Pre-oxidized Metallic Interconnects for Electrolytic Cell Stacks
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Solution Overview
Problem
Metallic interconnects in electrolytic cell stacks, particularly those made through powder metallurgy, suffer from dimensional distortions due to oxidation at high temperatures, which can lead to cell integrity issues during initial operation.
Innovation Solution
The interconnects are pre-oxidized in a high-temperature oxidizing ambient before being integrated into the stack, allowing oxide formation and reducing subsequent geometric distortions and stress on the cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metallic interconnects are made through powder metallurgy techniques, then manufacturing cost and ease of manufacture are improved, but dimensional stability and manufacturing precision deteriorate due to oxidation at high temperatures
Solution Approach 1:
The interconnect is pre-oxidized in a controlled manner before final assembly into the fuel cell stack. This preliminary oxidation action creates a stable oxide layer and establishes the final dimensions of the interconnect before it is installed, preventing subsequent dimensional changes that would occur if oxidation happened after assembly.
Solution Approach 2:
The patent applies a counter-action to the harmful oxidation effect by deliberately oxidizing the interconnect in a controlled environment before assembly. This preliminary anti-action prevents the uncontrolled oxidation that would otherwise occur after assembly, which would cause dimensional instability and damage to the cell stack.
2Reliability
If metallic interconnects are exposed to high temperature oxidizing ambient, then electrical conductivity and chemical stability are improved, but dimensional stability deteriorates due to oxidation-induced distortion
Solution Approach 1:
The interconnect undergoes preliminary oxidation at elevated temperature before assembly, allowing it to achieve its final stable dimensions and chemical composition. This preliminary action ensures that when the interconnect is later exposed to high temperature oxidizing conditions during fuel cell operation, no further significant dimensional changes occur.
Solution Approach 2:
The patent changes the oxidation state parameter of the interconnect material through controlled pre-oxidation. By adjusting oxidation temperature, time, and atmosphere during manufacturing, the interconnect achieves optimal dimensional stability and chemical stability for subsequent high-temperature operation without further distortion.
3Manufacturing precision
If pre-oxidation is performed on metallic interconnects, then dimensional stability in final assembly is improved, but additional manufacturing steps and process time are required
Solution Approach 1:
The pre-oxidation step is integrated into the interconnect manufacturing process itself, combining the oxidation treatment with the sintering or heat treatment operations already required for powder metallurgy fabrication. This merging of operations adds minimal complexity while achieving the dimensional stability benefit.
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 method significantly reduces dimensional changes and stress on the cells during subsequent heat-ups, preventing damage and ensuring the integrity of the electrolytic cell stack.
Implementation Method 1
oxidizing the metal interconnect prior to providing the oxidized metal interconnect into the electrolytic cell stack
Implementation Method 2
A major portion of these distortions is attributed to oxidation of the metal. It is believed that the extent of the distortion or dimensional instability is a direct function of the density of the part that has been pressed and sintered.
Data Source
AI summary
A method of making a metal interconnect for an electrolytic cell stack includes oxidizing the metal interconnect prior to providing the oxidized metal interconnect into the electrolytic cell stack. A pre-oxidized metal interconnect for an electrolytic cell stack would not substantially further oxidize upon exposure to a subsequent oxidizing ambient at a temperature of at least 900° C. prior to or after being provided into the electrolytic cell stack.