Metal-Supported SOFC Coating and Preoxidation for Cr Control
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Solution Overview
Problem
Metal-supported solid oxide fuel cells (MS-SOFCs) face challenges in achieving high power density and longevity due to rapid oxidation of the metal support, accelerated Cr poisoning of the cathode catalyst, and rapid catalyst coarsening, which are exacerbated by operating temperatures above 800°C, limiting their performance and durability for vehicular applications.
Innovation Solution
Implementing preoxidation of the metal support, atomic layer deposition (ALD) protective coatings, and in situ catalyst pre-coarsening during the fabrication process to reduce chromium evaporation and enhance catalyst stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If operating temperature is increased above 800°C, then power density is improved, but metal support oxidation rate increases rapidly
Solution Approach 1:
A chromium oxide layer is formed on the metal support surface to act as a protective intermediary barrier. This oxide layer prevents direct oxidation of the metal support while allowing the cell to operate at high temperatures for improved power density
Solution Approach 2:
The metal support is pre-oxidized during fabrication to form a protective chromium oxide layer before the cell begins operation. This preliminary oxidation prevents rapid oxidation during high-temperature operation, enabling sustained power density
2Power
If operating temperature is increased above 800°C, then power density is improved, but Cr poisoning of cathode catalyst is accelerated
Solution Approach 1:
The chromium oxide layer on the metal support acts as an intermediary that controls chromium release. It reduces chromium evaporation and migration to the cathode catalyst, preventing Cr poisoning while maintaining high operating temperatures for power density
3Power
If operating temperature is increased above 800°C, then power density is improved, but catalyst coarsening rate increases rapidly
Solution Approach 1:
The catalyst is pre-coarsened during fabrication to achieve a stable microstructure before operation. This preliminary coarsening reduces the driving force for further coarsening during high-temperature operation, maintaining catalyst performance and power density
4Reliability
If lower operating temperature is used, then catalyst stability is improved, but power density is constrained
Solution Approach 1:
The operating temperature is optimized to 650-700°C, changing the temperature parameter to achieve a balance between catalyst stability and power density. This parameter optimization allows the cell to maintain both reliability and performance
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
Combining these methods results in a two-order-of-magnitude decrease in degradation rate while preserving high performance, making MS-SOFCs suitable for vehicular applications with improved durability and power density.
Implementation Method 1
oxidizing the metal support of the device
Implementation Method 2
atomic layer deposition (ALD) protective coatings
Data Source
AI summary
This disclosure provides systems, methods, and apparatus related to metal-supported solid oxide electrochemical devices. In one aspect, a stainless steel support of a device is oxidized. A coating is deposited on an oxygen-electrode side of the stainless steel support of the device. The coating is operable to reduce chromium evaporation from the stainless steel support. A structure including an oxygen catalyst on the oxygen-electrode side of the device and a fuel catalyst on a fuel-electrode side of the stainless steel support of the device, with an electrolyte disposed between the oxygen catalyst and the fuel catalyst, is formed. The device is thermally treated at a temperature of about 10° C. to 400° C. above an operating temperature of about 600° C. to 800° C. of the device, the oxygen-electrode side of the device being in an oxidizing atmosphere and the fuel-electrode side of the device being in a reducing atmosphere.