Fuel Cell Durability Enhancement

Fuel cell system that maximizes catalyst performance restoration while minimizing response time degradation during power increases. The system has a fuel cell with a control device to execute a power restoration process for the catalyst by lowering the cell voltage. The control device predicts when a power increase request will come and determines the necessity and extent of the restoration based on the prediction. This allows targeted catalyst restoration without excessively lowering cell voltage during normal operation, preventing performance loss.

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Series-parallel fuel cell stack design, system, and control method to improve performance and longevity of high-power commercial fuel cell stacks. The stack has two identical sub-stacks connected in series using a central plate. The sub-stacks share the membrane electrode assembly, bipolar plates, and assembly process. But they have separate hydrogen and air channels, connected in parallel. Heat dissipation channels are series. This balances gas and temperature distribution between cells. A control method monitors voltage, air pressure, hydrogen flow, and coolant temperature to optimize stack operation.

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Fuel cell separator plate with channel shapes to reduce humidity variation inside the fuel cell stack. The separator plate has channels for the reaction gas flow. The channel shapes are designed to suppress water flow into the gas diffusion layers at certain locations. This prevents drying out or overhumidification of the membrane electrode assembly (MEA) in those areas. The channel shapes can have inclines, undercuts, or other features to control water flow. This reduces humidity variation and improves fuel cell performance by maintaining consistent moisture levels in the MEA.

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Fuel cell system with internal state control to suppress voltage fluctuations and deterioration of catalyst performance in fuel cells. The system has actuators to adjust internal state variables like membrane humidity and oxide film rate. A controller optimizes these variables to approach targets as current changes. By stabilizing internal conditions, it reduces voltage fluctuations and catalyst degradation compared to uncontrolled operation.

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Controlling sweep current in a multi-stage solid oxide fuel cell system to optimize performance by accurately sensing and adjusting the hydrogen concentration in the off-gas of each cell stack. The system has separate fuel electrodes for each stack, and a detection device to measure hydrogen content in the anode off-gas from the front stack. The sweep currents of the front and rear stacks are then adjusted based on the hydrogen level to prevent fuel starvation in the rear stack when the front stack's off-gas contains high hydrogen concentrations. This avoids fuel waste and improves overall system efficiency.

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Fuel cell design with improved water management for better performance over a wide operating temperature range. The key is optimizing the ratio of over-humidified gas diffusion resistance between the anode and cathode gas diffusion layers. By selecting materials with a resistance ratio of 0.4 or less, more water is drained from the cathode side when humid and less evaporates from the anode side when dry. This prevents drying at high temps while enhancing low temp drainage.

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A fuel cell system with flow path switching to mitigate local temperature rise in the cell stack as it degrades. The system has channels for anode and cathode gas flow, plus a switching mechanism in some channels. A controller monitors cell stack degradation based on temperature measurements. When local degradation is detected, the controller switches the gas flow path to move high-temperature gas away from the degraded area. This prevents excessive temperature rise and oxidation in the degraded region. The switching is repeated as degradation progresses.

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Improving the durability and conductivity of fuel cell membranes by adding a nanofiber antioxidant, cerium hydrogen phosphate (CeHPO4), to the membrane. The antioxidant scavenges destructive radicals produced in the fuel cell to protect the membrane without reducing proton conductivity like conventional antioxidants. The nanofiber form provides high dispersibility in the membrane. The membranes with dispersed CeHPO4 show improved proton conductivity and durability in fuel cells.

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An electrode catalyst layer for polymer electrolyte fuel cells that improves durability during repeated start-stop cycles. The layer contains catalyst-carrying carbon particles, a polymer electrolyte, and at least one of carbon fibers or organic electrolyte fibers. The fiber materials reduce thickness reduction due to carbon particle corrosion during start-stop cycling. The thickness after 10,000 cycles is at least 70% of the original.

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Fuel cell system with recirculation of exhaust gas to improve fuel utilization and suppress voltage fluctuations. The system has multiple fuel cell stacks divided into groups. The exhaust gas from one group is recirculated upstream to the other group. A discharge mechanism is provided to periodically release some exhaust gas to prevent nitrogen buildup. This allows recycling exhaust to increase fuel utilization without periodic nitrogen spikes and voltage fluctuations.

