Fire Retardant Paper Binder Composition for Pouch Cell Swelling

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Solution Overview

Problem

Current fire retardant solutions for pouch cell batteries are either heavy or complex, failing to adequately address the safety concerns of thermal runaway and swelling while maintaining necessary mechanical and insulation properties.

Innovation Solution

A fire retardant paper comprising refractory fibers, organic fibers, fire retardant materials, and a binder system with a combination of organic binders having different glass transition temperatures, providing flexibility and compressive resistance while preventing flame propagation and thermal runaway.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polymeric foam is used to separate and compress cells, then mechanical support and compression are provided, but fire retardant properties are lost and thermal runaway is accelerated

Engineering Contradiction:
Improvefire safetyVSAvoidthermal runaway acceleration
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention uses a composite material comprising cellulose fibers (natural fire-retardant material) combined with thermoplastic polymer binder and inorganic filler to create a separator that provides both mechanical support and fire retardant properties. The cellulose content of at least 30 wt% ensures inherent fire resistance while the polymer matrix provides structural integrity and compression capability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the chemical composition parameters by specifying at least 30 wt% cellulose content and controlled amounts of polymer binder (5-30 wt%) and inorganic filler (20-50 wt%), transforming the material from flammable polymeric foam to fire-retardant composite paper with improved thermal stability and fire safety properties.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If fire retardant materials are incorporated into module housing, then thermal runaway protection is provided, but weight and complexity increase

Engineering Contradiction:
Improvethermal runaway protectionVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention makes the cell separator multi-functional by combining fire retardant cellulose fibers with thermoplastic polymer binder that provides both mechanical support and compression forces. This single component replaces multiple separate functions (fire protection, mechanical support, compression) that would otherwise require separate structures, thereby reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention extracts the fire retardant function from the module housing structure and integrates it directly into the cell separator. By making the separator itself fire-retardant through cellulose incorporation, the need for separate fire protection structures in the housing is eliminated, simplifying the overall device architecture.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If fire retardant paper with high refractory fiber content is used, then fire resistance is improved, but flexibility and compressibility deteriorate

Engineering Contradiction:
Improvefire resistanceVSAvoidflexibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention creates a composite paper structure combining refractory fibers (for fire resistance) with thermoplastic polymer binder (for flexibility) and inorganic filler (for compression resistance). The synergistic combination allows the material to achieve fire resistance comparable to high-refractory-content papers while maintaining the flexibility and compressibility needed for battery cell separation and support.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention optimizes the composition parameters by controlling the refractory fiber content (20-65 wt%) and polymer binder content (5-30 wt%), achieving a balance where fire resistance is sufficient while flexibility and compressibility are maintained through the plasticizing effect of the polymer matrix.

Inventive Principle:
Principle #35Parameter changes

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 fire retardant paper effectively mitigates thermal runaway and swelling in pouch cell batteries by maintaining mechanical integrity and insulation, ensuring safety and performance without the drawbacks of existing solutions.

Implementation Method 1

the binder system comprises a first organic binder and a second organic binder, wherein the first organic binder has a lower glass transition temperature than the second organic binder, wherein the first organic binder has a glass transition temperature in the range of -100°C to 45°C and the second organic binder has a glass transition temperature in the range of 20°C to 100°C

Methodology Applied
Scientific EffectGlass transition:

Implementation Method 2

The fire retardant paper effectively mitigates thermal runaway and swelling in pouch cell batteries by maintaining mechanical integrity and insulation

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

C. 5.0 wt% to 65 wt% fire retardant material

Methodology Applied
Scientific EffectFire retardation:

Data Source

PatentEP4143381B1Fire retardant paper
Publication Date: 2024.08.28 THERMAL CERAMICS INC
  • EP4143381B1 patent drawingFigure 1
  • EP4143381B1 patent drawingFigure 2~3

AI summary

The invention relates to a fire retardant paper comprising reinforcing fibre, a fire retardant material and a binder system, wherein the binder system comprises a first organic binder and a second organic binder, wherein the first organic binder has a lower glass transition temperature than the second organic binder.