Chromium 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, which reduces the power generation capability of fuel cells.
Innovation Solution
An electrically conductive member is designed with a base member containing chromium and a covering part composed of elements with lower ionization energy and oxide formation energy, such as Ce and Fe, to reduce the growth of chromium oxide layers, thereby minimizing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chromium is used in the electrically conductive member, then corrosion resistance is improved, but chromium oxide layer growth increases internal resistance
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where different regions have different compositions: the base layer contains chromium for corrosion resistance, while the covering layer contains elements with lower ionization energy (Li, Na, K, Rb, Cs, Fr) and lower oxide formation energy (Fe, Ni, Ti, Si, Al, Mn, Co) to suppress oxide growth. This localized differentiation resolves the contradiction by having each layer perform its specialized function.
Solution Approach 2:
The patent uses composite materials by combining chromium-based base material with a covering layer of different elemental composition. The composite structure integrates the corrosion resistance of chromium with the oxide-suppressing properties of elements having lower ionization and oxide formation energies, thereby maintaining electrical conductivity while providing protective functionality.
2Reliability
If chromium oxide layer grows on the base member, then corrosion protection is improved, but electrical conductivity decreases
Solution Approach 1:
The patent applies parameter changes by selecting elements with specific physical and chemical parameters: lower ionization energy and lower oxide formation energy compared to chromium. These parameter changes in the covering layer elements enable them to form oxides more readily but with less volume growth, thereby protecting the chromium base while maintaining electrical conductivity pathways.
3Manufacturing precision
If covering part with lower ionization energy elements is added, then oxide growth is suppressed, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the electrically conductive member into distinct functional segments: a base member containing chromium and a covering part containing elements with lower ionization and oxide formation energies. This segmentation allows each part to be optimized independently for its specific function while maintaining overall system simplicity through clear functional separation.
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 effectively reduces the increase in internal resistance and maintains power generation capability by inhibiting the growth of chromium oxide layers, enhancing the durability and performance of fuel cells.
Implementation Method 1
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
Data Source
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.