Redox batteries

It is so universally applied that it may be found in combination with metal oxide cathodes (e.g., HgO, AgO, NiOOH, Mn02), with catalytically active oxygen electrodes, and with inert cathodes using aqueous halide or ferricyanide solutions as active materials ("zinc-flow" or "redox" batteries). The cell (battery) sizes vary from small button cells for hearing aids or watches up to kilowatt-hour modules for electric vehicles (electrotraction). Primary and storage batteries exist in all categories except that of flow-batteries, where only storage types are found. Acidic, neutral, and alkaline electrolytes are used as well. The (simplified) half-cell reaction for the zinc electrode is the same in all electrolytes ... 

There are three types of zinc-flow batteries (belonging in general to the group of flow or redox batteries) which have been studied intensively two of them are similar with respect to the reactants involved, the... 

Graphite and carbon electrodes are most commonly employed in industrial applications. Recent work on a large-scale redox battery systems based on... 

A redox battery using solutions with two different oxidation states of vanadium has recently been announced by the University of New South Wales in Sidney, Australia. When fully charged, each cell of the battery can generate a potential of about 1.5 V. A demonstration golf cart driven by the battery has been developed. Licences to industries in Thailand and Japan are underway for the production of large units for back-up power in solar houses or for peak demand in power stations. 

Developing technologies in vanadium science provide the basis for the last two chapters of this book. Vanadium(V) in various forms of polymeric vanadium pen-toxide is showing great promise in nanomaterial research. This area of research is in its infancy, but already potential applications have been identified. Vanadium-based redox batteries have been developed and are finding their way into both large-and small-scale applications. Lithium/silver vanadium oxide batteries for implantable devices have important medical applications. 

A ubiquitous characteristic of vanadium chemistry is the fact that vanadium and many of its complexes readily enter into redox reactions. Adjustment of pH, concentration, and even temperature have often been employed in order to extend or maintain system integrity of a specific oxidation state. On the other hand, deliberate attempts to use redox properties, particularly in catalytic reactions, have been highly successful. Vanadium redox has also been successfully utilized in development of a redox battery. This battery employs the V(V)/V(IV) and V(III)AT(II) redox couples in 2.5 M sulfuric acid as the positive and negative half-cell electrolytes, respectively. Scheme 12.2 gives a representation of the battery. The vanadium components in both redox cells are prepared from vanadium pentoxide. There are two charge-discharge reactions occurring in the vanadium redox cells, as indicated in Equation 12.1 and Equation 12.2. The thermodynamics of the redox reactions involved have been extensively studied [8],... 

The book includes discussion of the vanadium haloperoxidases and the biological and biochemical activities of vanadium(V), including potential pharmacological applications. The last chapters of the book step outside these boundaries by introducing some aspects of the future of vanadium in nanotechnology, the recyclable redox battery, and the silver/vanadium oxide battery. We enjoyed writing this book and can only hope that it will prove to provide at least a modicum of value to the reader. 

Chlorostannate and chloroferrate [110] systems have been characterized but these metals are of little use for electrodeposition and hence no concerted studies have been made of their electrochemical properties. The electrochemical windows of the Lewis acidic mixtures of FeCh and SnCh have been characterized with ChCl (both in a 2 1 molar ratio) and it was found that the potential windows were similar to those predicted from the standard aqueous reduction potentials [110]. The ferric chloride system was studied by Katayama et al. for battery application [111], The redox reaction between divalent and trivalent iron species in binary and ternary molten salt systems consisting of 1-ethyl-3-methylimidazolium chloride ([EMIMJC1) with iron chlorides, FeCb and FeCl j, was investigated as possible half-cell reactions for novel rechargeable redox batteries. A reversible one-electron redox reaction was observed on a platinum electrode at 130 °C. 

Redox battery - battery Redox buffer - buffer... 

