Structure engineering in interconnected porous hollow carbon spheres with superior rate capability for supercapacitors and lithium-sulfur batteries

Abstract

The application of hollow carbon spheres in energy storage devices is still hindered by their relatively low electron transmission and ion diffusion kinetics, as well as their insufficient storage sites. Herein, we prepare interconnected porous honeycomb hollow carbon spheres (IPHHCSs) using hard-templating route by increasing the concentration of template spheres and introducing cationic surfactants simultaneously. The as-obtained IPHHCSs show favorable features for ESD, such as large contacted areas between spheres, high specific surface areas (951 m2 g−1), hierarchical porous frameworks with high volume of mesopores, and rich N-doping (3.36%), achieving a lower interface-resistance between spheres, more ion-storage sites, and developed mesoporous channels for rapid ions diffusion. Thus, such a unique carbon architecture endows IPHHCSs a superior rate capability for supercapacitor and lithium-sulfur battery applications. The IPHHCSs supercapacitor’s electrode delivers a high specific capacitance of 295F g−1 at 1 A g−1, an outstanding rate capability (87% capacitance retention from 1 A g−1 to 20 A g−1), with a high cycling life stability (1.2% loss after 10,000 cycles). As for lithium-sulfur batteries, the IPHHCSs/S cathode with sulfur loading of 70% demonstrated an initial reversible capacity of 1160 mAh g−1 at 0.2C and an excellent rate performance with a capacity retention of 53% at 10C. More notably, IPHHCSs/S electrode could also enable a remarkable cyclic stability that possesses a reversible capacity of 285 mAh g−1 at 10C upon 1000 cycles with a low capacity degradation of 0.042% per cycle. Controllable design of interconnected porous HCSs structures could decrease interface-resistance and promote ion diffusion, which can be an effective way for developing high-rate supercapacitors and Li–S batteries.