Iridium Bipolar Plate Coating for Low-Resistance Corrosion Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bipolar plates in fuel cells and electrolyzers face challenges such as brittleness, high surface resistance, electrochemical degradation, and high production costs, particularly due to the use of gold coatings which are expensive and prone to corrosion.
Innovation Solution
A layer system comprising a metallic substrate with a base layer system including titanium and niobium, and a cover layer containing iridium and non-metallic elements like carbon, which forms a stable and conductive top layer with high corrosion resistance and low electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gold layer is applied to austenitic stainless steel substrate, then corrosion resistance is improved, but production cost increases significantly
Solution Approach 1:
The coating is divided into multiple functional layers: a base layer (chromium-containing layer) providing corrosion protection and a top layer (conductive coating) providing electrical conductivity. This segmentation allows each layer to be optimized for its specific function while using cost-effective materials, eliminating the need for expensive gold coating.
Solution Approach 2:
The invention replaces expensive precious metal coatings (gold, platinum) with cheaper alternative materials such as chromium-containing coatings and conductive polymer coatings. These cheaper coatings provide equivalent or superior performance in terms of corrosion resistance and electrical conductivity, significantly reducing production costs.
2Power
If metallic bipolar plates are used to reduce thickness and weight, then power output is improved, but surface oxides form causing high surface resistance and electrochemical degradation
Solution Approach 1:
The bipolar plate uses a composite structure combining metallic substrate with multiple coating layers. The base layer (chromium-containing) provides oxidation resistance, while the top conductive coating layer maintains low electrical resistance. This composite approach allows thin metallic plates to achieve both high power output and low surface resistance.
Solution Approach 2:
The invention changes the surface properties of the metallic plate through controlled oxidation and coating application. By creating a chromium oxide layer and subsequent conductive coating, the surface parameters are modified to achieve low electrical resistance while maintaining the bulk metallic properties for high power output.
3Reliability
If precious metal layers with thickness over 2 μm are applied to prevent dissolution, then corrosion resistance is improved, but production cost increases and layer complexity increases
Solution Approach 1:
The invention replaces thick precious metal layers with much thinner coatings of cheaper materials. The chromium-containing base layer (few micrometers) provides corrosion protection equivalent to thick precious metal layers, while the conductive top layer (nanometer to micrometer scale) provides electrical conductivity, reducing material costs significantly.
Solution Approach 2:
The invention changes the approach from using thick layers of expensive materials to thin layers of cheaper materials with optimized composition. By controlling the thickness and composition of the chromium-containing base layer and conductive top layer, equivalent protection is achieved at lower cost and reduced complexity.
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 proposed layer system achieves high corrosion resistance, low surface resistance, and extended service life, while reducing the use of precious metals, thus lowering production costs and improving the performance of fuel cells and electrolyzers.
Implementation Method 1
the cover layer is formed from a homogeneous or heterogeneous solid metallic solution or compound... which forms a stable and conductive top layer with high corrosion resistance
Implementation Method 2
a cover layer and a base layer system... the base layer system has at least a first base layer in the form of a metallic alloy layer comprising the chemical elements titanium and niobium... which forms a stable and conductive top layer with high corrosion resistance and low electrical resistance
Data Source
Figure 1
AI summary
The invention relates to a layer (3a), in particular for a bipolar plate (1) of a fuel cell or an electrolyzer, wherein the layer (3a) consists of a homogeneous or heterogeneous solid metallic solution or compound. According to the invention, the layer (3a) comprises either a first chemical element from the group of noble metals in the form of iridium, or a first chemical element from the group of noble metals in the form of iridium and a second chemical element from the group of noble metals in the form of ruthenium, as well as at least one further non-metallic chemical element from the group comprising nitrogen, carbon, boron, fluorine, and hydrogen. The invention further relates to a layer system (3), a bipolar plate (1) with such a layer system (3), a fuel cell, and an electrolyzer.