PFSA-Ionomer Polymer Blend for Fuel Cell Membrane Stability

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Solution Overview

Problem

Low equivalent weight fluorinated copolymers used in fuel cells suffer from water swelling at high humidity and membrane shrinkage at low humidity, leading to mechanical instability and reduced ionic conductivity, necessitating a polymer electrolyte with improved mechanical robustness and conductivity across a wide range of humidity conditions.

Innovation Solution

A polymer blend comprising a non-ionic fluoroelastomer and a perfluorosulfonic acid polymer, which provides enhanced mechanical properties, reduced water swelling, and maintained ionic conductivity, allowing for thin membrane formation without the need for annealing and support structures, and improved fuel cell performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If low equivalent weight fluorinated copolymers are used as polymer electrolytes, then ionic conductivity is improved, but mechanical stability deteriorates due to water swelling at high humidity and membrane shrinkage at low humidity

Engineering Contradiction:

Improveionic conductivityVSAvoidmechanical stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by blending low equivalent weight fluorinated copolymer (providing high ionic conductivity) with high equivalent weight fluorinated copolymer or fluorinated elastomer (providing mechanical stability). This composite approach allows the electrolyte membrane to simultaneously achieve high ionic conductivity and mechanical robustness across varying humidity conditions, resolving the contradiction between ionic conductivity and mechanical stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the parameter of equivalent weight distribution by using a blend of low equivalent weight (high conductivity) and high equivalent weight (high stability) fluorinated copolymers. This parameter optimization allows the membrane to maintain both high ionic conductivity and mechanical stability, as the different equivalent weight components compensate for each other's weaknesses under varying humidity conditions.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If low equivalent weight fluorinated copolymers are used, then ionic conductivity is improved, but mechanical robustness deteriorates, requiring support structures and annealing steps

Engineering Contradiction:

Improveionic conductivityVSAvoidmechanical robustness

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent uses composite materials by combining low equivalent weight fluorinated copolymer (high ionic conductivity) with high equivalent weight fluorinated copolymer or fluorinated elastomer (high mechanical robustness). This blend eliminates the need for external support structures like ePTFE and removes the requirement for high-temperature annealing steps, as the composite itself provides sufficient mechanical strength.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent extracts and eliminates the need for external support structures (ePTFE) and post-processing annealing steps by incorporating mechanical robustness directly into the polymer electrolyte blend formulation. The high equivalent weight component or fluorinated elastomer provides the necessary mechanical strength, allowing the membrane to be used independently without additional support layers or thermal treatment.

Inventive Principle:

Principle #2Taking out (Extraction)

3Use of energy by moving object

If fluorinated copolymers are used to achieve high ionic conductivity, then electrochemical performance is improved, but water swelling at high humidity and membrane shrinkage at low humidity occur

Engineering Contradiction:

Improveionic conductivityVSAvoidhumidity range performance

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent applies composite materials by blending low equivalent weight fluorinated copolymer (high ionic conductivity) with high equivalent weight fluorinated copolymer or fluorinated elastomer (dimensional stability). This composite structure allows the membrane to maintain stable dimensions across a wide humidity range while preserving high ionic conductivity, as the high equivalent weight component resists excessive swelling at high humidity and prevents shrinkage at low humidity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the equivalent weight distribution parameter by combining low and high equivalent weight fluorinated copolymers in specific ratios. This parameter adjustment allows the membrane to adapt to varying humidity conditions while maintaining both high ionic conductivity and dimensional stability, expanding the operational humidity range without sacrificing electrochemical performance.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7976730B2Blends of low equivalent molecular weight PFSA ionomers with Kynar 2751

Publication Date: 2011.07.12 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A polymer blend useful as an ion conductor in fuel cells includes a first polymer that includes a non-ionic segment and a second polymer that includes a sulfonic acid group.