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Co-MoP/PCNFs modified Celgard separator in Lithium-sulfur battery. [Display omitted] Rational design of separators is especially critical to solve the "shuttle effect" of lithium polysulfides (LiPSs) and the sluggish redox kinetics in lithium-sulfur batteries (LSBs). Here, the multi-functional nanocomposite involving Co-doped molybdenum phosphide (Co-MoP) nanofibers and porous carbon nanofibers (PCNFs) is designed and prepared through electro-blow spinning and phosphating process, which possesses multiple adsorption and catalytic sites and is acted as the functional material for LSBs separators. In this multifunctional nanocomposite, the prepared Co-MoP nanofibers can provide internal adsorption and catalytic sites for LiPSs conversion. And the interconnected nitrogen-doped PCNFs can be elaborated an efficient LiPSs mediator and accommodate the huge volume changes in the reaction process for LSBs. Benefiting from the multiple adsorptive and catalytic sites of the developed functional materials, the assembled LSBs with a Co-MoP/PCNFs modified separator display outstanding electrochemical performances, including an admirable capacity retention of 770.4 mAh g−1 after 400 cycles at 1.0 C, only 0.08 % capacity decay per cycle at 2.0 C, rate performance up to 5 C, and also decent areal capacity even under a high sulfur loading of 4.9 mg cm−2. The work provides a facile pathway towards multifunctional separators in LSBs, and it may also help deepen preparation method of MoP through the electrostatic blowing/electrospinning technology in other related energy storage fields. [ABSTRACT FROM AUTHOR]

YF 3 /CoF 3 co-doped 1D carbon nanofibers as S host. [Display omitted] Lithium-sulfur (Li-S) batteries have attracted extensive attention in the field of energy storage due to their high energy density and low cost. However, conundrums such as severe polarization, poor cyclic performance originating from shuttle effect of lithium polysulfides and sluggish sulfur redox kinetics are stumbling blocks for their practical application. Herein, a novel sulfur cathode integrating sulfur and polyvinylpyrrolidone(PVP)-derived N -doped porous carbon nanofibers (PCNFs) with embedded CoF 3 and YF 3 nanoparticles are designed and prepared though the electrostatic blowing technology and carbonization process. The unique flexible PCNFs with embedded polar CoF 3 and YF 3 nanoparticles not only offer enough voids for volume expansion to maintain the structural stability during the electrochemical process, but also promote the physical encapsulation and chemical entrapment of all sulfur species. Moreover, the uniform distribution of YF 3 /CoF 3 nanoparticles also can expose more binding active sites to lithium polysulfide and present more catalytic sites to the greatest extent. Therefore, the assembled cells with the prepared cathode exhibited stable performances with an outstanding initial capacity of 1055.2 mAh g−1 and an extended cycling stability of 0.029% per cycle during the 300 cycles at 0.5C. Even at a high sulfur loading of 2.1 mg cm−2, The YF 3 /CoF 3 doped-PCNFs exhibited a high discharge specific capacity of 1038 mAh g−1, and the decay rate is also as low as 0.05% over 1000 cycles. This work shares a convenient and safe strategy for the synthesis of multi-dimension, dual-functional and stable superstructure electrode for advanced Li-S batteries. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur (Li−S) batteries, possessing excellent theoretical capacities, low cost and nontoxicity, are one of the most promising energy storage battery systems. However, poor conductivity of elemental S and the "shuttle effect" of lithium polysulfides hinder the commercialization of Li−S batteries. These problems are closely related to the interface problems between the cathodes, separators/electrolytes and anodes. The review focuses on interface issues for advanced separators/electrolytes based on nanomaterials in Li−S batteries. In the liquid electrolyte systems, electrolytes/separators and electrodes system can be decorated by nano materials coating for separators and electrospinning nanofiber separators. And, interface of anodes and electrolytes/separators can be modified by nano surface coating, nano composite metal lithium and lithium nano alloy, while the interface between cathodes and electrolytes/separators is designed by nano metal sulfide, nanocarbon‐based and other nano materials. In all solid‐state electrolyte systems, the focus is to increase the ionic conductivity of the solid electrolytes and reduce the resistance in the cathode/polymer electrolyte and Li/electrolyte interfaces through using nanomaterials. The basic mechanism of these interface problems and the corresponding electrochemical performance are discussed. Based on the most critical factors of the interfaces, we provide some insights on nanomaterials in high‐performance liquid or state Li−S batteries in the future. [ABSTRACT FROM AUTHOR]

