Synthesis and electrochemical performance of sulfur–carbon composite cathode for lithium–sulfur batteries

In this paper, porous carbon was synthesized by an activation method, with phenolic resin as carbon source and nanometer calcium carbonate as activating agent. Sulfur–porous carbon composite material was prepared by thermally treating a mixture of sublimed sulfur and porous carbon. Morphology and electrochemical performance of the carbon and sulfur–carbon composite cathode were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectra (EIS), and galvanostatic charge–discharge test. The composite containing 39 wt.% sulfur obtained an initial discharge capacity of about 1,130 mA?h g^?1 under the current density of 80 mA?g^?1 and presented a long electrochemical stability up to 100 cycles.     

Carbon fiber-incorporated sulfur/carbon ternary cathode for lithium–sulfur batteries with enhanced performance

Journal of Solid State Electrochemistry - Smart construction of advanced sulfur cathodes is indispensable for the development of high performance lithium–sulfur (Li–S) batteries. Hence,...     

Hierarchically porous nitrogen-doped carbon as cathode for lithium–sulfur batteries

Porous nitrogen-doped carbon is an especially promising material energy storage due to its excellent conductivity, stable physicochemical properties, easy processability, controllable porosity and low price.Herein, we reported a novel well-designed hierarchically porous nitrogen-doped carbon(HPNC) via a combination of salt template(ZnCl_2) and hard template(SiO_2) as sulfur host for lithium–sulfur batteries. The low-melting ZnCl_2 is boiled off and leaves behind micropores and small size mesopores during pyrolysis process, while the silica spheres are removed by acid leaching to generate interconnected 3D network of macropores. The HPNC-S electrode exhibits an initial specific capacity of 1355 mAh g~(–1) at 0.1 C(1 C = 1675 m Ah g~(–1)), a high-rate capability of 623 m Ah g~(–1) at 2 C, and a small decay of 0.13% per cycle over 300 cycles at 0.2 C. This excellent rate capability and remarkable long-term cyclability of the HPNC-S electrode are attributed to its hierarchical porous structures for confining the soluble lithium polysulfide as well as the nitrogen doping for high absorbability of lithium polysulfide.     

CoNi-embedded nitrogen-enriched porous carbon framework for long-life lithium–sulfur batteries

Journal of Solid State Electrochemistry - Metal–organic framework (MOF) derivatives are excellent energy storage devices such as lithium–sulfur batteries. Here, a bimetallic...     

Nitrogen-doped hierarchical porous carbon derived from metal–organic aerogel for high performance lithium–sulfur batteries

Nitrogen-doped three-dimensional(3 D) porous carbon materials have numerous applications due to their highly porous structures, abundant structural nitrogen heteroatom decoration and low densities. Herein,nitrogen doped hierarchical 3 D porous carbons(NHPC) were prepared via a novel metal–organic aerogel(MOA), using hexamethylenetetramine(HMT), 1,3,5-benzenetricarboxylic acid and copper(II) as starting materials. The morphology, porous structure of the building blocks in the NHPC can be tuned readily using different amount of HMT, which makes elongation of the pristine octahedron of HKUST-1 to give rise to different aspect ratio rod-like structures. The as-prepared NHPC with rod-like carbons exhibit high performance in lithium sulfur battery due to the rational ion transfer pathways, high N-doped doping and hierarchical porous structures. As a result, the initial specific capacity of 1341 m A h/g at rate of 0.5 C(1 C = 1675 m A h/g) and high-rate capability of 354 m A h/g at 5 C was achieved. The decay over 500 cycles is 0.08% per cycle at 1 C, highlighting the long-cycle Li–S batteries.     

Grafting polymeric sulfur onto carbon nanotubes as highly-active cathode for lithium–sulfur batteries

Lithium–sulfur(Li–S)batteries are being explored as promising advanced energy storage systems due to their ultra-high energy density.However,fast capacity fading and low coulombic efficiency,resulting from the dissolution of polysulfides,remain a serious challenge.Compared to weak physical adsorptions or barriers,chemical confinement based on strong chemical interaction is a more effective approach to address the shuttle issue.Herein,we devise a novel polymeric sulfur/carbon nanotube composite for Li–S battery,for which 2,5-dithiobiurea is chosen as the stabilizer of long-chain sulfur.This offers chemical bonds which bridge the polymeric sulfur and carbon nanotubes.The obtained composite can deliver an ultra-high reversible capacity of 1076.2 m Ah g~(-1)(based on the entire composite)at the rate of 0.1 C with an exceptional initial Coulombic efficiency of 96.2%,as well as remarkable cycle performance.This performance is mainly attributed to the reaction reversibility of the obtained polymeric sulfur-based composite during the discharge/charge process.This was confirmed by density functional theory calculations for the first time.     

