Effect of Surface Chemistry of Solid-state Microwave Irradiation Assisted Reduced Graphene Oxide on Electric Double Layer Capacitance

摘要

An electric double layer capacitor (EDLC) is the most typical of electrochemical capacitor with high power density and long cycle life [1] The high power density is attributed to the charge storage mechanism of EDLC, which is a reversible, fast adsorption/desorption reaction of ions forming a nanoscale electric double layer between a carbonaceous active material and an electrolytic solution [2]. Considerable efforts have been devoted to the development of carbonaceous materials with a high specific capacitance, since a major shortcoming for an EDLC device is a relatively low energy density. Porous carbons such as activated carbon, activated carbon fiber, and carbon aerogel have been investigated as electrode materials for EDLC [3-5]. Activated carbon has a high specific surface area (up to 3000 m~2 g~(-1)), resulting from a large amount of micro- and meso-pores. However, the specific capacitance of activated carbon is not strictly proportional to its specific surface area, because large amount of micropores (< 2 nm), which cannot be easily accessible to electrolyte ions, does not contribute to the total capacitance of the material [3, 6]. In addition, a decrease in electric conductivity, which brings a negative effect on electrochemical properties, is inevitable when micro- or meso-pores are introduced into activated carbon [3, 7].