Perovskite Oxide Cathode Sr Concentration Gradient
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Solution Overview
Problem
Fuel cell output is reduced due to cathode deterioration, primarily caused by excessive Sr on the cathode surface exceeding the stoichiometric ratio, leading to SrO and SrSO4 formation.
Innovation Solution
A fuel cell design with a cathode containing perovskite oxide (ABO3) where the Sr concentration on the surface is controlled to be less than or equal to four times the La concentration, as measured by X-ray photoelectron spectroscopy, to inhibit Sr concentration and subsequent deterioration, using a barrier layer and surface processing to maintain optimal ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If perovskite oxide cathode is used with Sr at A site, then fuel cell performance is improved, but cathode deterioration occurs due to excessive Sr concentration on surface
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of Sr within the perovskite oxide structure. The Sr concentration is controlled to be higher in the bulk material to maintain high fuel cell output, while the surface Sr concentration is limited to ≤4 times the La concentration to prevent deterioration. This spatial variation in composition allows the cathode to simultaneously achieve high performance and long-term stability.
2Power
If Sr concentration on cathode surface increases, then fuel cell output increases, but SrO and SrSO4 formation occurs leading to output reduction
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Sr concentration parameter within the perovskite oxide. By limiting the surface Sr concentration to ≤4 times the La concentration while maintaining adequate bulk Sr content, the patent optimizes the electrochemical performance while preventing the formation of harmful SrO and SrSO4 compounds that would otherwise form at higher Sr concentrations.
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 approach prevents the reduction in fuel cell output by suppressing SrO and SrSO4 formation, reducing cathode deterioration and maintaining performance.
Implementation Method 1
A first ratio of a Sr concentration relative to an La concentration is detected by use of X-ray photoelectron spectroscopy on the surface of the cathode. The second ratio of a Sr concentration relative to a La concentration is detected by use of X-ray photoelectron spectroscopy on an exposed surface.
Data Source
AI summary
A fuel cell cathode contains a perovskite oxide as a main component. The perovskite oxide is expressed by the general formula ABO3 and including La and Sr at the A site. A solid electrolyte layer is disposed between an anode and the cathode. The cathode has a surface on an opposite side to the solid electrolyte layer. A first ratio of a Sr concentration relative to an La concentration is less than or equal to 4 times a second ratio of the Sr concentration relative to the La concentration. The first ratio is detected by the use of X-ray photoelectron spectroscopy on the surface of the cathode. The second ratio of a Sr concentration relative to a La concentration is detected by the use of X-ray photoelectron spectroscopy on an exposed surface exposed by surface processing of the surface and positioned within 5 nm of the surface in relation to a direction of thickness.