Fuel Cell Adhesive Bond Durability Wetting Drying Cycles
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Solution Overview
Problem
Solid polymer fuel cells face issues with bond durability between the gas diffusion layers and the solid polymer electrolyte membrane, leading to separation and performance decline due to dimensional changes from repeated wetting and drying, and existing adhesives do not provide sufficient strength to maintain the assembly.
Innovation Solution
An adhesive comprising a base compound with alkenyl groups, a cross-linking agent with Si—H groups, and an adhesion promoting agent, with a specific molar ratio of Si—H to alkenyl groups (1.0 to 5.0), forming a strong chemical bond to enhance durability and resistance to acid exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing adhesives are used to bond gas diffusion layers to the solid polymer electrolyte membrane, then the assembly can be manufactured, but the bond durability is insufficient leading to separation during repeated wetting and drying cycles
Solution Approach 1:
The patent changes the chemical parameters of the adhesive by specifying a base compound with alkenyl groups and a crosslinking agent with Si-H groups in a specific molar ratio (1.0 to 5.0). This chemical parameter change enables the adhesive to form strong chemical bonds with both the gas diffusion layer and solid polymer electrolyte membrane, preventing separation during repeated wetting and drying cycles while maintaining bond durability throughout the service life.
Solution Approach 2:
The patent creates a composite adhesive system combining the base compound (with alkenyl groups), crosslinking agent (with Si-H groups), and adhesion promoting agent. This composite material approach allows the adhesive to simultaneously achieve strong bonding to both substrates and resistance to dimensional changes from wetting and drying, resolving the contradiction between initial bond strength and long-term durability.
2Volume of moving object
If the solid polymer electrolyte membrane thickness is decreased to reduce fuel cell size, then the compactness improves, but the membrane strength is lowered making it more easily broken
Solution Approach 1:
The patent uses the adhesive layer as an intermediary between the gas diffusion layers and the solid polymer electrolyte membrane. This adhesive intermediary provides mechanical support and reinforcement to the thin membrane, compensating for the reduced membrane strength that results from decreasing membrane thickness. The adhesive forms strong chemical bonds that prevent membrane breakage while allowing the use of thinner membranes for compact fuel cell design.
3Strength
If a high crosslinking ratio is used to improve bond strength, then the adhesive strength increases, but the curing temperature increases which may damage the solid polymer electrolyte membrane
Solution Approach 1:
The patent optimizes the molar ratio parameter between Si-H groups and alkenyl groups to be between 1.0 and 5.0. This parameter optimization allows the adhesive to achieve high bond strength through effective crosslinking while maintaining a lower curing temperature that does not damage the solid polymer electrolyte membrane. The specific ratio ensures sufficient crosslinking density for strong bonding without requiring excessive thermal energy.
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 adhesive significantly improves bond durability, prevents separation of the gas diffusion layers from the solid polymer electrolyte membrane, and reduces the heat required for curing, thereby maintaining the integrity and performance of the fuel cell assembly.
Implementation Method 1
a cross-linking agent having a structure represented by general formula (2); an adhesion promoting agent; and a reaction catalyst, in which a ratio of moles of Si—H groups contained in the cross-linking agent relative to moles of alkenyl groups contained in the base compound
Implementation Method 2
a base compound having a structure represented by the following general formula (1); a cross-linking agent having a structure represented by the following general formula (2)
Implementation Method 3
an adhesion promoting agent
Data Source
AI summary
An adhesive suitable for solid polymer fuel cells is provided that has sufficient bond durability, so that the solid polymer electrolyte membrane and the gas diffusion layer do not separate, even with the solid polymer electrolyte fuel cell repeatedly wetting and drying, and changing in dimension. An adhesive including a base compound, a cross-linking agent, an adhesion promoting agent, and a reaction catalyst is employed using a specific base compound having alkenyl groups, and a specific cross-linking agent having Si—H groups, in which the ratio of moles of the above Si—H group relative to moles of the above alkenyl group (moles of Si—H group/moles of alkenyl group) is adjusted to the range of 1.0 to 5.0.