Fuel Cell Separator Plate Wettability Modification
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Solution Overview
Problem
Excessive water accumulation in fuel cell flow field channels leads to reduced performance, increased gas flow resistance, and parasitic load on system components, necessitating improved water management and surface electrical conductivity in fuel cell systems.
Innovation Solution
Surface treatment of separator plates using an aqueous solution of hydrogen peroxide with transition metal salts to increase wettability and reduce electrical contact resistance, combined with silanization to modify hydrophobicity or hydrophilicity, thereby enhancing water management and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flow field channels are made hydrophobic to facilitate water removal, then water droplets become unstable and require less time to remove, but water accumulation occurs causing channel blockage and reduced fuel cell performance
Solution Approach 1:
The patent applies different wettability properties to different locations on the separator plate surface. Specifically, the flow field channels are made hydrophobic to promote water removal, while the ribs are made hydrophilic to facilitate water spreading and prevent channel blockage. This local differentiation of surface properties resolves the contradiction between efficient water removal and prevention of channel blockage.
2Loss of energy
If the separator plate surface is made more conductive to reduce electrical resistance, then ohmic losses decrease, but water management capability deteriorates leading to excessive water accumulation
Solution Approach 1:
The patent uses silane treatments to create localized electrical conductivity enhancements on the separator plate surface without compromising overall water management. By applying conductive coatings or treatments specifically to certain areas of the separator plate while maintaining the hydrophobic/hydrophilic pattern, the patent reduces ohmic losses while preserving the water channeling functionality.
3Ease of operation
If chemical treatments are applied to modify surface wettability, then water distribution improves, but surface electrical conductivity may be reduced
Solution Approach 1:
The patent employs composite surface treatments that combine hydrophobic/hydrophilic chemical treatments with conductive materials. The separator plate surface is treated with silanes or other compounds that provide both the desired wettability characteristics and maintain or enhance electrical conductivity. This composite approach allows simultaneous achievement of improved water distribution and preserved electrical conductivity.
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
Significantly reduces water blockages, pressure drop, and flow resistance in fuel cells, improving performance and reducing parasitic loads, while decreasing contact resistance and ohmic losses through the fuel cell stack.
Implementation Method 1
reacting the separator plate with an aqueous solution of hydrogen peroxide. The aqueous solution of hydrogen peroxide comprises one or more salts of one or more transition metals
Implementation Method 2
modifying the wettability of the separator plate by treating the separator plate with a solution comprising one or more silanes
Implementation Method 3
promotes water removal via the film flow along the channel walls and via capillary mechanisms
Data Source
AI summary
A method of surface treating a separator plate of a fuel cell comprises reacting the separator plate with an aqueous solution of hydrogen peroxide. The aqueous solution of hydrogen peroxide comprises one or more salts of one or more transition metals. The one or more transition metals have variable oxidation states. This method makes the surface of the separator plate hydrophilic (˜35 deg contact angle of water) and improves its electrical conductivity. The method of surface treating a separator plate (e.g., a graphite and/or graphite composite plate) of a fuel cell can further comprise a method of modifying wettability of the separator plate comprising treating the separator plate with a solution comprising one or more silanes. In another embodiment, a method of modifying wettability of a separator plate (e.g., a stainless steel separator plate) of a fuel cell comprises treating the separator plate with a solution comprising one or more silanes without a surface treating step prior to treating the separator plate with the solution comprising one or more silanes.