Fuel Cell Separator Stainless Steel With Low Contact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stainless steel separators for polymer fuel cells face challenges with high interfacial contact resistance due to oxide films formed during bright annealing, requiring additional costly coating processes to improve conductivity.
Innovation Solution
An austenitic stainless steel composition with specific alloying elements and a manufacturing method involving bright annealing followed by alternating current electrolysis in a sulfuric acid solution to reduce interfacial contact resistance without additional surface treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stainless steel is bright-annealed in a reducing atmosphere to prevent surface defects and control tension, then surface quality and mechanical properties are improved, but an oxide film with high resistance is formed on the surface
Solution Approach 1:
The patent applies alternating current electrolysis to change the chemical state of the oxide film on the stainless steel surface. By controlling the electrolysis parameters (current density, time, electrolyte composition), the high-resistance oxide film is converted into a low-resistance conductive layer, resolving the contradiction between maintaining surface quality from bright annealing and reducing interfacial contact resistance.
2Reliability
If a coating process is applied to reduce interfacial contact resistance, then electrical conductivity is improved, but manufacturing cost and manufacturing time increase
Solution Approach 1:
The patent uses alternating current electrolysis to enable the stainless steel surface to self-modify its properties. The electrolysis process directly transforms the oxide film into a conductive state without requiring external coating materials or additional coating equipment, thereby reducing manufacturing steps and costs while achieving the desired low contact resistance.
3Reliability
If a coating process is applied to reduce interfacial contact resistance, then electrical conductivity is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive noble metal coatings (such as gold or platinum) with an inexpensive alternating current electrolysis treatment. The electrolysis uses common electrolytes and requires no precious materials, achieving the same functional effect of reducing contact resistance at a fraction of the material cost.
4Reliability
If additional post-processing steps are applied to improve contact resistance, then interfacial contact resistance is reduced, but device complexity increases
Solution Approach 1:
The patent combines the surface treatment and contact resistance reduction into a single alternating current electrolysis step. This integrated process simultaneously achieves surface cleaning, oxide film modification, and conductivity improvement, eliminating the need for separate coating and treatment steps, thereby simplifying the overall manufacturing process.
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 method effectively lowers interfacial contact resistance to 10 mΩ·cm2 or less, improving the electrical conductivity of stainless steel separators for fuel cells without increasing manufacturing costs or time.
Implementation Method 1
bright-annealed in a reducing atmosphere using hydrogen or nitrogen for recrystallization and removal of residual stress
Implementation Method 2
an oxide film formed by bright annealing
Implementation Method 3
performing alternating current electrolysis on the bright-annealed material in a sulfuric acid solution
Data Source
AI summary
Disclosed is an austenitic stainless steel for a fuel cell separator with improved contact resistance. The austenitic stainless steel for a fuel cell separator with improved contact resistance according to an embodiment of the present disclosure includes, in percent by weight (wt %), at most of C (excluding 0), at most 3.0% of Si (excluding 0), at most 3.0% of Mn (excluding 0), 20 to 30% of Cr, 8 to 20% of Ni, at most 0.003% of S, at most 0.03% of P, at most 0.6% of Mo (excluding 0), at most 0.8% of Cu (excluding 0), 0.1 to 0.3% of N, at most 2.0% of W (excluding and the remainder being Fe and other inevitable impurities.