MoP-MoO 2 /PCNFs modified Celgard separator in Lithium-sulfur battery. [Display omitted] • Investigating on the formation process of the heterostructured MoP-MoO 2 nanobelts. • Exploring the functions of various Mo-based heterojunctions in Li-S batteries. • Synergistic effect of LiPS desorption based PCNFs and heterostructured MoP-MoO 2. • The LSB with MoP-MoO 2 /PCNFs presents 856.9 mAh g−1 at 1C after 400 cycles. Lithium-sulfur batteries have ultra-high theoretical energy densities, which make them one of the most promising next-generation energy storage systems. However, it is still difficult to achieve large-scale commercialization because of fast capacity fade and poor rate capabilities. These problems are mainly caused by the severe shuttle effect of lithium polysulfide (LiPS) and slow redox kinetics. To solve these barriers, herein a modification strategy of functional separator is prepared by coating heterostructured and defective MoP-MoO 2 with porous carbon nanofibers (PCNFs) on the surface of a commercial separator. Moreover, for the first time, we detailly explored the formation processes of various heterojunction (MoP-MoO 2 , Mo 3 P-MoO 2 and MoP-Mo 3 P) derived from MoO 3 nanobelts and put forward some conceptions for the constituting heterostructured MoP-MoO 2 through the phosphorization of MoO 3 precursor. The functional coating layer exhibits both satisfactory interception ability for LiPS shuttle and fast LiPS conversion ability due to abundant anchoring sites of heterostructured MoP-MoO 2 nanobelts and shortened lithium ion channels of the prepared PCNFs. Benefiting from these advantages, the assembled Li-S battery with MoP-MoO 2 /PCNFs separator delivered a high specific capacity of 1078.9 mAh g−1 at 1C and 1056.7 mAh g−1 at 2C, excellent cycling stability (856.9 mAh g−1 after 400 cycles at 1C and 630.1 mAh g−1 after 500 cycles at 2C). The cell with MoP-MoO 2 /PCNFs separator manifested outstanding cycle performance with fading rate of 0.08 % at 0.5C after 300 cycles under a sulfur loading of 4.0 mg cm−2. The novel work will provide a new strategy by which the modified separator with the heterostructured transition metal phosphides and oxides can be applied for high-performance Li–S batteries and shows great potential for practical application. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries have been considered as one of the most promising energy storage candidates due to their high energy density and low cost. However, the low electrical conductivity of elemental sulfur, notorious LiPS shuttle and sluggish redox kinetics bring about fast capacity fade and poor rate capabilities. To solve these problems, herein a modification strategy of functional separator is introduced by coating heterostructured MoP–MoS 2 and porous carbon nanofibers (PCNFs) on the surface of a Celgard separator. Moreover, for the first time, we detailly discuss the effect of the ratio of component (MoP:MoS 2) in the heterostructured MoP–MoS 2 materials on the electrochemical performance. The coating layer exhibits both satisfactory interception ability for LiPS shuttle and fast LiPS conversion ability due to abundant anchoring sites of MoP–MoS 2 heterojunction nanoflowers and shortened lithium ion channel of the prepared PCNFs. Benefiting from these advantages, the assembled Li–S battery with a MoP-50/PCNFs separator exhibits 1090.02 mAh g-1, and high discharge capacity of 884.67 mAh g-1 even after 300 cycles at 1 C. The initial discharge capacity of MoP-50/PCNFs separator at 2 C and 5 C are about 1050.4 and 728.22 mAh g-1, and retains about 698.4 mAh g-1 after 400 cycles and 431.28 mAh g-1 after 500 cycles. The novel work will provide a new strategy by which the modified separator with transition metal phosphides can be applied in the design of high-performance Li–S batteries and shows great potential for practical application. MoP-x/PCNFs modified Celgard separator in Lithium-sulfur battery. [Display omitted] • Preparing Flower-like heterostructured MoP–MoS 2. • Designing various heterostructured MoP–MoS 2 materials (MoP: MoS 2 = 100:0, 75:25, 50:50, 25:75, 0:100). • Porous carbon nanofiber with dual functions of lithium polysulfudes adsorption through one-step electrostatic blowing method. • Researching the catalytic kinetic mechanism of the "solid-liquid-solid" mutual conversion process for transition metal phosphide. • Exploring the cycle performance of Celgard separator modified with MoP–MoS 2 -50/PCNFs. