Preparation of mesoporous carbons from amphiphilic carbonaceous material for high-performance electric double-layer capacitors

Abstract

Amphiphilic carbonaceous material (ACM), with nanoscale dispersion in alkaline aqueous solutions, is synthesized from green needle coke. As a special precursor with small particle size, plenty of functional groups and widened d 002 simultaneously, ACM guarantees subsequent ACM-based activated carbons (AACs) with high specific surface area over 3000 m 2 g −1 as well as well-developed mesoporous structure after KOH activation. Such pore properties enable AACs’ high performances as electrode materials for electric double-layer capacitors (EDLCs). In particular, surface area up to 3347 m 2 g −1 together with notable mesopore proportion (26.9%) gives sample AAC814 outstanding EDLC behaviors during a series of electrochemical tests including galvanostatic charge/discharge, CV and electrochemical impedance spectroscopy. The electrode gets satisfactory gravimetric and volumetric specific capacitance at the current density of 50 mA g −1, up to 348 F g −1 and 162 F cm −3, respectively. Furthermore, for the mesoporosity, there is only a slight capacitance reduction for AAC814 as the current density reaches 1000 mA g −1, indicating its good rate performance. It is all the ACM's unique characteristics that make AACs a sort of competitive EDLC electrode materials, both in terms of specific capacitance and rate capability.