Low-cost,porous carbon current collector with high sulfur loading for lithium–sulfur batteries

Li–S batteries with a porous carbon current collector (PCCC), high sulfur loading (2.3 mg cm^− 2, equal to 80 wt.% sulfur content), high capacity, and long cycle life have been fabricated with a simple one-step paste absorption method. The intimate contact between the insulating sulfur and the embedded conductive matrix allows high active material loading. The high absorptivity of electrolyte by the PCCC facilitates efficient retention of soluble polysulfides within the PCCC, so the 3D cathode architecture stabilizes the electrochemical reaction within the porous space.     

Electrocatalysis of polysulfide conversion via sulfur–cobalt CoS2 on a carbon nanotube surface as a cathode for high-performance lithium–sulfur batteries

Journal of Solid State Electrochemistry - Lithium–sulfur batteries received intense attention because of their high-energy density and inexpensive active material. However, the poor...     

Edge sulfurized graphene nanoplatelets via vacuum mechano-chemical reaction for lithium–sulfur batteries

Lithium–sulfur batteries have great potential for high energy applications due to their high capacities,low cost and eco-friendliness. However, the particularly rapid capacity decay owing to the dissolution and diffusion of polysulfide intermediate into the electrolyte still hamper their practical applications.And the reported preparation procedures to sulfur based cathode materials are often complex, and hence are rather difficult to produce at large scale. Here, we report a simple mechano-chemical sulfurization methodology in vacuum environment applying ball-milling method combined both the chemical and physical interaction for the one-pot synthesis of edge-sulfurized grapheme nanoplatelets with 3D porous foam structure as cathode materials. The optimal sample of 70%S–Gn Ps-48 h(ball-milled 48 h) obtains 13.2 wt% sulfur that chemically bonded onto the edge of Gn Ps. And the assembled batteries exhibit high initial discharge capacities of 1089 mAh/g at 0.1 C and 950 mAh/g at 0.5 C, and retain a stable discharge capacity of 776 mAh/g after 250 cycles at 0.5 C with a high Coulombic efficiency of over 98%. The excellent performance is mainly attributed to the mechano-chemical interaction between sulfur and grapheme nanoplatelets. This definitely triggers the currently extensive research in lithium–sulfur battery area.     

Cyclability of sulfur/dehydrogenated polyacrylonitrile composite cathode in lithium–sulfur batteries

Sulfur/dehydrogenated polyacrylonitrile composite has been studied as cathode material for lithium–sulfur rechargeable batteries. Nonetheless, capacity fading has been a challenge for the commercialization of batteries. In this study, characterization techniques of scanning electron microscopy, energy dispersive X-ray spectroscopy, elemental analysis, cyclic voltammetry, and electrochemical impedance spectroscopy are used to investigate the change of cathode properties with charge–discharge cycles. Elemental analysis reveals that sulfur accumulates on the surface of the composite at the end of charge, and the sulfur formation decreases with cycle number. Scanning electron microscopy observations indicate that cathode surface morphology changes significantly after several cycles. By modeling the electrochemical impedance spectra of the cell in different discharge states, we suggest that capacity fading arises mainly from the formation and accumulation of irreversible Li₂S (and Li₂S₂) on the cathode surface.     

Insight into demand-driven preparation of single-atomic mediators for lithium–sulfur batteries

Lithium-sulfur(Li-S) batteries have attracted considerable attention as one of the most appealing energy storage systems.Strenuous efforts have been devoted to tackling the tremendous challenges,mainly pertaining to the severe shuttle effect,sluggish redox kinetics and lithium dendritic growth.Single-atomic mediators as promising candidates exhibit impressive performance in addressing these intractable issues.Related research often utilizes a trial-and-error approach,proposing solutions to fabri...     

Synthesis and application of single-atom catalysts in sulfur cathode for high-performance lithium–sulfur batteries

Lithium–sulfur(Li-S) batteries are regarded as one of the most promising energy storage devices because of their low cost, high energy density, and environmental friendliness. However, Li-S batteries suffer from sluggish reaction kinetics and serious “shuttle effect” of lithium polysulfides(LiPSs), which causes rapid decay of battery capacity and prevent their practical application. To address these problems, introducing single-atom catalysts(SACs) is an effective method to improve the electroch...     

