Monopolar fuel cell stack coupled together without use of top or bottom cover plates or tie rods
BRIEF SUMMARY OF THE INVENTIONA novel stack design is disclosed below that overcomes the limitations of the conventional bipolar fuel stacks bipolar fuel stacks is proposed. This new stack design offers a two-to-three fold improvement in power densities, suitable for manufacturing, uses inexpensive plastic materials, and straightforward to troubleshoot and assemble. Such a stack design will substantially improve the commercialization of portable direct methanol fuel cell power sources.
More particularly, the invention is a monopolar fuel cell stack comprising a plurality of sealed unit cells coupled together. Each unit cell comprises a first cathode, a first membrane electrode assembly disposed adjacent to the first cathode, and an anode plate disposed adjacent to the first membrane electrode assembly. The anode plate has an anode and an internal channel defined therein for flow of fuel through the anode plate. An inlet manifold is coupled to the anode plate and communicates with the channel within the anode plate. An outlet manifold is coupled to the anode plate and communicates with the channel within the anode plate. Fuel flows from the inlet manifold through the channel in contact with the anode plate and flows out through the outlet manifold. A second membrane electrode assembly is disposed adjacent to the anode plate. A second cathode is disposed adjacent to the second membrane. The inlet and outlet manifolds are arranged and configured to couple to the inlet and outlet manifolds respectively of an adjacent one of the plurality of unit cells to permit fuel flow in common into all of the inlet manifolds of the plurality of the unit cells when coupled together in a stack and out of all of the outlet manifolds of the plurality of unit cells when coupled together in a stack.
The first and second cathode are included as part of a corresponding first and second cathode plate. Each inlet and outlet manifold is configured to space each unit cell from each adjacent unit cell to provide an air gap between adjacent unit cells when the plurality of unit cells are coupled together to form the stack. At least the inlet and outlet manifolds are composed of plastic. Each of the inlet and outlet manifolds are arranged and configured to snap fit into adjacent inlet and outlet manifolds respectively to provide a common inlet and outlet manifold for the stack for the plurality of unit cells. The snap fit is a zip-lock coupling.
The stack may further comprise an inlet and outlet header coupled to the common inlet and outlet manifold for the stack for the plurality of unit cells and a current collector for electrically connecting the anodes of the anode plate with the cathodes in a predetermined connection topology. The stack may further comprise sealing gaskets between the first and second cathode plates on one hand and the first and second membrane electrode assemblies on the other, and further between the first and second membrane electrode assemblies on one hand and the anode plate on the other. In the illustrated embodiment the fuel flowing through the anode plate is liquid methanol.
The invention is also a method of fabricating a monopolar fuel cell stack comprising the steps of separately assembling a plurality of sealed unit cells, and snap fitting the plurality of sealed unit cells together to form the stack.
While the apparatus and method has or will be described for the sake of grammatical fluidity with functional explanations, it is to be expressly understood that the claims, unless expressly formulated under 35 USC 112, are not to be construed as necessarily limited in any way by the construction of "means" or "steps" limitations, but are to be accorded the full scope of the meaning and equivalents of the definition provided by the claims under the judicial doctrine of equivalents, and in the case where the claims are expressly formulated under 35 USC 112 are to be accorded full statutory equivalents under 35 USC 112. The invention can be better visualized by turning now to the following drawings wherein like elements are referenced by like numerals.
Patents:
US 7,585,577 [MORE INFO]
Type of Offer: Sale
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