SOEC Air Electrode Strontium Getter Against SrZrO3 Formation
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Solution Overview
Problem
The reaction of strontium (Sr) in the air electrode with solid oxide electrolyte materials in SOECs forms an insulating SrZrO3 phase, which is highly detrimental to the cell's performance.
Innovation Solution
Incorporation of a strontium getter material, such as titanium dioxide (TiO2), in the air-side electrode layers to trap strontium and prevent its diffusion into the electrolyte, either through co-firing or split-firing processes, thereby reducing the formation of SrZrO3.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If strontium-containing materials are used in the air-side electrode to improve electrochemical performance, then the electrochemical performance is enhanced, but strontium reacts with the solid oxide electrolyte to form insulating SrZrO3 phase which degrades cell performance
Solution Approach 1:
A strontium getter layer is introduced as an intermediary between the strontium-containing air-side electrode and the solid oxide electrolyte. This getter layer selectively captures strontium atoms, preventing them from reacting with the electrolyte to form insulating SrZrO3, while allowing the electrochemical benefits of strontium-containing electrode materials to be retained.
Solution Approach 2:
The harmful strontium atoms are extracted from the electrode structure by the strontium getter layer, which selectively removes and traps strontium before it can diffuse into the electrolyte. This extraction process maintains the electrochemical functionality of the electrode while eliminating the source of the harmful reaction.
2Ease of manufacture
If co-firing or split-firing processes are used to manufacture SOECs, then manufacturing flexibility is improved, but strontium diffusion into the electrolyte occurs during high-temperature processing, forming insulating SrZrO3 phase
Solution Approach 1:
The strontium getter layer is incorporated into the electrode structure before the high-temperature co-firing or split-firing process. This preliminary placement ensures that when strontium becomes mobile during firing, the getter layer is already in position to capture it immediately, preventing SrZrO3 formation even during extended high-temperature processing.
Solution Approach 2:
The introduction of the strontium getter layer changes the chemical environment and reaction dynamics during the firing process. By adding this new material component with specific chemical affinity for strontium, the system's behavior during high-temperature processing is fundamentally altered to favor strontium trapping over SrZrO3 formation.
3Device complexity
If strontium is allowed to react with the electrolyte, then the electrode material can be simplified, but the electrolyte's conductivity is reduced due to insulating SrZrO3 phase formation
Solution Approach 1:
The strontium getter layer serves as a protective intermediary that preserves electrolyte conductivity by preventing strontium from reaching and reacting with the electrolyte. This intermediary layer maintains the simple electrode material composition while protecting the electrolyte's electrical properties.
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
Prevents the formation of insulating SrZrO3, maintaining the electrolyte's conductivity and enhancing the operational efficiency and manufacturing throughput of SOECs.
Implementation Method 1
Incorporation of a strontium getter material, such as titanium dioxide (TiO2), in the air-side electrode layers to trap strontium and prevent its diffusion into the electrolyte
Data Source
AI summary
A solid oxide electrochemical cell includes a solid oxide electrolyte, a fuel-side electrode located on a first side of the solid oxide electrolyte, and an air-side electrode located on a second side of the solid oxide electrolyte. The air-side electrode includes a strontium getter material, a current collector layer and a functional layer located between the current collector layer and the second side of the solid oxide electrolyte.