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (LSBs) have attracted increasing attention due to high theoretical energy density and low cost of sulfur. However, there are still many challenges regarding sulfur cathodes such as the "shuttle effect" of polysulfides, insulating properties of sulfur and Li 2 S 2 /Li 2 S, and the sluggish redox kinetics. In this study, the nanorod-like Sb-doped SnO 2 nanofibers (ATO NFs) with hollow structure were prepared by the electro-blown spinning technology and calcination processes, and used as a sulfur host for cathode materials. The internal hollow structure and the nanorod-like structure on the surface of the nanofibers with the increased specific surface area are beneficial to load sulfur and improve transport channels of electrons and lithium ions. And the hollow nanofibers also can well accommodate to huge volume changes in the reaction process. More importantly, the ATO NFs with hollow structure have good physical confinement and chemical adsorption performance to polysulfides. Based on these merits, the ATO NFs composite cathode exhibits a high initial discharge specific capacity of 765.3 mAh g−1 and maintains 550.6 mAh g−1 after 900 cycles at a rate of 2 C with 1.9 mg cm−2 sulfur loading. More importantly, high initial area discharge specific capacity of the electrode is 5.5 mAh cm−2 at 0.1 C with sulfur loading of 5.6 mg cm−2. Even, at a rate of 0.2 C, the area capacity still is stabilized at 3.5 mAh cm−2 after 100 cycles. The work illustrates that the ATO NFs for LSBs exhibit good cycling stability over a long period of time, entering the ranks of high performance and ultra-stable capacity. And it also facilitate to expand the scope of application of ATO NFs in other related energy storage fields. [Display omitted] • A novel nanorod-like Sb-doped SnO 2 nanofibers is successfully designed and prepared. • The prepared ATO are beneficial to load sulfur and enhance transport channels of electrons and lithium ions. • The ATO based electrode can greatly suppress shuttle effect of polysulfides and play important in catalytic conversion. • The assembled Li-S battery with the ATO based electrode presents stable long-term cycle performance. [ABSTRACT FROM AUTHOR]

• •Rational structure designs and their applications of 2D materials for Li-S and Li-Se batteries are summarized. • •An overview of recent advances in the preparations and designs of various 2D materials are reviewed. • •Properties of 2D materials for battery systems affecting electrochemical performance are discussed. • •An insightful perspective is outlined for the future research in 2D materials for Li-S and Li-Se batteries. Lithium-sulfur (Li-S) and lithium-selenium (Li-Se) batteries have gradually triggered enormous attention in the field of secondary energy conversion and storage due to excellent theoretical capacities and advanced theoretical energy densities, which are nearly an order of magnitude higher than widely used lithium ion battery. But the commercialization processes of Li-S/Se batteries are slow due to the poor conductivity of elemental S/Se and insoluble low-order lithium polysulfides (polyselenides), severe "shuttle effect" of soluble high-order lithium polysulfides (polyselenides) and slow reaction kinetics during the process of redox reaction. Nowadays, the rationally designed two dimensional (2D) materials in the compositions of Li-S/Se batteries have presented conspicuous merits and can greatly enhance the electrochemical performances of the batteries. This review firstly highlights the distinctive structural merits of various 2D materials for advanced Li-S/Se cells. Then an overview of recent advances in the designs and preparations of different 2D materials with well-designed shapes, tailored structures, selective chemical constituents and their corresponding electrochemical properties combining the physical confinement, chemical adsorption, catalytic effect et al.. Finally, some challenges and viewpoints in this field are also discussed. The comprehensive review will help researchers to well learn rational designs including modification based on structure and engineering of 2D materials for effectively enhancing electrochemical performances of Li-S/Se cells, which eventually lead the batteries to be a practically commercial applications for power source. [ABSTRACT FROM AUTHOR]