Electrochemical Capacitors: Challenges and Opportunities for Real-World Applications

Abstract

People today are very familiar with different battery technologies, from small zinc-air button cells to AAA alkali cells to spiral wound lithium ion laptop batteries to fifty-pound lead acid batteries found in automobiles. This situation has come about because people rely heavily on battery power. Common battery applications include, for instance, power for cell phones, Sony Walkman, PDAs, laptop computers, Ipod players, digital cameras, and on and on. In sharp contrast, people today are much less familiar with capacitor technologies, although capacitors also store energy.

CNT-based Materials as Electrodes for Flexible Supercapacitors

“…The energy density is the quantity of energy stored per unit of mass, whereas power density represents the quantity of power per unit of mass. SCs and capacitors are recognized as high power density systems, while fuel cells and batteries are defined as high energy density systems (Yu et al 2013;Miller and Burke 2008;Winter and Brodd 2004). Comparatively to batteries and fuel cells, supercapacitors and capacitors have high power density (10 kW/kg), fast charge-discharge cycles (within seconds), exceptional reversibility (90-95%), extensive cycle life (>1x10 5 ), large coulombic efficiencies and operate safely (Zhao et al 2011;Zhong et al 2015).…”

A Short Review on the Electrochemical Performance of Hierarchical and Nitrogen-Doped Activated Biocarbon-Based Electrodes for Supercapacitors

“…SCs are promising energy storage devices, and have attracted extensive attention due to their rapid charge and discharge rates, high power density, and long life [3]. Two main mechanisms are responsible for storing energy in supercapacitors: the electrical double layer capacitance (EDLC) and the pseudocapacitance [4][5][6]. The EDLC behavior is a characteristic of carbon derivatives with a high surface area favored by available sites for charge accumulation in a Helmholtz double layer at the electrode-electrolyte interface.…”

Spray Deposition of Supercapacitor Electrodes using Environmentally Friendly Aqueous Activated Graphene and Activated Carbon Dispersions for Industrial Implementation

“…Moreover, they can be charged and discharged also more than 0.5-1 mln times due to the absence of chemical reactions involved. [6][7] In 1978, NEC went on to produce the first commercially successful double-layer capacitors. [8] Currently, most of the commercial supercapacitors are produced using various kinds of nanostructured carbons, most commonly activated carbons which provide the best combination of textural and electrical properties.…”

“…Supercapacitors store less energy compared to batteries (>5 Wh/Kg), but deliver energy very quickly and therefore to show a very large specific power >20 kW/Kg (for full packaged device). Moreover, they can be charged and discharged also more than 0.5–1 mln times due to the absence of chemical reactions involved [6–7] …”