Cr2N Coated Fuel Cell Separator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional metallic separators for fuel cells face high manufacturing costs and corrosion issues, leading to increased interfacial contact resistance and reduced performance due to the formation of oxide films and high electrical resistivity, limiting their widespread industrial application.
Innovation Solution
A metallic separator with a Cr2N layer formed on the surface of a base metal, such as stainless steel, is fabricated using a nickel strike process followed by chromium plating and nitriding, under controlled nitrogen partial pressure and cooling conditions to prevent the formation of CrN, resulting in improved corrosion resistance and reduced electrical resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a metallic separator is used to reduce cost and weight, then manufacturing cost and weight are reduced, but corrosion resistance deteriorates and oxide films form on the surface
Solution Approach 1:
The patent applies composite materials by combining a metallic base material (such as stainless steel) with a chromium nitride coating layer. This composite structure provides both the weight reduction benefits of metal and the corrosion resistance of the ceramic-like chromium nitride layer, effectively resolving the contradiction between weight reduction and corrosion resistance maintenance.
Solution Approach 2:
The patent changes the surface composition and chemical properties of the metallic separator by forming a chromium nitride layer through nitriding treatment. This parameter change in surface chemistry transforms the reactive metal surface into a stable, corrosion-resistant chromium nitride surface, maintaining reliability while using lightweight metal基材.
2Ease of manufacture
If a metallic separator is used to reduce cost and weight, then manufacturing cost is reduced, but electrical resistivity increases due to oxide film formation
Solution Approach 1:
The chromium nitride coating forms a composite structure with the metallic base, where the chromium nitride layer prevents oxide film formation on the metal surface. This composite approach maintains low electrical resistivity by preventing the formation of high-resistivity oxide films, while still providing cost advantages over graphite separators.
Solution Approach 2:
The chromium nitride coating is applied in advance to the metallic separator surface to prevent oxide film formation. This preliminary protective action blocks the oxidation process before it can occur, thereby preventing the increase in electrical resistivity that would result from oxide film formation, while maintaining the cost benefits of using metal基材.
3Volume of moving object
If separator thickness is reduced to make the stack compact, then volume is reduced, but manufacturing precision becomes more difficult to achieve
Solution Approach 1:
The nitriding process parameters (temperature, time, nitrogen potential) are optimized to achieve uniform chromium nitride layer formation on thin metallic separators. This parameter optimization enables precise control of the coating thickness and quality even on thin substrates, allowing reduced separator thickness while maintaining manufacturing precision through controlled surface treatment rather than relying solely on substrate thickness.
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 Cr2N layer enhances corrosion resistance and reduces interfacial contact resistance by 50%, enabling a more efficient and cost-effective fuel cell separator with a thinner design, thus addressing the limitations of conventional separators.
Implementation Method 1
a chromium nitride layer is fabricated on the surface of a metallic base material
Implementation Method 2
forming a Cr2N layer on a chromium-plated layer by adjusting the nitriding condition
Implementation Method 3
plating chromium on the surface of the base metal
Data Source
AI summary
Provided are a metallic separator for fuel cell in which a Cr2N layer is formed on the surface of base metals, and a method of fabricating the metallic separator or fuel cell. The method comprises: plating chromium layer on the surface of the base metal; and forming a Cr2N layer by nitriding the chromium-plated layer in properly selected nitriding conditions. Only the Cr2N layer, which has lower electrical resistivity than CrN, is selectively fabricated on the surface of the base metal. The interfacial contact resistance of the separator is reduced and the efficiency of the fuel cell can be improved. In addition, since a low-priced general metals or alloys such as stainless steels, carbon steels, alloy steels or even nonferrous alloys can be used as the base metal, the cost of the fabrication of metallic separator can be significantly reduced. The thickness of the separator can be made as small as to 0.2 mm, the weight and total thickness of a fuel cell stack can be significantly reduced.