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Flexible energy devices with high energy density and long cycle life are considered to be promising applications in portable electronics. In this study, silicon/carbon nanofiber (Si@CNF) core–shell electrode has been prepared by the coaxial electrospinning method. The precursors of polyimide (PI) were for the first time used to form the core–shell structure of Si@CNF, which depicts outstanding flexibility and mechanical strength. The effect of doping concentrations of silicon (Si) nanoparticles embedded in the fiber is investigated as a binder-free anode for lithium-ion batteries. A 15 wt% doped composite electrode demonstrates superior performance, with an initial reversible capacity of 621 mA h g−1 at the current density of 100 mA g−1 and a high capacity retention up to 200 cycles. The excellent cycling performance is mainly due to the carbonized PI core–shell structure, which not only can compensate for the insulation property of Si but also has the ability to buffer the volume expansion during the repeated charge–discharge process.

Owing to the large interlayer spacing and the excellent theoretical capacity of MoSe2, it has great potential to be applied as an anode material for sodium‐ion batteries. However, the rate performance of MoSe2 is strongly limited by the insufficient intrinsic electron transfer kinetics. Herein, a simple two‐step hydrothermal method to construct MoSe2/Bi2Se3 heterostructures was developed by growing MoSe2 nanosheets onto Bi2Se3 nanoflakes directly. The typical topological insulator possesses ultrafast surface electronic conductivity, which makes the batteries exhibit a superior rate capability and considerable cycling stability. At a high rate of 10 A g−1, the MoSe2/Bi2Se3 electrode still delivered a superior capacity of 244 mA h g−1 (about 60 % of the discharge capacity at 0.1 A g−1), which is better than that in some of the previously reported MoSe2/carbon composites. It also can compare with some of the MoSe2‐containing complex sandwich architectures. Such unique rate performance is bound strongly with high interlayer spacing and rapid electron transfer kinetics. Besides, the different Fermi level energies of Bi2Se3 (work function is 5.61 eV) and MoSe2 (work function is 4.3 eV) probably induce a built‐in electric field nearby the heterofaces. The electric force could promote Na ions diffusibility upon cycling, leading to high reversible capacity and excellent rate performance. [ABSTRACT FROM AUTHOR]

In this paper, single crystalline Bi2Se3 nanostructures including nanowires, nanoribbons, nanoplates and bridge-like nanostructures have been grown by physical vapor deposition. By investigating the morphological evolution of the Bi2Se3 nanostructures, we found that Bi2Se3 nanoribbons with the long axis along ＜112̅0＞ could facilitate the formation of bridge-like nanostructures. Subsequently, a two-step growth process had been developed to increase both the size and the amount of the bridge-like Bi2Se3 nanostructures effectively, which shows great promise to realize the growth of large-size two-dimensional materials for various optoelectronic and spintronic applications. [ABSTRACT FROM AUTHOR]