Cell stack, bromine

Figure 1.39 shows the principle of the zinc/bromine battery. In Fig. 1.39, the cell stack consists of only three cells. Actual batteries contain stacks of 50 or more cells. Except the two end plates, all electrodes are bipolar. They consist of an electron-conducting plate of carbon plastic enframed by insulating plastic. On the positive side, a porous layer of carbon increases the surface to increase the reaction rate of bromine. In the center of each cell, a microporous separator is positioned as used in lead-acid batteries (e.g. Daramic ) to suppress the direct contact between bromine and zinc as far as possible. 

Finite self-discharge. This value applies if electrolyte is not circulating. Self-discharge is limited to that due to the amount of bromine in die cell stacks. 

A great deal of flexibility is available when designing zinc/bromine battery systems. Batteries can be custom built for a particular application, where multiple modules share a single set of electrolyte reservoirs or where each module contains a complete system of cell stacks, reservoirs, and controls. Modules can be stacked to conserve the footprint in energy storage applications, and reservoirs can be made to match the space available in electric vehicles. 

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