Polysulfides bromine

Ge SH, Yi BL, Zhang HM (2004) Study of a high power density sodium polysulfide/bromine energy storage cell. J Appl Electrochem 34 181-185. doi 10.1023/B JACH.0000009936. 

Zhao P, Zhang H, Zhou H, Yi B (2005) Nickel foam and carbon felt applications for sodium polysulfide/bromine redox flow battery electrodes. Electrochim Acta 51 1091-1098. doi 10. 1016/j.electacta.2005.06.008... 

The electrode materials for redox flow batteries can be classified into two-dimensional (2D) and three-dimensional (3D) types. CF is conunonly used as a 3D electrode, while carbon cloth, carbon black, and AC are 2D electrodes. Typically, in a sodium polysulfide/bromine RFB, CF, carbon cloth, carbon black, and AC are main electrode materials for an aqueous bromide/bromine couple, and AC, metal foam, and CF are main electrode materials for a negative half-cell. 

Innogy, United Kingdom Innogy (formerly National Regenesys Polysulfide/bromine Utility storage... 

Regenesys (polysulfide/bromine) 2000 Battery 20 20 - UtUity energy storage Very large sceile... 

Zhou H, Zhang H, Zhao P, Yi B (2006) A comparative study of carbon felt and activated carbon based electrodes for sodium polysulfide/bromine redox flow battery. Electrochim Acta 51 6304-6312. doi 10.1016/j.electacta.2006.03.106... 

Oxidation may be achieved in the presence of oxygen or air. Other suitable oxidants include sulfur, sodium polysulfide, iron (III) chloride, potassium ferro-cyanide (III) or potassium dichromate, peroxydisulfate or salts of aromatic nitro-sulfonic acids. An aqueous/alkaline medium is used in the presence of a high boiling organic solvent which is not miscible with water or which is almost immiscible with water. Cyclization with chlorosulfonic acid can be followed directly by oxidation with bromine to afford the thioindigo system, without separation of the intermediate. 

The polycondensation of dibromomethane with bis(benzenethiol) instead of bisphenol also shows stoichiometrically imbalanced polymerization behavior (Scheme 63) [253]. When 1.5 equivalents of dibromomethane was reacted with dithiol in NMP at 75 °C for 4 h, polysulfide with the maximum inherent viscosity (//jn, = 0.50 dbg ) was obtained. On the basis of the model reaction, a reactive intermediate, in which a bromine in dibromomethane is substituted with the mercapto group of the monomer, is estimated to be 61 times more reactive than dibromomethane. 

Flow cells (also redox flow cells, flow batteries) are similar to batteries, except that the electrodes are catalysts for the chemical reaction, which occurs as a microporous membrane allows ions to pass from one electrolyte solution to another. Among flow cells are types that use zinc and bromine, vanadium in two types with different states, or polysulfide and bromine as the pairs of electrolytes. The advantages of flow cells are that they are capable of a large number of cycles, and the electrolytes can be replenished. 

Carbon-based materials with a large surface area, suitable porosity, and low electronic resistance are usually used as 3D electrode materials for RFBs, including zinc/ bromine, all-vanadium, bromine-polysulfide, and zinc-cerium RFBs [4]. These carbon-based materials are made of polymer binders and conductive particles and include polymer-impregnated graphite plates, conductive carbon-polymer composites, and polymer-impregnated flexible graphite, which are low-cost and lightweight and have better mechanical properties. 

Molybdenum and tungsten powders with average particle size 10-20/pm (99.99%) have been used in these procedures. Such powders are generally free of oxide forms, but if old samples are used, they should be heated in a stream of H2 (1000°C, 1 h) prior to use. Commercially available 99.5% liquid bromine is recommended to avoid the need to remove H2O. Commercial 20% ammonium polysulfide (NH4)2Sy can be used, or alternatively solutions can be prepared by passing H2S through a suspension of sulfur (15 g) in 25% aqueous NH3 (110 mL) until complete dissolution of the sulfur occurs. White crystalline 98.5%... 

The PSB is an attractive chemistry due to the low cost, high abundance, and high solubility of both polysulfide and bromine in aqueous electrolytes. Considered applicable in MW/MWh class installations, this chemistry has been extensively studied since the earlier 1990s with several large-scale demonstration undertaken by various companies (e.g., Regenesys Technology) [14]. The electrode reactions are ... 

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