Electrolyzer Bipolar Plate Coating for Low Contact Resistance
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Solution Overview
Problem
In electrochemical cells, such as electrolyzers, the formation of oxide layers on metallic plates and porous transport layers leads to increased contact resistance and corrosion, reducing performance and stability, especially under high voltages, where materials like stainless steel and titanium are not stable, and existing coatings like gold and platinum are costly and prone to oxidation.
Innovation Solution
A porous transport layer comprising Ir, Ru, Rh, or Os, or their oxides, with a loading of 0.010 g/m² to 2.0 g/m², is applied to the bipolar plate and porous transport layer, providing high corrosion resistance without affecting performance, as the oxides formed have good electrical conductivity and bond well with passivation layers, reducing the need for additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel or titanium plates are used in electrolyzers, then corrosion resistance is improved, but contact resistance increases due to oxide layer formation
Solution Approach 1:
A porous transport layer comprising Ir, Ru, Rh, Os or their oxides is introduced as an intermediary between the bipolar plate and the electrode. This intermediate layer prevents direct contact between the oxide layer on the bipolar plate and the electrode, thereby eliminating the harmful effect of increased contact resistance while preserving the corrosion resistance of the bipolar plate material.
Solution Approach 2:
The invention changes the material composition parameters of the porous transport layer to include specific noble metals (Ir, Ru, Rh, Os) or their oxides with controlled loading amounts (0.010-2.0 g/m²). These parameter changes ensure the layer maintains low contact resistance even when the underlying bipolar plate forms oxide layers, thus resolving the contradiction between corrosion resistance and contact resistance.
2Reliability
If gold or platinum coatings are applied to bipolar plates, then corrosion resistance is improved, but manufacturing cost increases
Solution Approach 1:
The invention changes the material composition parameters by using Ir, Ru, Rh, or Os and their oxides instead of traditional gold or platinum coatings. By controlling the loading amount to 0.010-2.0 g/m², the manufacturing cost is reduced while maintaining effective corrosion resistance and electrical conductivity performance.
Solution Approach 2:
The porous transport layer is designed as a composite material system combining Ir, Ru, Rh, Os or their oxides with a porous structure. This composite approach provides both corrosion resistance and electrical conductivity at lower cost compared to pure precious metal coatings like gold or platinum.
3Reliability
If thicker coatings are applied in electrolyzers, then corrosion resistance is improved, but material cost increases
Solution Approach 1:
The invention optimizes the coating material parameters by selecting Ir, Ru, Rh, Os or their oxides with specific loading amounts (0.010-2.0 g/m²). This parameter optimization achieves effective corrosion resistance with minimal material quantity, avoiding the need for thick coatings and thereby reducing material costs.
Solution Approach 2:
The porous transport layer with Ir, Ru, Rh, Os or their oxides provides self-protecting corrosion resistance that does not require thick applications. The layer's inherent properties enable effective protection at low loading amounts, eliminating the need for excessive material usage.
4Ease of manufacture
If no coating is applied to bipolar plates, then manufacturing cost is reduced, but oxidation of the plate material occurs leading to performance reduction
Solution Approach 1:
The porous transport layer serves as a protective intermediary between the bipolar plate and the harsh electrochemical environment. It prevents direct oxidation of the bipolar plate material while maintaining electrical conductivity, thus protecting performance without requiring expensive thick precious metal coatings.
Solution Approach 2:
The invention changes the protective layer parameters by using Ir, Ru, Rh, Os or their oxides with optimized loading (0.010-2.0 g/m²). This provides adequate corrosion protection and performance stability at low material cost, avoiding both the oxidation problems of uncoated plates and the high costs of thick coatings.
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 solution achieves high corrosion resistance and maintains low contact resistance even after corrosion tests, eliminating the need for removing passivation layers and reducing manufacturing costs, while ensuring long-term stability under high anodic potentials.
Implementation Method 1
the resulting oxide layers cause high contact resistance... However, the resulting oxide layers cause high contact resistance, which reduces the cell's performance... The coatings of metallic iridium, ruthenium, rhodium, and osmium can be oxidized under the conditions in the electrolyzer. The resulting oxides do not lead to a reduction in performance.
Implementation Method 2
the oxides formed have good electrical conductivity and bond well with passivation layers... It is currently assumed that this is due to the fact that the oxides themselves are highly electrically conductive and therefore do not result in any, or even a significant, increase in the resistance of the bipolar plate or porous transport layer.
Data Source
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AI summary
The invention relates to a bipolar plate and to a porous transport layer for an electrolyser, having a layer (S), which contains a component (K) selected from Ir, Ru, Rh, Os, oxides or mixtures thereof, wherein the loading of the total quantity of Ir, Ru, Rh, Os in metallic and oxidic form, based on Ir, Ru, Rh, Os, is less than 20.0 g/m², based on the layer (S). The invention further relates to a method for the production thereof and to the use thereof in an electrolyser. The invention further relates to the use of the layer (S) as a corrosion prevention layer in electrochemical systems.