Electrochemical energy conversion device

Electrochemical energy conversion devices are pervasive in our daily lives. Batteries, fuel cells and supercapacitors belong to the same family of energy conversion devices. They are all based on the fundamentals of electrochemical thermodynamics and kinetics. All three are needed to service the wide energy requirements of various devices and systems. Neither... 

There is a large, growing family of ionic solids in which certain ions exhibit unusually rapid transport. These materials have come to be known as fast ion conductors (FICs). In some cases, the rapid ion transport is accompanied by appreciable electronic conduction as well. There is tremendous interest in the science and technology of fast ion conductors in view of their potential use as electrodes or electrolyte materials in electrochemical energy conversion devices (Hagenmuller van Gool, 1978 Chandra, 1981 Goodenough, 1984). 

Figure 10. Power densities and energy densities for a variety of electrochemical energy conversion devices. The question of how much and how rapidly energy per unit mass can be called up is decisive for electrochemical applications.65 Reprinted from M. Winter, J.O. Besenhard, M.E. Spahr, P. Novak, Adv. Mater., 10 (1998), 725-763. Copyright 1998 with permission from Wiley-VCH Verlag GmbH.

Figure 3.3.2 Principle of a fuel cell as an electrochemical energy conversion device. Inside a fuel cell, fuel, e.g. hydrogen, and an oxidant, typically oxygen, combine electrochemically to form products, e.g. water, and electricity and some excess heat (not shown). Figure adapted from ref. [4]...

Fuel cells are versatile electrochemical energy conversion devices. They represent an integral component of an emerging strategy toward a future sustainable energy... 

Fuel cell An electrochemical energy conversion device. It produces electricity from various external quantities of fuel (on the anode side) and oxidant (on the cathode side). These react in the presence of an electrolyte. Fuel cells are different from batteries in that they consume reactant, which must be replenished, while batteries store electrical energy chemically in a closed system... 

Methanol is a potentially attractive fuel for electrochemical energy conversion devices (which is just another name for fuel cells) for two reasons first, because it is relatively easily oxidized electrochemically, and secondly because it can be cheaply manufactured from hydrogen and can, in effect, serve as a chemical means of storing... 

Fabio H. B. Lima was bom in Brazil in 1978. He graduated in Chemistry at University of Sao Paulo, Sao Carlos, in 2001. He obtained his Ph.D. in Physical Chemistry in the same institution, in 2006, with a stage at the Brookhaven National Laboratory. He spent 12 months as a postdoctoral fellow at the Chemistry Institute of Sao Carlos (IQSC) between 2006 and 2008. He is currently interested in synthesis and electrocatalysis for reactions involved in electrochemical energy conversion devices such as regenerative fuel cells (H2/O2 and HCOOH/CO2), rechargeable metal-air batteries, direct hydrazine, borohydride and ethanol fuel cells. Publication of scientific research includes 36 articles in journals, 3 chapters in books and more than 50 scientific summaries in collective books and proceedings. 

Micro fuel cells are miniature electrochemical energy conversion devices that generate... 

The main problem in the development of an efficient electrochemical energy conversion device (fuel cell) is in the sluggish ORR kinetics even on the most catalytically active electrode materials, for example, on... 

The literature is replete with claims that RTlLs will be used in more efficient and safer electrochemical energy-conversion devices. However, many of the studies in which such claims are made have only considered physicochemical properties of the RTlLs and their effects on, e.g. mass transfer or electrochemical windows of RTlLs. Others have built prototype devices and tested their performance but have not optimised the electrocatalyst composition and/or structure. It is our opinion that many of these proposed devices may only be realised if the kinetics of the electr(x hemical reactions occurring in such devices are studied with a view to optimising the electrodes compositions indeed, it is widely claimed that sluggish kinetics of the ORR in aqueous media are largely to blame for the slow uptake of... 

Electrodes consisting of supported metal catalysts are used in electrosynthesis and electrochemical energy conversion devices (e.g., fuel cells). Nanometer-sized metal catalyst particles are typically impregnated into the porous structure of an sp -bonded carbon-support material. Typical carbon supports include chemically or physically activated carbon, carbon black, and graphitized carbons [186]. The primary role of the support is to provide a high surface area over which small metallic particles can be dispersed and stabilized. The porous support should also allow facile mass transport of reactants and products to and from the active sites [187]. Several properties of the support are critical porosity, pore size distribution, crush strength, surface chemistry, and microstructural and morphological stability [186]. 

Electrochemists should consider the poor performance of stacks of batteries and fuel cells connected in series, compared to the performance of single cells. The solution to this problem is probably by microprocessor monitoring and control of each of the cells in the stack, making it possible to disconnect a malfunctioning cell for later replacement. Although not an electrochemical problem per se, its solution could increase the viability of electrochemical energy conversion devices considerably. 

A widespread interest for the electrochemical oxygen reduction reaction (ORR) has two aspects. The reaction attracts considerable attention from fundamental point of view, as well as it is the most important reaction for application in electrochemical energy conversion devices. It has been in the focus of theoretical considerations as four-electron reaction, very sensitive to the electrode surface structural and electronic properties. It may include a number of elementary reactions, involving electron transfer steps and chemical steps that can form various parallel-consecutive pathways [1-3]. 

Nanotechnology is a very active field of science and technology, which has major implications in electrochemistry and in many other fields. In this chapter we shall limit our discussion to some fundamental aspects of the physics of nanoparticles that are relevant to the preparation of electrode materials in electrochemical energy-conversion devices. The many ingenious methods of preparation and application of nanopartides in electrochemistry are widely discuss in the literature and wiU not be treated here. 

The purpose of the present book is to satisfy this need. The book starts by covering the basic subjects of interfacial electrochemistry. This is followed by a description of some of the most important techniques (such as cyclic voltammetry, the rotating disc electrode, electrochemical impedance spectroscopy, and the electrochemical quartz-crystal microbalance). Finally, there is a rather detailed discussion of electroplating (including alloy deposition), corrosion, and electrochemical energy conversion devices (batteries, fuel cells and super-capacitors). 

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