Stainless Steel Separator with Segmented Strike Layer
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Solution Overview
Problem
Polymer electrolyte fuel cells require separators with excellent corrosion resistance and adhesion properties to maintain durability and efficiency, but existing metal separators face issues with high contact resistance and peeling of the Sn alloy layer, especially when made thinner.
Innovation Solution
A stainless-steel foil separator with a Sn alloy layer and a strike layer, where the strike layer's coverage is limited to 2% to 70% and distributed in island form with a maximum diameter of 1 μm or less, and optionally coated with a Sn-containing oxide layer, to enhance adhesion and prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a continuous strike layer is formed on the substrate to improve adhesion of the Sn alloy layer, then adhesion property is improved, but corrosion resistance deteriorates due to continuous corrosion of the strike layer
Solution Approach 1:
The strike layer is segmented into isolated island portions distributed on the substrate surface, with each island having a maximum diameter of 1 μm or less and coverage of 2% to 70%. This segmentation prevents continuous corrosion pathways while maintaining adhesion at the island-substrate interfaces, resolving the contradiction between adhesion improvement and corrosion resistance.
Solution Approach 2:
The strike layer is applied locally in specific island regions rather than uniformly across the entire substrate surface. This local application provides adhesion enhancement exactly where needed at the Sn alloy layer-substrate interface, while leaving other areas free from the strike layer's corrosion susceptibility, thus balancing adhesion and corrosion resistance.
2Quantity of substance
If the Sn alloy layer is made thinner to reduce material cost and improve compactness, then manufacturing cost and size are reduced, but corrosion resistance deteriorates
Solution Approach 1:
The strike layer islands are formed preliminarily on the substrate before applying the thin Sn alloy layer. These pre-formed islands provide localized adhesion anchors and corrosion protection zones, enabling the Sn alloy layer to be made thinner while maintaining overall corrosion resistance through the strike layer's protective islands.
Solution Approach 2:
The separator employs a composite structure combining the substrate, strike layer islands, and thin Sn alloy layer. This composite architecture leverages the substrate's structural integrity, the strike layer's adhesion and localized corrosion resistance, and the thin Sn alloy layer's corrosion protection, achieving both cost reduction and maintained reliability.
3Reliability
If graphite is used as separator material to achieve low contact resistance and high corrosion resistance, then electric conductivity and durability are improved, but mechanical strength and processability deteriorate due to brittleness and high processing cost
Solution Approach 1:
The invention replaces expensive, brittle graphite separators with a cost-effective metal substrate (such as stainless steel) that offers superior mechanical strength and processability. The substrate serves as a durable, replaceable base that can be easily formed into complex shapes, eliminating graphite's manufacturing limitations while maintaining functional performance.
Solution Approach 2:
The metal substrate is combined with a thin Sn alloy layer and strike layer islands to create a composite separator that achieves graphite-like corrosion resistance and electrical conductivity. The metal substrate provides the mechanical strength and processability that graphite lacks, while the Sn alloy coating delivers the chemical inertness and conductive properties, creating a material that surpasses graphite in overall performance.
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 solution provides a fuel cell separator with improved corrosion resistance and adhesion properties, maintaining durability and efficiency while allowing for compactness and low material costs.
Implementation Method 1
a strike layer with which a surface of the substrate is coated
Implementation Method 2
excellent corrosion resistance and adhesion property
Data Source
AI summary
The surface of a substrate made of stainless-steel foil is coated with a Sn alloy layer, with a strike layer in between. The coverage of the strike layer on the substrate is 2% to 70%.