Membrane Electrode Assembly with Asymmetric Intermediate Layers

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Solution Overview

Problem

Solid polymer electrolyte fuel cells face challenges in achieving sufficient gas diffusivity, water discharge, and moisture retentivity, leading to inadequate electric power generation performance, especially under varying humidity conditions.

Innovation Solution

A membrane electrode assembly with two intermediate layers having distinct pore size ranges between the electrode catalyst layers and gas diffusion layers, where the cathode side has a larger pore volume per unit area and unit mass than the anode side, optimizing gas diffusion and water discharge while maintaining moisture retentivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the pore volume in intermediate layers is increased to improve gas diffusivity and water discharge, then gas diffusion performance is improved, but moisture retentivity deteriorates

Engineering Contradiction:

Improvegas diffusivityVSAvoidmoisture retentivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies different pore volume characteristics to different locations (anode side vs cathode side) of the membrane electrode assembly. The intermediate layer on the anode side has a first pore volume optimized for moisture retention, while the intermediate layer on the cathode side has a second pore volume optimized for gas diffusion and water discharge. This local differentiation resolves the contradiction by allowing each side to have optimized properties for its specific functional requirements.

Inventive Principle:

Principle #3Local quality

2Reliability

If the humidity of reductive gas or oxidative gas is increased to maintain moisture in the membrane, then moisture retentivity is improved, but gas diffusivity deteriorates

Engineering Contradiction:

Improvemoisture retentivityVSAvoidgas diffusivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements local quality by creating intermediate layers with different pore volumes on opposite sides of the membrane. The anode-side intermediate layer maintains higher pore volume for moisture retention, while the cathode-side intermediate layer has optimized pore volume for gas diffusion. This structural differentiation allows the system to maintain moisture without compromising gas diffusivity.

Inventive Principle:

Principle #3Local quality

3Duration of action of moving object

If long-time operation continues to generate electric power, then energy production is sustained, but excessive moisture accumulates inhibiting gas diffusion

Engineering Contradiction:

Improveoperation durationVSAvoidgas diffusivity

Core Design Contradiction:

Duration of action of moving objectVSProductivity

Solution Approach 1:

The patent ensures continuous effective operation by designing intermediate layers that continuously manage moisture and gas transport. The differentiated pore volumes enable continuous gas diffusion and water discharge throughout operation, preventing the accumulation of excessive moisture that would otherwise inhibit gas diffusion over time. This maintains productivity throughout extended operation periods.

Inventive Principle:

Principle #20Continuity of useful action

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

This configuration ensures excellent electric power generation performance across a wide range of humidity conditions by enhancing gas diffusivity and water discharge capabilities, maintaining optimal moisture levels in the membrane.

Implementation Method 1

a solid polymer electrolyte membrane having proton conductivity

Methodology Applied

Scientific EffectProton conductivity: Conduction (electrical)

Implementation Method 2

two intermediate layers comprising pores and disposed respectively between one of the electrode catalyst layers and the gas diffusion layer pairing therewith

Methodology Applied

Scientific EffectGas diffusion: Diffusion

Implementation Method 3

the volume per unit area and per unit mass of the pores falling within a pore size range from 0.1 to 10 μm in the intermediate layer in the cathode side is larger than the volume per unit area and per unit mass of the pores falling within a pore size range from 0.1 to 10 μm in the intermediate layer in the anode side

Methodology Applied

Scientific EffectWater discharge: Permeation

Data Source

PatentUS7807314B2Membrane electrode assembly for use in solid polymer electrolyte fuel cell

Publication Date: 2010.10.05 HONDA MOTOR CO LTD

AI summary

A membrane electrode assembly that includes a cathode electrode catalyst layer and an anode electrode catalyst layer respectively disposed on one side and the other side of a solid polymer electrolyte membrane, gas diffusion layers disposed respectively on the sides of the electrode catalyst layers; and intermediate layers having pores and disposed respectively between the electrode catalyst layer and the gas diffusion layer and between the electrode catalyst layer and the gas diffusion layer. The volume per unit area and per unit mass of the pores having pore size of 0.1 to 10 μm in the intermediate layer in the cathode side is larger than that in the intermediate layer in the anode side. The pore volume of the intermediate layer in the cathode side is 1.7 to 4.3 μl/cm2/mg and that of the intermediate layer in the anode side is 0.5 to 1.4 μl/cm2/mg.