Conventional Design Principles and Their Drawbacks

From the very beginning of the new period of fuel cell development in 1960, the conventional design of most types of fuel cells and fuel cell stacks was based on two principles, which for a long time seemed to be unshakable  

The two fuel cell reactants (fuel and oxidizer) must be strictly segregated from each other. Each reagent must be supplied with its own electrode and precautions must be made to avoid its reaching the other ( undesirable ) electrode. This is necessary to prevent direct chemical reagent interaction and estabhshing of mixed electrode potentials (both these factors lead to considerable reactant and efficiency losses). 

The most convenient way to establish a series connection of individual fuel cells in stacks and batteries is to use the filter-press design with bipolar electrodes and bipolar plates between two adjacent individual cells (as described in Section 1.2.2). 

The practical realization of these principles is connected with difficulties and new problems  

Fuel Cells Problems and Solutions, Second Edition. Vladimir S. Bagotsky. 

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