PVDF Bonding Layer for Fuel Cell Bipolar Plate Sealing

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Solution Overview

Problem

Existing methods for bonding components in fuel cells, such as PEM fuel cells, face challenges in achieving long-lasting tight sealing due to material incompatibility, thermal instability, and permeability issues, especially at high temperatures.

Innovation Solution

A polymer adhesive made from thermoplastic fluoropolymers, specifically polyvinylidene difluoride (PVDF) and its co-polymers, is used to create a durable and chemically inert bonding layer between plates, which is mixed with solvents and surfactants to form a homogeneous liquid mixture that can be applied at room temperature and cured under pressure, ensuring strong adhesion and impermeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional bonding methods are used for fuel cell plates, then assembly is simple, but sealing reliability deteriorates at high temperatures

Engineering Contradiction:

Improvesealing reliabilityVSAvoidhigh temperature stability

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent applies parameter changes by carefully controlling the curing temperature range (above PVDF melting point but below plate binder melting point) and pressure parameters during bonding. This resolves the contradiction by enabling reliable sealing at high temperatures through optimized process parameters rather than relying on conventional high-temperature resistant adhesives that may compromise other performance aspects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining PVDF polymer adhesive with graphite-containing plates. The PVDF provides high-temperature sealing reliability while the graphite plates provide structural integrity and electrochemical stability. This composite approach resolves the contradiction between simple assembly and high-temperature sealing reliability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If PVDF adhesive is used for bonding plates, then chemical stability improves, but manufacturing complexity increases due to multi-step process

Engineering Contradiction:

Improvechemical stabilityVSAvoidmanufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges multiple functions into a single adhesive material: PVDF provides both the bonding function and the chemical stability function. Instead of using separate adhesive layers for bonding and separate coatings for chemical resistance, the PVDF polymer performs both roles simultaneously, reducing manufacturing complexity while maintaining chemical stability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes phase transitions of PVDF (melting and crystallization) during the bonding process. By controlling temperature through the PVDF melting point, the adhesive transitions from solid to liquid state for bonding, then crystallizes to provide chemical stability. This phase transition mechanism enables both chemical stability and relatively simple manufacturing through temperature-controlled processing.

Inventive Principle:

Principle #36Phase transitions

3Use of energy by moving object

If adhesive is applied at room temperature, then energy consumption decreases, but adhesion strength may be insufficient without curing

Engineering Contradiction:

Improveenergy consumptionVSAvoidadhesion strength

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent utilizes the phase transition of PVDF from solid to liquid at its melting point during curing. The brief thermal energy input causes PVDF to melt and flow, enhancing adhesion strength by improving contact with the plate surfaces. After curing, PVDF crystallizes to provide long-term adhesion strength. This phase transition approach minimizes energy consumption while ensuring sufficient adhesion strength.

Inventive Principle:

Principle #36Phase transitions

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 PVDF-based adhesive provides excellent adhesion and longevity, maintaining impermeability and chemical stability at high temperatures, significantly reducing the risk of leakage and enhancing the durability of fuel cell stacks.

Implementation Method 1

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

the applied to the bipolar plate, for example by painting or screen brushing, and then heated under pressure, for example at a temperature between 150° C. and 200° C. with a duration up to 5 hours

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS11929526B2Method for bonding two plates together for a fuel cell, especially gluing bipolar plates in a fuel cell

Publication Date: 2024.03.12 FISCHER ECO SOLUTIONS

AI summary

A method for bonding two plates together for a fuel cell, wherein the method comprises applying an adhesive to the surface of at least one of the plates and pressing the two plates together with the adhesive in between. The adhesive contains a mixture in the range of 0.01% to 30% PVDF and a solvent, and optionally a surfactant.