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Physical confinement through particular nanostructures is inadequate to avoid the shuttle effect in the lithium–sulfur batteries. Electrocatalysts are based on chemisorption to fix polysulfides on the sulfur cathode and catalyze the conversion of polysulfides. Herein, a novel electrocatalyst consisting of iridium and rGO as support was prepared and employed as the additive to the sulfur cathode. Due to selective catalytic property and changes in activation energy, the formation of polysulfides is slightly inhibited and the transformation of polysulfides is accelerated. Finally, the accumulation of polysulfides and shuttle effect are alleviated. Due to the strong interaction between the polysulfide and catalyst, capacity retention and rate performance were greatly improved. [ABSTRACT FROM AUTHOR]

Dissolution and free diffusion of polysulfides in ether‐based electrolyte during cycling causes fast capacity decay and low columbic efficiency in lithium‐sulfur batteries. In this work, poly(2‐ethyl‐2‐oxazoline) (PEtOx), as an additive of sulfur cathodes, can gelatinate the electrolyte in the presence of polysulfide species, which can anchor the uncontrollable diffusion of polysulfides during the discharge process. Additionally, pore structures can form in the sulfur cathode after the dissolution of PEtOx into the electrolyte. As a result, the sulfur converted from polysulfides during subsequent charging processes will deposit more uniformly in the porous cathode. This "dissolution‐redeposition" mechanism effectively reduces the loss of active materials, providing beneficial guidance for practical Li−S batteries. [ABSTRACT FROM AUTHOR]

As a widely used electrocatalyst in fuel cells, metallic platinum has achieved great success in terms of kinetic promotion. Still plagued by a familiar problem, owing to the sluggish kinetics of irreversible Li2S2/Li2S species deposition, lithium−sulfur batteries with high theoretical energy are far from being realized. Inspired by the similarity between oxygen and sulfur, being in the same group, commercially available Pt/C was investigated here to explore the possible effect on the sulfur cathode. The electrochemical tests show that the electrode with 2 wt% Pt added delivers a 61 % enhancement in the discharging specific capacity compared to the control electrode after 200 cycles at 0.5 C, along with an average coulombic efficiency of 98.3 %. It is proven that these beneficial results can be attributed to the favorable capability of polysulfide immobilization and effective inhibition of self-discharging behavior. The ex situ XPS analysis and the increased exchange current density further reveal that the involved platinum nanoparticles could not only function as a static chemical absorber for polysulfide species, but, more importantly, to promote the redox kinetic effectively as an electrochemical catalyst. The positive effect of utilizing commercial Pt/C materials directly on sulfur cathodes is of great significance in developing sulfur cathodes for Li/S batteries. [ABSTRACT FROM AUTHOR]

Spent sulfidic caustics (SSC) from caustic desulfurization are toxic hazards to the environment and humans. A new one-step process is proposed firstly to decrease the concentration of SSC and to assemble a high-performance sulfur cathode synchronously by electrolyzing a simulating solution with flexible carbon felt (CF) at 15 mA cm−2. The CF that electrolyzed for 8 hours with a sulfur content of 36.6 wt % or 5.63 mgsulfur cm−2 stands out from three S/CF composites in terms of areal capacity and cycling stability. XRD, TEM, thermogravimetric analysis, and Raman spectroscopy were then used to characterize the materials. Values of 4.03 mA h cm−2 over 150 cycles at 0.2 C and 2.34 mA h cm−2 after 90 cycles at 0.5 C can be attributed to an appropriate ratio of the external/inner sulfur content. The beneficial results prove the feasibility of an innovative mode of 'pollutant disposal with synchronous application', which integrates environmental management with the development of storage energy materials efficiently and eliminates the tedious individual disposal of pollutants and preparation of slurry-derived sulfur cathodes. [ABSTRACT FROM AUTHOR]

Poly(ethylene oxide)-coated sulfur/carbon (S/C/PEO) composite with a high sulfur loading is prepared to improve the performance of lithium-sulfur batteries. By magnetic string, 3.7 wt% PEO is coated onto the surface of ball-milling obtained S/C composite, leading to synthesis of S/C/PEO composite containing 78 wt% S. It is confirmed from a series of measurements that PEO covers the S/C composite uniformly, and PEO coating is quite effective in stabilizing the electrochemical performance. When employed as cathode for lithium-sulfur batteries, S/C/PEO delivers an initial discharge capacity of 989.6 mAh g and remains 648.3 mAh g after 110 cycles at a discharge/charge rate of 1 C (based on sulfur weight). Meanwhile, the coulomb efficiency of S/C/PEO composite reaches to ~98 % during the latter 105 cycles. The improved electrochemical performance can be attributed to the formation of PEO coating layer which can keep a tight contact between carbon and sulfur and lead to improved conductivity. Moreover, the PEO coating can act as a flexible cushion to accommodate volume changes of sulfur cathode as well as a barrier to trap soluble polysulfide intermediates during the charge-discharge processes. [ABSTRACT FROM AUTHOR]

Lithium sulfur batteries have brought significant advancement to the current state-of-art battery technologies due to their high theoretical specific energy of 1675 mAh g −1 . However, the rapid capacity degradation, mainly caused by polysulfide dissolution, remains a significant challenge prior to practical applications. In this work, a sulfur cathode modified by bifunctional nafion/γ-Al 2 O 3 membrane has been successfully prepared, which can remarkably immobilize the polysulfides within the unique cathode structure due to its ions selectivity and absorbent capacity. A high initial discharge capacity of 1448.0 mAh g −1 can be achieved at 1C and 788.6 mAh g −1 preserved after 200 cycles, indicating a slow degradation. Furthermore, the coulombic efficiency maintains as high as 97% during cycling. The excellent electrochemical properties can be attributed to the bifunctional and stable membrane which can dramatically reduce the shuttle effect and keep integrated even after charging–discharging for 200 cycles. [ABSTRACT FROM AUTHOR]

