Fuel Cell Separator Plate Molding for Thin Conductive Laminates
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Solution Overview
Problem
Current methods for producing thin bipolar plates for fuel cells are complex and inefficient, particularly in dispersing polyphenylene sulfide (PPS) in aqueous media due to its poor wetting properties, which affects the electrical properties and requires high polymer loading in extrusion processes, leading to suboptimal mechanical and electrical performance.
Innovation Solution
A method involving the formation of a malleable precursor sheet with a thermoplastic polymer blend of PTFE and PPS, combined with carbon fibers and particles, which is then hot-compression molded into a thin, electrically conductive separator plate, optimizing the dispersion and alignment of carbon fibers for enhanced mechanical and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high polymer loading is used in extrusion process to disperse PPS, then PPS dispersion is improved, but electrical properties deteriorate
Solution Approach 1:
The patent changes the processing parameters by using hot-compression molding instead of extrusion, and by controlling the polymer content to be below 30 wt.%, thereby achieving good dispersion without compromising electrical properties
Solution Approach 2:
The patent uses a master batch as an intermediary carrier to pre-disperse PPS with carbon particles, which then facilitates uniform distribution in the final compound without requiring high polymer loading
2Length of stationary object
If multi-step process is used to produce thin BPPs from powdered compound, then thickness is reduced, but process complexity increases
Solution Approach 1:
The patent combines multiple steps (compounding, sheet formation, and molding) into a streamlined process where a master batch is prepared once and then used to produce thin BPPs in a single compression molding step, reducing overall process complexity
Solution Approach 2:
The patent performs preliminary dispersion of PPS and carbon particles in a master batch before the final molding step, which simplifies the subsequent production of thin BPPs by eliminating the need for complex multi-step processing
3Strength
If carbon fiber length is increased to improve mechanical properties, then flexural strength is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent optimizes the carbon fiber length parameter to a specific range (0.5-2 mm) that provides sufficient flexural strength while being compatible with the compression molding process, avoiding the manufacturing difficulties associated with much longer fibers
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 process results in bipolar plates with improved mechanical strength, reduced areal specific resistance, and increased electrical conductivity, meeting or exceeding the DOE's 2020 targets for transportation applications, with a self-organized laminate structure and reduced material usage.
Implementation Method 1
hot-compression molded into a thin, electrically conductive separator plate
Implementation Method 2
hot-compression molded
Implementation Method 3
electrically conductive separator plate
Implementation Method 4
thermoplastic polymer blend of PTFE and PPS
Data Source
AI summary
For production of a separator plate in a fuel cell, a malleable precursor sheet is made by mixing thermoplastic polymer, carbon fibers, and electroconductive carbon particles, which is then hot-compression molded as a single layer or multi-layer structure or multi-layer structure, where the layer thickness is less than the length of the carbon fibers.