2D porous carbon nanosheets constructed using few-layer graphene sheets by a “medium-up” strategy for ultrahigh power-output EDLCs

Abstract

2D porous carbon nanosheets (PCNs) occupy the foreground in the field of electric double-layer capacitors (EDLCs). However, the mass production of PCNs with ultrathin thicknesses is still a serious challenge. Herein, PCNs constructed of few-layer graphene sheets were synthesized from a sulfonated pitch (SP) carbon precursor and soft-template F127 by a “medium-up” strategy. SP serves as a “medium material”, while F127 acts as a “string” and “spacer”, which plays the leading role of structure directing and prevents the self-restacking of small graphene layers. After activation, sample PCN6 with high carbon yield is constructed with a thickness of only 1.3 nm, sufficient specific surface area of 3006 m² g⁻¹ and high e-conductivity of 135 S m⁻¹. By virtue of its unique architecture, the PCN6-based EDLC exhibits excellent energy storage properties. In EMIMBF₄ electrolyte, it demonstrates an ultrahigh C_g of 157.8 F g⁻¹ (57.4 F cm⁻³) at 20 A g⁻¹, possessing a top-level rate capacity C_20/0.05 of 86.7%. Simultaneously, its energy density can retain up to 67.1 W h kg⁻¹ at a high power density of 17.5 kW kg⁻¹. The ingenious structural design of PCNs can afford inspiration for constructing other 2D architecture carbon materials.