Lightweight Bipolar Plate Joining With Silicon-Carbon Bonding
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Solution Overview
Problem
The production of bipolar plates for electrochemical devices is challenging due to the difficulty in obtaining thin titanium foils and welding them, as well as the complexity of maintaining electrical and thermal conductivity, especially in achieving low weight and cost-effectiveness.
Innovation Solution
A method involving carbon fiber plate base bodies infiltrated with carbon allotropes, such as graphite or graphene, and joined using locally applied silicon, which reacts with carbon to form a silicon-carbon compound, creating a lightweight, electrically and thermally conductive bipolar plate with integrated flow channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If titanium-based alloys are used for bipolar plates, then weight is reduced by around half, but production becomes problematic due to difficulty in obtaining thin foils and complexity of welding
Solution Approach 1:
The patent uses carbon fiber reinforced plastic (CFRP) composite material for bipolar plates. The carbon fiber provides high strength and electrical conductivity, while the plastic matrix provides corrosion resistance and ease of manufacturing. This composite approach achieves low weight without the manufacturing difficulties of thin titanium foils.
Solution Approach 2:
The patent changes the material parameter from metallic (titanium) to polymer-composite (CFRP). This parameter change enables achieving low weight while avoiding the thin foil fabrication and welding complexities associated with titanium, as the composite can be formed through molding processes.
2Ease of manufacture
If stainless steel is used for bipolar plates, then manufacturing is easier, but weight is high with specific gravity up to 8 g/cm³
Solution Approach 1:
The patent replaces heavy stainless steel with carbon fiber reinforced plastic composite. The carbon fiber provides structural strength and electrical conductivity, while the plastic matrix provides corrosion resistance. This achieves weight reduction while maintaining manufacturability through molding processes.
Solution Approach 2:
The patent uses polymer-composite material that is easier and cheaper to manufacture than stainless steel, accepting that the material may have different longevity characteristics but achieving cost-effectiveness through simplified manufacturing processes.
3Weight of moving object
If graphite or graphite composite is used for bipolar plates, then weight is reduced, but joining panels while maintaining electrical and thermal conductivity is complex
Solution Approach 1:
The patent uses carbon fiber reinforced plastic composite that combines the low weight of graphite with the manufacturing advantages of polymer composites. The thermoplastic matrix allows for easier joining through welding or adhesive bonding while maintaining electrical conductivity through the carbon fiber network.
Solution Approach 2:
The patent changes from pure graphite or graphite composite to carbon fiber reinforced thermoplastic composite. This parameter change maintains the low weight and high conductivity of graphite while adding the processing and joining advantages of thermoplastic materials.
4Reliability
If metallic bipolar plates are used, then electrical conductivity is achieved, but corrosion protection layer is required adding complexity
Solution Approach 1:
The patent uses carbon fiber reinforced plastic composite where the carbon fiber provides inherent electrical conductivity and the plastic matrix provides inherent corrosion resistance. This eliminates the need for separate corrosion protection layers required with metallic plates, reducing overall complexity.
Solution Approach 2:
The carbon fiber reinforced plastic composite performs multiple functions simultaneously: the carbon fiber provides electrical conductivity and structural strength, while the plastic matrix provides corrosion resistance and structural integrity. This multi-functionality eliminates the need for separate corrosion protection layers.
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 method produces bipolar plates with a significantly lower specific weight (approximately 2.3 g/cm³) that are corrosion-resistant, have excellent thermal properties, and are cost-effective, using industrially available materials, while maintaining high electrical and thermal conductivity.
Implementation Method 1
heating the joints at least locally so that the silicon melts and with adjacent carbon to form a silicon-carbon compound reacts
Implementation Method 2
heating the joints at least locally so that the silicon melts
Implementation Method 3
providing a first plate base body and a second plate base body as shaped fiber bodies having carbon fibers
Implementation Method 4
excellent thermal properties, and are cost-effective, while maintaining high electrical and thermal conductivity
Data Source
Figure 1~3
AI summary
A method for producing a bipolar plate for an electrochemical device is proposed, comprising providing a first plate body and a second plate body as carbon fiber-containing fiber-shaped bodies, each with a joining surface and a usable surface facing away from it, infiltrating the plate bodies with at least one carbon allotrope, locally applying silicon to respective joining sites in the joining surfaces, placing the joining surfaces on top of each other so that the joining sites are on top of each other and the usable surfaces of the two plate bodies are facing away from each other, and at least locally heating the joining sites so that the silicon melts and reacts with adjacent carbon to form a silicon-carbon compound.