Flat Bipolar Plates in Fuel Cell Systems
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Solution Overview
Problem
Conventional fuel cell systems face inefficiencies due to complex cooling and humidification requirements, corrosion, high costs, and the scarcity of platinum, leading to increased weight, volume, and manufacturing costs, which hinder market penetration for fuel cell vehicles.
Innovation Solution
A fuel cell system with flat bipolar plates and fiber-structured gas diffusion layers, where the gas-carrying area is exclusively through the gas diffusion layers, reducing the need for platinum and enabling a compact, modular design with external cooling channels and the use of cheaper membrane materials, allowing for higher operating temperatures and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If profiled bipolar plates with cooling channels are used, then cooling performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The bipolar plate structure is segmented into two functional zones: a completely flat active area for electrochemical reactions and a separate edge area for cooling channels and flow fields. This segmentation allows the active area to remain simple and flat while the edge area handles all cooling functions, resolving the contradiction between cooling performance and structural complexity.
Solution Approach 2:
The cooling channel structure is extracted from the active area of the bipolar plate and relocated to the edge area. This extraction eliminates the need for complex profiled structures in the active area, reducing manufacturing complexity while maintaining cooling functionality through dedicated edge-area channels.
2Temperature
If thick bipolar plates with cooling channels are used, then cooling is improved, but overall cell height and weight increase
Solution Approach 1:
The cooling channels are positioned in the edge area rather than occupying the thickness of the active area. This dimensional repositioning allows cooling functionality to be added without increasing the overall cell height or active area thickness, thereby avoiding additional weight while maintaining cooling capability.
3Temperature
If complex flow fields are incorporated, then cooling performance is improved, but manufacturing cost and production complexity increase
Solution Approach 1:
The bipolar plate is segmented into a flat active area and an edge area, where all complex flow field features are confined to the edge area. This segmentation simplifies the active area manufacturing while allowing complex cooling channels to be integrated only in the edge area, reducing overall production complexity.
Solution Approach 2:
Different regions of the bipolar plate have different structural qualities: the active area is completely flat with simple manufacturing requirements, while the edge area contains the complex cooling channels. This local differentiation optimizes manufacturing ease for the critical active area while maintaining cooling functionality in the edge area.
4Power
If platinum catalysts are used, then power density is improved, but material cost and scarcity issues worsen
Solution Approach 1:
The invention changes the material parameter by replacing platinum-based catalysts with non-precious metal catalysts in the membrane-electrode assembly. This parameter change reduces dependence on scarce platinum while maintaining adequate power density through alternative catalytic materials and optimized cell design.
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 results in a more efficient, cost-effective, and compact fuel cell system with reduced material costs, improved power density, and enhanced performance, enabling faster start-up and tolerance for temperature differences, while minimizing the use of platinum and simplifying manufacturing processes.
Implementation Method 1
two gas diffusion layers in the form of a fiber structure adjoining the larger surfaces of the membrane-electrode assembly
Implementation Method 2
cooling channels for conducting a coolant
Implementation Method 3
membrane-electrode assembly, two gas diffusion layers... and a bipolar plate producing the electrical connection
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a fuel cell system having a plurality of individual fuel cells which are combined to a stack, each of said individual fuel cells consisting of a substantially planar membrane-electrode unit, two gas diffusion layers in the form of a fiber structure and of a bipolar plate, which establishes the electrical connection to the adjacent individual fuel cell that is located above or below, wherein the gas diffusion layers adjoin the larger surfaces of the membrane electrode unit, which are located opposite of one another. The bipolar plate according to the invention comprises an active region surrounded by an edge region. In order to create a fuel cell system of the above-mentioned type, which is particularly thin, has no disadvantages in terms of weight, volume and power and moreover can be achieved in a cost-effective manner, it is proposed according to the invention that the bipolar plates in the active region have a completely flat design so that the gas-carrying region is formed exclusively by the gas diffusion layers, what amounts to at least 60% of the height of an individual fuel cell.