Fuel Cell Stack

Additional components of a cell are best described by using a typical cell schematic, Figure 1-3.
This figure depicts a PAFC. As with batteries, individual fuel cells must be combined to produce
appreciable voltage levels and so are joined by interconnects. Because of the configuration of a
flat plate cell, Figure 1-3, the interconnect becomes a separator plate with two functions: 1) to
provide an electrical series connection between adjacent cells, specifically for flat plate cells, and
2) to provide a gas barrier that separates the fuel and oxidant of adjacent cells. The interconnect
of a tubular solid oxide fuel cell is a special case, and the reader is referred to Section 5 for its
slightly altered function. However, all interconnects must be an electrical conductor and
impermeable to gases. Other parts of the cell of importance are 1) the structure for distributing
the reactant gases across the electrode surface and which serves as mechanical support, shown as
ribs in Figure 1-3, 2) electrolyte reservoirs for liquid electrolyte cells to replenish electrolyte lost
over life, and 3) current collectors (not shown) that provide a path for the current between the
electrodes and the separator of flat plate cells. Other arrangements of gas flow and current flow
are used in fuel cell stack designs, and are mentioned in Sections 3 through 6 for the various type
cells.