Polyacrylonitrile@metal organic frameworks composite-derived heteroatoms doped carbon@encapsulated cobalt sulfide as superb sodium ion batteries anode

Abstract

Considering the finite resources of nonrenewable fossil fuels and urgent demands of modern society, sodium ion batteries (SIBs) featuring low cost, considerable natural supply and environmental friendless, show huge prospects in energy storage field, especially in constructing massive energy storage networks. Here, we propose a facile polyacrylonitrile@metal organic frameworks composite-derived sulfuration method, for acquiring heteroatoms doped carbon@encapsulated CoS2 nanoparticles (NSPCFS@CoS2) as SIBs anode. This electrode shows long and steady cycling process at 1 A g−1. After running 2095 cycles, it maintains a capacity of 546.3 mA h g−1. An exceedingly low capacity fading ratio of 0.013% per cycle can be acquired. Also, it gives high discharge capacities of 540.7 and 493.6 mA h g−1, even at 4 and 8 A g−1, separately. In addition, NSPCFS@CoS2 possesses a comparative or even better rate capability than other CoS2 based materials and other types of metal sulfides. Overall, this electrode exhibits superior cycling and rate performances. Additionally, its Na+ reaction kinetics and storage mechanism are deeply investigated.