Fuel Cell Separator Composite Layering for Conductivity and Strength
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Solution Overview
Problem
The existing separator members for fuel cells using expanded graphite sheets face issues with strength and toughness due to their thickness and low toughness, which affects their conductivity and gas impermeability.
Innovation Solution
A separator member with a graphite layer of 50 g/m2 or less and a volume resistivity of 3 mΩ·cm or less, layered on a resin layer, along with a conductive fiber base material and a second resin layer, to enhance conductivity and strength while maintaining gas impermeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an expanded graphite sheet is used to improve conductivity, then the conductivity is improved, but the strength and toughness decrease due to thickness and low material toughness
Solution Approach 1:
The patent changes the thickness parameter of the graphite layer from conventional thick expanded graphite sheets to a thin layer with controlled layering amount (50 g/m2 or less). This parameter change maintains sufficient conductivity while dramatically improving strength and toughness, resolving the contradiction between conductivity and mechanical strength.
Solution Approach 2:
The patent creates a composite structure by layering the thin graphite layer on top of a resin layer. This composite material approach combines the high conductivity of graphite with the high strength and toughness of the resin base material, achieving both improved conductivity and maintained mechanical properties.
2Reliability
If conventional thick graphite sheets are used, then conductivity is achieved, but manufacturing complexity increases due to swelling and the need for mold release agents
Solution Approach 1:
The patent changes the thickness parameter of the graphite layer to a thin layer (50 g/m2 or less), which eliminates the swelling problem encountered with thick graphite sheets. This parameter change simplifies the manufacturing process by eliminating the need for mold release agents and reducing processing complexity.
Data Source
AI summary
A separator member for a fuel cell includes: a first resin layer including a resin; and a graphite layer that is layered on the first resin layer and substantially made of graphite. The layering amount of the graphite layer is 50 g/m2 or less, and the volume resistivity of the graphite is 3 mΩ·cm or less.