Bipolar Plate Bilayer Structure for Corrosion-Resistant PEM Electrolysis
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Solution Overview
Problem
Existing bipolar plates in PEM-based water electrolyzers suffer from corrosion, mechanical stress, and limited scalability due to thin coatings like TiN, which crack under bending, and are costly, limiting their performance and scalability.
Innovation Solution
A bilayer structure of different metal sheets, such as stainless steel and titanium or its alloys, with clinch bonding and optional coatings, provides enhanced corrosion resistance and conductivity, suitable for large-scale production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVD-based coatings (TiN, CrN, TiCN, TiC) are applied to protect bipolar plates from corrosion, then corrosion resistance is improved, but the coatings crack under bending or mechanical stress and detach from thin substrates
Solution Approach 1:
The patent applies a composite coating structure consisting of a metallic bond coat (Ni, Ni-alloy, or Cu) combined with a ceramic top coat (TiN, TiCN, or TiC). The bond coat layer provides ductility and adhesion to the substrate, while the ceramic top coat provides corrosion resistance. This composite structure prevents cracking and detachment that occurs with single-layer coatings on thin substrates.
2Ease of manufacture
If single-ply thin metal sheets (VA steel or Ti) are used as bipolar plates, then manufacturing cost and weight are reduced, but corrosion occurs at grain boundaries and hydrogen embrittlement develops
Solution Approach 1:
The patent uses composite material structures: either a dual-metal sheet construction (stainless steel + titanium) or a coated metal sheet where a corrosion-resistant alloy layer is applied to a ductile substrate. This provides both cost-effectiveness and corrosion resistance, preventing grain boundary corrosion and hydrogen embrittlement while maintaining manufacturability.
3Reliability
If thick protective coatings are applied to ensure corrosion protection, then corrosion resistance is improved, but electrical conductivity decreases and contact resistance increases
Solution Approach 1:
The patent creates different coating thicknesses in different regions: a thicker bond coat layer for corrosion protection and adhesion, and a thinner top coat layer (0.5-5 μm) to maintain electrical conductivity. The metallic bond coat specifically provides low contact resistance in electrical contact regions while the ceramic top coat provides corrosion protection where needed.
4Reliability
If PVD coating process is used for bipolar plates, then corrosion resistance is improved, but component dimensions are limited to less than 1.2 m and production costs increase
Solution Approach 1:
The patent segments the coating process into two separate PVD steps: first applying a metallic bond coat, then applying a ceramic top coat. This segmented approach allows each layer to be optimized independently and enables coating of larger components by processing them in sections or using larger PVD chambers for each layer.
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 offers improved corrosion resistance, high electrical conductivity, and scalability, extending the lifetime of PEM electrolysis cells while reducing costs.
Implementation Method 1
PVD-based coatings: TiN, CrN, TiCN or TiC
Implementation Method 2
clinch bonding
Data Source
AI summary
A bipolar plate that is configured for electrolysis has a lower metal sheet and an upper metal sheet. The lower and upper metal sheets are interlinked and the materials of the metal sheets are distinctly different from each other, meaning that one of them is iron-based or nickel-based and the other is not, or an alloying element is present to a greater or lesser degree, or a proportion of an alloying element differs between the materials of the two metal sheets.