Rational design of coaxial-cable MoSe2/C: Towards high performance electrode materials for lithium-ion and sodium-ion batteries

A novel coaxial-cable MoSe2/hollow carbon nanofiber composites (denoted as coaxial-cable MoSe2/C composites) is fabricated employing selenium/carbon core-shell composite as the template, carbon and selenium resource. Hollow carbon nanofibers are uniformly decorated with few-layered and ultrasmall MoSe2 nanosheets by the observation of TEM. When calculated on the basis of the whole composite, coaxial-cable MoSe2/C composites not only show high lithium specific capacity (658 mAh g−1) and excellent cycling performance (almost 100% capacity retention even after 100 cycles at a current density of 0.5 A g−1) but also exhibit a high-rate capability of 524 mAh g−1 at the rate of 3 A g−1. When evaluated as an anode for sodium storage, a specific capacity of 423 mAh g−1and 395 mAh g−1 is achieved at 0.5 A g−1 and 1 A g−1 after 100 cycles, respectively. Excellent cycling stability and rate performance of the coaxial-cable MoSe2/C composites can be ascribed to the synergic effects of few-layered and ultrasmall MoSe2 nanosheets as well as hollow carbon nanofibers. Our study not only provides a facile synthetic method for both lithium-ion and sodium-ion batteries, but also exploits a novel way to the combination of Se-based compounds and carbon matrix.