هواژل مبتنی بر گرافین و گرافین اکسید
Abstract
1- Introduction
2- Graphene Oxide
3- Aerogels
4- Supercapacitor and Energy Storage
5- Supercapacitor applications of graphene and graphene oxide based aerogels
۶٫ Conclusion References
Abstract
Graphene and graphene-based materials have a high potential, especially in energy storage technology. Thanks to the three-dimensional (3D) structures developed with this material, their importance in the production and application of energy storage devices has increased. Studies on supercapacitor applications of graphene-based aerogels have begun to arouse interest in recent years. In this study, recent studies on aerogel supercapacitors, in which researchers have shown great interest, have been compiled and collected. In this study, production methods and properties of graphene oxide, properties and production of aerogels, production and applications of graphene/graphene oxide aerogels are discussed. In this way, the data is presented and discussed in an organized way for the researchers who study or who want to study in this field.
Introduction
Today’s rapidly depleted energy resources and the deteriorating ecological balance prioritized the need for energy storage systems. Moreover, the growing popularity of telecommunications equipment, backup storage devices, portable electronic devices, cardiac pacemakers and hybrid electric vehicles has aroused great interest towards energy storage devices. In this context, supercapacitors, which are mostly preferred among various energy storage devices, are electrochemical energy storage devices that cover the gap between batteries and dielectric capacitors with their high-power density, high specific energy and long life (>100,000 cycles) [1]. Furthermore, flexible solidstate supercapacitors are important for wearable electronic devices [[2], [3]].
Graphene, which come into prominence with wide specific surface area (SSA) (2630 m2 g−۱ ), high electrical conductivity and chemical stability, as well as excellent mechanical, thermal and optical properties, has become popular especially for supercapacitors. However, a serious loss in surface area is observed due to the re-stacking of graphene layers during chemical reduction. The conversion of graphene nanotubes to graphene aerogel having a stable three-dimensional network solves this problem. The re-stacking problem resulting from π-π interactions between graphene layers and the Van der Waals forces are solved and the layers are chemically bonded together. Thus, the structure is intended to provide better performance in supercapacitors with much higher electronic conductivity, rapid charge transport between the layers and the resulting high surface area. The most interesting feature of GOs is that they are well protected by a hexagonal structure having functional groups such as hydroxyl, epoxide, carboxyl and some randomly distributed alkyl groups in the plane, together with a clear AB stacking order. Hydroxyl and epoxide functional groups are located close to each other in the basal planes, whereas carboxyl and alkyl groups are located at the edges of GO flakes. With longer oxidation times, hydroxyl groups are converted to more epoxide groups in the basal plane.