Applications of Supercapacitors

Supercapacitors have several practical applications including Transportation — The most promising market for supercapacitors is in the transportation industry. They can be used in automobiles by coupling them with other energy sources, particularly batteries. They can also improve fuel efficiency by storing energy when an automobile is braking 

Long life, with little degradation over hundreds of thousands of charge cycles 

Extremely low internal resistance (ESR), consequent high cycle efficiency (95% or more), and extremely low heating levels 

Improved safety, no corrosive electrolyte, and low toxicity of materials environmentally friendly 

Simple charge methods no full charge detection needed no danger of overcharging 

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Kim, J., and Kim, S. (2014). Preparation and electrochemical property of ionic liquid-attached graphene nanosheets for an application of supercapacitor electrode, Electrochim. Acta, 119, pp. 11-15. 

Schneuwly, A. and R. Gallay. 2000. Properties and applications of supercapacitors from the state-of-the-art to future trends. 1-10. 

Li, J., Wang, X., Huang, Q., Gamboa, S., Sebastian, P.J., 2006. Studies on preparation and performances of carbon aerogel electrodes for the application of supercapacitor. Journal of Power Sources 158 (1), 784—788. 

Ukraine s Y. Maletin et al. presented a comprehensive overview describing state of the art as well as future development trends in supercapacitors, as the fifth paper in this chapter. The authors establish key performance bars for supecapacitors upon meeting those, supercapacitors may start to compete with batteries. Also, this paper highlights so-called hybrid applications where supercapacitors complement operation of batteries and/or fuel cells. Optimization of supercapacitor performance through varying electrode thickness is contemplated in length. 

Under severe conditions (above 700°C), a potassium vapor is formed. It plays a special role in the activation of carbonaceous materials, easily penetrating in the graphitic domains that form cage-like micropores. The efficient development of micropores, which often gives a few-fold increase of the total specific surface area, is very useful for the application of these materials in supercapacitors [13-14]. 

Another interesting type of novel carbons applicable for supercapacitors, consists of a carbon/carbon composite using nanotubes as a perfect backbone for carbonized polyacrylonitrile. Multiwalled carbon nanotubes (MWNTs), due to their entanglement form an interconnected network of open mesopores, which makes them optimal for assuring good mechanical properties of the electrodes while allowing an easy diffusion of ions. 

Electronically conducting polymers (ECPs) such as polyaniline (PANI), polypyrrole (PPy) and po 1 y(3.4-cthy 1 cncdi oxyth iophcnc) (PEDOT) have been applied in supercapacitors, due to their excellent electrochemical properties and lower cost than other ECPs. We demonstrated that multi-walled carbon nanotubes (CNTs) prepared by catalytic decomposition of acetylene in a solid solution are very effective conductivity additives in composite materials based on ECPs. In this paper, we show that a successful application of ECPs in supercapacitor technologies could be possible only in an asymmetric configuration, i.e. with electrodes of different nature. 

Combined with appropriate amorphous carbon precursors graphite intercalation compounds could be used in one-stage process of production of carbon-carbon composites, which could possess attractive properties for such applications as supercapacitors elements, sorbents as well as catalyst supports and materials for energy- and gas-storage systems. 

C.Y. Liu, A.J. Bard, F. Wudl, I. Weitz, and J.R. Heath, Electrochemical characterization of films of single-walled carbon nanotubes and their possible application in supercapacitors. Electrochem. Solid... 

G. Ning, Z. Fan, G. Wang, J. Gao, W. Qian, F. Wei, Gram-scale synthesis of nanomesh graphene with high surface area and its application in supercapacitor electrodes, Chemical Communications, 47 (2011) 5976. 

After the description of chemical structure and control of meso-architecture and surface area, selected applications of such carbon materials as battery electrodes, supercapacitors, and in the design of controlled hybrid heterojunctions were presented. In the Li battery, coating or hybridization with hydrothermal carbon brought excellent capacities at simultaneous excellent stabilities and rate performances. This was exemplified by hybridization with Si, Sn02 (both anode materials) as well as LiFeP04 (a cathode material). In the design of supercapacitors, porous HTC carbons could easily reach the benchmark of optimized activated traditional carbons, with better stability and rate performance. 

In this respect, this review provides a comprehensive survey of synthetic methods and physicochemical properties of the porous carbon materials. Furthermore, as electrochemical applications of the porous carbons to electrode materials for supercapacitor, the effects of geometric heterogeneity and surface inhomogeneity on ion penetration into the pores during double-layer charging/ discharging are discussed in detail by using ac-impedance spectroscopy, current transient technique, and cyclic voltammetry. 

In the past five years, many ion conducting polymers and gel electrolytes have been investigated for EDLC application. Figure 15 shows the capacities of various carbon electrodes in SPE or gel electrolytes. The values listed in this figure do not satisfy the requirements for EV. However, it is expected that the requirements of supercapacitors for EV can be achieved by development of devices based on composite electrodes and gel electrolyte systems as described in this chapter. 

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