Fuel Cell Stack Load Bearing Member Design

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Solution Overview

Problem

Fuel cell stacks face damage due to repetitive stress from expansion and shrinkage of gas diffusion layers, which existing bonding methods fail to adequately address, leading to potential breakage under compressive and tensile loads.

Innovation Solution

Incorporating anode and cathode side load bearing members that receive compressive loads and feature a load cancelling mechanism to mitigate the effect of tensile loads, thereby stabilizing the membrane electrode assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a bonding member is used to join insulating members of adjacent single cells, then the insulating members can be prevented from cracking by allowing deformation of the fuel cell stack, but the bonding member cannot receive compressive loads acting on the anode and cathode separators

Engineering Contradiction:

Improveprevention of insulating member crackingVSAvoidload receiving capability

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The load bearing member is designed to perform multiple functions simultaneously: it acts as a bonding member to join insulating members (preventing cracking) and as a load receiving structure to bear compressive loads on anode and cathode separators. This multi-functional design resolves the contradiction by integrating both functions into a single component rather than using separate bonding and load-bearing elements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The load bearing member may be constructed using composite materials that combine the properties needed for both bonding and load bearing. The composite structure allows the member to maintain flexibility for deformation accommodation while providing sufficient strength to receive compressive loads, thus resolving the contradiction between bonding function and load-bearing capacity.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the gas diffusion layers expand and shrink due to gas pulsation, then the fuel cell operates dynamically, but the membrane electrode assembly is subjected to repetitive stress leading to damage

Engineering Contradiction:

Improvedynamic operation capabilityVSAvoidmembrane electrode assembly durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The load bearing member is designed with load cancelling means that provide beforehand cushioning to the membrane electrode assembly. When gas pulsation causes expansion and shrinkage of gas diffusion layers, the load bearing member absorbs and cancels the resulting tensile loads before they can damage the membrane electrode assembly, thus protecting it during dynamic operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The load bearing member incorporates load cancelling means that act as a counterbalancing mechanism. When tensile loads are generated by gas diffusion layer deformation during dynamic operation, the load bearing member provides an opposing force to cancel these tensile loads, preventing repetitive stress damage to the membrane electrode assembly while allowing dynamic operation to continue.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Reliability

If the adhesion strength is decreased to cancel tensile load effects, then the membrane electrode assembly is protected from breakage, but the bonding strength between components is reduced

Engineering Contradiction:

Improveprotection from tensile load damageVSAvoidadhesion strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The load bearing member is designed with non-uniform adhesion characteristics. The adhesion strength is locally adjusted so that in regions where tensile loads occur during dynamic operation, the adhesion is designed to be lower to allow load cancellation and protect the membrane electrode assembly. In other regions, the adhesion strength is maintained or enhanced to ensure proper bonding and load bearing functionality. This spatial variation in adhesion quality resolves the contradiction between protecting from tensile damage and maintaining bonding strength.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10297839B2Fuel cell stack and load bearing method involving use of fuel cell stack

Publication Date: 2019.05.21 NISSAN MOTOR CO LTD

AI summary

A fuel cell stack has stacked individual fuel cells, each of the fuel cells having a cell frame, and an anode separator and a cathode separator disposed on respective sides of the cell frame, in which an electrolyte membrane joined with an anode side gas diffusion layer and a cathode side gas diffusion layer on respective sides thereof is disposed in the cell frame, an anode side load bearing member that bonds and fixes the anode separator, the cell frame, and the gas diffusion layer to each other, so as to receive a compressive load acting in a stacking direction of the fuel cell, and a cathode side load bearing member that bonds and fixes the cathode separator, the cell frame, and the gas diffusion layer to each other so as to receive a compressive load acting in the stacking direction of the fuel cell.