One-step vapor-pressured induced synthesis of spherical-like Co9S8/N, S-codoped carbon nanocomposites with superior rate capability as lithium-ion-battery anode

Abstract

As high theoretical capacity and excellent electrical conductivity, Co9S8 as a promising electrode material in lithium-ion batteries (LIBs) has attracted wide attention. In the present work, a simple vaporpressured induced route is developed for fabricating spherical-like Co9S8/N, S-codoped carbon nanocomposites (Co9S8/NSC), in which Co9S8 nanoparticles with an average size of 100 nm are encapsulated into N, S-codoped carbon matrix, by pyrolysis of mixture of cobalt isooctanoate dissolved into dimethylformamide and thiourea in a sealed vessel for the first time. As anode for LIBs, the Co9S8/NSC shows an excellent reversible capacity, a superior rate performance, and a long cycling stability. For example, a high capacity of 975.3 mA h g-1 can be achieved after 100 cycles at 0.1 A g-1. When cycled at 1 A g-1, it also maintains a high specific capacity of 791.5 mA h g-1 after 1000 cycles. Besides, it also shows a superior rate performance (329.8 mAh g-1 at 20 A g-1). Such superior performances may arise from its structural advantages that the smaller Co9S8 nanoparticles encapsulated into N, S-codoped carbon could enhance active sites, electrical conductivity, and structural stability.