Zinc-bromine cell development

Various materials have been used as separators in zinc—bromine cells. Ideally a material is needed which allows the transport of zinc and bromide ions but does not allow the transport of aqueous bromine, polybromide ions, or complex phase structures. Ion selective membranes are more efficient at blocking transport then nonselective membranes.These membranes, however, are more expensive, less durable, and more difficult to handle then microporous membranes (e.g., Daramic membranes).The use of ion selective membranes can also produce problems with the balance of water between the positive and negative electrolyte flow loops. Thus, battery developers have only used nonselective microporous materials for the separator. 

The theoretical cell potential of a zinc-bromine battery is 1.82 V, and its practical energy density is around 65-75 Wh kg Both are better potential and energy level than those of VRBs systems. Meanwhile, more than 80% of the energy efficiency and low-cost chemical reactants made the zinc-bromine battery one of the most developed, commercially ready flow battery systems (Figure 7). 

The zinc/chlorine battery was a predecessor of the zinc/bromine battery. It had been developed in the 1960s and 1970s for vehicle application (cf., e.g. Ref. 76, p. 302). It is based on the cell reaction... 

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