Porous yolk–shell-structured carbon nanospheres for electrochemical energy storage

Abstract

Yolk–shell-structured nanospheres have attracted potential applications in various fields due to their unique structural properties, which combines the advantages of mesoporous carbon and hollow structure. Herein, uniform porous yolk–shell carbon nanospheres (PYCNs) were obtained through a two-step coating employing resorcinol–formaldehyde (RF) resin spheres as a core, which is widely used due to its low-cost, high carbon residue and stability. The pre-formed RF spheres cores were subsequently coated with double shells of compact silica layer and polybenzoxazine/silica (PB/SiO2) hybrid in sequence, in which the intermediate silica layer and the silica from PB/SiO2 hybrid layer were subsequently etched off to create gap of yolk–shell structure and mesopore of shell for PYCNs. The resultant PYCNs possessed uniform spherical morphology with yolk–shell structure, mesoporous shell and a certain of N-doping, which endows it with a better electrochemical performance in supercapacitor than that of solid carbon spheres derived from RF spheres pyrolysis directly.