A yolk-shell sulfur/carbon (S/C) composite for the cathode of lithium-sulfur batteries was successfully prepared by an accessible method with tetrahydrofuran as solvent. The as-prepared composites are characterized by thermal gravimetric, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption and desorption. In this composite, sulfur particle is encapsulated in the carbon shell even entering into the micropores of carbon Bp2000. The electrochemical performance of the S/C composites is evaluated. The results indicate that the S/C composite with 50 wt% sulfur content shows good reversibility, excellent rate capability, and slow degradation. It delivers an initial capacity of 784.4 mAh g (based on sulfur weight) and preserves at 598.3 mAh g after 195 cycles at 1C. It achieves a high-capacity retention of 76.27 % from the 5th to 200th cycle, and as high as 91.19 % during the latter 150 cycles. The improvement is mainly attributed to the favorable structure of the S/C composite, in which the carbon cannot only facilitate transport of electrons and Li ions but also trap polysulfides and retard the shuttle effect during charge/discharge process. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a nafion coated electrode is prepared to improve the performance of lithium sulfur batteries. It is demonstrated from a series of measurements that the nafion layer is quite effective in reducing shuttle effect and enhancing the stability and the reversibility of the electrode. When measured under the rate of 0.2 C, the initial discharge capacity of the nafion coated electrode can reach 1084 mAh g−1, with a Columbic efficiency of about 100%. After 100 charge/discharge cycles, this electrode can also deliver a reversible capacity of as high as 879 mAh g−1. Significantly, the charge-transfer resistance of the electrode tends to be reducing after coated with an appropriate thickness of nafion film. The cation conductivity as well as anion inconductivity is considered to be the dominant factor for the superior electrochemical properties. [Copyright &y& Elsevier]

Turning stone into gold: The cover image depicts a green and efficient route to convert spent sulfidic caustic (SSC) into advanced energy‐storage materials. Compared with the conventional methods to transform sulfide separately, the novel strategy to recycle sulfide from SSC is particularly striking, not only decreasing the polluting sulfide successfully, but also simultaneously fabricating a sulfur/carbon composite for lithium–sulfur batteries. The composite with the appropriate inner/external ratio of sulfur content exhibited excellent areal capacity and good cycling performance. These excellent results prove the feasibility of an innovative method of “pollutant disposal with synchronization application”, which integrates environmental management with storage‐energy‐material development efficiently, replacing the tedious methods of disposing of pollutant and preparing the slurry‐derived sulfur cathode individually. More details can be found in the Full Paper by Wenlong Huang and Zhongqiang Shan et al. from Tianjin(Peiyang) University of China on page 1282 in Issue 8, 2017 (DOI: 10.1002/ente.201600611). [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li–S) batteries are considered to have the best development prospect for electric vehicles. But enhancing the cycling performance of Li–S batteries is necessary and urgent. Mesoporous MgO particles (MMgO) are prepared by surfactant templating method and used to prepare cathode materials for the first time. The prepared MMgO has a hexagonal flake-like structure with a thickness of 50–80 nm, a transverse length of 150–350 nm, a processing area of 181.56 m2/g, an average pore diameter of 3.11 nm and a pore volume of 0.26 cc/g. MMgO shows low intensity and slightly broader diffraction peaks in the XRD pattern, indicating the presence of lattice distortion, defects, dislocations or unsaturated valence bonds. MMgO particles are uniformly distributed on the sulfur surface to provide high surface area, many active sites and interconnected channel structure, which makes more sulfur contact with MMgO to be adsorbed, activated and participated in charge and discharge reaction. The Li–S battery containing sulfur/MMgO composite at weight ratio 90:10 shows the best cyclic stability with capacity retention rate 84.7% after 100 cycles at 0.2 C. The initial specific capacity of a Li–S battery with sulfur/MMgO composite at weight ratio 70:30 can reach 1062 mAh/g at 0.2 C, which is much higher than sulfur/commercial MgO at the same weight ratio. [ABSTRACT FROM AUTHOR]

Hybrid nanostructures containing one-dimensional (1D) carbon nanotubes (CNTs) and three-dimensional (3D) mesoporous carbon sphere have many promising applications due to their unique physical chemical properties. In this study, a novel 3D hierarchical carbon material (MCCNT) composed of mesoporous carbon sphere core and nitrogen rich CNTs shell is successfully prepared via an aerosol spray and subsequent chemical vapor deposition (CVD) processes. Owning to its well defined porous structure and favorable conductive framework, MCCNT is used as a potential sulfur host in lithium sulfur batteries through a classic melt-diffusion method. When cycled at a current density of 0.2 C (1 C = 1675 mA h g −1 ), it delivers an initial capacity as high as 1438.7 mAh g −1 . Even if the current density increase to 1 C, the specific capacity still remain up to 534.6 mAh g −1 after 300 cycles. The enhanced electrochemical performance can be attributed to the hybrid structure of MCCNT, in which, the porous core works as a host to confine sulfur and accommodate volume expansion and the external CNTs provide excellent electron and ion conductive frame work. Furthermore, the in-situ doped nitrogen on the surface of CNTs enables effective trapping of lithium polysulfides, leading to a much-improved cycling performance. [ABSTRACT FROM AUTHOR]