Rare-Earth Praseodymium Oxide Electrode for Buffer-Layer-Free SOFCs
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Solution Overview
Problem
There is a need for electrode materials with suitable properties for use in electrochemical cells, particularly in solid oxide fuel cells (SOFCs) and solid oxide electrolyser cells (SOECs).
Innovation Solution
The development of an electrode for electrochemical cells comprising a first layer with a first electrode material of the formula Pr(1-x)LnxO(2-0.5x-δ), where Ln is a rare earth metal, δ is the degree of oxygen deficiency, and 0.01≤x≤0.4. This material is designed to optimize oxygen vacancy concentration and ion mobility, enhancing the electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ceramic-supported SOFCs are used, then the electrochemical function is achieved, but the mechanical strength is low and they are vulnerable to fracture
Solution Approach 1:
A buffer layer comprising gadolinium-doped ceria (CGO) is introduced as an intermediary between the air electrode and the zirconia layer. This buffer layer acts as a mediator that prevents direct contact and potential harmful reactions between the air electrode materials and zirconia, while also providing mechanical support and improving the overall reliability of the cell structure.
Solution Approach 2:
The invention uses composite material structures including the CGO buffer layer combined with zirconia and air electrode materials. This composite approach creates a multi-layered system where each material contributes its specific properties: CGO provides ionic conductivity and chemical stability, zirconia provides structural support, and the air electrode provides electrochemical activity, collectively enhancing mechanical strength and fracture resistance.
2Object-affected harmful factors
If a buffer layer is added between the air electrode and zirconia layer, then protection against harmful reactions is achieved, but the device complexity increases
Solution Approach 1:
The invention optimizes the composition parameters of the buffer layer, specifically using gadolinium-doped ceria with controlled doping levels. By adjusting the chemical composition and stoichiometry of the CGO layer, the material achieves optimal protection against harmful reactions while maintaining compatibility with adjacent layers, thus reducing the need for additional protective layers.
Solution Approach 2:
The buffer layer is strategically positioned only where needed - between the air electrode and zirconia layer at specific interfaces where harmful reactions are most likely to occur. This localized approach provides protection at critical interfaces without unnecessarily complicating the entire cell structure, maintaining simplicity in regions where protection is not required.
3Reliability
If multiple layers are used in the electrode structure, then electrochemical performance is optimized, but the manufacturing process becomes more complex
Solution Approach 1:
The invention combines multiple functional layers into an integrated multi-layered air electrode structure where the CGO buffer layer, zirconia layer, and air electrode materials are deposited together in a coordinated manner. This merging of functions into a single integrated component simplifies the overall manufacturing process compared to assembling separate components, while maintaining the electrochemical performance benefits of the multi-layer structure.
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 proposed electrode material demonstrates improved electrochemical activity, stability, and reduced susceptibility to contamination, leading to enhanced performance in SOFCs and SOECs. It also eliminates the need for a buffer layer between the air electrode and the zirconia layer, simplifying manufacturing and reducing costs.
Implementation Method 1
the electrolyte of the SOFC conducts oxygen ions from a cathode to an anode located on opposite sides of the electrolyte
Implementation Method 2
SOFC fuel cell units produce electricity using an electrochemical conversion process that oxidises fuel
Implementation Method 3
SOC fuel cell units can also, or instead, operate as regenerative fuel cells (or reverse fuel cells) units, often known as solid oxide electrolyser fuel cell units, for example to separate hydrogen and oxygen from water, or carbon monoxide and oxygen from carbon dioxide
Data Source
AI summary
An electrode for an electrochemical cell is disclosed which has a first layer containing a first electrode material of formula Pr(1-x)LnxO(2-0.5x-δ). Ln is selected from at least one rare earth metal, 8 is the degree of oxygen deficiency, and 0.01≤x≤0.4. The rare earth metal may be a lanthanide, scandium or yttrium. Also disclosed is an electrochemical cell having such an electrode and methods of making such an electrochemical cell. The electrochemical cell may be an electrolytic cell, an oxygen separator, a sensor or a fuel cell. Also disclosed are materials of formula Pr(1-x)LnxO(2-0.5x-δ) and Pr(1-x)SmxO(2-0.5x-δ).