Fuel Cell Terminal Layer Design for Leakage Prevention
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Solution Overview
Problem
Solid oxide fuel cell devices face issues with fuel gas leakage due to oxygen penetration through dense materials, leading to silver material degradation and thermal stress, which reduces durability and performance.
Innovation Solution
A novel fuel cell unit design featuring a thin-film silver terminal layer with low pore-forming effects, combined with a stainless steel cap containing aluminum and an insulating film, eliminates the need for conductive caps and reduces Cr contamination, enhancing durability and electrical current extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dense material (glass) is used to form an air-tight seal between the cap and fuel cell, then fuel gas leakage is prevented, but oxygen penetrates through the dense material and reacts with hydrogen in the silver material, causing pore formation and expansion
Solution Approach 1:
A peeling prevention layer is introduced as an intermediary between the solid electrolyte layer and the terminal layer. This layer acts as a barrier that prevents oxygen from penetrating through the solid electrolyte layer to reach the silver-containing terminal layer, thereby eliminating the harmful reaction that causes pore formation while maintaining the air-tight sealing function of the glass seal.
Solution Approach 2:
The peeling prevention layer is designed to inherently prevent the harmful reaction between oxygen and hydrogen in the silver material. By positioning this layer between the oxygen source (outside environment) and the silver material, the system uses the layer's own presence to block oxygen penetration, making the structure self-protecting against the harmful effect.
2Reliability
If silver material is used for conductive connection between fuel cell and cap, then electrical conductivity is improved, but oxygen and hydrogen react within the silver material to form water vapor, causing expansion and seal failure
Solution Approach 1:
The peeling prevention layer serves as a protective intermediary that shields the silver-containing terminal layer from oxygen exposure. This allows the silver material to maintain its excellent electrical conductivity function while preventing the harmful internal reaction that would otherwise cause expansion and seal failure.
Solution Approach 2:
The peeling prevention layer is positioned beforehand to cushion or protect the silver material from oxygen exposure. By having this protective layer in place before any potential reaction can occur, the system prevents the harmful effects of oxygen-hydrogen reactions within the silver material, thereby maintaining both conductivity and seal integrity.
3Productivity
If continuous operation of fuel cell device is maintained, then electricity generation is sustained, but expansion of silver material due to continuous water vapor formation eventually breaks the air-tight seal
Solution Approach 1:
The peeling prevention layer acts as a permanent intermediary barrier that prevents oxygen from reaching the silver material throughout continuous operation. This eliminates the progressive pore formation and expansion that would otherwise occur over time, thereby maintaining seal durability even during sustained electricity generation.
Solution Approach 2:
By having the peeling prevention layer in place beforehand, the system cushions against the cumulative effects of continuous operation. The layer prevents oxygen penetration from the start, so even during prolonged operation, the silver material remains protected and does not undergo progressive expansion that would break the seal.
4Power
If conventional cap structure with silver material is used, then electrical current extraction is achieved, but thermal stress and Cr contamination reduce durability
Solution Approach 1:
The fuel cell unit employs a composite structure consisting of multiple layers including the solid electrolyte layer, the peeling prevention layer, and the terminal layer containing silver. This composite structure combines the electrical conductivity of silver with the protective properties of the peeling prevention layer, achieving both effective current extraction and enhanced durability by preventing thermal stress and contamination.
Solution Approach 2:
The peeling prevention layer serves as an intermediary that protects the silver-containing terminal layer from environmental exposure. This layer prevents Cr contamination and reduces thermal stress on the silver material, thereby maintaining the electrical current extraction function while significantly improving the overall durability of the fuel cell unit.
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 significantly reduces fuel gas leakage, prevents silver material degradation, and increases the durability of the fuel cell unit by minimizing pore formation and thermal stress, while also inhibiting Cr contamination and improving electrical current extraction efficiency.
Implementation Method 1
a solid oxide fuel cell (SOFC) device is an electricity-generating device that employs an oxide ion conducting solid electrolyte layer that serves as an electrolyte
Implementation Method 2
generate electricity by reforming a starting material gas to obtain a fuel gas
Implementation Method 3
reacting the fuel gas with an oxidant gas, as well as to a fuel cell array that uses the fuel cell units
Implementation Method 4
an air-tight seal is formed using a dense material (glass) in addition to a silver seal
Data Source
AI summary
A fuel cell array comprises a plurality of serially connected fuel cell units. A respective fuel cell unit comprises a fuel cell and a cap capped on each end of the fuel cell. The fuel cell unit further comprises an electrically conductive terminal layer forming an outermost laminate of the fuel cell at one end of the fuel cell. The terminal layer is directly laminated on a fuel electrode layer and directly laminated on a solid electrolyte layer. The fuel cell unit further comprises a glass material forming a sealing layer circumferentially around the fuel cell to fill between the inner surface of the cap and the outer surface of the fuel cell. The plurality of fuel cell units are electrically connected in series through the electrically conductive terminal layer, not through the cap.