Conductive Bonding Agents for SOFC Electrode Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current solid oxide fuel cell (SOFC) stack designs face challenges with mechanical integrity and electrical contact due to excessive compressive forces, thermal expansion differences, and inadequate bonding strength between electrodes and interconnects, leading to potential delamination and reduced electrochemical performance.
Innovation Solution
A method using conductive bonding agents, such as anode and cathode bonding agents comprising metal and ceramic powders, applied as pastes or tapes, which form a permanent, thermally stable, and electrically conductive bond between electrodes and interconnects without requiring excessive mechanical compression, utilizing primary and secondary phases to enhance adhesion and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical compression is used to ensure good electrical contact between electrodes and interconnects, then electrical conductivity is improved, but the mechanical integrity deteriorates due to excessive compressive forces on brittle ceramic components
Solution Approach 1:
The patent replaces the mechanical compression system with a chemical bonding system. Conductive bonding agents are applied to the interfaces between electrodes and interconnects, and upon heating, these agents form strong chemical bonds that provide both mechanical strength and electrical conductivity without requiring excessive compressive forces on the brittle ceramic components.
Solution Approach 2:
The patent uses composite bonding agents that combine conductive materials (such as metal powders or conductive ceramics) with bonding materials. This composite approach allows the bonding agent to simultaneously provide mechanical adhesion strength and electrical conductivity, resolving the contradiction between mechanical integrity and electrical contact.
2Reliability
If bulky compression mechanisms are used to maintain mechanical integrity and electrical contact, then reliability is improved, but device complexity and weight increase
Solution Approach 1:
The patent eliminates the need for bulky mechanical compression mechanisms by substituting them with chemical bonding agents. The bonding agents create permanent bonds between components that maintain both mechanical integrity and electrical contact without requiring external compression devices, thereby reducing device complexity and weight.
3Ease of manufacture
If conventional bonding materials are used at elevated temperatures, then manufacturing is simplified, but the bonding strength deteriorates due to creep and loss of strength in tie rod and bellows materials
Solution Approach 1:
The patent selects bonding agents with specific material properties that remain stable at elevated operating temperatures. The bonding agents are chosen or formulated to have low creep resistance and maintained strength at high temperatures, unlike conventional tie rod and bellows materials. This parameter selection ensures both ease of manufacture and sustained bond strength under operating conditions.
Solution Approach 2:
The patent employs composite bonding materials that combine materials with complementary properties: some components facilitate bonding during manufacturing while others maintain strength and resist creep at elevated operating temperatures. This composite approach allows the bonding material to perform both manufacturing and long-term operational functions effectively.
4Ease of manufacture
If direct mechanical compression is used to assemble stacks, then manufacturing is simplified, but thermal stress increases due to thermal expansion differences between stack components
Solution Approach 1:
The patent replaces mechanical compression with chemical bonding, which creates a more compliant interface that can better accommodate differential thermal expansion between stack components. The bonding agents allow for slight movements and stress distribution, reducing the buildup of thermal stresses while maintaining assembly simplicity.
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 method provides improved mechanical strength, electrical conductivity, and reduced thermal stress, maintaining stack integrity and performance without the need for excessive compression, while minimizing dimensional changes and contact resistance.
Implementation Method 1
form a permanent, thermally stable, and electrically conductive bond between electrodes and interconnects
Implementation Method 2
provide good electrical contact between the electrodes and interconnect components
Data Source
AI summary
A method and related bonding compositions for use in assembling a solid oxide fuel cell (“SOFC”) stack having thermally and chemically stable and electrically conductive bonds between alternating fuel cells and interconnect components in the stack. The improved method and materials allow for the assembly of solid oxide fuel cells having a stronger and more reliable bond with good electrical contact in situ between the SOFC interconnect layers (plates) and the electrodes. The bonding materials and method according to the invention provide good electrical performance while maintaining the mechanical and electrical integrity of SOFC stacks without requiring excessive mechanical compression of the stack as exemplified by prior art systems. The preferred bonding agents comprise a primary phase that provides the electrical conduction path during fuel cell operation, as well as the mechanical strength necessary to insure a reliable connection between the interconnect and the relevant anode or cathode surfaces of the fuel cell. Secondary phases can be added in small amounts to the primary phase to improve adhesion. An exemplary method according to the invention also contemplates various different steps for pre-treating the surfaces of the interconnect plates and electrodes to improve their surface bonding properties.