Supercapacitors: from the Leyden jar to electric busses

Abstract

Supercapacitors are introduced and reviewed as devices with very high electric power capability suggested to support and supplement other devices for electrochemical energy storage and conversion with higher energy content but lower power. They are currently of significant importance on the device and local (end-user) level already providing resources to meet power surge demands. In larger mobile systems (vehicles) they help meeting this demand and also offer high power storage capabilities when braking. On an even higher level, they can provide support for maintaining power quality and help in peak shaving. A brief historic background and general information is followed by an overview of materials and their combination into already marketed devices and in possible systems under development.

How to measure and report the capacity of electrochemical double layers, supercapacitors, and their electrode materials

“…Applicability of this approach in particular with low scan rates was confirmed elsewhere [71]; data from CVs were found to be close to true equilibrium double layer capacity values (i.e., not affected by diffusion effects) as compared with the data from impedance measurements. These considerations are equally valid for electrode materials showing a pseudocapacitive behavior [27,[72][73][74][75].…”

“…Although the correct technical term is capacitance among electrochemists, the term capacity is frequently used, almost like a synonym. This confusion has been addressed elsewhere before[74]. Only recently in the debate about capacitive, pseudocapacitive, and non-pseudocapacitive behaviors of electrochemical interfaces in particular in supercapacitor electrodes attempts have been made to turn this rather harmless confusion and habit into a problem, apparently based on rather artificial arguments[75].…”

Intrinsically conducting polymers and their combinations with redox-active molecules for rechargeable battery electrodes: an update

“…Why and how it is frequently reported nevertheless has been discussed elsewhere (Ge et al 2020(Ge et al , 2021Holze and Wu 2021). Storage capabilities in terms of theoretical and/or theoretical gravimetric or volumetric charge densities (sometimes slightly imprecisely called capacities (see Dubal et al 2015Dubal et al , 2016a, in units of A•s•g −1 ) can be calculated. In case of a battery electrode (material) with a well-established electrode reaction equation calculation of a theoretical value of a gravimetric charge density assuming complete conversion of the reactants and exact knowledge of the electrode reaction (Beck and Euler 1984) is no problem.…”

“…Because the amount of charge stored with these materials depends on the change of electrode potential a value of charge specified with respect to this change and the mass (in units of A s V −1 g −1 or F g −1 ) can be provided based on experimental data. Theoretical storage capabilities (sometimes also called capacitances, see (Dubal et al 2015(Dubal et al , 2016a) are difficult to establish (Ge et al 2021). For supercapacitor electrode materials utilizing redox reactions this problems becomes even more intricate.…”

Composites and Copolymers Containing Redox-Active Molecules and Intrinsically Conducting Polymers as Active Masses for Supercapacitor Electrodes—An Introduction

“…Supercapacitors have been established as a means of electrical energy storage in a vast range of sizes, from tiny ones in environmental and medical applications across numerous mobile applications in, e.g., telecommunication, to large ones in electric vehicles in mass transit. Introductory overviews are available [ 1 , 2 , 3 ], and in numerous monographs presumably all aspects from basic functional principles to materials and applications are treated [ 4 , 5 , 6 , 7 , 8 , 9 ]. Initially, carbon-based electrode materials were used in preference, using the electrochemical double layer capacity for charge and thus energy storage (EDLC supercapacitors).…”