Stainless Steel Fuel Cell Separator Surface for Low Contact Resistance
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Solution Overview
Problem
Fuel cell separators made from ultra-thin stainless steel with bright-annealed surfaces exhibit high contact resistance due to a small contact area with the gas diffusion layer (GDL).
Innovation Solution
The surface of the stainless steel separator is modified by forming five or more fine protrusions of 10 to 100 nm in height, increasing the real surface length and thereby enhancing the contact area with the GDL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bright-annealed surface is used on ultra-thin stainless steel separators, then the manufacturing process is simplified and corrosion resistance is maintained, but the contact area with the gas diffusion layer is reduced, leading to increased contact resistance
Solution Approach 1:
The patent applies preliminary action by forming protrusions on the separator surface during the manufacturing process (before assembly) through controlled oxidation or mechanical treatment. This pre-formed surface structure ensures low contact resistance is built into the separator itself, eliminating the need for additional surface modification steps after manufacturing and avoiding increased contact resistance issues that would arise from using purely bright-annealed surfaces.
2Reliability
If fine protrusions are formed on the separator surface to increase the contact area with the gas diffusion layer, then the contact resistance is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing complex mechanical surface treatment processes with chemical or self-organizing processes. Instead of using mechanical means to create protrusions (which would add manufacturing complexity), the invention utilizes controlled oxidation or spontaneous surface instability during annealing to naturally form the protrusion structure. This substitution simplifies the manufacturing process while achieving the desired surface morphology for low contact resistance.
Data Source
AI summary
Provided are a metal material, for a fuel cell separator, having: five or more fine protrusions of 10 to 100 nm on the metal material surface coming into contact with a GDL in a fuel cell; and a real surface length/protrusion-free apparent surface length ratio of 1.15 or more based on a cross-section observed by a transmission electron microscope. The metal material is characterized by having a contact resistance of 10 mΩ·cm2 or less by forming fine protrusions on the surface.