Novel porous CoS1.097@carbon nanofibers as flexible and binder-free anode material for sodium-ion batteries

Abstract

Transition metal sulfides (TMSs) have received numerous attention as anode materials for sodium-ion batteries because of the high theoretical capacity. So far, the Na-storage performance of TMSs is still unsatisfactory due to the structural degeneration that induced by the volume change upon redox process. Herein, a novel flexible and binder-free anode material of porous CoS1.097@carbon nanofibers was facilely constructed by means of the electrospinning, carbonization and sulfidation processes. The porous CoS1.097@carbon nanofibers display unique structure with CoS1.097 nanoparticles confined into porous N-doped carbon nanofibers, and can provide sufficient active sites, high electrical conductivity, reduced ion diffusion distance, abundant ion migration pathways, desirable voids for alleviating the volume variation, and rigid structural stability for efficient Na-storage. In consequence, the flexible and binder-free electrode material delivers high initial discharge capacity, enhanced rate capability and long-term cycling life. Besides, intrinsic diffusion and electrochemical storage behavior of Na+ ions were emphatically disclosed. This work paves a facile route for the synthesis of flexible and binder-free TMSs-based anode materials, promoting the practical application of wearable sodium-ion batteries.