Fuel Cell Anode Catalyst Layer With Oxygen-Dependent Resistance
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Solution Overview
Problem
Fuel cells experience deterioration in power generation performance due to catalyst degradation caused by oxygen reduction reactions when air is present in the fuel gas channel, leading to increased size and cost in existing solutions that use inert gases for purging.
Innovation Solution
A fuel cell system with an anode catalyst layer that has a resistance-changing property, where the electrical resistance is higher under an oxygen atmosphere than under a hydrogen atmosphere, using an ion-conductive binder and electrically conductive ceramic materials like tantalum-doped titanium oxide to suppress oxygen reduction reactions without the need for inert gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inert gas is used to purge air from the fuel gas channel before re-starting the fuel cell, then catalyst degradation is prevented, but the size and cost of the apparatus increase due to additional tanks and control devices
Solution Approach 1:
The patent extracts the harmful oxygen reduction reaction capability from the anode catalyst layer by selectively removing or deactivating the oxygen reduction catalyst. This allows the anode to maintain hydrogen oxidation capability while preventing catalyst degradation during air presence, eliminating the need for inert gas purging systems.
Solution Approach 2:
The patent applies different functional properties to different parts of the anode catalyst layer. Specifically, it creates regions with suppressed oxygen reduction capability while maintaining hydrogen oxidation capability, allowing selective catalytic activity based on local requirements.
2Device complexity
If the oxygen reduction capability of the anode catalyst layer is lowered to prevent catalyst degradation, then inert gas purging is unnecessary, but power generation performance deteriorates
Solution Approach 1:
The patent creates spatial differentiation within the anode catalyst layer, with some regions having suppressed oxygen reduction capability and other regions maintaining both hydrogen oxidation and oxygen reduction capabilities. This ensures power generation performance is maintained in the active regions while preventing degradation in the protected regions.
Solution Approach 2:
The anode catalyst layer is segmented into functionally distinct regions: one type of catalyst particle or region suppresses oxygen reduction to prevent degradation, while another type maintains oxygen reduction capability for power generation. This segmentation allows simultaneous achievement of durability and performance.
3Reliability
If anti-corrosion treatment is applied to the anode catalyst layer to prevent oxygen reduction reactions, then catalyst degradation is suppressed, but hydrogen oxidation capability is reduced
Solution Approach 1:
The patent applies different catalytic properties to different parts of the anode catalyst layer. Some catalyst particles are treated to suppress oxygen reduction while maintaining hydrogen oxidation, whereas other particles maintain full catalytic activity for power generation, thus balancing stability and efficiency.
Solution Approach 2:
The anode catalyst layer uses a composite structure containing different types of catalyst particles with distinct functions. One component suppresses oxygen reduction for protection, while another component maintains hydrogen oxidation and oxygen reduction for power generation, creating a functionally composite catalytic system.
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
This configuration effectively prevents catalyst degradation, maintains hydrogen oxidation capability, and improves power generation efficiency while reducing the size and cost of the fuel cell system by eliminating the need for inert gas purging.
Implementation Method 1
an anode catalyst layer having a resistance-changing property, that is, a property that the electrical resistance of the anode catalyst layer when the anode catalyst layer is under an oxygen atmosphere is higher than the electrical resistance of the anode catalyst layer when the anode catalyst layer is under a hydrogen atmosphere
Implementation Method 2
using an ion-conductive binder and electrically conductive ceramic materials like tantalum-doped titanium oxide
Implementation Method 3
effectively prevents catalyst degradation, maintains hydrogen oxidation capability
Data Source
Figure 1
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Figure 3A~3C
AI summary
A cell (11) includes: a membrane electrode assembly (12); and a pair of separators (13, 14), between which the membrane electrode assembly is interposed. The membrane electrode assembly includes a polymer electrolyte membrane, an anode catalyst layer disposed on a first main surface of the polymer electrolyte membrane, and a cathode catalyst layer disposed on a second main surface of the polymer electrolyte membrane. The anode catalyst layer contains a first catalyst material having an activity against a hydrogen oxidation reaction and a first electrically conductive material whose electrical resistance under a hydrogen atmosphere and whose electrical resistance under an oxygen atmosphere are different from each other. The cathode catalyst layer contains a second catalyst material having an activity against an oxygen reduction reaction and a second electrically conductive material different from the first electrically conductive material. An electrical resistance of the cell when the anode catalyst layer is under an oxygen atmosphere is more than twice the electrical resistance of the cell when the anode catalyst layer is under a hydrogen atmosphere.