Fuel Cell Separator Surface Treatment for Low Contact Resistance
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Solution Overview
Problem
Solid polymer fuel cell separators made from stainless steel or titanium alloys face challenges in achieving low contact resistance and maintaining flatness, which are essential for efficient energy conversion and stacking, while also requiring high workability and low production costs.
Innovation Solution
A method involving the use of low ion release conductive substances like Au, WC, or TaN buried in the surface of stainless steel or titanium alloy separators, with specific surface roughness and particle size conditions, to reduce contact resistance and prevent ion release, ensuring flatness and stability for stacking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stainless steel or titanium alloy separators are used to achieve high workability and low cost, then productivity and manufacturing cost are improved, but contact resistance increases and flatness deteriorates
Solution Approach 1:
The patent applies local quality by treating only the surface layer of the separator with conductive substances (Au, WC, or TaN) rather than modifying the entire separator. This surface treatment creates a localized conductive pathway that reduces contact resistance without altering the bulk material properties of the stainless steel or titanium alloy, thereby maintaining high workability and low cost while improving electrical contact performance.
Solution Approach 2:
The patent creates a composite structure by combining stainless steel or titanium alloy base material with embedded conductive substance particles. The composite consists of the metal matrix (providing mechanical strength and workability) and dispersed conductive particles (providing low contact resistance), achieving a balance between productivity and reliability.
2Productivity
If stainless steel or titanium alloy separators are used to achieve high workability and low cost, then productivity and manufacturing cost are improved, but flatness deteriorates
Solution Approach 1:
The flatness improvement is achieved locally through surface treatment with conductive substances rather than requiring changes to the entire separator structure. The surface layer modification provides the necessary flatness for stacking while the bulk material maintains its high workability characteristics.
3Reliability
If conventional conductive substances are used on separator surface, then contact resistance is reduced, but ion release increases causing deterioration
Solution Approach 1:
The patent selects conductive substances (Au, WC, TaN) that provide durable low contact resistance without significant ion release. These materials are chosen for their stability and low reactivity, effectively serving as long-lasting conductive layers that do not deteriorate through ion release, unlike conventional conductive materials.
Solution Approach 2:
The patent changes the material parameters by selecting specific conductive substances with inherent low ion release properties. The selection of Au, WC, or TaN represents a parameter change in material composition that simultaneously achieves low contact resistance and minimizes ion release, resolving the contradiction between reliability and harmful factors.
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 approach results in separators with a contact resistance of 15 mΩcm² or less and improved flatness, enabling efficient energy conversion and cost-effective production, suitable for fuel cell applications.
Implementation Method 1
a contact resistance value with respect to carbon paper of 15 mΩcm2 or less at a surface pressure of 1 MPa
Implementation Method 2
an arithmetic mean roughness (Ra) of 0.5 to 5.0 μm, a 10-point mean roughness (Rz) of 3 to 20 μm, and an average spacing of surface relief shapes (Sm) of 300 μm or less
Data Source
AI summary
The present invention releases a method of producing a metal separator for a solid polymer fuel cell by stainless steel, titanium, or titanium alloy during which securing lower cost and mass producibility by using a material having a high workability to form a complicated shape by a high productivity, then using an inexpensive blast process to drive a conductive substance into the surface of the metal separator member, that is, provides a stainless steel, titanium, or titanium alloy solid polymer fuel cell separator comprised of stainless steel, titanium, or titanium alloy in the surface of which a low ion release conductive substance is buried, having an arithmetic mean roughness (Ra) of the separator surface of 0.5 to 5.0 μm, having a 10-point mean roughness (Rz) of 3 to 20 μm, having an average spacing of surface relief shapes (Sm) of 300 μm or less, having values of a warp rate and twist rate of a separator of 0.1 or less, and having a contact resistance value with respect to carbon paper of 15 mΩcm2 or less at a surface pressure of 1 MPa.