Fuel Cell Catalyst Ink Composition to Suppress Membrane Swelling

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Solution Overview

Problem

The existing catalyst inks used in fuel cells tend to permeate through the electrolyte membrane, leading to swelling and subsequent cracks or wrinkles in the catalyst layer, which affects the integrity and performance of the fuel cell.

Innovation Solution

A catalyst ink formulation with a solvent having a solubility parameter greater than 18.0, comprising water and at least 35% ethanol, and including carbon fibers, which reduces solvent penetration and enhances dispersibility, thereby suppressing cracks and wrinkles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional catalyst ink with low solubility parameter solvent is used, then the solvent can penetrate the electrolyte membrane and swell it, but this causes cracks and wrinkles in the catalyst layer

Engineering Contradiction:

Improvecatalyst layer integrityVSAvoidsolvent penetration and swelling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the solubility parameter of the solvent from conventional values (≤18.0) to a higher value (>18.0). This parameter change reduces the solvent's affinity for the electrolyte membrane, preventing penetration and swelling that cause catalyst layer defects, while maintaining effective catalyst delivery

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite solvent system comprising water and alcohol (≥35% by mass), rather than a single solvent. This composite approach allows optimization of both membrane compatibility and catalyst layer formation properties, achieving non-penetration while maintaining reliability

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If the solvent has high penetration ability, then it can wet the electrolyte membrane surface well, but it causes dissolution and swelling of the membrane

Engineering Contradiction:

Improvesurface wettingVSAvoidelectrolyte membrane stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

By increasing the solubility parameter above 18.0, the patent modifies the solvent's interaction characteristics with the electrolyte membrane. This parameter change reduces excessive affinity that causes swelling, while still allowing adequate surface wetting for uniform catalyst layer formation

Inventive Principle:

Principle #35Parameter changes

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 catalyst ink effectively minimizes solvent absorption by the electrolyte membrane, maintaining the structural integrity of the catalyst layer and enhancing the fuel cell's performance by reducing cracks and wrinkles.

Implementation Method 1

a solubility parameter of the solvent is greater than 18.0

Methodology Applied

Scientific EffectSolubility parameter:

Implementation Method 2

the catalyst ink including ionomer, catalyst metal particles, carbon and a solvent

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentUS20250266466A1Catalyst ink

Publication Date: 2025.08.21 HONDA MOTOR CO LTD

AI summary

A catalyst ink is for forming a catalyst layer by being coated on a surface of an electrolyte membrane of a fuel cell, the catalyst ink including ionomer, catalyst metal particles, carbon and a solvent, in which a solubility parameter of the solvent is greater than 18.0, the solvent includes water and an alcohol at least containing ethanol, and the concentration of ethanol in the solvent is 35% by mass or more.