Redox flow battery system

Nikiforidis G, Berlouis L, Hall D, Hodgson D (2013) Impact of electrolyte composition on the performance of the zinc-cerium redox flow battery system. J Power Sources 243 691-698. doi 10.1016/j.jpowsour.2013.06.045... 

Redox flow battery systems are promising devices, because the tendency is toward the development of low-cost systems, and future developments seem to be leaning toward choosing less toxic redox couples, more abundant materials, more stable membranes and effective recycling processes. Electrolytes can always be reused provided there is no precipitation of oxides - a phenomenon which occurs at low temperature. 

T. Tanaka, T. Sakamoto, N. Mori, T. Shigematsu, and F. Sonoda, Development of a 60-kW Class Redox Flow Battery System. Proc. 3d Int. Conf. of Batteries for Utility Energy Storage, Kobe, Japan, 1991, pp. 411-423. 

P. Modiba, Electrolytes for Redox Flow Battery Systems, University of Stellenbosch, 2010. 

Another system under investigation is the iron/ chromium redox flow battery (Fe/Cr RFB) developed by NASA. The performance requirements of the membrane for Fe/Cr RFB are severe. The membrane must readily permit the passage of chloride ions, but should not allow any mixing of the chromium and iron ions. An anionic permselective membrane CDIL-AA5-LC-397, developed by Ionics, Inc., performed well in this system. ° It was prepared by a free radical polymerization of vinylbenzyl chloride and dimethylaminoethyl methacrylate in a 1 1 molar ratio. One major issue with the anionic membranes was its increase in resistance during the time it was exposed to a ferric chloride solution. The resistance increase termed fouling is related to the ability of the ferric ion to form ferric chloride complexes, which are not electrically repelled by the anionic membrane. An experiment by Arnold and Assink indicated that... 

Comparison of energy density (kWh/m ) for various storage systems of electric power such as pumped hydropower, redox-flow battery, lead battery, NAS battery and methylcyclohexane (MCH) and decalin (TEPCO = Tokyo Electric Power Company). 

The Zn/Br redox flow battery (RFB) is a modular system comprising a cell stack containing functional electrodes attached to current collectors (separated via membranes), electrolyte storage tanks/reservoirs, delivery pumps and pipes. The RFB relies on the electrolyte circulation system to deliver electrochemically active species to electrode surfaces in order to achieve charge transfer and cause electrical current to flow. A simple Zn/Br unit cell is illustrated in Fig. 2.1, with multiple such cells combined in series to create a practical battery. 

Yang JH, Yang HS, Ra HW et al (2015) Effect of a surface active agent on performance of zinc/bromine redox flow batteries Improvement in current efficiency and system stability. J Power Sources 275 294-297. doi 10.1016/j.jpowsour.2014.10.208... 

Redox flow batteries have been studied for almost 40 years, ever since the first concept reported by Thaller in 1976 [6]. NASA-Lewis Research Centre developed the first complete redox energy storage system based on the Fe(III)/Fe(II) and Cr(III)/Cr (II) redox couples as the positive and negative active species, respectively. Since then, redox flow batteries have been significantly developed, leading to various systems. Generally, two major principles can classify RFBs. 

Based on the occurrence of phase transition, redox flow batteries can be classified as a true system or a hybrid system. In a true system, active species dissolve in the electrolytes all the time, and no second phase other than liquid is formed on the electrode. For a hybrid system, at least one kind of active species is insoluble solid or gas. In the next chapter, we will introduce different types of redox flow batteries using this method. 

Distinguished from true redox flow batteries, hybrid RFB systems employ partially soluble redox couples as active materials, either as a solid or a gas. Hybrid RFBs are more complicated than true RFBs because a new phase, different from the electrolytes, forms on the electrode. A zinc-bromine battery is considered as the prototypical hybrid RFB. 

For all technical applications, small overpotentials are desirable with corrosion reactions being the notable exception. In industrial processes (electrolysers [2, 3]), energy storage systems (e.g., redox flow batteries [4, 5]) and further systems, mass transport is generally enhanced by circulating electrolyte solutions, using three-dimensional electrodes or applying other means of artificially enhanced convectimi. 

Storage for grid-connected energy systems Cost VRLA. Sodium-sulfur. Lithium-ion. Redox flow batteries... 

Redox flow batteries (or systems) are present in ranges from ten to several himdred kW, and even beyond a MW for grid support or transport,... 

Not all systems can be described using these definitions, since there are also combined systems such as metal-air batteries [8-10] which contain a battery electrode (metal anode) and a fuel cell electrode (air cathode), or redox flow batteries [11,12] which are a form of rechargeable battery in which electrolyte containing one... 

We conclude with the point that the main competitive technologies for hydrogen batteries are redox flow batteries (VRB Power Systems) and sodium-sulfur (NaS) batteries (NGK Insulators). 

Joerissen et al. (2004) made a detailed technical and economic analysis of the potential of vanadium redox flow batteries in various low-power energy systems in which the primary source of electrical energy would be solar batteries and wind power generators, both highly variable. The authors noted as a drawback in long-term operation of the battery at elevated temperatures that part of the pentavalent vanadium may precipitate as insoluble oxide (V2O5). 

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