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Improving the durability and lifespan of fuel cells by avoiding stack deterioration due to mixed potential and reverse currents when the fuel cell is restarted after being stopped. The fuel cell deterioration avoidance method involves selectively recirculating air and hydrogen, controlling anode hydrogen pressure, and managing cooling water temperature based on diagnostic criteria like open circuit decay time and current distribution deviation. This prevents degradation by avoiding conditions prone to mixed potential and reverse currents when restarting the fuel cell.

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Membrane electrode assembly (MEA) for polymer electrolyte fuel cells that prevents reverse voltage. The MEA has a design where the anode catalyst layer is on the microporous layer (MPL) instead of directly on the polymer electrolyte membrane. An oxygen evolution reaction (OER) catalyst layer is formed on the MPL and anode side. This prevents deactivation of the OER catalyst due to carbon oxidation during reverse voltage operation. The MEA also allows removing carbon from the anode catalyst layer for improved durability and performance stability over time. The OER catalyst layer prevents water electrolysis and carbon oxidation at the interface during reverse voltage.

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Hydrogen exhaust device for fuel cell systems that reduces pressure fluctuations and improves electrical performance and system reliability compared to conventional hydrogen exhaust methods. The device includes a steam trap, buffer solenoid valve, buffer tank, and drain solenoid valve. The steam trap collects water from the hydrogen. The buffer tank provides a volume to absorb pressure fluctuations. The buffer solenoid valve allows controlled hydrogen exhaust from the buffer tank to reduce pressure spikes. The drain solenoid valve allows draining of excess water from the steam trap.

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Fuel cell system that enhances fuel cell lifetime by controlling hydrogen partial pressure in the cell membrane. The system calculates the optimal target hydrogen partial pressure based on the catalyst location in the membrane. A controller adjusts the gas supply to achieve the target. This reduces chemical degradation of the membrane. The catalyst suppresses hydrogen peroxide formation when hydrogen is over-rich. By limiting hydrogen partial pressure, the catalyst location maximizes the suppression effect.

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Fuel cell hydrogen supply system that estimates fuel cell deterioration and adjusts hydrogen supply to compensate. The system estimates fuel cell stack deterioration based on changes in pressure when opening/closing a hydrogen supply valve. It uses this estimated deterioration level to estimate the hydrogen concentration. This allows precise control of hydrogen supply to compensate for fuel cell degradation. The system avoids additional sensors by inferring stack degradation from pressure changes during valve operation. This enables accurate control of hydrogen supply to the anode side of the fuel cell as the stack degrades.

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Fuel cell stack with short-circuiting mechanism to prevent degradation during start-up and shut-down without damaging individual cells. The fuel cells in the stack have a printed short-circuit element on the backside of the bipolar plate facing away from the gas diffusion layer. This allows the cells to be short-circuited by contact between the elements when stacked. The stack also has a pressurized compartment between the cells that can be filled with gas or liquid to pressurize the cells during short-circuiting. This prevents potential differences between cells and reduces degradation during start-up and shut-down.

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An electrode for a polymer electrolyte membrane fuel cell that contains an antioxidant to improve the durability of the fuel cell. The antioxidant is cerium hydrogen phosphate dispersed as nanofibers. Adding this antioxidant to the catalyst layer of the fuel cell electrode helps protect the membrane from chemical degradation during operation. The antioxidant scavenges radicals that can attack and degrade the electrolyte membrane, thereby minimizing performance loss over time.

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A fuel cell membrane electrode design with improved durability against high potential corrosion and reverse poling. The fuel cell membrane electrode has a thermistor incorporated to monitor voltage and prevent damage. The electrode structure is a proton exchange membrane with catalyst layers on each side, diffusion layers, and an external thermistor. The thermistor allows real-time voltage monitoring during fuel cell operation. This enables early detection of high potential or reverse poling conditions to prevent catalyst layer damage.

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A system and method for purging condensate water and hydrogen from a fuel cell stack in a way that improves operation stability and efficiency by accurately and adaptively managing the purging process. The system includes a purge valve that selectively directs the purged water/hydrogen to either the atmosphere or back into the fuel cell humidifier based on stack pressure and conditions.

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Fuel cell stack design with integrated online monitoring to improve stack performance and reliability. The design involves adding a dummy cell with sensors at the stack ends to measure the working state of the first and last cells. This provides real-time monitoring of stack imbalances and allows optimizing operating conditions to mitigate issues like low voltage startup and condensation. The integrated monitoring enables controlling stack input/output based on cell-by-cell data instead of just stack totals.

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