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Summary: To address volume expansion from active sulfur and shuttle effect from polysulfides during the electrochemical process of lithium sulfur batteries, nitrogen/sulfur co‐doping porous active carbons (NS‐PACs) derived from biomass cattail were manufactured by one‐step activated hydrothermal method. The effects of N/S atoms co‐doping and the activation of KOH on NS‐PACs were investigated in the macro‐morphology, micro‐structure, and electrochemical performance using scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), Brunauer‐Emmett‐Teller (BET), as well as galvanostatic charge/discharge tests. The experimental data demonstrated that the NS‐PACs show stable foam‐likes porous structure, and the specific surface area (SSA) and pore volumes are 2155.81 m2g−1 and 1.43 cm3g−1, respectively, and reveals perfect N/S atoms doping with S atomic content of 1.4% and N atomic content of 0.78%. Moreover, the initial discharge capacity of NS‐PACs is 1477.8 mAh g−1 at 0.1 C and the extraordinary long‐run cycling stability after 500 cycles reaches 803.4 mAh g−1 at 2.0 C. These outstanding electrochemical performances of NS‐PACs are associated with efficient physical confinement by porous architecture together with the potent chemical adsorption of N/S atoms with polysulfide. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries are more promising and attractive than lithium‐ion batteries owing to a higher charge‐storage capacity. However, their commercial applications are hindered by an undesirable polysulfide shuttling effect during the cycling procedure. Herein, nitrogen and sulfur codoped carbon nanotubes intertwined with flower‐like molybdenum disulfide (NSCNTs/MoS2) were synthesized by using a feasible hydrothermal method and used as effective lithium polysulfides (LiPSs) tamers. The NSCNTs/MoS2 had a strong hybrid structure with strong interfacial interactions for physical confinement, chemical adsorption, and electrocatalytic conversion of intermediate LiPSs during the charge–discharge process. The NSCNTs intensified the flexibility and constructed a conductive framework for rapid ion/electron transfer, whereas the electrocatalysis of MoS2 managed the sulfur reaction chemistry in two ways: it chemically immobilized LiPSs through Li−S bonds and kinetically sped up the sulfur redox reactions. Owing to these merits, the Li–S cell with a NSCNTs/MoS2 host and NSCNTs/MoS2‐coated separator (NSCNTs/MoS2/S‐NM) exhibited a high reversible capacity of 814 mAh g−1 at 1.0 C and long‐lasting cycling durability with an ultralow capacity decay of 0.02 % per cycle over 1000 cycles. Accordingly, rationally integrating the concepts of physical immobilization, chemical capture, and electrocatalysis to establish a multifaced cell structure for the architecture of high‐performance Li–S batteries is a significant strategy. [ABSTRACT FROM AUTHOR]

A kind of yarn‐like nitrogen‐doped carbon nanotubes microsphere (NSCNT) is synthesized in one‐step synthesis, and sulfur is added by melting immersion to form carbon nanotube microspheres/sulfur composites (NSCNT/S). The morphology, structure and electrochemical property of the obtained NSCNT/S are explored by field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD) and electrochemical tests. The results show that NSCNT possesses a high N content and unique mesoporous carbon framework with large specific surface area of 1029 m2 g−1, which can not only favor rapid electron and Li‐ion transfer but also effectively mitigate dissolved polysulfides via strong chemical and physical adsorption. Due to the synergetic interaction of NSCNT, the NSCNT/S delivers a high initial discharge capacity of 1241.3 mAh g−1 at 0.1 C and large rate capacity of 1175.5 mAh g−1 at 1 C with ultralow capacity decay of 0.1 % per cycle and high areal mass loading of 3.1 mg cm−2. This eco‐friendly NSCNT/S can offer an appealing improvement for the applications of high‐performance lithium‐sulfur batteries. Playing with a yarn ball: yarn‐like nitrogen‐doped carbon nanotube microspheres (NSCNT) are synthesized following a one‐step approach. Sulfur is added by melting immersion to form composites (NSCNT/S). The morphology, structure and electrochemical properties of the obtained NSCNT/S are explored. High discharge capacity and large rate capacity render this eco‐friendly NSCNT/S as an appealing improvement for the applications of high‐performance lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

A novel, sulfur host, Mn 3 O 4 -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. Mn 3 O 4 -CNTs microspheres are caddice-like balls that are interwoven with CNTs that contains Mn 3 O 4 nanoparticles. These novel Mn 3 O 4 -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. [ABSTRACT FROM AUTHOR]

A kind of nitrogen-doped activated microporous carbon sphere/sulfur composite (NAMCS/S) is deliberately designed and prepared via a controllable solvothermal method and a liquid phase in-situ sulfur deposition technology. The structure characteristic and composition analysis of samples are conducted with X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), field-emission scanning electron microscopy (FESEM) and high resolution transmission electron microscope (HRTEM). The electrochemical performances are characterized by galvanostatic charge-discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The results show that the nitrogen-doped activated microporous carbon spheres (NAMCS) present uniform spherical morphology, abundant nitrogen content of 9.64 wt%, and large specific surface areas of 1578.6 m 2 /g. Compared with the activated microporous carbon sphere/sulfur (AMCS/S) composite, the NAMCS/S composite with same sulfur loading of 64 wt% can deliver a higher initial capacity of 1004.6 mAh/g and a stable capacity retention of 79.1% after 100 cycles at 0.1 C rate as well as a remarkable Coulombic efficiency of 93% and relative low capacity decay of 0.2% per cycle. These effective improvements are attributed to the change of surface physicochemical property, chemical interaction between nitrogen functionality and polysulfides and the physical adsorption of abundant microporous structure. [ABSTRACT FROM AUTHOR]

