Solid Oxide Electrochemical Device Sealing via Intermediate Thermal Processing
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Solution Overview
Problem
Solid oxide electrochemical device stacks face challenges due to thermal and chemical expansion mismatch between ceramic and metal components, leading to stress and potential seal failure, making it difficult to assemble and maintain efficient power generation without defects.
Innovation Solution
A method involving the application of a bonding agent and sealing agent between electrodes and interconnects, with intermediate heating to bond and seal the components, allowing for presealing of anode layers before final assembly, enabling disassembly for testing and reducing stress from volume reduction and thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic and metal components are sealed together to form solid oxide electrochemical device stacks, then the devices can operate at high temperatures for efficient power generation, but thermal and chemical expansion mismatch causes stress and potential seal failure
Solution Approach 1:
The patent applies parameter changes by modifying the chemical state of the anode material from nickel oxide (non-conductive) to nickel (conductive) through controlled reduction at elevated temperatures. This chemical transformation alters the physical and electrical properties of the anode, enabling it to become electrically conductive while managing volumetric changes to maintain seal integrity during high-temperature operation
Solution Approach 2:
The patent implements preliminary action by performing the chemical reduction of nickel oxide to nickel before final device assembly and sealing. This preliminary reduction step allows the anode to achieve its final volumetric state and electrical conductivity before being sealed to interconnects, preventing stress-induced seal failure that would occur if reduction happened after sealing
2Reliability
If nickel oxide in the anode is reduced to nickel at high temperature, then electrical conductivity is achieved, but physical volume reduction places additional stress on seals and can cause seal failure
Solution Approach 1:
The chemical reduction of nickel oxide to nickel is performed as a preliminary action before final sealing operations. This timing allows the anode to complete its volumetric contraction and achieve electrical conductivity while still mechanically free, preventing stress concentration on seals that would occur if reduction happened after the device was sealed
Solution Approach 2:
The patent employs beforehand cushioning by designing the sealing system to accommodate the expected volumetric reduction of the anode during reduction. The seal geometry and material selection are optimized in advance to absorb the dimensional changes without failing, providing a buffer against the stress induced by anode shrinkage
3Productivity
If multiple solid oxide electrochemical assemblies are sealed together in a single process to form an integral stack, then manufacturing efficiency is improved, but any defect in one seal renders the entire stack unusable
Solution Approach 1:
The patent applies segmentation by dividing the sealing process into separate stages: first sealing individual electrochemical assemblies to interconnects, then assembling sealed units into stacks. This modular approach allows defective assemblies to be identified and replaced without compromising the entire stack, improving reliability while maintaining manufacturing efficiency through standardized sub-assembly processes
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 enhances the reliability and productivity of solid oxide electrochemical device stacks by allowing for non-destructive testing and replacement of defective units, reducing stress and improving the sealing process, thereby maintaining efficient power generation and extending the lifespan of the devices.
Implementation Method 1
heating the first interconnect, the first electrode, the electrolyte, the second electrode, the second interconnect, the bonding agent, and the sealing agent to at least one intermediate temperature for at least one intermediate length of time, and then to a curing temperature, for a curing time, effective to bond and seal the first electrode to the first interconnect
Implementation Method 2
During thermal cycles, various components of the solid oxide electrochemical device stack expand and/or contract in different ways due to the difference in the coefficient of thermal expansion of the materials of construction
Implementation Method 3
heating to at least one intermediate temperature for at least one intermediate length of time, and then to a curing temperature, effective to bond and seal... reducing stress from volume reduction and thermal expansion differences
Data Source
AI summary
A method for manufacturing a solid oxide electrochemical device comprising disposing electrolyte between a first electrode and a second electrode, applying a bonding agent between the first electrode and a first interconnect, applying a sealing agent between the first electrode and the first interconnect, disposing a second interconnect adjacent to the second electrode, heating the first interconnect, the first electrode, the electrolyte, the second electrode, the second interconnect, the bonding agent, and the sealing agent to at least one intermediate temperature for at least one intermediate length of time, and then to a curing temperature, for a curing time, effective to bond and seal the first electrode to the first interconnect, wherein the at least one intermediate temperature is less than the curing temperature.