Abstract: A fuel cell stack is disclosed with modified electrolyte matrices for limiting the electrolytic pumping and electrolyte migration along the stack external surfaces. Each of the matrices includes marginal portions at the stack face of substantially greater pore size than that of the central body of the matrix. Consequently, these marginal portions have insufficient electrolyte fill to support pumping or wicking of electrolyte from the center of the stack of the face surfaces in contact with the vertical seals. Various configurations of the marginal portions include a complete perimeter, opposite edge portions corresponding to the air plenums and tab size portions corresponding to the manifold seal locations. These margins will substantially limit the migration of electrolyte to and along the porous manifold seals during operation of the electrochemical cell stack.

Abstract: A matrix material for a molten carbonate fuel cell is described which is flexible, pliable and has rubber-like compliance at room temperature. The matrix has three components comprising fine inert particulate material, larger crack attenuating ceramic particulate material, and an organic polymeric binder. A process of assembling a molten carbonate fuel cell utilizing the compliant matrix material is also described. The compliant matrix material is inserted into a molten carbonate fuel cell stack utilizing fuel cell anodes with sufficient porosity to contain excess electrolyte. The fuel cell is heated up to a temperature sufficient to remove the polymer binder and cause a portion of the electrolyte material present in the anode to wick into the matrix to substantially fill it completely.

Abstract: A matrix material for a molten carbonate fuel cell is described which is flexible, pliable and has rubber-like compliance at room temperature. The matrix has three components comprising fine inert particulate material, larger crack attenuating ceramic particulate material, and an organic polymeric binder. A process of assembling a molten carbonate fuel cell utilizing the compliant matrix material is also described. The compliant matrix material is inserted into a molten carbonate fuel cell stack utilizing fuel cell anodes with sufficient porosity to contain excess electrolyte. The fuel cell is heated up to a temperature sufficient to remove the polymer binder and cause a portion of the electrolyte material present in the anode to wick into the matrix to substantially fill it completely.

Abstract: A molten carbonate fuel cell matrix material is described made up of a matrix tape portion and a bubble barrier portion. The matrix tape portion comprises particles inert to molten carbonate electrolyte, ceramic particles and a polymeric binder, the matrix tape being flexible, pliable and having rubber-like compliance at room temperature. The bubble barrier is a solid material having fine porosity up to about 50% by volume, optionally being bonded to the matrix tape. In operation in a fuel cell, the polymer binder burns off leaving the matrix and bubble barrier providing superior sealing, stability and performance properties to the fuel cell stack.

Abstract: A molten carbonate fuel cell matrix material is described made up of a matrix tape portion and a bubble barrier portion. The matrix tape portion comprises particles inert to molten carbonate electrolyte, ceramic particles and a polymeric binder, the matrix tape being flexible, pliable and having rubber-like compliance at room temperature. The bubble barrier is a solid material having fine porosity preferably being bonded to the matrix tape. In operation in a fuel cell, the polymer binder burns off leaving the matrix and bubble barrier providing superior sealing, stability and performance properties to the fuel cell stack.

Abstract: A fuel cell module comprising a stack of fuel cells with reactant gas manifolds sealed against the external surfaces of the stack includes a constraint system for providing a compressive load on the stack wherein the constraint system maintains the stack at a constant height (after thermal expansion) and allows the compressive load to decrease with time as a result of the creep characteristics of the stack. Relative motion between the manifold sealing edges and the stack surface is virtually eliminated by this constraint system; however it can only be used with a stack having considerable resiliency and appropriate thermal expansion and creep characteristics.

Abstract: Fuel cell performance is degraded by recycling a portion of the cathode exhaust through the cells and, if necessary, also reducing the total air flow to the cells for the purpose of permitting operation below a power level which would otherwise result in excessive voltage.

Abstract: In a fuel cell power plant comprising a plurality of stacks of molten carbonate fuel cells the CO.sub.2 produced at the anodes of the cells is combined with the process air for the cathode side of the stacks. The CO.sub.2 rich mixture is fed from stack to stack in series through the cathode sides thereof with heat being removed from the cathode side exhaust streams between consecutive stacks. This process improves cell performance by increasing the CO.sub.2 partial pressure within the stacks. The process also makes it possible to reduce the required heat exchanger heat transfer area needed to cool the cell exhaust products.

Abstract: A flow scheme for feeding a reactant gas to the cells of a fuel cell stack wherein the cells are connected electrically in series. For example, the fuel gas is passed in parallel over a portion of each fuel electrode and thereupon into a mixing manifold which directs the exhausted gases in parallel over a different portion of each fuel electrode and thereupon into another manifold. This is continued, depending upon the stack configuration, with the exhausted gases passing back and forth in parallel over different portions of the fuel electrodes and exhausting into a manifold until the fuel gas has covered the entire fuel electrode of each cell in the stack. This reduces the harmful effect of a blockage within the reactant gas chamber of a cell and also reduces the harmful effect caused by a maldistribution of current in one of the cells in the stack.

Abstract: A cooler for removing waste heat from a stack of fuel cells includes a plurality of tubes for carrying the coolant through the stack. The tubes are disposed adjacent the nonelectrolyte side of electrodes in the stack in grooves or passageways formed in the surface of plates which separate one cell in the stack from another. Since the tubes are exposed to the electrolyte used in the stack they must be made from or at least include a protective coating of material which is stable in the electrolyte. Preferably this material is also a dielectric to prevent shunt currents from passing into the tubes and coolant which may be water.