In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

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A review of electrode materials for electrochemical supercapacitors

Overview of current development in electrical energy storage technologies and the application potential in power system operation

Because of their availability, adjustable microstructure, varieties of forms, and large specific surface area, porous carbon materials are of increasing interest for use in hydrogen storage adsorbents and electrode materials in supercapacitors and lithium–sulfur cells from the viewpoint of social sustainability and environmental friendliness. Therefore, much effort has been made to synthesize and tailor the microstructures of porous carbon materials via various activation procedures (physical and chemical activation). In particular, the chemical activation of various carbon sources using KOH as the activating reagent is very promising because of its lower activation temperature and higher yields, and well-defined micropore size distribution and ultrahigh specific surface area up to 3000 m2 g−1 of the resulting porous carbons. In this feature article, we will cover recent research progress since 2007 on the synthesis of KOH-activated carbons for hydrogen and electrical energy storage (supercapacitors and lithium–sulfur batteries). The textural properties and surface chemistry of KOH-activated carbons depend on not only the synthesis parameters, but also different carbon sources employed including fossil/biomass-derived materials, synthetic organic polymers, and various nanostructured carbons (e.g. carbon nanotubes, carbon nanofibers, carbon aerogels, carbide-derived carbons, graphene, etc.). Following the introduction to KOH activation mechanisms and processing technologies, the characteristics and performance of KOH-activated carbons as well as their relationships are summarized and discussed through the extensive analysis of the literature based on different energy storage systems.

KOH activation of carbon-based materials for energy storage

Energy storage systems (ESSs) are enabling technologies for well-established and new applications such as power peak shaving, electric vehicles, integration of renewable energies, etc. This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies. Special attention is given to the different applications, providing a deep description of the system and addressing the most suitable storage technology. The main objective of this paper is to introduce the subject and to give an updated reference to nonspecialist, academic, and engineers in the field of power electronics.

Energy Storage Systems for Transport and Grid Applications

by J. Biggs and C. Tang, Maidenhead, England,
Open University Press, 2007, 360 pp., £29.99, ISBN-13: 978-0-335-22126-4

Teaching for quality learning at university

This paper studies the impact of fuel-cell (FC) performance and control strategies on the benefits of hybridization. One of the main weak points of the FC is slow dynamics dominated by a temperature and fuel-delivery system (pumps, valves, and, in some cases, a hydrogen reformer). As a result, fast load demand will cause a high voltage drop in a short time, which is recognized as a fuel-starvation phenomenon. Therefore, to employ an FC in vehicle applications, the electrical system must have at least an auxiliary power source to improve system performance when electrical loads demand high energy in a short time. The possibilities of using a supercapacitor or a battery bank as an auxiliary source with an FC main source are presented in detail. The studies of two hybrid power systems for vehicle applications, i.e., FC/battery and FC/supercapacitor hybrid power sources, are explained. Experimental results with small-scale devices (a polymer electrolyte membrane FC of 500 W, 40 A, and 13 V; a lead-acid battery module of 33 Ah and 48 V; and a supercapacitor module of 292 F, 500 A, and 30 V) in a laboratory authenticate that energy-storage devices can assist the FC to meet the vehicle power demand and help achieve better performance, as well as to substantiate the excellent control schemes during motor-drive cycles.

Comparative Study of Fuel-Cell Vehicle Hybridization with Battery or Supercapacitor Storage Device

Energy management of fuel cell/solar cell/supercapacitor hybrid power source

Fuel cells (FCs) hold great promise as a clean energy conversion technology. A large research effort is underway to develop the FC for applications ranging from small portable electronic devices to automotive transport, as well as residential combined heat and power supplies. These applications have a large emerging market and widespread adoption should lead to a reduced dependence on fossil fuels as well as encourage the development of a hydrogen economy. FCs produce low DC voltage, so that it is most often connected to electric networks through a step-up DC/DC converter. This article first introduces electrical characteristics, power electronic requirements, and different types of FCs and is then followed by a discussion of the various topologies of step-up DC/DC converters used for FCs' power-conditioning system. The examinations of several different approaches to power-conditioning systems for single and multiple FC combinations have been reviewed. High-power DC distributed power systems supplied by FC invokes the need to parallel power modules with interleaving technique. By method of the parallel converter modules with interleaving algorithm for an FC generatorfor high-power applications, inductor size (ferrite core and Litzwire) are simple to design and fabricate, and the FC ripple current can be virtually reduced to zero. As a result, the FC mean current is nearly equal to the FC rms current. The main drawback of the multiphase approach is added circuit complexity, requiring measurement and balancing of each phase current as the larger number of control components illustrates.

Fuel cell high-power applications

This paper presents the characteristics of a PEM fuel cell, especially a fuel (hydrogen and oxygen) starvation problem. This phenomenon is an original demonstration in the domain of fuel cell research. Naturally, a fuel cell power source is always connected with a power electronic converter (power conditioning circuit) to boost a low dc voltage to a higher utility level. Therefore, to present fuel cell characteristics, a fuel cell power conditioning circuit (classical boost converter) is designed and implemented in the GREEN/INPL laboratory. The studied PEM fuel cell is 500 W, 40 A, around 13 V, designed and manufactured by the ZSW Company. Experimental results authenticate the fuel cell characteristics when the fuel cell power source is operated with a power electronic converter at a switching frequency of 25 kHz. The high switching frequency and significant step load (fuel starvation effect) to the fuel cell voltage and current are clearly illustrated.

Analysis of a Fuel Starvation Phenomenon of a PEM Fuel Cell

This paper presents a design and implementation of a high power dc distributed system supplied by a fuel cell generator. A proposed parallel power converter with interleaving algorithm is chosen to boost a low dc voltage of fuel cell to a dc bus utility level. The present interleaved step-up converter is composed of two identical boost converters connected in parallel. Modules are controlled by interleaved switching signals, which have the same switching frequency and the same phase shift. During the past decade, power electronics research has focused on the development of interleaved parallel converters. For an interleaving technique with a real fuel cell source, this work is the first presentation; it is not just a fuel cell simulation. So, the design and experimental verification of 1.2-kW prototype converter at a switching frequency of 25 kHz connected with a Nexatrade PEM fuel cell system (1.2-kW, 46-A) in a laboratory are presented. Experimental results corroborate the excellent system performances. The fuel cell ripple current can be reduced. As a result, the fuel cell mean current is nearly equal to the fuel cell rms current.

Panarit Sethakul

Papers

Comparative Study of Fuel-Cell Vehicle Hybridization with Battery or Supercapacitor Storage Device

Energy management of fuel cell/solar cell/supercapacitor hybrid power source

Fuel cell high-power applications

Analysis of a Fuel Starvation Phenomenon of a PEM Fuel Cell

Design and implementation of 2-phase interleaved boost converter for fuel cell power source