Honeycomb-like nitrogen and sulfur dual-doped hierarchical porous biomass-derived carbon/sulfur composites (NSHPC/S) are successfully fabricated for high energy density lithium-sulfur batteries. The effects of nitrogen, sulfur dual-doping on the structures and properties of the NSHPC/S composites are investigated in detail by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and charge/discharge tests. The results show that N, S dual-doping not only introduces strong chemical adsorption and provides more active sites but also significantly enhances the electronic conductivity and hydrophilic properties of hierarchical porous biomass-derived carbon, thereby significantly enhancing the utilization of sulfur and immobilizing the notorious polysulfide shuttle effect. Especially, the as-synthesized NSHPC-7/S exhibits high initial discharge capacity of 1204 mA h g−1 at 1.0 C and large reversible capacity of 952 mA h g−1 after 300 cycles at 0.5 C with an ultralow capacity fading rate of 0.08 % per cycle even at high sulfur content (85 wt %) and high active material areal mass loading (2.8 mg cm−2) for the application of high energy density Li-S batteries. [ABSTRACT FROM AUTHOR]

The practical applications for Li–S batteries rely on the restriction of shuttle effect from polysulfides and the improvement of conductivity of sulfur and Li 2 S. 3D hierarchical nitrogen-doped graphene/carbon nanotubes (N-GCNTs) microspheres were prepared by one-step ultrasonic spraying deposition method. N-GCNTs microspheres are consisted of sucrose, graphene and water-soluble carbon nanotubes and are named according to different mass ratio, like N-GCNTs-1 (1:1:1), N-GCNTs-2 (1:3:1) and N-GCNTs-3 (1:5:1). N-GCNTs-2 microspheres have 3D porous structure with abundant of N atoms which is constituted by the intertwine of nanotubes and graphene, and maintained the characteristics of 1D and 2D nano-carbon. By contrast, N-GCNTs-1 microspheres shows broken microspheres connected by a few CNTs, and N-GCNTs-3 microspheres expose the smoother and integrated spheres which are hardly found CNTs. N-GCNTs-2 microspheres mainly manifest the eminent physical characterization for big BET specific surface area (575. 8 m2g-1) and pore volumes (0. 303568 cm3g-1) and high sulfur content (87.5%). Moreover, N-GCNTs-2 microspheres show the high initial discharge capacities of 1465. 1 mAh g−1 at 0.1 C , good cycle stability of 1315. 1 mAh g−1 after 200 cycles and outstanding long-term cycling performance of 849. 1 mAh g−1 after 500 cycles at 2.0 C. The N-GCNTs-2 microspheres effectively enhance the electrochemical performance of cathodes for lithium-sulfur batteries due to 3D hierarchical porous structure and successful N-doping. • A novel sulfur host was fabricated by one-step ultrasonic method. • N-GCNTs microspheres have 3D porous conductive structure with perfect N-doping. • N-GCNTs microspheres retain the structural features of 1D CNT and 2D graphene. • N-GCNTs microspheres can effectively prevent the dissolution of polysulfide. [ABSTRACT FROM AUTHOR]

Nanostructured porous carbon materials are widely used as sulfur host materials in order to enhance sulfur utilization and improve electrical performance in Li-S batteries. However, owing to interface incompatibility between the nanocarbon with homogeneous nonpolar surface and intrinsic polar sulfur guests, the cathode materials still face poor stability during the long-term cycling process. Herein, based on a highly effective sulfur host, namely manganese oxide nanosheets grown on both sides of the N-doped hollow porous carbon nanospheres (NHCSs@MnO 2 ), we put forward a rational physical and chemical dual-encapsulation strategy for the application of advanced Li-S batteries. The multifunctional, integrated and hollow hybrid nanospheres can provide efficient electron-modified interface, hold much more active material, and importantly face-to-face effectively prevent polysulfide dissolution and diffusion via the synergistic restriction, thus the developed NHCSs@MnO 2 /S composite exhibits an initial discharge capacity of 1249 mAh g −1 at 0.5 C and a sustainable cycling stability with ultralow capacity decay of only 0.041% per cycle over 1000 cycles, implying its great prospects for the improved cyclability and electrochemical performance as application of advanced Li-S battery. [ABSTRACT FROM AUTHOR]

Based on first-principles calculations, the hierarchical porous carbon/sulfur composites decorated by ionic surfactants (SDBS, SDS, CTAB) are firstly reported as the cathode materials for advanced lithium-sulfur batteries. The morphology, structure and electrochemical properties of the as-synthesized hierarchical porous carbon/sulfur composites are characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherm, Raman spectra, thermogravimetric analyses (TGA) and electrochemical tests. First-principles calculations reveal that lithium polysulfides (LiS and Li 2 S) can bind strongly to the O or N functional groups in the surfactants. Additionally, the hierarchical porous carbon, which derived from a very cheap and abundant cellulose bio-waste lotus seedpod shells, possesses a large specific surface area (2923.04 m 2 /g) and a high pore volume (1.4823 cm 3 /g). Hence, an outstanding initial capacity of 1138 mAh/g at a high discharge rate of 0.5 C with large areal mass loading of 3.2 mg/cm 2 and high sulfur contents of 86.55 wt% is obtained. Even after 100 cycles, the cathode material still represents an excellent cycling stability with reversible capacity of 1116 mAh/g at 0.1 C, low capacity decay of 0.16% per cycle and high coulombic efficiency of about 97%. [ABSTRACT FROM AUTHOR]