A layered-template-nanospace-confinement strategy for production of corrugated graphene nanosheets from petroleum pitch for supercapacitors

Abstract

Corrugated graphene nanosheets (CGNSs) with abundant short pores for ion transport are highly demanded as one of the most promising electrode materials for high-performance supercapacitors. However, the efficient production of CGNSs remains a big challenge. Herein, a layered-template-nanospace-confinement strategy coupled with in situ chemical activation is reported to synthesize CGNSs from petroleum pitch. Firstly, petroleum pitch was mixed with potassium hydroxide (KOH) particles, and the mixture was dispersed between and onto the sheet-like nano-MgO templates. Secondly, the nano-MgO templates coated with petroleum pitch and KOH mixture were heated, in which the petroleum pitch was polymerized, leading to interconnected film in the layered-template-confinement-nanospace. At the same time, the thin films were activated in situ by KOH in the nanospace, and yielding CGNSs after removing the template by acid washing. The thin sheet-like CGNSs feature many wrinkles and hierarchical short pores, and have a high specific surface area up to 2132m2g−1 and a big lateral size/thickness aspect ratio. As electrodes for supercapacitors, the CGNSs show a high capacitance of 280Fg−1 at 0.05Ag−1 in 6M KOH electrolyte, an excellent rate performance with capacitance remaining at 233Fg−1 at 20Ag−1 and a superior cycle stability with over 96.8% capacitance retention after 1000 charge–discharge cycles at 1Ag−1. This layered-template-nanospace-confinement strategy may pave an efficient way for large scale production of electrode materials from cheap petroleum pitch for high-performance supercapacitors.