Enhancing Ion Adsorption Capability through the Strong Interaction in Co₉S₈‐Carbon Hybrids Achieves Superior Sodium Ion Storage

Abstract

Metal sulfides materials are promising anode candidates for Na+ storage due to their low cost and high theoretical capacity, while the complex phase transition and inevitable volume expansion during cycling restrain their practical applications. Herein, a simple one‐pot manipulation strategy was designed to construct Co9S8 nanoparticles strongly encapsulated in carbon nanotubes (Co9S8@C/NTs) composite structure with enhanced structural stability and reaction kinetics, resulting in greatly improved Na+ storage performance. Specifically, the obtained Co9S8@C/NTs could exhibit an impressive capacity of 500 mAh g‐1 at 0.5 A g‐1 after 100 cycles and exceptional cycling stability over 600 cycles with 88% capacity retention at 1 A g‐1. Furthermore, the theoretical calculations combined with systematic characterizations confirm that the strong interaction between Co9S8 and the carbon matrix could greatly enhance the Na+ adsorption ability and facilitate the electron transfer dynamics for superior Na+ storage capability. More importantly, the full cell device can deliver an outstanding energy density of 144.32 Wh kg‐1 and a decent cycling life with 82% capacity retention of almost 100 cycles at 0.1 A g‐1. This work could provide more inspiration for designing advanced metal sulfide nanocomposites and demonstrate fascinating prospects for commercial application.