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Abstract SnSb alloy is a promising anode material for lithium-ion batteries due to its high specific capacity. However, the large volume change in the process of charge/discharge causes significant pulverizing of SnSb alloy particles, which leads to a rapid capacity fading. This paper reports the synthesis of homogenous SnSb nanoparticles that are embedded in N-doped porous carbon nanofibers through electrospinning technique with LiN 3 serving as poregen agent. This distinctive structure prevents the direct contact of SnSb nanoparticles with the electrolyte and provides enough space for the volume change of SnSb alloy during the Li+ insertion/extraction process, enabling this material to deliver a high reversible capacity of 892 mA h g−1 after 100th cycle at 100 mA g−1, and a stable capacity of 487 mA h g−1 after 1000 cycles at 2000 mA g−1. These results highlight the importance of the synergistic effect of SnSb alloy nanoparticles and N-doped porous carbon nanofibers for the high performance of lithium-ion batteries. Highlights • N-doped porous carbon nanofibers were prepared by electrospinning and calcination. • Lithium azide functions as a porogen reagent to generate porous structures. • A capacity of 892 mA h g−1 can be maintained after 100 cycles at 100 mA g−1 for the anode material. [ABSTRACT FROM AUTHOR]

• Synthesis of porous PAN/S nanofibers by using electrospinning method. • Porous nanofibrous morphology enhances the ions and electrons conductivity. • The porous PAN/S shows a high reversible capacity of 1144 mA h g−1 after 100 cycles at 0.2 C. • The porous PAN/S delivers a high rate performance with capacity of 794 mAh g−1 at 2 C after 500 cycles. ga1 Lithium–sulfur (Li–S) batteries have attracted great interest for next-generation batteries owing to their high capacity density and low cost. However, the drawbacks of the low conductivity of sulfur, serious "shuttle effect" and huge volume expansion during the charging/discharging cycles greatly limit their practical applications. In this work, we report the synthesis of porous sulfurized poly(acrylonitrile) (PAN/S) nanofibers via thermal treatment of PAN/poly(methyl methacrylate) (PMMA) nanofibers with elemental sulfur, resulting in 48 wt% of covalently bound sulfur formed in the composite. The unique porous structure of nanofibers enables enhanced diffusion dynamics of ions and electrons, thus improving the reactivity and conductivity of sulfur. As a consequence, the porous PAN/S cathode delivers a high reversible capacity of 1144 mA h g−1 after 100 cycles at a current rate of 0.2 C and a high rate performance with a reversible discharge capacity of 794 mA h g−1 at 2 C after 500 cycles. [ABSTRACT FROM AUTHOR]

Transition-metals have emerged as promising catalyst candidates for improving the hydrogen storage properties of MgH2. However, the preparation of uniformly dispersed and extra-fine transition-metals catalysts with high catalytic activity still remains a challenge. In this paper, an electrospinning-based reduction approach is presented to generate nanostructured nickel catalyst, which is protected from irreversible fusion and aggregation in subsequent high-temperature pyrolysis, in carbon nanofibers (Ni@C) in situ. The obtained Ni@C reveals remarkable catalytic effect on improving the hydrogen storage properties of MgH2. For example, the MgH2-10 wt%Ni@C composite delivers dehydrogenation capacities of 5.79 wt% and 6.12 wt% at 280 °C and 300 °C, respectively, whereas the as-milled MgH2 hardly decomposes at the same temperature. By Arrhenius plots, the calculated Ea of the dehydrogenation of MgH2-10 wt%Ni@C is 93.08 kJ mol−1, which is 94.33 kJ mol−1 lower than that of the as-milled MgH2. Furthermore, the microstructure of Ni@C is remained during the re/dehydrogenation process and the Ni nanoparticles are still distributed homogeneously in the composite, accounting for the excellent cycling performance. This study could render combinations of ultrafine metal nanoparticles with carbon accessible, thereby, extending opportunities in catalytic applications for hydrogen storage. The homogeneously distributed Ni with refined particle size in carbon nanofibers has been synthesized successfully. A certain proportion of Ni@C and commercial MgH 2 were mechanically mixed by high-energy ball milling and the Ni@C were uniformly dispersed on the surface of MgH 2 , which enhanced the interface interaction and reduced the apparent activation energy of the dehydrogenation of MgH 2 -10 wt % Ni@C. Image 1 • Ni nanoparticles in-situ encapsulated in carbon nanofibers has been synthesized successfully by electrospinning technique. • The Ni@C catalyst was uniformly dispersed on the surface of MgH 2 by high-energy ball milling. • The MgH 2 -10 wt %Ni@C delivers a hydrogen release of 5.91 wt% in 500 s at 325 °C. • The hydrogen storage capacity of the MgH 2 -10 wt %Ni@C composite can be maintained without degradation after 20 cycles. [ABSTRACT FROM AUTHOR]