SOFC Interconnector Bilayer Structure for Oxidation Resistance

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Solution Overview

Problem

Solid oxide fuel cells (SOFCs) face challenges in oxidation resistance due to thermal stress, leading to potential damage from oxidizing gas ingress during emergency stops, where fuel gas supply is interrupted, causing cracks and reduced performance.

Innovation Solution

A fuel cell stack configuration incorporating a porous ceramic film covering the interconnector film between adjacent fuel cells, which mitigates thermal stress and prevents oxidizing gas penetration, enhancing oxidation resistance by forming a bilayer structure with the interconnector film and electrolyte.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a thin solid electrolyte is used to improve performance, then power generation efficiency is improved, but film strength decreases and cracks are more likely to occur due to thermal stress

Engineering Contradiction:

Improvepower generation efficiencyVSAvoidfilm strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies a porous ceramic film specifically in the intermediate region between fuel side electrodes, creating a localized protective structure where thermal stress concentrates. This allows the electrolyte to remain thin for high efficiency while the porous ceramic film provides localized stress relief and crack prevention in the most vulnerable area.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by combining the dense electrolyte film with a porous ceramic film. The porous ceramic film has different mechanical and thermal properties that complement the electrolyte, providing stress relief and crack resistance while maintaining the thin-film configuration for high power generation efficiency.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the fuel gas supply is stopped during abnormality or failure, then safety is improved, but oxidizing gas enters the fuel side electrode causing oxidation and damage in a short time

Engineering Contradiction:

ImprovesafetyVSAvoidoxidation resistance time

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The porous ceramic film is pre-installed in the intermediate region to provide protective cushioning before emergency situations occur. When fuel gas supply is stopped and temperature changes rapidly, this pre-positioned porous ceramic film immediately provides stress relief and prevents oxidizing gas penetration, extending the time available for safe shutdown procedures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a porous ceramic film is added to cover the interconnector film, then oxidation resistance is improved, but device complexity increases

Engineering Contradiction:

Improveoxidation resistanceVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The porous ceramic film is applied only in the intermediate region between fuel side electrodes where thermal stress and oxidizing gas penetration risks are highest. This localized application provides maximum protection with minimum added complexity, avoiding the need to modify the entire fuel cell structure.

Inventive Principle:

Principle #3Local quality

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 solution effectively improves the oxidation resistance and durability of SOFCs, reducing the frequency of repairs and extending operation time by suppressing damage from oxidizing gas ingress during emergency stops, while maintaining power generation performance.

Implementation Method 1

cracks are more likely to occur due to thermal stress generated by temperature changes

Methodology Applied

Scientific EffectThermal stress: Thermal Expansion

Implementation Method 2

the porous ceramic film covering at least the interconnector film in a region between a first fuel side electrode of one single fuel cell of adjacent single fuel cells and a second fuel side electrode of the other single fuel cell

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS11824244B2Fuel cell stack, fuel cell module, power generation system, and method of producing fuel cell stack

Publication Date: 2023.11.21 MITSUBISHI HEAVY IND LTD

AI summary

A fuel cell stack includes: a substrate; a first fuel cell including a fuel side electrode, an electrolyte, and an oxygen side electrode on the substrate, the first fuel cell being a single fuel cell; a second fuel cell including a fuel side electrode, an electrolyte, and an oxygen side electrode on the substrate, the second fuel cell being a single fuel cell; an interconnector film electrically connecting the fuel side electrode of the first fuel cell and the oxygen side electrode of the second fuel cell; and a porous ceramic film covering at least the interconnector film in a region between the fuel side electrode of the first fuel cell and the fuel side electrode of the second fuel cell.