Bowl-shaped carbon loaded Co9S8 nanoparticles connected by carbon nanotubes with excellent rate performance for sodium-ion batteries

Abstract

Sodium-ion batteries (SIBs) are expected to replace lithium-ion batteries in the energy storage sector owing to their low cost and abundant resources. However, developing suitable anode materials to meet the high energy density requirements of SIBs remains an ongoing challenge. Herein, we design a hollow nitrogen-doped bowl-like carbon decorated with Co9S8 nanoparticles linked by carbon nanotubes (HNBC@Co9S8@CNTs) as an anode material for SIBs. The HNBC@Co9S8@CNTs electrode exhibits impressive rate performance (449.3 mAh g−1 at 5 A g−1) and cycling stability (426.5 mAh g−1 after 500 cycles at high current density of 1 A g−1) due to the advantages of highly conductive three-dimensional (3D) interconnected structures. In addition, its pseudo-capacitance and sodium storage diffusion kinetics are analyzed in depth using Cyclic Voltammetry (CV) and galvanostatic intermittent titration technique (GITT). The results elucidate that the partially surface-induced capacitive sodium storage, highly conductive 3D interconnected structures, and fast reaction kinetics synergistically contribute to the high-rate performance. This work may provide new insights for the fabrication of various metal sulfide or sulfide composites with high sodium storage capacity.