Preparation of highly condensed porous carbon used in EDLCs with high voltage and high volumetric energy density

Abstract

Conventional porous carbons as the electrode material for electric double layer capacitors (EDLCs) normally have low volumetric energy density due to the low density and poor withstanding voltage characteristic. Therefore, it is very meaningful to construct porous carbon with high density and high voltage resistance. In this paper, using sulfonated pitch and graphene oxide as precursors, highly condensed porous carbon (SGx) with improved withstanding voltage characteristic is prepared by the π-π conjugated interaction and simple chemical activation with secondary high temperature treatment. The prepared porous carbon material with 3 wt% graphene oxide (SG3%) well-balances the specific surface area (SSA) and packing density, exhibiting high SSA of 2700 m2 g−1 and high packing density of 0.53 g cm−3. Besides, low oxygen content (9.82 at.% of surface O atoms) and stable surface chemical composition (ether bonds dominating) avoid the side reactions between the oxygen-containing functional groups and electrolyte, thus improving the withstanding voltage characteristics. At 3.2 V voltage in TEABF4/PC electrolyte, Cv and the maximum energy density reach 80.6 F cm−3 (1 A g−1) and 31.1 Wh L−1, respectively. Almost no capacity fading is found after 20,000 cycles testing. This work provides a new strategy for the development of high withstanding voltage EDLCs.