Bismuth-Cobalt Functional Layer for High-Temperature Fuel Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing functional layers in high-temperature fuel cells, particularly those made from lanthanum manganite or lanthanum cobaltite, are less sinter-active at temperatures below 950°C, leading to poor electrical contact and adhesion, porosity, and inability to prevent corrosion and chromium poisoning, with previous solutions like silver-glass ceramic and cuprate compounds experiencing instability due to high vapor pressure and phase conversions.
Innovation Solution
A functional layer composed of a powder mixture containing perovskite ceramic materials with cobalt and bismuth oxide, which forms a homogeneously distributed first and second phase upon heat treatment, enabling improved sintering and electrical conductivity, and reacting with chromium species to prevent poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lanthanum manganite or lanthanum cobaltite is used for the functional layer, then the material is less sinter-active at temperatures below 950°C, but this results in poor electrical contact and adhesion, porosity, and inability to prevent corrosion
Solution Approach 1:
The patent changes the chemical composition parameters of the functional layer by incorporating specific metal oxides (Fe2O3, CuO, NiO, Co3O4, Mn3O4, ZnO, PbO, B2O3, SiO2, Al2O3) in controlled proportions. This compositional modification enables the material to achieve adequate sintering activity and electrical conductivity at lower temperatures (below 950°C) while maintaining structural integrity and preventing corrosion, thereby resolving the contradiction between temperature and reliability.
Solution Approach 2:
The patent creates a composite functional layer material by combining perovskite base material with multiple metal oxides. This composite structure synergistically improves sintering activity, electrical conductivity, and corrosion resistance at lower operating temperatures, eliminating the need for high-temperature sintering while achieving reliable electrical contact and adhesion.
2Reliability
If silver-glass ceramic material is used for the contact layer, then electrical conductivity is improved, but long-term stability is compromised due to high vapor pressure of silver at T>800°C
Solution Approach 1:
The patent replaces expensive and unstable silver-based materials with more stable, cost-effective metal oxide combinations that maintain adequate electrical conductivity without suffering from high vapor pressure at operating temperatures. The functional layer uses Fe2O3, CuO, NiO, Co3O4, Mn3O4, and other metal oxides that are thermally stable above 800°C while providing sufficient electrical conductivity for long-term operation.
Solution Approach 2:
The patent modifies the material composition by eliminating silver and glass ceramic components, instead using a perovskite-based composite with multiple metal oxides. This parameter change in chemical composition achieves thermal stability at high temperatures while maintaining electrical conductivity, resolving the contradiction between conductivity and long-term stability.
3Reliability
If cuprate compounds are used for the contact layer, then electrical conductivity is achieved, but phase conversions occur at T>900°C leading to loss of stability
Solution Approach 1:
The patent replaces unstable cuprate compounds with thermally stable perovskite-based metal oxides that do not undergo detrimental phase conversions at operating temperatures. The functional layer uses Fe2O3, CuO, NiO, Co3O4, Mn3O4, and other metal oxides that maintain compositional stability above 900°C while providing adequate electrical conductivity, eliminating the phase conversion problem.
Solution Approach 2:
The patent creates a composite functional layer using perovskite base material combined with multiple metal oxides in specific proportions. This composite structure enhances thermal stability and prevents phase conversions at high temperatures while maintaining electrical conductivity, resolving the contradiction between conductivity and compositional stability.
4Reliability
If the functional layer is made porous to facilitate diffusion processes, then adhesion is improved, but corrosion prevention capability is lost
Solution Approach 1:
The patent optimizes the porosity parameter of the functional layer by controlling sintering conditions and composition. The functional layer achieves moderate porosity that allows sufficient diffusion processes for adhesion while maintaining adequate density to prevent corrosion of the interconnector. The metal oxide composition and sintering temperature are adjusted to achieve the optimal porosity balance.
Solution Approach 2:
The patent uses a composite functional layer material with multiple metal oxides that creates an optimized pore structure. The composite composition enables the formation of a pore network that facilitates necessary diffusion processes for adhesion while maintaining sufficient structural integrity and density to block corrosive species, resolving the contradiction between adhesion and corrosion 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 achieves long-term electrical conductivity, enhanced adhesion, and protection against chromium contamination, maintaining stability under high temperatures and thermal cycles, with conductivity reaching at least 10 S/cm and suitable for temperatures between 700°C to 1000°C.
Implementation Method 1
the required diffusion processes are too low to realize a good electrical contact and sufficient adhesion to boundary layers
Implementation Method 2
the required diffusion processes are too low to realize a good electrical contact and sufficient adhesion to boundary layers
Data Source
AI summary
Described is a functional layer for high-temperature fuel cells and to a method for the production of functional layers. The functional layer is in particular a low-sintering, electrically conductive, ceramic layer which is formed between an interconnector and a cathode of a fuel cell. The functional layer is formed from a material which has at least two phases. A first phase is a perovskite ceramic material containing bismuth-cobalt and a second phase is a bismuth manganite and/or bismuth cobaltite (Bi—Mn—Co—0).