Metal-free supercapacitor with aqueous electrolyte and low-cost carbon materials

Abstract

Electric double-layer capacitors (EDLCs) or supercapacitors (SCs) are fast energy storage devices with high pulse efficiency and superior cyclability, which makes them useful in various applications including electronics, vehicles and grids. Aqueous SCs are considered to be more environmentally friendly than those based on organic electrolytes. Because of the corrosive nature of the aqueous environment, however, expensive electrochemically stable materials are needed for the current collectors and electrodes in aqueous SCs. This results in high costs for a given energy-storage capacity. To address this, we developed a novel low-cost aqueous SC using graphite foil as the current collector and a mix of graphene, nanographite, simple water-purification carbons and nanocellulose as electrodes. The electrodes were coated directly onto the graphite foil by using casting frames and the SCs were assembled in a pouch cell design. With this approach, we achieved a material cost reduction of greater than 90% while maintaining approximately one-half of the specific capacitance of a commercial unit, thus demonstrating that the proposed SC can be an environmentally friendly, low-cost alternative to conventional SCs.

Influence of Substrate in Roll-to-roll Coated Nanographite Electrodes for Metal-free Supercapacitors

“…Due to the high electric conductivity and large surface area of nanographites, such as graphene and graphite nanoplatlets, these materials have gained a large interest for use in energy storage devices and printed electronics [1][2][3][4] . Nanographites can be produced by a large variety och routes, but for large-scale production liquid exfoliation techniques seem to be the most promising methods [5][6][7][8][9] .…”

Sustainable Utilization of Biomass Refinery Wastes for Accessing Activated Carbons and Supercapacitor Electrode Materials

“…[42][43][44][45] All tested AC samples except Chem-900-2 did not exhibit sufficiently good electrochemical properties (Figure 1a), apparently owing to their microporous character.T hus,e ven the larger specific surface area (SSA) of the microporous Chem-900-4 (SSA BET = 862 m 2 g À1 )d oes not ensure specific capacitance as high as the capacitance of the mesoporous Chem-900-2 with lower SSA (SSA BET = 756 m 2 g À1 ,T able 1). The properties were assessedb y meanso fcyclic voltammetry (CV) andgalvanostatic charge/discharge( GCD) measurements within the potential window À1 to À0.1 Vb yu sing at hree-electrode system and 6 m aqueous KOH solution, which is aw idely applied aqueous electrolyte for SCs.…”

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

“…Devices for these purposes include supercapacitors [64,80,130], hydrogen storage devices [131], electrodes for hydrogen evolution reaction [132], lithium ion batteries [133], actuators [81], solar steam generators [82] and electric heating membranes [83]. These devices can be based on pure nanocellulose/nanocarbon composites without additives [80][81][82][83]. However, they often contain additives such as manganese oxide (MnO), which contributes to faradaic pseudocapacitance in supercapacitors [130] or polypyrrole, which acts as an insulator, but its oxidized derivatives are good electrical conductors [134].…”

“…In addition to its advantageous combination with nanocarbon materials, nanocellulose is an appealing material for biomedical applications due to its tunable chemical fluorescence and luminescence [26,71,72] photothermal activity [56], hydrolytic stability [61], nanoporous character and high adsorption capacity [49,61]. Nanocellulose/nanocarbon composites can therefore be used in a wide range of industrial and technological applications, such as water purification [22,29,43,49,54,56,61,[73][74][75][76], the isolation and separation of various molecules [22,74,[77][78][79], energy generation, storage and conversion [21,23,44,47,64,[80][81][82][83][84][85], biocatalysis [86], food packaging [67][68][69]87], construction of fire retardants [48], heat spreaders [70] and shape memory devices [38,[88][89][90]. These comp...…”