New perspectives arising from isothermal oxidation. The next chapter of this book describes the greatly altered perspective of the fuel cell industry, when Grove s ideas are updated. The second chapter describes the detail of Regenesys, or ESS-RGN. This system has changed hands, as noted above, and information is available from http //www.vrbpower.com/. (The initials VRB stand for Vanadium Redox Battery, a low-power alternative to Regenesys.) The new 2005 VRB Power Systems shorthand is ESS-VRB for 2.5 to 10 MW and ESS-RGN for 10 to 100 MW. In Chapter 2 the reader will be acquainted with ESS-RGN, one of the two VRB fuel cell systems (incompressible liquid based) which can be termed complete . The redox battery uses small pumps as circulators. 

Eigure 2.3 Power storage in redox battery with liquid reagents... 

Because vanadium ions exist in four different oxidation states (as V2+, V3+, V02+ and V02+) in aqueous solution, redox couples can be formed by all vanadium ions. The emf of a vanadium redox battery is 1.4 V and the electrode kinetics are higher than those of the Fe-Cr battery. Also, the energy density of the battery can be increased due to the high solubility of vanadium salts.257 In the battery, vanadium sulfate solution is used,... 

P.S. Fedkiw and R.W. Watts, A mathematical model for the iron/chromium redox battery, J. Electrochem. Soc., 1984, 131, 701 R.A. Assink, Fouling mechanism of separator membranes for the iron/chromium redox battery, J. Membr. Sci., 1984, 17, 205-217 C. Abnold, Jr., R.A. Assink, Structure-property relationship of anionic exchange membranes for Fe/Cr redox storage batteries, J. Appl. Polym. Sci., 1984, 29,... 

Based on their early fundamental research of all-VRFBs, Skyllas-Kazacos et al. [25] also first developed some commercial products, for example, a 1 kW vanadium redox battery (VRB) cell stack. By employing 1.5-2 M vanadium sulphate, sulphuric acid in both half-cells, over 85% of theoretical capacity and 70-80% energy efficiency was obtained. Then in 1994, a 4 kW/12 kWh vanadium battery was evaluated in a demonstration solar house by Thai Gypsum Products Ltd. in Thailand under a license lirom the UNSW [26]. 

Sum E, Rychcik M, Skyllas-Kazacos M. Investigation of the V(V)/V (IV) system for use in the positive half-cell of a redox battery. J Power Sources 1985 16 85-95. 

Skyllas-Kazacos M, Peng C, Cheng M. Evaluation of precipitation inhibitors for supersaturated vanadyl electrol3des for the vanadium redox battery. Electrochem Solid-State Lett 1999 2 121-2. 

Skyllas-Kazacos M, Kasherman D, Hong R, Kazacos M. Characteristics and performance of 1 kW UNSW vanadium redox battery. J Power Sources 1991 35 399-404. 

Matsuda Y, Tanaka K, Okada M, Takasu Y, Morita M. A rechargeable redox battery utilizing ruthenium complexes with non-aqueous organic electrolyte. J Appl Electrochem 1988 18 909-14. 

Sukkar T, Skyllas-Kazacos M. Water transfer behaviour across cation exchange membranes in the vanadium redox battery. J Membr Sci 2003 222 235 7. 

Zhang Q, Dong QF, Zheng MS, Tian ZW. The preparation of a novel anion-exchange membrane and its application in all-vanadium redox batteries. J Membr Sci 2012 421 232-7. 

The operational principle of a vanadium-vanadium redox flow cell (vanadium redox battery or VRB) is illustrated in Figure 12.8. 

Hagedom NH (1983) The iron-chromium redox battery. Abstr Pap Am Chem Soc 186 28... 

If the counter electrode is not in contact with the same redox electrolyte but with a different one which is separated from the first one by a membrane as shown in Fig. 1.15, such systems can be used as redox batteries in which the light energy can be stored directly. The membrane is necessary in order to prevent the direct reaction between the two redox systems. This membrane therefore must... 

---