Fuel Cell Catalyst Recovery via Predictive Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fuel cell systems face performance degradation due to oxide films on platinum catalysts, with existing refresh processing methods only effective for single-stage voltage reduction, failing to remove type-II oxide films, which can lead to inadequate catalyst layer recovery and reduced responsiveness during high-load requests.
Innovation Solution
A fuel cell system with a control apparatus that predicts output increase requests and adjusts the voltage reduction level for performance recovery processing, allowing for selective removal of type-I and type-II oxide films based on predicted timing, balancing performance recovery with minimal impact on responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output voltage of the fuel cell stack is decreased to a second reduction voltage to remove type-II oxide film, then the catalyst layer performance is sufficiently recovered, but the responsiveness to high-load requests deteriorates
Solution Approach 1:
The control apparatus performs preliminary removal of type-I oxide film by decreasing the output voltage to the first reduction voltage before the high-load request occurs. This preliminary action partially recovers catalyst performance and removes the easier-to-remove type-I oxide film, preparing the catalyst layer for subsequent type-II oxide film removal without immediately impacting responsiveness to high-load requests.
Solution Approach 2:
The oxide film removal process is segmented into two distinct stages: first removing type-I oxide film at a higher reduction voltage (0.4V to 0.6V), then removing type-II oxide film at a lower reduction voltage (0.05V to 0.4V). This segmentation allows the system to address different oxide film types at different voltage levels, balancing performance recovery with responsiveness requirements.
2Reliability
If the supply of air to the fuel cell stack is stopped to perform refresh processing, then the oxide film is removed and catalyst performance is recovered, but the productivity during the processing period is reduced
Solution Approach 1:
The fuel cell stack continues to operate and generate electricity during the refresh processing period. The control apparatus maintains continuous operation by managing the voltage reduction process without completely stopping the air supply or power generation, thereby maintaining productivity while still achieving oxide film removal and catalyst performance recovery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively maximizes catalyst layer performance recovery while minimizing the influence on responsiveness to output increase requests, ensuring adequate drivability and power generation capabilities.
Implementation Method 1
the supply of air (oxidant gas) to the fuel cell stack is stopped and the output voltage of the fuel cell stack is forcibly decreased by a DC/DC converter so that the cell voltage is lowered to a reduction voltage (e.g., 0.6 V or lower) to thereby remove an oxide film from the surface of the platinum catalyst
Data Source
AI summary
A fuel cell system according to the present invention comprises: a fuel cell including a membrane-electrode assembly in which electrodes, each having a catalyst layer, are arranged on both surfaces of a polymer electrolyte membrane; and a control apparatus that performs performance recovery processing for the catalyst layer by decreasing an output voltage of the fuel cell to a predetermined voltage, wherein the control apparatus predicts a timing of an output increase request being made to the fuel cell and determines the necessity and content of the performance recovery processing based on a result of the prediction.