ABSTRACT
Supercapacitors-also called electrochemical capacitors-are a new type of electrochemical energy storage system applied for harvesting energy and delivering high power in a short time. Their main energy storage mechanism is based on charging an electrical double-layer (EDL) at the electrode-electrolyte interface of high surface area electrode materials. They have attracted attention for a variety of applications, especially in hybrid systems combining with batteries and fuel cells, because of their high power density, excellent cyclic stability, and rapid response to external loading on a powertrain [1-4]. However, their main disadvantage is the relatively low energy density (5-6 Wh/kg based on activated carbon [AC]), which is significantly lower than that of a lithium ion rechargeable battery (~150 Wh/kg). Numerous efforts have been made to resolve this problem. In these works, various
5.1 Introduction .................................................................................................. 171 5.2 Graphene-Based EDLCs ............................................................................... 173
5.2.1 Electrode Materials Based on Graphene .......................................... 174 5.2.2 Electrode Materials Based on Graphene Hybrid Composites .......... 177 5.2.3 Electrode Materials Based on Porous Graphene .............................. 180 5.2.4 Electrode Materials Based on GNRs ................................................ 183 5.2.5 Effect of the Electrolyte .................................................................... 186
5.3 Graphene-Based Electrode Materials with Pseudocapacitive Properties ..... 190 5.3.1 Electrode Materials Based on Graphene-Metal-Oxide Composites... 190 5.3.2 Electrode Materials Based on Graphene-Conductive Polymers ...... 193 5.3.3 Electrode Materials Based on Graphene with Heteroatoms in
Carbon Network ................................................................................ 196 5.4 Graphene-Based Hybrid Supercapacitor ...................................................... 199
5.4.1 Hybrid Supercapacitor in Aqueous Electrolyte ................................200 5.4.2 Asymmetric Supercapacitor in Organic Electrolyte .........................203
