ABSTRACT
For many years, a range of problems including fossil fuel exhaustion, environmental pollution, and climate change have been taking place due to the changing global landscape, such as industrial development and growing human population. According to the aforementioned issues, energy has emerged as a promising candidate, which is a solution of a primary concern of the major world powers and scientic community. In addition to excavating and utilizing new energy, such as solar or wind energy [1-4], there is urgent need for the development of efcient energy storage systems (ESSs) as well as new technologies associated with energy conversion and storage. In this regard, one of the greatest challenges attracting signicant research interest is how to construct highly efcient, low-cost, and environment-friendly ESS devices including highly efcient, low-cost, and environment-friendly properties. Thereby, portable electronic devices, extreme progress of memory backup devices, and the development of hybrid electric vehicles have come up with a fast-increasing demand for ESSs. Many effective and practical technologies for ESSs,
such as lithium batteries [5-7], fuel cells [8-11], and electrochemical supercapacitors (SCs) [12-14], therefore, have been reported. Among those ESSs, SCs, which also known as electrochemical capacitors or ultracapacitors, are expected to be the best potential candidate owing to the high power density, rapid charging/discharging, and long cyclic life compared to batteries and fuel cells [15-17]. Further developments have unfolded that SCs can be a sublime candidate in complementing batteries or fuel cells in their energy storage functions by providing backup power supplies to protect against power disruptions [18]. To the best of our knowledge, SCs can be divided into two categories: electrical double-layer capacitors (EDLCs) and pseudocapacitors. EDLCs are built from two carbon-based electrodes an electrolyte and a separator (Figure 153) [19]. In EDLCs, there is no transfer of charge or ion exchange between the electrode and electrolyte and electrostatic charge taking place during the working process. As the voltage is applied, charge accumulates on the electrode surfaces. The diffusion of ions from the electrolyte to the separator via the pores of the electrode of the opposite charge occurs. Hence, the electrodes are designed to preclude the
Introduction ............................................................................................................................................................................... 258 Fabrication Routes and Architectures of 3D Graphene-Based Supercapacitor ........................................................................ 259
Fabrication Routes of 3D Graphene-Based Supercapacitor ................................................................................................. 259 Self-Assembly of GO or rGO in Solution Method.......................................................................................................... 260 Self-Assembly of GO/rGO at the Interface Approach .................................................................................................... 260 Self-Assembly of GO/rGO Derivatives in Solutions....................................................................................................... 260 Template-Directed Approach .......................................................................................................................................... 260
Three-Dimensional Architectures of Graphene-Based Supercapacitor ............................................................................... 261 Three-Dimensional Foam Structure ................................................................................................................................ 261 Three-Dimensional Wavy Wrinkle .................................................................................................................................. 262 Three-Dimensional Interconnected Porous Framework .................................................................................................. 263 Three-Dimensional Macroporous Spherical Interconnected Network ............................................................................ 266
Three-Dimensional Graphene Composite-Based Supercapacitors .......................................................................................... 269 Three-Dimensional Graphene/Metal Oxide/Hydroxide Composite-Based Supercapacitors .............................................. 269 Three-Dimensional Graphene/Conducting Polymer Composite-Based Supercapacitors ................................................... 276 Three-Dimensional Graphene/Nitrogen Composite-Based Supercapacitors ...................................................................... 278 Three-Dimensional Graphene-/Carbon Nanotube-Based Supercapacitors ......................................................................... 279
Conclusions and Outlook .......................................................................................................................................................... 280 References ................................................................................................................................................................................. 281
recombination of the ions in electrolyte, resulting in the generation of a double layer of charge at each electrode. These double layers, coupled with an increase in surface area and a decrease in the distance between electrodes, allow EDLCs to obtain higher energy densities. During the charging-discharging process, the electrolyte concentration remains constant, suggesting that energy is stored in the double-layer interface.
