Fuel Cell Separator with Buried Conductive Particles

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Solution Overview

Problem

The use of metallic separators in fuel cells results in increased contact resistances due to a passive film with high electric resistance, leading to higher manufacturing costs when conductive particles are applied uniformly across the separator's surface.

Innovation Solution

Conductive particles are selectively buried in projecting parts of the separators, and carbon fibers are buried in other projecting parts, only where contact with adjacent separators or gas diffusion layers occurs, reducing the amount of conductive material needed and lowering manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive particles are disposed on the entire surface of the separator, then the electric resistance on the surface is reduced, but the manufacturing cost increases due to increased amount of conductive particles

Engineering Contradiction:

Improveelectric resistanceVSAvoidamount of conductive particles

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by disposing conductive particles only in specific regions where contact is required (edges and protruding portions) rather than uniformly across the entire separator surface. This targeted approach reduces the quantity of conductive particles needed while maintaining sufficient conductivity in critical areas, thereby resolving the contradiction between reducing electric resistance and minimizing material consumption.

Inventive Principle:

Principle #3Local quality

2Productivity

If metallic separators are used, then productivity and manufacturing cost are improved, but contact resistance increases due to passive film formation

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidcontact resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the surface parameters of the metallic separator by introducing conductive particles into specific regions. This modifies the electrical properties of the separator surface without changing the bulk material or manufacturing process, thereby reducing contact resistance while maintaining the productivity advantages of metallic separators.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by combining metallic separator material with conductive particles in specific regions. This composite approach allows the separator to retain the mechanical and manufacturing advantages of metal while adding localized electrical conductivity to overcome the passive film issue.

Inventive Principle:

Principle #40Composite materials

3Reliability

If conductive particles are disposed on the entire surface, then conductivity is improved, but the amount of conductive material increases leading to higher manufacturing cost

Engineering Contradiction:

ImproveconductivityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent implements local quality by concentrating conductive particles only in regions requiring conductivity (edges and protruding portions) rather than applying them uniformly across the entire surface. This selective disposition maintains necessary conductivity while significantly reducing the amount of expensive conductive material required, thereby lowering manufacturing costs.

Inventive Principle:

Principle #3Local quality

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 approach improves conductivity specifically where needed, reducing contact resistances and manufacturing costs while maintaining effective fuel cell performance.

Implementation Method 1

conductive particles are disposed so that they penetrate a passive film formed on a surface of a separator

Methodology Applied

Scientific EffectPassive film penetration:

Implementation Method 2

the carbon fibers buried in these projecting parts come into contact with the first and second gas diffusion layers, respectively

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11205784B2Fuel cell and method for manufacturing separator for fuel cell including conductive particles and carbon fibers buried in projecting parts

Publication Date: 2021.12.21 TOYOTA JIDOSHA KK

AI summary

A fuel cell according to the present disclosure includes separators 11 and 12 made of metal and having projection-depression shapes, and gas diffusion layers 13 and 14. Conductive particles 21 are buried in a projecting part on one surface of each of the separators 11 and 12, and carbon fibers 22 are buried in a projecting part on the other surface of each of the separators 11 and 12. The projecting parts on the one surfaces of the separators 11 and 12 abut against each other so that the conductive particles 21 buried in these projecting parts come into contact with each other. Further, the projecting parts on the other surfaces of the separators 11 and 12 abut against the gas diffusion layers 13 and 14, respectively, so that the carbon fibers 22 buried in these projecting parts come into contact with the gas diffusion layers 13 and 14, respectively.