Energy conversion electrochemical

Michael Krumpelt, Ph D , Manager, Fuel Cell Technology, Argonne National Laboratory Member, American In stitute of Chemical Engineers, American Chemical Society, Electrochemical Society. (Electrochemical Energy Conversion)... 

In some instances, however, pai t of the chemical energy bound in relatively high-enthalpy compounds can be converted directly to electricity as these reactants are converted to produc ts of lower enthalpy (galvanic action). A process in the opposite direc tion also is possible for some systems an elec tric current can be absorbed as the increased chemical energy of the higher-enthalpy compounds (electrolytic action). The devices in which electrochemical energy conversion processes occur are called cells. 

The reciprocal value, / = l/V/Ah of the coulometric efficiency is called the charging factor. The coulometric efficiency for electrochemical energy conversion is about 70-90 percent for nickel/cadmium and nearly 100 percent for lithium-ion accumulators [14]. 

Hodes G, Manassen J, Cahen D (1977) Photo-electrochemical energy conversion electro-catalytic sulphur electrodes. J Appl Electrochem 7 181-182... 

These new experimental approaches gave renewed motivation to the study of classical organic electrode reactions for direct electrochemical energy conversion. The present contribution intends to give a survey of the recent progress in the study of methanol oxidation attained by application of the above mentioned techniques. 

Z.S. Wronski, On the possibility of mechano-chemical activation of powders used in electrochemical power sources. In 200 Years of Electrochemical Energy Conversion - Bicentenary of Volta s Invention of the Energy Pile, International Society of Electrochemistry (ISE) Symposium, ISE, Geneva, 5-10 September (1999). University of Pavia, Pavia, Italy (CD ROM), pp. 830. 

Dr. Ralph J. Brodd is President of Broddarp of Nevada. He has over 40 years of experience in the technology and market aspects of the electrochemical energy conversion business. His experience includes all major battery systems, fuel cells, and electrochemical capacitors. He is a Past President of the Electrochemical Society and was elected Honorary Member in 1987. He served as Vice President and National Secretary of the International Society of Electrochemistry as well as on technical advisory committees for the National Research Council, the International Electrotechnic Commission, and NEMA and on program review committees for the Department of Energy and NASA. 

Figure 3. Simplified Ragone plot of the energy storage domains for the various electrochemical energy conversion systems compared to an internal combustion engine and turbines and conventional capacitors.

The energy storage and power characteristics of electrochemical energy conversion systems follow directly from the thermodynamic and kinetic formulations for chemical reactions as adapted to electrochemical reactions. First, the basic thermodynamic considerations are treated. The basic thermodynamic equations for a reversible electrochemical transformation are given as... 

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). 

In this section, a number of electrocatalytic processes will be discussed where surface chemical bonding plays a central role in the reaction mechanism. The selection of reactions is far from complete and not representative of the wide range of technologically important electrocatalytic processes. The selection is biased towards the areas of electrochemical energy conversion and fuel cell electrochemistry, which have been catalyzing a renewed interest in the field of electrochemistry. 

J. O M. Bockris, B.E. Conway, E. Yeager and R.E. White, Electrochemical Energy Conversion and Storage, Comprehensive Treatise of Electrochemistry, Vol. 3, Plenum Press, New York, 1981. 

In practical applications, where the maximum yield of a product or electricity in electrochemical energy conversion systems at the lowest energy cost is desirable, the rate of mass transport should be fast enough in order not to limit the overall rate of the process. For electroanalytical applications, such as polarography or gas sensors, on the other hand, the reaction must be limited by the transport of the reactant since the bulk concentration which is of interest is evaluated from the limiting con-vective-diffusional current. 

The whole discipline of electrocatalysis emerged in this context mainly in relation to a vivid interest in electrochemical energy conversion and it is at present one of the most important areas of electrochemical research. 

Flow-Wise One-Dimensional Electrochemical Energy Conversion... 

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.

Frackowiak has more than 150 publications and several chapters and patents to her name. The number of her citations exceeds 2500. She is a member of the advisory board of the International Conferences on Intercalation Compounds and was the organizer of ISIC12 in Poznan in 2003. She is a member of the advisory board of the journal Energy and Environmental Science as well as the coordinator of many international projects. She is Chair Elect of Division 3 Electrochemical Energy Conversion and Storage of the International Society of Electrochemistry. 

---