Compressed Graphite Thermal Sheets for Battery Pack Heat Dissipation

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Solution Overview

Problem

Large format prismatic lithium-ion battery packs face challenges in maintaining optimal operating temperatures, which affects their life cycle, rated capacity, and charge/discharge rates due to inadequate heat transfer in stacked configurations.

Innovation Solution

A thermal management assembly using compressed expanded natural graphite thermal transfer sheets positioned between prismatic batteries, with a cover plate and heat sink, facilitates efficient heat transfer through apertures with curved sidewalls, ensuring effective heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If batteries are arranged in a stacked configuration inside a housing, then space utilization and energy density are improved, but heat transfer becomes inadequate and thermal management deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidheat transfer

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

Thermal transfer sheets made of compressed expanded natural graphite are introduced as intermediary components between the battery cells and the heat sink. These sheets facilitate efficient thermal coupling and heat transfer from the battery surfaces to the heat dissipation system, resolving the thermal management issue while maintaining the stacked configuration for high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical state and properties of the thermal management material by using compressed expanded natural graphite with specific porosity and thermal conductivity parameters. This material parameter optimization enables effective heat transfer through the stacked battery configuration without compromising energy density

Inventive Principle:

Principle #35Parameter changes

2Temperature

If thermal transfer sheets are positioned between batteries, then heat transfer efficiency is improved, but device complexity increases

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidassembly complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The cover plate is designed with integrated apertures that serve multiple functions: guiding the thermal transfer sheets into position, providing structural support, and enabling heat sink attachment. This multi-functionality reduces the need for separate components and simplifies the overall assembly process despite the addition of thermal management features

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If apertures with curved sidewalls are used in the cover plate, then thermal transfer sheet positioning is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvepositioning precisionVSAvoidaperture fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The apertures in the cover plate feature curved sidewalls that guide the thermal transfer sheets into proper positioning. The curved geometry provides self-aligning features that ensure precise placement of the thermal sheets between the batteries and heat sink, improving positioning precision through geometric design

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

This solution enhances the thermal management of battery packs by reducing thermal gradients, improving energy density, and extending the life cycle and capacity of lithium-ion batteries by efficiently transferring heat away from the cells.

Implementation Method 1

a plurality of thermal transfer sheets made from sheets of compressed expanded natural graphite. Each thermal transfer sheet is positioned to contact the major surface of at least one of the prismatic batteries

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a heat sink and the top face. At least a portion of each of the thermal transfer sheets is secured between a heat sink and the top face

Methodology Applied

Scientific EffectHeat dissipation: Heat Sink

Data Source

PatentUS9343784B2Battery pack assembly having thermal transfer sheets and heat sink

Publication Date: 2016.05.17 NEOGRAF SOLUTIONS LLC

AI summary

A battery pack thermal management assembly draws heat from prismatic batteries having opposed major surfaces and arranged in a stacked configuration inside a housing. The thermal management assembly includes a plurality of thermal transfer sheets made from sheets of a compressed mass of exfoliated graphite particles. Each thermal transfer sheet is positioned to contact the major surface of at least one of the prismatic batteries. A cover plate has a top face and a bottom face and includes a plurality of apertures through which the plurality of thermal transfer sheets extend. The apertures include at least one curved sidewall and the thermal transfer sheets are bent over the curved sidewall. At least a portion of each of the thermal transfer sheets is secured between a heat sink and the top face.