum, for the first time, was used as a new type of sulfur host for lithium-sulfur batteries and exhibited outstanding electrochemical performance, even over traditional porous carbon hosts. A Mo-S composite, with 80 wt% sulfur loading, delivered reversible capacities of 1003 mAh g−1 after 130 cycles at 0.1 C, and 786 mAh g−1 after 100 cycles at 5.0 C. Further analysis using in situ X-ray diffraction, cyclic voltammetry, and density functional theory calculations demonstrated that the Mo surface can not only effectively trap polysulfides, but also catalytically decompose polysulfides and Li2S.

A porous N-doped carbon aggregate as sulfur host for lithium-sulfur batteries

Lithium-sulfur batteries have been regarded as one of the most prospective energy storage systems due to low cost and high energy density. However, the inferior cycle stability mainly due to the dissolution of polysulfides seriously restricts its practical application. Herein, a porous N-doped carbon nanofiber/carbon nanotube aggregate is obtained through the chemical oxidation combined with chemical vapor deposition method for lithium-sulfur batteries. The favorable microstructure and configuration exhibit good ability of localizing and retaining dissolved intermediate polysulfides through the in situ growth of carbon nanotube bushes on the carbonized polyaniline (PANI) nanofiber. Moreover, the three-dimensional conductive carbon as a matrix facilitates the electron transfer and reversible electrochemical reaction of active materials during cycling. This advantageous structure exhibits excellent electrochemical performance with high initial discharge capacity of 1018 mA h g−1 and stable capacity of 591 mA h g−1 at 1 C after 500 cycles.

Lithium–Sulfur Batteries: Dodecylamine‐Induced Synthesis of a Nitrogen‐Doped Carbon Comb for Advanced Lithium–Sulfur Battery Cathodes (Adv. Mater. Interfaces 9/2018)

A novel dodecylamine micelle-induced self-assembling method for constructing N-doped carbon combs from close-packed hollow submicron carbon spheres is reported by Kaiming Liao, Zongping Shao and co-workers in article number 1701659. The highly interconnected N-doped carbon comb can serve as a new type of sulfur host for lithium-sulfur batteries, delivering an outstanding performance. Cover illustrator: Yijun Zhong.

Porous-Shell Vanadium Nitride Nanobubbles with Ultrahigh Areal Sulfur Loading for High-Capacity and Long-Life Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries hold great promise for the applications of high energy density storage. However, the performances of Li-S batteries are restricted by the low electrical conductivity of sulfur and shuttle effect of intermediate polysulfides. Moreover, the areal loading weights of sulfur in previous studies are usually low (around 1-3 mg cm-2) and thus cannot fulfill the requirement for practical deployment. Herein, we report that porous-shell vanadium nitride nanobubbles (VN-NBs) can serve as an efficient sulfur host in Li-S batteries, exhibiting remarkable electrochemical performances even with ultrahigh areal sulfur loading weights (5.4-6.8 mg cm-2). The large inner space of VN-NBs can afford a high sulfur content and accommodate the volume expansion, and the high electrical conductivity of VN-NBs ensures the effective utilization and fast redox kinetics of polysulfides. Moreover, VN-NBs present strong chemical affinity/adsorption with polysulfides and thus can efficiently suppress the shuttle effect via both capillary confinement and chemical binding, and promote the fast conversion of polysulfides. Benefiting from the above merits, the Li-S batteries based on sulfur-filled VN-NBs cathodes with 5.4 mg cm-2 sulfur exhibit impressively high areal/specific capacity (5.81 mAh cm-2), superior rate capability (632 mAh g-1 at 5.0 C), and long cycling stability.

N-doped yolk-shell hollow carbon sphere wrapped with graphene as sulfur host for high-performance lithium-sulfur batteries

N-doped yolk-shell hollow carbon sphere wrapped with reduced graphene oxide (rGO/N-YSHCS) is designed and fabricated as sulfur host for lithium-sulfur batteries. The shuttle effect of polysulfides can be suppressed effectively by the porous yolk-shell structure, graphene layer and N-doping. A good conductivity network is provided for electron transportation through the graphene layer coupled with the unique yolk-shell carbon matrix. Such unique structure offers the synthesized rGO/N-YSHCS/S electrode with a high reversible capacity (800mAhg−1 at 0.2 C after 100 cycles) and good high-rate capability (636mAhg−1 at 1 C and 540mAhg−1 at 2 C).

CeO2-webbed carbon nanotubes as a highly efficient sulfur host for lithium-sulfur batteries

The lithium-sulfur batteries have obtained tremendous interest as the next-generation of rechargeable battery systems due to the high theoretical specific capacity of sulfur, 1675mAhg−1. However, the practical application of lithium-sulfur batteries is still hindered by fast capacity fading and poor cycling stability. In this work, CeO2-webbed carbon nanotubes (CeO2@CNT) is designed and synthesized by solvothermal reaction and used as a conceptually new sulfur host for lithium-sulfur batteries. In this unique architecture, the carbon nanotubes form a three-dimension porous conductive network to provide fast electron paths. In addition, the nanosized CeO2 crystallites can chemically bind polysulfides to suppress the polysufides diffusion into electrolyte. As a result, the lithium-sulfur batteries based on this electrode material exhibit high specific capacity, superior cycling stability, and good rate capability. Reversible specific capacities of 1359 and 715mAhg−1 are achieved at rates of 0.1 and 1C, respectively, together with an excellent cycling stability of 0.07% capacity decay per cycle over 600 cycles at 0.5 C.

