Conductive Coating Interface for Fuel Cell Stack Contact Stability
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Solution Overview
Problem
In fuel cell stacks, high pressing forces to achieve electrical contact between bipolar plates and gas diffusion layers can damage the gas diffusion layer, reduce its porosity, and lead to inhomogeneous gas distribution, due to poor bonding properties of carbon fibers and Teflon.
Innovation Solution
An electrically conductive coating is applied between the bipolar plate and the gas diffusion layer to establish a material-locking and form-locking connection, reducing the need for high pressing forces and improving electrical contact, using a coating material with a thixotropic flow behavior and containing conductive fillers like graphite or silver, which is cured at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressing forces are applied to achieve electrical contact between bipolar plate and gas diffusion layer, then electrical contact is improved, but the gas diffusion layer is damaged and porosity is reduced
Solution Approach 1:
A coating layer is applied to the bipolar plate serving as an intermediary between the bipolar plate and the gas diffusion layer. This coating provides bonding sites that enable strong adhesion to the gas diffusion layer without requiring high pressing forces, thus preventing damage while ensuring reliable electrical contact.
Solution Approach 2:
The surface properties of the bipolar plate are changed by applying a coating with different material characteristics. This coating has optimized bonding properties that allow it to adhere strongly to the gas diffusion layer at lower pressing forces, changing the interface parameters to resolve the contradiction between contact quality and damage prevention.
2Reliability
If high pressing forces are applied to achieve electrical contact, then transition resistance decreases, but gas distribution becomes inhomogeneous
Solution Approach 1:
The coating acts as a mediator that provides a compliant interface between the rigid bipolar plate and the porous gas diffusion layer. This allows for uniform pressure distribution and maintains the porous structure's integrity, ensuring homogeneous gas distribution while achieving low transition resistance through improved electrical contact.
3Stability of the object's composition
If high pressing forces are applied to establish electrical contact, then contact stability is improved, but structural integrity of gas diffusion layer is reduced
Solution Approach 1:
The coating layer serves as a protective intermediary that bonds to both the bipolar plate and the gas diffusion layer. This creates a stable, multi-layered structure where the coating absorbs mechanical stresses, maintaining contact stability while protecting the fragile gas diffusion layer from direct compression damage.
4Strength
If pressing force is reduced to prevent damage, then structural integrity is maintained, but electrical contact and bonding strength are insufficient
Solution Approach 1:
The coating provides the necessary bonding function that would otherwise require high pressing forces. By applying this intermediary layer with optimized adhesive properties, strong electrical contact and bonding strength are achieved through chemical adhesion rather than mechanical compression, allowing low pressing forces to be used while maintaining structural integrity.
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
This solution enhances the electrical contact between the bipolar plate and gas diffusion layer, reduces transition resistance, prevents damage to the gas diffusion layer, and improves gas distribution, while avoiding the need for compressive forces, thus maintaining the structural integrity and efficiency of the fuel cell stack.
Implementation Method 1
using a coating material with a thixotropic flow behavior
Implementation Method 2
the coating is electrically conductive... improves electrical contact... reduces transition resistance
Data Source
AI summary
The invention relates to a fuel cell stack (1) comprising at least one bipolar plate (3), at least one gas diffusion layer (5) and at least one electrolyte, in particular at least one membrane (7), wherein a coating (9) is arranged as a connecting means between the at least one bipolar plate (3) and the at least one gas diffusion layer (5) and the coating (9) is electrically conductive. The invention further relates to a method for producing the fuel cell stack (1).