Chromium-Based Conductive Member Coating for Low-Resistance Fuel Cells
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Solution Overview
Problem
The internal resistance of electrically conductive members in fuel cell stack devices increases, leading to a reduction in power generation capability.
Innovation Solution
The use of an electrically conductive member with a specific structure comprising a base member made of stainless steel and a coating layer containing cerium oxide and chromium oxide, along with a covering part made of cerium and iron oxides, to reduce the growth of chromium oxide layers and minimize internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin sheet is used as a separator in an electrochemical cell, then the cell can be manufactured with simplified processes, but the resin sheet may swell or shrink due to solvent absorption or desorption, causing contact with electrodes and reducing cell performance
Solution Approach 1:
The patent applies parameter changes by controlling the crosslinking degree of the resin sheet within a specific range (5-60%) to balance dimensional stability and manufacturing ease. By adjusting this physical parameter, the resin sheet achieves sufficient stability to prevent electrode contact while maintaining the advantages of resin-based manufacturing processes
Solution Approach 2:
The patent uses composite materials by combining resin with inorganic particles (such as alumina, silica, or boehmite) to create a reinforced resin sheet. This composite structure provides dimensional stability and prevents swelling/shrinking while maintaining the manufacturing simplicity of resin-based separators
2Reliability
If a porous polymer sheet is used as a separator, then ion permeability is improved, but the sheet lacks mechanical strength and requires reinforcement with glass fiber or metal mesh, increasing complexity
Solution Approach 1:
The patent creates a composite material by embedding inorganic particles within the resin matrix of the porous sheet. This composite structure provides the necessary mechanical strength without requiring additional reinforcement layers, thereby maintaining ion permeability while eliminating the need for glass fiber or metal mesh
Solution Approach 2:
The patent applies local quality by strategically selecting and distributing inorganic particles with specific properties (such as high modulus of elasticity) within the resin matrix. This localized reinforcement provides mechanical strength precisely where needed while preserving the overall porosity and ion transport properties of the separator
3Volume of moving object
If the thickness of the porous polymer sheet is reduced to achieve smaller cell size, then the cell volume decreases, but the sheet becomes more susceptible to deformation and contact with electrodes
Solution Approach 1:
The patent uses composite materials with inorganic particles to reinforce the porous resin sheet, enabling it to maintain dimensional stability at reduced thicknesses. The inorganic particles provide structural support that prevents deformation and electrode contact, allowing the separator to be thinner without compromising stability
Solution Approach 2:
The patent applies parameter changes by optimizing the crosslinking degree and inorganic particle content to achieve the desired balance between thickness and dimensional stability. By adjusting these parameters, the separator can be made thinner while maintaining sufficient mechanical properties to prevent electrode contact
4Stability of the object's composition
If crosslinking is increased to improve dimensional stability of the resin sheet, then swelling and shrinking are reduced, but the sheet becomes excessively rigid and difficult to manufacture
Solution Approach 1:
The patent applies parameter changes by establishing an optimal range for crosslinking degree (5-60%) that balances dimensional stability with manufacturability. Within this range, the resin sheet achieves sufficient stability to prevent swelling and shrinking while remaining flexible enough for standard manufacturing processes
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 configuration effectively reduces the internal resistance, thereby enhancing the power generation capability of the fuel cell stack devices.
Implementation Method 1
a content of 5% to 60% by mass of inorganic particles serving as a spacer
Implementation Method 2
the porous polymer sheet contains 5 wt % or more of electroconductive filler particles
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
An electrically conductive member includes a base member and a covering part located on the base member and containing a first element and a second element. The base member contains chromium. The first element is one or more elements having a smaller first ionization energy than chromium and a smaller free energy of formation of oxide per mole of oxygen than chromium. The second element is one or more kinds of elements selected from the group consisting of Fe, Ni, Ti, Si, Al, Mn, and Co.