Fuel Cell Plate Stress Distribution via Peripheral Holder

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Solution Overview

Problem

The existing fuel cell stacks using solid oxide electrolytes face issues with uneven stresses on brittle electrolyte layers due to corrugated gas separators, which can lead to deterioration of electric-power generating ability, especially under high and low temperature variations.

Innovation Solution

A fuel cell design featuring a cell plate with a solid electrolyte, cathode, and anode layers supported by a porous metal plate, with an electroconductive gas separator and a holder member that applies compressive force without directly affecting the electrolyte, ensuring even stress distribution and gas sealability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large load is applied to the fuel cell stack in the stacking direction to ensure gas seal and electric connection, then the gas seal and electric connection are improved, but the brittle solid electrolyte layers are subjected to uneven stresses from corrugated gas separator convex portions, which may cause deterioration of electric-power generating ability

Engineering Contradiction:

Improvegas seal and electric connectionVSAvoiduneven stresses on solid electrolyte layers

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention divides the load-bearing function into two separate components: the cell plate maintains gas seal and electric connection, while the holder member applies compressive force only to the peripheral portions. This segmentation prevents the solid electrolyte layer from being subjected to uneven stresses from corrugated gas separators, while still ensuring reliable gas seal and electric connection through the cell plate structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The holder member acts as an intermediary component that applies compressive force to the cell plate at its peripheral portions without directly contacting or transmitting uneven stresses to the solid electrolyte layer. This intermediary structure allows the beneficial compressive force to be applied while protecting the brittle electrolyte from harmful localized stresses.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If thick solid electrolyte layers are used to attain strength against thermal stress, then the strength against thermal stress is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvestrength against thermal stressVSAvoidmanufacturing of thick solid electrolyte layers

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention changes the parameter of solid electrolyte layer thickness from millimeter order (thick) to sub-millimeter order (thin), making the layers thinner and easier to manufacture. This is made possible by the holder member structure that provides mechanical support and distributes compressive force, allowing thin electrolyte layers to maintain sufficient thermal stress resistance without requiring excessive thickness.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If the whole fuel cell stack is formed into a donut shape with gases supplied through central portions, then thermal stresses are managed, but the device complexity increases and manufacturing becomes more difficult

Engineering Contradiction:

Improvethermal stress managementVSAvoiddonut shape configuration

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Instead of forming the entire fuel cell stack into a complex donut shape with central gas supply, the invention inverts the approach by using flat cell plates with peripheral holding structures. The holder member applies compressive force at the periphery, achieving thermal stress management through a simplified, planar configuration rather than a three-dimensional donut structure.

Inventive Principle:

Principle #13The other way round (Inversion)

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 design enhances the durability and longevity of the solid electrolyte layer, maintains high electric-power generating ability, reduces thermal expansion effects, and simplifies gas management, leading to improved reliability and efficiency.

Implementation Method 1

a solid electrolyte, a cathode substance layer which is formed on one surface of the solid electrolyte, and an anode substance layer which is formed on the other surface of the solid electrolyte

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a holder member which holds a part of the cell plate

Methodology Applied

Scientific EffectMechanical compression: Compression

Data Source

PatentUS7811716B2Fuel cell

Publication Date: 2010.10.12 NISSAN MOTOR CO LTD

AI summary

A fuel cell comprises: a cell plate (11; 110; 110A, 110B); an electroconductive gas separator (13; 130; 130A; 130B) which cooperates with the cell plate, to form a gas passage; and a holder member (15; 150; 150A; 150B) which holds a part of the cell plate. The cell plate includes a supporting body (37; 370; 370A; 370B), and a cell (39; 390; 390A; 390B) formed on the supporting body. The cell includes a solid electrolyte (43), a cathode substance layer (45) formed on one surface of the solid electrolyte, and an anode substance layer (41) formed on the other surface of the solid electrolyte.