OH-Type Anion-Exchange Elastomer for Fuel Cell Electrodes
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Solution Overview
Problem
The stability, durability, and flexibility of OH-type or carbonic acid-type anion-exchange hydrocarbon-based elastomers are affected by the residual amount of double bonds, leading to gelation and inhomogeneous dispersion issues when used as ion-conductivity imparting agents in fuel cells, resulting in reduced output voltage and durability due to bonding defects and crack formation in the electrode layer.
Innovation Solution
Controlling the iodine value of the elastomer within a specific range and using a combination of solvents with different permittivity to achieve uniform dissolution and high concentration without gelation, ensuring appropriate viscosity and improved bonding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the residual amount of double bonds in the elastomer is increased to improve flexibility and bonding properties, then the elastomer becomes more flexible and bonds better, but gelation occurs leading to inhomogeneous dispersion and reduced durability
Solution Approach 1:
The patent controls the iodine value (a measure of double bond content) within a specific range of 30-150 to optimize the balance between flexibility/bonding and gelation resistance. This parameter control prevents excessive cross-linking while maintaining adequate bonding properties.
Solution Approach 2:
The patent specifies different iodine value ranges for different elastomer components (e.g., SEBS with iodine value 10-50, SIS with iodine value 50-150) to achieve local optimization of bonding and stability in different regions of the ion-conductivity imparting agent composition.
2Reliability
If the concentration of the elastomer in the organic solvent is increased to improve ion conductivity, then ion conductivity improves, but gelation occurs leading to inhomogeneous dispersion
Solution Approach 1:
The patent uses a composite system combining specific elastomers (SEBS, SIS, or SBS) with carefully selected organic solvents (toluene, chloroform, dichloromethane, tetrahydrofuran) in optimized weight ratios. This composite approach enables high elastomer concentration (5-20 wt%) while preventing gelation through the synergistic interaction between the controlled elastomer structure and solvent properties.
Solution Approach 2:
The patent controls the elastomer concentration in the organic solvent within the range of 5-20 wt% to achieve high ion conductivity while preventing gelation. This concentration optimization balances ion conductivity enhancement with compositional stability.
3Stability of the object's composition
If the iodine value is decreased to improve stability, then stability improves, but flexibility and bonding properties deteriorate
Solution Approach 1:
The patent optimizes the iodine value within the range of 30-150 to achieve the optimal balance between stability and flexibility. This parameter optimization ensures that the elastomer maintains adequate double bond content for flexibility while limiting excessive cross-linking that would reduce stability.
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 approach results in an anion-exchange hydrocarbon-based elastomer with balanced stability, durability, and flexibility, enhancing the ion conductivity and bonding properties of the catalyst electrode layer, leading to increased fuel cell durability and output voltage.
Implementation Method 1
a hydroxide ion, generated by bringing the catalyst included in the electrode into contact with oxygen and water in the oxidizing agent chamber side catalyst electrode layer 5, conducts in the solid polymer electrolyte membrane 6 and moves into the fuel chamber 7
Implementation Method 2
a fuel such as hydrogen gas or methanol, etc. is supplied into said fuel chamber 7 via the fuel gas flow hole 2, and oxygen or oxygen containing gas such as air to act as an oxidizing agent is also supplied into the oxidizing agent chamber 8 via the oxidizing gas flow hole 3
Implementation Method 3
an electron, generated in the fuel chamber side catalyst electrode layer 4 simultaneously with the proton, moves to the oxidizing agent chamber side catalyst electrode layer 5 through the external load circuit, so that it is possible to use the above reaction energy as an electric energy
Data Source
AI summary
The present invention aims at providing an optimal constitution and production method for an OH-type anion-exchange hydrocarbon-based elastomer used when manufacturing a catalyst electrode layer of a solid polymer type fuel cell, in view of a balance of stability, durability and flexibility. Also, the present invention aims to provide an ion-conductivity imparting agent comprising the OH-type anion-exchange hydrocarbon-based elastomer, wherein the elastomer is uniformly dissolved or dispersed and has appropriate viscosity even with a high concentration. The anion-exchange hydrocarbon-based elastomer of the present invention has an iodine value of 3 to 25, contains an anion-exchange group having OH−, CO32− and/or HCO3− as a counterion in its molecule and is poorly-soluble in water. The hydrocarbon-based elastomer can preferably be used as an ion-conductivity imparting agent for forming a catalyst electrode layer by mixing an organic solvent.