Fluorinated Polymer Electrolyte Membrane for Fuel Cells
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Solution Overview
Problem
Conventional polymer electrolyte fuel cell membranes face limitations in reducing electrical resistance while maintaining mechanical strength and dimensional stability, especially when the concentration of ionic groups is increased to enhance conductivity.
Innovation Solution
A polymer electrolyte membrane comprising a fluorinated proton conductive polymer and a fluorinated reinforcing material, with specific conditions for proton conductivity and equivalent weight, is used to achieve high mechanical strength and dimensional stability, even when thin and with increased ionic group concentration, thereby reducing electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the polymer electrolyte membrane is made thin to reduce electrical resistance, then electrical resistance decreases, but mechanical strength decreases making the membrane difficult to process and handle
Solution Approach 1:
The patent applies composite materials by combining a fluorinated proton conductive polymer with a fluorinated reinforcing material (such as porous PTFE film, fibrils, woven fabric, or nonwoven fabric). This composite structure allows the membrane to be made thin for low electrical resistance while the reinforcing material provides the necessary mechanical strength and dimensional stability.
2Loss of energy
If the concentration of ionic groups is increased to reduce electrical resistance, then electrical resistance decreases, but water content per unit volume increases significantly leading to increased volume change and decreased durability
Solution Approach 1:
The fluorinated reinforcing material in the composite structure provides dimensional stability that constrains the volume expansion of the polymer electrolyte membrane when water content increases. This allows higher ionic group concentration for low electrical resistance while maintaining durability through the stabilizing effect of the reinforcing material.
Solution Approach 2:
The patent specifies that the equivalent weight of the vinyl ether type monomer is at most 400 per 1 mol of ionic groups, which controls the density of ionic groups in the polymer. This parameter control allows optimization of electrical resistance while managing water content and volume change characteristics.
3Reliability
If the polymer electrolyte membrane contains water to enable proton conduction, then proton conductivity is maintained, but dimensions increase in the lengthwise direction causing wrinkles and impaired gas flow
Solution Approach 1:
The fluorinated reinforcing material embedded in the polymer electrolyte membrane provides a rigid framework that maintains dimensional stability. This allows the membrane to contain sufficient water for proton conductivity while the reinforcing material prevents excessive swelling and wrinkle formation that would impair gas flow.
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 membrane/electrode assembly provides high output and excellent durability, maintaining mechanical strength and dimensional stability even when thin and containing water, while achieving low electrical resistance.
Implementation Method 1
a fluorinated proton conductive polymer... the proton conductivity is at least 0.06 S/cm... electrical resistance
Data Source
AI summary
To provide a polymer electrolyte membrane for polymer electrolyte fuel cells having high mechanical strength and excellent dimensional stability when it contains water even when it is made thin and the concentration of ionic groups is increased so as to reduce the electrical resistance, and a membrane/electrode assembly providing high output and having excellent durability.