Bipolar Plate Composition for Conductivity Without PVDF Insulating Domains
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Solution Overview
Problem
Current methods for producing bipolar plates face challenges in achieving high thermal and electrical conductivity, mechanical properties, and easy processing, particularly due to the formation of insulating domains during compression molding, which affects the performance and manufacturing efficiency of polymer/carbon composite bipolar plates.
Innovation Solution
A method involving melt-blending a fluorinated polymer with a first conductive filler, grinding the mixture into powder, and then mixing it with a second conductive filler, such as graphite, to create a conductive fluorinated polymer composition that can be easily processed and compression-molded into bipolar plates with improved conductivity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compression molding is used to manufacture bipolar plates, then manufacturing efficiency is improved, but insulating domains of PVDF form that reduce electrical and thermal conductivity
Solution Approach 1:
The patent applies preliminary action by pre-dispersing carbon black in PVDF using high-shear mixing before compression molding. This pre-dispersion prevents the formation of insulating PVDF domains during molding, ensuring continuous conductive networks are established beforehand. The carbon black-PVDF master batch is prepared in advance with proper dispersion, then combined with graphite particles before final molding, eliminating the conductivity problem while maintaining manufacturing efficiency.
Solution Approach 2:
The patent uses composite materials by creating a multi-component system consisting of PVDF binder, carbon black dispersant, and graphite conductive filler. The carbon black serves as a dispersing agent that also contributes to conductivity, while graphite provides the primary conductive network. This composite approach ensures both good dispersion of carbon components and high electrical/thermal conductivity, resolving the contradiction between processing ease and conductivity.
2Reliability
If high carbon black content is used to improve conductivity, then electrical and thermal conductivity improve, but dispersion difficulty increases forming isolating domains
Solution Approach 1:
The patent uses carbon black as an intermediary substance that serves dual functions: dispersing the PVDF polymer matrix and providing electrical/thermal conductivity. The high-shear mixing process creates a carbon black-PVDF master batch where carbon black particles are uniformly distributed, preventing PVDF isolating domains. This intermediary approach allows high carbon content (up to 40 wt% or more) while maintaining good dispersion and conductivity.
Solution Approach 2:
The patent applies parameter changes by using high-shear mixing conditions (high shear rate and temperature) to dramatically improve carbon black dispersion in PVDF. The increased shear force during mixing overcomes the aggregation tendency of carbon black, achieving uniform distribution at high concentrations. This parameter change enables high conductivity without the dispersion difficulties that would normally prevent it.
3Reliability
If graphite particles are used as conductive filler, then conductivity improves, but particle aggregation occurs reducing processing ease
Solution Approach 1:
The patent merges multiple conductive components (carbon black and graphite) into a unified composite system. Carbon black provides fine-scale dispersion and conductivity, while graphite particles provide bulk conductivity. The high-shear mixing process combines these components into a homogeneous master batch that can be easily processed. This merging approach allows graphite to be used at lower concentrations with improved distribution, reducing aggregation issues while maintaining high 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
The approach results in bipolar plates with high in-plane and through-plane conductivity, thermal conductivity, and enhanced mechanical properties like flexural and compressive strength, reducing the need for post-treatment processes like sand blasting and improving manufacturing efficiency.
Implementation Method 1
a binder comprising a fluorinated polymer in which a conductive filler is dispersed
Implementation Method 2
bipolar plates with high in-plane and through-plane conductivity
Implementation Method 3
bipolar plates with high in-plane and through-plane conductivity, thermal conductivity
Data Source
AI summary
The invention relates to a method for producing a composition comprising the steps of: melt-blending a fluorinated polymer, preferably a polyvinylidene fluoride polymer, with a first conductive filler so as to obtain a conductive fluorinated polymer; grinding to powder said conductive fluorinated polymer; mixing the powder of conductive fluorinated polymer with a second conductive filler. The invention also relates to a composition comprising a second conductive filler and particles of conductive fluorinated polymer, wherein the particles of conductive fluorinated polymer comprise a fluorinated polymer matrix in which a first conductive filler is dispersed The invention also relates to a method for producing a bipolar plate and to a bipolar plate.