Double-Morphology CoS₂ Anchored on N-Doped Multichannel Carbon Nanofibers as High-Performance Anode Materials for Na-Ion Batteries

Abstract

Na-ion batteries (NIBs) have attracted increasing attention given the fact that sodium is relatively more plentiful and affordable than lithium for sustainable and large-scale energy storage systems. However, the shortage of electrode materials with outstanding comprehensive properties has limited the practical implementations of NIBs. Among all the discovered anode materials, transition-metal sulfide has been proven as one of the most competitive and promising ones due to its excellent redox reversibility and relatively high theoretical capacity. In this study, double-morphology N-doped CoS₂/multichannel carbon nanofibers composites (CoS₂/MCNFs) are precisely designed, which overcome common issues such as the poor cycling life and inferior rate performance of CoS₂ electrodes. The conductive 3D interconnected multichannel nanostructure of CoS₂/MCNFs provides efficient buffer zones for the release of mechanical stresses from Na⁺ ions intercalation/deintercalation. The synergy of the diverse structural features enables a robust frame and a rapid electrochemical reaction in CoS₂/MCNFs anode, resulting in an impressive long-term cycling life of 900 cycles with a capacity of 620 mAh g^-1 at 1 A g^-1 (86.4% theoretical capacity) and a surprisingly high-power output. The proposed design in this study provides a rational and novel thought for fabricating electrode materials.