Bimodal Porosity Cathode Bond Layer for SOFC Interconnects
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Solution Overview
Problem
Solid oxide fuel cells face performance issues due to suboptimal interconnects, which can warp or deform under high temperatures, leading to variable electrical contact and reduced efficiency, as traditional solid interconnects lack stability and compatibility with other cell components.
Innovation Solution
A cathode bond layer with bimodal porosity, composed of lanthanum and strontium materials, is applied between the cathode interconnect and cathode, enhancing electrical contact and physical integrity by increasing oxygen mass transport and mechanical strength, while being thermally stable and chemically compatible with other fuel cell components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid interconnects are used to join fuel cell components, then structural integrity is provided, but the interconnects may warp or deform under high temperatures leading to variable electrical contact
Solution Approach 1:
The patent applies a porous bond layer between the interconnect and electrode components. This porous structure accommodates thermal expansion and deformation while maintaining contact, resolving the contradiction between providing structural integrity through solid interconnects and ensuring stable electrical contact despite warping at high temperatures.
Solution Approach 2:
The patent uses a composite structure combining a solid interconnect with a porous bond layer made of ceramic or ceramic-metal composite materials. This composite approach allows the solid interconnect to provide structural strength while the porous bond layer compensates for thermal deformation, ensuring reliable electrical contact.
2Reliability
If a bond layer is applied to improve electrical contact and dimensional tolerance, then electrical conductivity and physical integrity are enhanced, but oxygen mass transport may be impeded
Solution Approach 1:
The patent employs a porous bond layer that simultaneously provides electrical conductivity and maintains oxygen mass transport pathways. The porous structure allows oxygen to diffuse through the bond layer to reach the cathode-electrolyte interface while the layer also improves electrical contact and dimensional tolerance between components.
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 bimodal porosity cathode bond layer improves the overall performance of solid oxide fuel cells by increasing oxygen mass transport and power density, maintaining structural integrity, and ensuring compatibility with other components, thus addressing the limitations of traditional interconnects.
Implementation Method 1
The bond layer permits the transport of oxygen from the air source for the fuel cell, to the cathode-electrolyte interface
Implementation Method 2
The bond layer also functions to transport electrons from the outer circuit to the cathode-electrolyte interface
Implementation Method 3
heat-treating the applied bond paste mixture at a temperature of at least about 650° C., so as to remove substantially all volatile content from the mixture
Implementation Method 4
heat-treating the applied bond paste mixture at a temperature of at least about 650° C., so as to remove substantially all volatile content from the mixture
Implementation Method 5
heat-treating the applied bond paste mixture at a temperature of at least about 650° C., so as to remove substantially all volatile content from the mixture, and to cause the formation of a microstructure having bimodal porosity
Data Source
AI summary
An electrically-conductive layer of material having a composition comprising lanthanum and strontium is described. The material is characterized by a microstructure having bimodal porosity. Another concept in this disclosure relates to a solid oxide fuel cell attached to at least one cathode interconnect by a cathode bond layer. The bond layer includes a microstructure having bimodal porosity. A fuel cell stack which incorporates at least one of the cathode bond layers is also described herein, along with related processes for forming the cathode bond layer.