Selectively Conducting Anode for Fuel Cell Durability

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Solution Overview

Problem

Solid polymer electrolyte fuel cells face significant performance degradation due to repeated startup and shutdown cycles, especially when low catalyst loadings are used, leading to issues with durability and voltage reversal tolerance.

Innovation Solution

Incorporating a mixed layer comprising a selectively conducting material and carbon between the anode and anode gas diffusion layer, with the selectively conducting material having significantly lower electrical resistance in the presence of hydrogen than in air, and optionally using a bilayer structure with a separate selectively conducting layer, to enhance durability and voltage reversal tolerance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a selectively conducting component is incorporated in the anode to improve startup/shutdown durability, then durability is improved, but voltage reversal tolerance decreases

Engineering Contradiction:

Improvestartup/shutdown durabilityVSAvoidvoltage reversal tolerance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The anode is segmented into multiple functional layers: a first anode layer in contact with the solid polymer electrolyte, and a second anode layer (selectively conducting component) in contact with the first anode layer. This segmentation allows each layer to perform its specific function - the first layer maintains voltage reversal tolerance while the second layer provides startup/shutdown durability by preventing air-fuel transitions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The selectively conducting component is positioned locally at specific regions where it is most needed - in contact with the first anode layer rather than extending over the entire anode surface. This localized placement optimizes its function in preventing air ingress while minimizing interference with overall cell performance and voltage reversal pathways.

Inventive Principle:

Principle #3Local quality

2Reliability

If higher catalyst loadings are used to reduce performance degradation, then durability is improved, but cost increases

Engineering Contradiction:

Improveperformance durabilityVSAvoidcatalyst loading

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The selectively conducting component is extracted as a separate functional element from the traditional anode structure. By removing air ingress pathways at the anode interface, this extracted component prevents the conditions that lead to catalyst degradation, thereby protecting the catalyst and extending durability without requiring increased catalyst quantities.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If additional purge steps are added to prevent air ingress during shutdown, then durability is improved, but device complexity and shutdown time increase

Engineering Contradiction:

Improvestartup/shutdown durabilityVSAvoidshutdown procedure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The selectively conducting component is pre-installed in the anode structure before operation begins. This preliminary action creates a permanent barrier against air ingress that eliminates the need for additional purge steps during shutdown procedures. The protective function is already in place, requiring no additional operational complexity.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If a selectively conducting layer is extended over the entire anode surface, then startup/shutdown durability is improved, but voltage reversal tolerance decreases

Engineering Contradiction:

Improvestartup/shutdown durabilityVSAvoidvoltage reversal tolerance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The anode is divided into functional segments where the selectively conducting component occupies only the portion needed for preventing air ingress, rather than covering the entire surface. This segmentation allows voltage reversal currents to dissipate through remaining conductive pathways while maintaining durability benefits in the protected regions.

Inventive Principle:

Principle #1Segmentation

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 approach improves startup/shutdown durability and voltage reversal tolerance while maintaining commercially acceptable performance, as demonstrated by improved voltage retention and reduced degradation over numerous cycles.

Implementation Method 1

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

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a mixed layer comprising a selectively conducting material and carbon in between the anode and anode gas diffusion layer

Methodology Applied

Scientific EffectElectrical Conductivity: Conduction (electrical)

Data Source

PatentUS10069148B2Fuel cell with selectively conducting anode

Publication Date: 2018.09.04 FORD MOTOR CO

AI summary

Use of a selectively conducting anode component in solid polymer electrolyte fuel cells can reduce the degradation associated with repeated startup and shutdown, but can also adversely affect a cell's tolerance to voltage reversal along with its performance. It was shown that these adverse affects can be mitigated against in certain ways. However, improved results can be obtained by employing a selectively conducting component which comprises a mixed layer of a selectively conducting material and carbon. The mixed layer contacts the side of the anode opposite the solid polymer electrolyte.