Abstract: A cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent disposed in the granule bed, wherein a transverse cross-sectional distribution of the porous absorbent in the granule bed varies in a longitudinal direction from a first position to a second position. In another embodiment, a cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent coating on a surface adjacent to the granule bed.

Abstract: A cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent disposed in the granule bed, wherein a transverse cross-sectional distribution of the porous absorbent in the granule bed varies in a longitudinal direction from a first position to a second position. In another embodiment, a cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent coating on a surface adjacent to the granule bed.

Abstract: An electrochemical cell is provided that includes a cathode chamber including a cathode material and an ion sequestering material, an anode chamber including a molten alkali metal material and a separator disposed in an ionic conductivity path between the cathode chamber and the anode chamber. The electrochemical cell demonstrates a reduced increase in discharge resistance.

Abstract: A cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent disposed in the granule bed, wherein a transverse cross-sectional distribution of the porous absorbent in the granule bed varies in a longitudinal direction from a first position to a second position. In another embodiment, a cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent coating on a surface adjacent to the granule bed.

Abstract: A cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent disposed in the granule bed, wherein a transverse cross-sectional distribution of the porous absorbent in the granule bed varies in a longitudinal direction from a first position to a second position. In another embodiment, a cell cathode compartment comprises a granule bed comprising metal granules, metal halide granules, and sodium halide granules, a separator adjacent to the granule bed, a liquid electrolyte dispersed in the granule bed, and a porous absorbent coating on a surface adjacent to the granule bed.

Abstract: A technique that is usable with a fuel cell includes providing a fuel and oxidant mixture to a reactant chamber of the fuel cell to regulate an electrode potential of the fuel cell during startup or shutdown of the fuel cell.

Abstract: A technique that is usable with a fuel cell system having a fuel cell stack includes storing in a memory a healthy behavior pattern and an unhealthy behavior pattern for the fuel cell stack, comparing observed behavior of the fuel cell stack to the healthy and unhealthy behavior patterns, and classifying the observed behavior as healthy or unhealthy based on the comparison. The technique further includes modifying the stored healthy behavior pattern and the stored unhealthy behavior pattern based upon the occurrence of a predetermined event, such as the detection of an unhealthy condition, the issuance of an alarm, or the passage of a time interval. Modifying the behavior patterns enhances the accuracy of the health classification since the modification takes into account actual system behavior and any performance degradation that may occur over time.

Abstract: A technique that is usable with a fuel cell stack includes detecting a negative cell voltage condition of the fuel cell stack and operating the fuel cell stack for an amount of time during which the negative cell voltage condition is present until the amount of time exceeds a first time threshold. The technique further includes determining the first time threshold based on the magnitude of the negative cell voltage.

Abstract: A technique to shut down a fuel cell stack includes reducing an oxidant flow through the fuel cell stack, and decreasing the current of the fuel cell stack while maintaining an approximately constant rate of fuel flow to the fuel cell stack. Once the power output of the fuel cell stack reaches zero due to the depletion of oxygen at the cathode, the fuel flow to the fuel cell stack anode is then halted. Then, the stack is either isolated from the reactant streams, or the cathode is briefly purged by the fuel before the stack is isolated from the reactant streams, or both the anode and the cathode are purged in sequence by air before the stack is isolated from the reactant streams.

Abstract: In one aspect, the invention features a method including contacting a first gas to an anode of a fuel cell, and contacting a second gas to a cathode of the fuel cell. The first gas is capable of interacting with the anode to form protons, and the second gas is substantially free of a gas capable of being reduced by the cathode.