Lightweight, free-standing 3D interconnected carbon nanotube foam as a flexible sulfur host for high performance lithium-sulfur battery cathodes

The still hindered practical application of lithium-sulfur (Li-S) batteries with a high theoretical energy density of 2.6 kWh kg−1 can only be feasible by a simple and scaling-up fabrication of highly stable sulfur-based cathodes. Herein, a free-standing, mechanically flexible, binder-free 3D interconnected carbon nanotube ‘foam’ (CNTF) is prepared by a single-step facile method and used as a sulfur host in Li-S batteries. For the first time, such a simple method has been adopted for the preparation of free-standing CNT scaffolds for use in Li-S cells, as our method is free from the widely reported solvent-based techniques such as vacuum infiltration of CNTs to obtain free-standing forms but requires further purification and/or drying. A high-areal sulfur loading of 7.1mgScm−2, accounting to a total electrode mass of 10.9mgelectrodecm−2, with yet high electrochemical sulfur utilization of 72% is achievable by the foam-like CNT structure. Reversible areal capacities of up to 9mAhcm−2 at extremely low electrode weight (800mAhgelectrode−1) and specific capacities up to 1378mAhgS−1 are demonstrated. The interconnected porous network acts as a reservoir for trapping soluble lithium polysulfide compounds and greatly improves the sulfur reutilization. The lightweight CNT scaffold further provides enduring electrical contact with the sulfur species, resulting in excellent cycling stability and a potentially high gravimetric energy density desirable for automobiles and aerospace applications. The CNTF/sulfur composite cathode exhibits better rate performance and cycling stability than most of the recently reported CNT-based cathode materials for Li-S batteries.

Complex Hollow Nanostructures: Synthesis and Energy-Related Applications.

Hollow nanostructures offer promising potential for advanced energy storage and conversion applications. In the past decade, considerable research efforts have been devoted to the design and synthesis of hollow nanostructures with high complexity by manipulating their geometric morphology, chemical composition, and building block and interior architecture to boost their electrochemical performance, fulfilling the increasing global demand for renewable and sustainable energy sources. In this Review, we present a comprehensive overview of the synthesis and energy-related applications of complex hollow nanostructures. After a brief classification, the design and synthesis of complex hollow nanostructures are described in detail, which include hierarchical hollow spheres, hierarchical tubular structures, hollow polyhedra, and multi-shelled hollow structures, as well as their hybrids with nanocarbon materials. Thereafter, we discuss their niche applications as electrode materials for lithium-ion batteries and hybrid supercapacitors, sulfur hosts for lithium-sulfur batteries, and electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. The potential superiorities of complex hollow nanostructures for these applications are particularly highlighted. Finally, we conclude this Review with urgent challenges and further research directions of complex hollow nanostructures for energy-related applications.

Scalable Synthesis of Honeycomb-like Ordered Mesoporous Carbon Nanosheets and Their Application in Lithium-Sulfur Batteries.

There is a growing need to improve the electrical conductivity of the cathode and to suppress the rapid capacity decay during cycling in lithium-sulfur (Li-S) batteries. This can be achieved by developing facile methods for the synthesis of novel nanostructured carbon materials that can function as effective cathode hosts. In this Article, we report the scalable synthesis of ordered mesoporous carbon nanosheets (OMCNS) via the etching of self-assembled iron oxide/carbon hybrid nanosheets (IO-C NS), which serve as an advanced sulfur host for Li-S batteries. The obtained two-dimensional (2D) nanosheets have close-packed uniform cubic mesopores of ∼20 nm side length, and the gap between the pores is ∼4 nm, which resembles the honeycomb structure consisting of an ordered array of hexagonal pores. We loaded OMCNS with sulfur by a simple melting infusion process and evaluated the performance of the resulting OMCNS-sulfur composites as the cathode material. As a result, the sulfur-loaded OMCNS hybrid (OMCNS-S) electrode infiltrated with 70 wt % sulfur delivers a high and stable reversible capacity of 505.7 mA h g-1 after 500 cycles at 0.5 C-rate with excellent capacity retention (a decay of 0.081% per cycle) and excellent rate capability (580.6 mA h g-1 at a high current density of 2 C). The improved electrochemical properties could be attributed to the fact that the uniform cubic mesopores offer sufficient space for the volume expansion of sulfur inside them and therefore trap the polysulfides during the charging-discharging process. Therefore, these unique structured carbon nanosheets can be promising candidates for other energy-storage applications.

Double-Shelled Nanocages with Cobalt Hydroxide Inner Shell and Layered Double Hydroxides Outer Shell as High-Efficiency Polysulfide Mediator for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li-S batteries. Here, we have designed and synthesized double-shelled nanocages with two shells of cobalt hydroxide and layered double hydroxides (CH@LDH) as a conceptually new sulfur host for Li-S batteries. Specifically, the hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur (75 wt %), but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. When evaluated as cathode material for Li-S batteries, the CH@LDH/S composite shows a significantly improved electrochemical performance.

Frontispiz: Hollow Carbon Nanofibers Filled with MnO2Nanosheets as Efficient Sulfur Hosts for Lithium-Sulfur Batteries

Lithium-Schwefel-Batterien Die Synthese von mit MnO2-Nanoschichten gefüllten Kohlenstoffnanofasern und deren Verwendung als Schwefelmatrix in Lithium-Schwefel-Batterien werden von X. W. Lou et al. in ihrer Zuschrift auf S. 13078 ff. vorgestellt.