CoS2 Nanoparticles Wrapping on Flexible Freestanding Multichannel Carbon Nanofibers with High Performance for Na-Ion Batteries

Exploration for stable and high-powered electrode materials is significant due to the growing demand for energy storage and also challengeable to the development and application of Na-ion batteries (NIBs). Among all promising electrode materials for NIBs, transition-mental sulfides have been identified as potential candidates owing to their distinct physics-chemistry characteristics. In this work, CoS2 nanomaterials anchored into multichannel carbon nanofibers (MCNFs), synthesized via a facile solvothermal method with a sulfidation process, are studied as flexible free-standing electrode materials for NIBs. CoS2 nanoparticles uniformly distributed in the vertical and horizontal multichannel networks. Such nanoarchitecture can not only support space for volume expansion of CoS2 during discharge/charge process, but also facilitate ion/electron transport along the interfaces. In particular, the CoS2@MCNF electrode delivers an impressively high specific capacity (537.5 mAh g-1 at 0.1 A g-1), extraordinarily long-term cycling stability (315.7 mAh g-1 at at 1 A g-1 after 1000 cycles), and excellent rate capacity (537.5 mAh g-1 at 0.1 A g-1 and 201.9 mAh g-1 at 10 A g-1) for sodium storage. Free-standing CoS2@MCNF composites with mechanical flexibility provide a promising electrode material for high-powered NIBs and flexible cells.