An odyssey of lithium metal anode in liquid lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries exhibit outstanding energy density and material sustainability. Enormous effects have been devoted to the sulfur cathode to address redox kinetics and polysulfide intermediates shuttle. Recent attentions are gradually turning to the protection of the lithium metal anodes, since electrochemical performances of Li–S batteries are closely linked to the working efficiency of the anode side, especially in pouch cells that adopt stringent test protocols. This Perspective article summarizes critical issues encountered in the lithium metal anode, and outlines possible solutions to achieve efficient working lithium anode in Li–S batteries. The lithium metal anode in Li–S batteries shares the common failure mechanisms of volume fluctuation, nonuniform lithium flux, electrolyte corrosion and lithium pulverization occurring in lithium metal batteries with oxide cathodes, and also experiences unique polysulfide corrosion and massive lithium accumulation. These issues can be partially addressed by developing three-dimensional scaffold, exerting quasi-solid reaction, tailoring native solid electrolyte interphase (SEI) and designing artificial SEI. The practical evaluation of Li–S batteries highlights the importance of pouch cell platform, which is distinguished from coin-type cells in terms of lean electrolyte-to-sulfur ratio, thin lithium foil, as well as sizable total capacity and current that are loaded on pouch cells. This Perspective underlines the development of practically efficient working lithium metal anode in Li–S batteries.     

Synthesis and electrochemical performance of TiO2–sulfur composite cathode materials for lithium–sulfur batteries

Titania–sulfur (TiO₂–S) composite cathode materials were synthesized for lithium–sulfur batteries. The composites were characterized and examined by X-ray diffraction, nitrogen adsorption/desorption measurements, scanning electron microscopy, and electrochemical methods, such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. It is found that the mesoporous TiO₂ and sulfur particles are uniformly distributed in the composite after a melt-diffusion process. When evaluating the electrochemical properties of as-prepared TiO₂–S composite as cathode materials in lithium–sulfur batteries, it exhibits much improved cyclical stability and high rate performance. The results showed that an initial discharge specific capacity of 1,460 mAh/g at 0.2 C and capacity retention ratio of 46.6 % over 100 cycles of composite cathode, which are higher than that of pristine sulfur. The improvements of electrochemical performances were due to the good dispersion of sulfur in the pores of TiO₂ particles and the excellent adsorbing effect on polysulfides of TiO₂.     

Nano-wire networks of sulfur–polypyrrole composite cathode materials for rechargeable lithium batteries

Polypyrrole (PPy) nanowire was synthesized through a surfactant mediated approach. The sulfur–polypyrrole (S–PPy) composite materials were prepared by heating the mixture of element sulfur and polypyrrole nanowire. The materials were characterized by FTIR, SEM. PPy with special morphology serves as conductive additive, distribution agent and absorbing agents, which effectively enhanced the electrochemical performance of sulfur. The initial discharge capacity of the active materials was 1222 mA h g⁻¹ the remaining capacity is 570 mA h g⁻¹ after 20th cycles.     

Catalytic performance of binary transition metal sulfide FeCoS2/rGO for lithium–sulfur batteries

Journal of Solid State Electrochemistry - The FeCoS2/rGO was synthesized by a one-step hydrothermal method, which has the advantages of environmental friendliness and low cost. Dense and...     

A comparison of sulfur loading method on the electrochemical performance of porous carbon/sulfur cathode material for lithium–sulfur battery

To get a high sulfur loaded porous carbon/sulfur cathode material with an excellent performance, we investigated four different sulfur loading treatments. The samples were analyzed by the Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD) patterns, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). We proved that it is more effective to introduce the sulfur into the pores of porous carbon at 300 °C than at 155 °C. Especially, the porous carbon/sulfur composite heated in a sealed reactor at 300 °C for 8 h presents a fine sulfur load with sulfur content of 78 wt.% and exhibits an excellent electrochemical performance. The discharge capacity is 760, 727, 744, 713, and 575 mAh g^?1 of sulfur at a current density of 80, 160, 320, 800, and 1,600 mA g^?1 based on the sulfur/carbon composite, respectively. What is more, there is almost no decay at the current density of 800 mA g^?1 for 50 cycles and coulombic efficiency remains over 95 %.     

Ether-compatible lithium sulfur batteries with robust performance via selenium doping

The increasing demand of the green energy storage system encourages us to develop a higher energy storage system to take the place of the present lithium-ion batteries with limited energy/power densities[1,2].Among the diverse candidates。