摘要:
To reduce degradation of a solid polymer fuel cell during startup and shutdown, a selectively conducting component is incorporated in electrical series with the anode components in the fuel cell. The component is characterized by a low electrical resistance in the presence of hydrogen or fuel and a high resistance in the presence of air. High cathode potentials can be prevented by integrating such a component into the fuel cell. A suitable selectively conducting component can comprise a layer of selectively conducting material, such as a metal oxide.
摘要:
By incorporating a selectively conducting component in electrical series with the anode components in a solid polymer fuel cell, degradation during startup and shutdown can be reduced. As a result, the startup and shutdown procedures can be simplified and consequently certain system apparatus may be omitted. The anode does not need to be rapidly purged with hydrogen on startup or with air on shutdown. Additionally, the auxiliary load usually employed during such purging is not required.
摘要:
The degradation associated with repeated startup and shutdown of solid polymer electrolyte fuel cells comprising PtCo alloy cathode catalysts can be particularly poor. However, a marked and unexpected improvement in durability is observed as a result of incorporating a selectively conducting component in electrical series with the anode components in the fuel cell.
摘要:
By incorporating a selectively conducting component in electrical series with the anode components in a solid polymer fuel cell, degradation during startup and shutdown can be reduced. As a result, the startup and shutdown procedures can be simplified and consequently certain system apparatus may be omitted. The anode does not need to be rapidly purged with hydrogen on startup or with air on shutdown. Additionally, the auxiliary load usually employed during such purging is not required.
摘要:
Improved water distribution can be obtained within the cells of a fuel cell series stack by maintaining a suitable temperature difference between the cathode and anode sides of each cell in the stack during shutdown.
摘要:
Apparatus and methods of ceasing operation of an electric power generating system improve the cold starting capability of the system. The system comprises a fuel cell stack connectable to an external circuit for supplying power to the external circuit. The stack comprises at least one solid polymer fuel cell, and the system further comprises a fuel passage for directing a fuel stream through the stack and an oxidant passage for directing an oxidant stream through the stack, a sensor assembly connected to the stack for monitoring a parameter indicative of stack performance, a controller for controlling at least one stack operating parameter, and a control system communicative with the sensor assembly and stack operating parameter controller. The method comprises adjusting at least one stack operating parameter to cause the stack to operate under a drying condition that causes a net outflux of water from the stack, operating the stack under the drying condition until the water content in the stack has been reduced, and interrupting supply of power from the stack to the external circuit.
摘要:
A diagnostic method for an electrochemical fuel cell is described wherein a non-steady state polarization curve is obtained. In particular, a current sweep is applied to, for example, a catalyst coated membrane (CCM), membrane electrode assembly (MEA), fuel cell, plurality of fuel cells and the resulting voltage obtained is recorded. At low current densities, the ramp rate may be relatively slow and relatively fast at higher current densities. The ramp rate may increase in discrete steps or continuously throughout the current sweep. A polarization curve of voltage as a function of current may thus be obtained with the entire current sweep lasting less than 20 seconds and more.
摘要:
Use of noble metal alloy catalysts, such as PtCo, as the cathode catalyst in solid polymer electrolyte fuel cells can provide enhanced performance at low current densities over that obtained from the noble metal itself. Unfortunately, the performance at high current densities has been relatively poor. However, using a specific bilayer cathode construction, in which a noble metal/non-noble metal alloy layer is located adjacent the cathode gas diffusion layer and a noble metal layer is located adjacent the membrane electrolyte, can provide superior performance at all current densities.
摘要:
A fuel cell system comprising a fuel cell stack and at least one hydration sensor apparatus for measuring membrane hydration in the fuel cell stack is disclosed. The hydration sensor apparatus comprises (1) an electrically insulated sensor comprising a polymer electrolyte membrane, (2) a power supply, and (3) a load resistor. The sensor, the power supply and the load resistor of the hydration sensor apparatus are electrically connected and the sensor of the hydration sensor apparatus is fluidly connected to the fuel cell stack such that, during operation of the fuel cell system, the polymer electrolyte membrane of the hydration sensor apparatus is exposed to a fuel fluid stream of the fuel cell stack.
摘要:
Ruthenium or a Ruthenium compound is applied to an anode structure according to a predetermined pattern, with only part of the anode active area containing Ru. The parts of the MEA that do not contain Ru are not expected to suffer degradation from Ru cross-over, so that overall degradation of the cell will be diminished. Having less precious metals will also translate into less cost.