Poly(phenylene alkylene) Ionomers for AEMFC Stability

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Solution Overview

Problem

Anion exchange membrane fuel cells (AEMFCs) face challenges in developing chemically stable anion exchange membranes and optimized ionomers that maintain mechanical and chemical integrity, facilitate ion and water transport, and balance conductivity and water swelling properties for efficient operation.

Innovation Solution

The development of poly(phenylene alkylene)-based ionomers with a flexible backbone and sidechain-attached ammonium cations, which can function as both membrane and electrode binder, enhancing chemical stability and permeability while maintaining low interfacial resistance and water swelling characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If BTMA cations are used in AEM membranes, then good chemical stability is achieved, but insufficient stability for long-term use occurs

Engineering Contradiction:

Improvechemical stabilityVSAvoidlong-term stability

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical structure parameters of the cationic groups by replacing BTMA with alternative cations such as imidazolium, guanidinium, pyridinium, or phosphonium groups. These structural modifications enhance chemical stability while maintaining the essential ion exchange functionality, thereby resolving the contradiction between achieving good chemical stability and ensuring long-term durability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite polymer structures combining different backbone materials (poly(phenylene), poly(phenylene oxide), poly(ether-imide), poly(arylene ether sulfone), poly(ether ether ketone)) with various cationic groups. This composite approach allows optimization of both chemical stability and long-term performance by selecting complementary material properties that work synergistically.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the same polymer is used for both membrane and ionomer, then manufacturing simplicity is achieved, but increased interfacial resistance occurs

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidinterfacial resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by using different polymers for the membrane and ionomer components. The membrane polymer is optimized for chemical stability and ion conduction, while the ionomer polymer is specifically designed with enhanced mechanical properties and catalytic activity. This localized optimization of properties for different functional regions reduces interfacial resistance while maintaining manufacturing feasibility through separate component fabrication and assembly.

Inventive Principle:

Principle #3Local quality

3Reliability

If quaternized 4,4'-diazobicyclo-[2.2.2]-octane cations are used, then improved stability to alkaline conditions is achieved, but device complexity increases

Engineering Contradiction:

Improvestability to alkaline conditionsVSAvoidcation structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the cationic group design into distinct functional categories (imidazolium, guanidinium, pyridinium, phosphonium) with well-defined structural characteristics. Each category provides specific stability benefits while maintaining manageable structural complexity. This segmentation allows selection of the most appropriate cation type based on specific application requirements without unnecessarily increasing overall system complexity.

Inventive Principle:

Principle #1Segmentation

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 poly(phenylene alkylene)-based ionomers demonstrate improved chemical stability and flexibility, enabling efficient ion and water transport, reducing interfacial resistance, and maintaining structural integrity under high pH conditions, thus enhancing the performance and efficiency of AEMFCs.

Implementation Method 1

AEMs are typically made with polymers that have pendant cationic groups... the membrane to conduct hydroxide ions from the cathode to the anode

Methodology Applied

Scientific EffectIon exchange: Ion Exchange

Implementation Method 2

The role of the ionomer is to maximize the transport of ions, fuel, oxygen, and water within the electrodes

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS9534097B2Poly(phenylene alkylene)-based lonomers

Publication Date: 2017.01.03 NATIONAL TECHNOLOGY & ENGINEERING SOLUTIONS OF SANDIA LLC

AI summary

A composition and method of forming a composition including a compound including a poly(phenylene) backbone represented by the following formula:wherein each of R1, R2 and R3 may be the same or different and is H or an unsubstituted or inertly-substituted aromatic moiety; wherein Ar1 is an unsubstituted or inertly-substituted aromatic moiety; wherein R4 is an alkylene, perfluoroalkyl, polyethylene glycol, or polypropylene glycol moiety; wherein each of R6, R7, R8, R9, R10 and R11 is H or a monovalent hydrocarbon group including two to 18 carbon atoms, with the proviso that each R6, R7, R8, R9, R10 and R11 cannot be H; and wherein each of Y6, Y7, Y8, Y9, Y10 and Y11 may be the same or different and is H or a functional group are disclosed. The composition can be used as anion-exchange membranes and as an electrode binder material in anion exchange membrane fuel cells.