Fuel Cell Separator Structure for Controlled Coolant Manifold Corrosion

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Solution Overview

Problem

Fuel cell stacks face reduced lifespan due to electrolytic corrosion in coolant manifolds, leading to increased costs from sacrificial members and corrosion-resistant materials, and a need for an inexpensive configuration that extends life.

Innovation Solution

A fuel cell stack design with stainless steel separators featuring a sacrificial electrolytic corrosion region adjacent to the coolant manifold, where the separator shape promotes electrolytic corrosion by increasing surface area, reducing corrosion concentration and using an inexpensive material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sacrificial member is separately provided to deal with electrolytic corrosion in the coolant manifold, then corrosion protection is improved, but the number of parts increases and cost increases

Engineering Contradiction:

Improvecorrosion protectionVSAvoidnumber of parts

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the sacrificial corrosion protection function directly into the separator structure by forming a sacrificial electrolytic corrosion region on the separator surface adjacent to the coolant manifold. This integration eliminates the need for separate sacrificial members, reducing part count while maintaining corrosion protection functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The separator is designed to serve multiple functions: it acts as both the structural separator component and the sacrificial corrosion protection element through the formed corrosion region. This multi-functionality eliminates the need for dedicated sacrificial members while maintaining protective capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If the separator base material is changed from inexpensive stainless steel to highly corrosion-resistant material such as titanium, then corrosion resistance is improved, but cost increases

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of using expensive corrosion-resistant material throughout the entire separator, the patent applies corrosion protection locally by forming a sacrificial electrolytic corrosion region only in the specific area adjacent to the coolant manifold where corrosion occurs. This allows the use of inexpensive stainless steel for the bulk separator material while providing targeted corrosion protection where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs a sacrificial corrosion region that is designed to corrode preferentially, protecting the main separator structure. This sacrificial region acts as a disposable protective element that sacrifices itself to prevent corrosion of the expensive separator material, enabling the use of cheaper base materials.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If electrolytic corrosion is concentrated in the coolant lead-in or lead-out region, then corrosion protection of other regions is improved, but the life of the fuel cell stack is shortened

Engineering Contradiction:

Improveprotection of separator regionsVSAvoidfuel cell stack life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent pre-forms a sacrificial electrolytic corrosion region on the separator surface in the coolant lead-in or lead-out region before the fuel cell stack operates. This preliminary preparation ensures that when electrolytic corrosion occurs during operation, it is directed to this pre-designed sacrificial region, protecting other separator regions while containing the corrosion damage to a controlled area that does not compromise overall stack life.

Inventive Principle:

Principle #10Preliminary 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

The design extends the life of the fuel cell stack while maintaining an inexpensive configuration by promoting electrolytic corrosion in controlled regions and reducing corrosion concentration, thus enhancing durability and cost-effectiveness.

Implementation Method 1

electrolytic corrosion becomes concentrated, shortening the life of the fuel cell stack

Methodology Applied

Scientific EffectElectrolytic corrosion: Electrolysis

Data Source

PatentUS20230369615A1Fuel cell stack

Publication Date: 2023.11.16 TOYOTA JIDOSHA KK

AI summary

In a fuel cell stack, a separator includes, in a region adjacent to a coolant manifold of the unit cell in a planar direction, a sacrificial electrolytic corrosion region that is not adhered to an insulating sheet adjacent in a laminating direction, and a sealing region that is adjacent to the sacrificial electrolytic corrosion region in the planar direction and is adhered to the insulating sheet. The sacrificial electrolytic corrosion region includes a coolant lead-in or lead-out region and a region other than the coolant lead-in or lead-out region. A shape of the separator in the coolant lead-in or lead-out region is a flat plate shape that is in contact with the insulating sheet, and a shape of the separator in the region other than the coolant lead-in or lead-out region of is an uneven shape that is at least partially out of contact with the insulating sheet.