Expanded Graphite Hybrid Filler for Battery Thermal Management

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Solution Overview

Problem

Conventional heat radiation composites for battery applications suffer from thermal anisotropy, low heat conduction efficiency, and weight increase due to filler orientation and interfacial resistance, limiting their effectiveness in managing heat generated by high-capacity batteries in electric vehicles.

Innovation Solution

A high heat radiation composite is developed by filling expandable polymeric beads into heat-treated expanded graphite, which is then dispersed into a matrix polymer using an extrusion/injection process, enhancing heat transfer characteristics and overcoming thermal anisotropy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If planar fillers such as boron nitride or graphite are used to improve heat radiation, then heat transfer efficiency increases, but thermal anisotropy occurs due to filler orientation in injection direction

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidthermal anisotropy

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The patent embeds globular filler particles inside the planar filler structure to create a nested hybrid configuration. This nesting approach allows the planar fillers to provide heat transfer pathways while the embedded globular fillers prevent excessive orientation and reduce thermal anisotropy, resolving the contradiction between heat transfer efficiency and thermal stability.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent creates a hybrid composite material combining planar fillers (boron nitride or graphite) with globular fillers in a polymer matrix. This composite structure leverages the high thermal conductivity of planar fillers while using globular fillers to maintain isotropic distribution, thereby achieving both efficient heat transfer and reduced thermal anisotropy.

Inventive Principle:

Principle #40Composite materials

2Temperature

If densely filled heat radiation composite material is manufactured by injection molding, then heat radiation characteristics improve, but workability reduces due to low resin flowability

Engineering Contradiction:

Improveheat radiation characteristicsVSAvoidworkability

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent changes the shape parameter of fillers from planar to globular, and optimizes the size distribution parameters of the hybrid filler mixture. This parameter optimization improves resin flowability during injection molding while maintaining effective heat radiation characteristics, thereby resolving the contradiction between heat radiation performance and manufacturing ease.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If high filling ratio of filler is used to improve heat conduction, then heat transfer efficiency increases, but weight increases

Engineering Contradiction:

Improveheat conduction efficiencyVSAvoidweight

Core Design Contradiction:

TemperatureVSWeight of moving object

Solution Approach 1:

Instead of using only heavy planar fillers, the patent inverts the approach by incorporating lighter globular fillers alongside planar fillers. This inversion in filler selection strategy reduces the overall weight while maintaining heat conduction efficiency through the hybrid structure, resolving the contradiction between heat conduction and weight.

Inventive Principle:

Principle #13The other way round (Inversion)

4Temperature

If interfacial resistance between matrix resin and filler is reduced to improve heat conduction, then heat transfer efficiency increases, but manufacturing complexity increases

Engineering Contradiction:

Improveheat conduction efficiencyVSAvoidmanufacturing complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent employs a simple yet effective approach of using spherical filler particles that naturally provide good interfacial contact with the matrix resin, eliminating the need for complex surface treatments or specialized manufacturing processes. This straightforward solution reduces interfacial resistance and improves heat conduction without significantly increasing manufacturing complexity.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 composite achieves improved thermal conductivity, reduced interfacial resistance, and maintained mechanical properties, enabling effective heat radiation and increased reliability and lifespan of battery systems for electric vehicles.

Implementation Method 1

hybrid filler comprising expanded graphite filled with expandable polymeric beads that has been heat-treated

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The composite has better heat radiation characteristics than a typical heat-radiating composite

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

dispersed into a matrix polymer by an extrusion/injection process

Methodology Applied

Scientific EffectShear stress: Shear Stress

Data Source

PatentUS9296871B2High heat radiation composite and a method of fabricating the same

Publication Date: 2016.03.29 HYUNDAI MOTOR CO LTD

AI summary

The present disclosure provides a high heat radiation composite material including a hybrid filler comprising expanded graphite filled with expandable polymeric beads, and a fabrication method thereof. In the method, a dispersion solution is prepared by dispersing expandable polymeric beads in ethanol. Expanded graphite is immersed in the dispersion solution, and heat-treated to remove ethanol, thereby producing the hybrid filler. The hybrid filler is dispersed into the matrix polymer via an extrusion/injection process, thereby producing the composite material.