SOEC Interconnector Coating Structure for Chromium and Thermal Stress
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Solution Overview
Problem
The performance of solid oxide electrochemical cell stacks deteriorates due to chromium element adherence from high Cr steel interconnectors, leading to issues like cracking and spalling of oxide layers, which are exacerbated by thermal expansion differences and limited coating methods for protective films.
Innovation Solution
An interconnector design featuring an iron-base alloy metal base with a spinel or perovskite oxide protective film and an interlayer to relieve stress, where the interlayer has a higher self-diffusion coefficient than the metal base to prevent cracking and spalling, and the protective film is composed of materials like Co, Ni, Mn, or Cu to enhance conductivity and thermal expansion matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high Cr steel is used for interconnectors to achieve heat resistance, then heat resistance is improved, but chromium element adherence to electrodes occurs causing performance deterioration
Solution Approach 1:
A protective film comprising spinel oxide or perovskite oxide is formed on the surface of the high Cr steel interconnector. This protective film acts as an intermediary layer that prevents chromium elements from evaporating and adhering to the electrodes, while allowing the high Cr steel substrate to maintain its heat resistance functionality.
Solution Approach 2:
The interconnector is designed as a composite structure combining high Cr steel substrate with a protective film of spinel oxide or perovskite oxide. This composite material approach allows the system to simultaneously achieve the heat resistance of high Cr steel and the chromium-scattering prevention properties of the oxide protective film.
2Reliability
If perovskite oxide is used for protective film to achieve high electric conductivity, then electric conductivity is improved, but thermal expansion difference causes oxide layers to break away
Solution Approach 1:
The patent specifies precise compositional parameters for the protective film, controlling the ratios of metal elements (such as Co, Ni, Mn, Cu) and oxide content to adjust the thermal expansion coefficient of the protective film to match that of the high Cr steel substrate, thereby preventing delamination while maintaining high electric conductivity.
3Stability of the object's composition
If spinel oxide composition is adjusted to decrease thermal expansion difference and improve adhesiveness, then adhesion is improved, but composition variations occur within interconnectors and between batches
Solution Approach 1:
The patent establishes specific compositional ranges and ratios for metal elements (Co, Ni, Mn, Cu) and oxides in the protective film formulation. By controlling these parameters within defined ranges, the thermal expansion coefficient is matched to the substrate while maintaining compositional uniformity and minimizing batch-to-batch variations.
4Reliability
If protective film is applied to inhibit Cr scatter, then chromium adherence is reduced, but coating methods are limited and application difficulty increases
Solution Approach 1:
The patent specifies precise compositional parameters including the ratios of metal elements and oxide content, which enable the protective film to be formed with controlled properties. These parameter specifications facilitate reproducible coating processes while achieving the desired chromium scattering resistance.
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 effectively inhibits chromium vaporization, improves adhesion, and reduces thermal stress-induced cracking and spalling, enhancing the durability and reliability of the solid oxide electrochemical cell stacks by using an interlayer with higher self-diffusion coefficients and a protective film with suitable thermal expansion properties.
Implementation Method 1
an interlayer disposed between the metal base and the protective film for relieving stress
Implementation Method 2
inhibits chromium vaporization, improves adhesion, and reduces thermal stress-induced cracking and spalling
Implementation Method 3
the interlayer has a higher self-diffusion coefficient than the metal base to prevent cracking and spalling
Implementation Method 4
reduces thermal stress-induced cracking and spalling, enhancing the durability and reliability
Data Source
AI summary
An interconnector for a solid oxide electrochemical cell stack of at least one embodiment includes a metal base that contains an iron-base alloy containing chromium, a protective film provided on a surface of the metal base, and an interlayer provided between the metal base and the protective film arranged to relieve stress.