Bipolar Plates With Offset Welds For Fuel Cell Current Homogeneity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel cells face issues with heterogeneous current density distribution across membrane/electrode assemblies due to localized corrosion and increased electrical resistance, leading to reduced performance and increased manufacturing costs, particularly due to corrosion of metal flow plates.
Innovation Solution
The use of bipolar plates with offset welds between adjacent metal sheets forces currents to take sinuous paths, optimizing current density homogeneity across the proton-exchange membrane without increasing weld density, thus reducing corrosion and extending fuel cell lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If welds are placed at the bottom of channels in bipolar plates to reduce manufacturing costs, then manufacturing cost is reduced, but current density becomes heterogeneous leading to localized corrosion and increased electrical resistance
Solution Approach 1:
The patent introduces asymmetry in weld placement by offsetting welds between adjacent bipolar plates. Instead of superimposing welds at the same position, the welds are deliberately placed at different locations (different longitudinal and/or transverse positions) to create an asymmetric current path distribution that promotes homogeneous current density across the membrane/electrode assembly.
Solution Approach 2:
The patent utilizes the spatial dimension by offsetting welds not only in the longitudinal direction but also in the transverse direction between adjacent bipolar plates. This multi-dimensional offsetting creates a more distributed current path network, transforming the current flow from concentrated paths to a more homogeneous distribution across the active area.
2Manufacturing precision
If standardized weld placement is used in bipolar plates, then manufacturing precision is improved, but current density homogeneity deteriorates causing heterogeneous fuel cell functioning
Solution Approach 1:
The patent deliberately introduces asymmetry in the weld placement pattern between adjacent bipolar plates. While each individual weld maintains manufacturing precision, the relative positioning between welds on adjacent plates is asymmetric (offset), which prevents current concentration and promotes homogeneous current density distribution across the membrane/electrode assembly.
3Reliability
If metal flow plates are used to improve electrical conductivity, then electrical conductivity is improved, but corrosion resistance deteriorates due to oxidation in acidic and oxidizing environments
Solution Approach 1:
The patent employs composite construction by joining two metal sheets through welding to form bipolar plates. This composite structure maintains high electrical conductivity through the metal components while the welded joint configuration (with offset welds between adjacent plates) indirectly protects against corrosion by ensuring homogeneous current distribution, which prevents localized overheating and accelerates corrosion.
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 enhances the homogeneity of current density, improves resistance to corrosion, and extends the service life of fuel cells without increasing manufacturing costs, contrary to traditional methods that prioritize standardized weld placement for minimal electrical resistance.
Implementation Method 1
The bipolar plates comprise two facing metal sheets fixedly attached by welds
Implementation Method 2
The use of bipolar plates with offset welds between adjacent metal sheets forces currents to take sinuous paths
Implementation Method 3
Each cell has an electrolytic membrane enabling only the passage of protons and not the passage of electrons
Implementation Method 4
Within the fuel cell's active area, at the anode, molecular hydrogen or hydrogen (H2) used as fuel is ionized to produce protons passing through the membrane
Implementation Method 5
At the cathode, oxygen is reduced and reacts with the protons to form water
Data Source
AI summary
A fuel cell includes three membrane-electrode assemblies. and first and second bipolar metal plates interposed between the membrane-electrode assemblies. Each of the bipolar plates comprises two metal sheets facing a respective membrane-electrode assembly and fixedly attached by welds. The two metal sheets comprise successive guiding channels for guiding gas extending in a common longitudinal direction. The guiding channels are distributed in a transversal direction The welds are made in bottoms of the guiding channel and include welds of the first bipolar plate and welds of the second bipolar plate. Some of the welds of the first bipolar plate are not superimposed on the welds of the second bipolar plate and are offset longitudinally and transversally relative to the welds of the second bipolar plate.