Polymer-Coated PCM Graphite Composite for Flexible Battery Cooling

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Solution Overview

Problem

Phase change material (PCM) composites with graphite matrices in thermal management systems for lithium-ion batteries face limitations due to low mechanical strength, brittleness, inflexibility, and compressibility, which can lead to mechanical stress and electrical short-circuits during battery expansion and contraction cycles.

Innovation Solution

A thermal management composite is developed by incorporating a carbon or graphite matrix with a phase change material and a polymer material, where the polymer is dispersed within or coated onto the matrix, enhancing mechanical properties and electrical resistivity to improve flexibility, compressibility, and thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If graphite matrix is used in PCM composite, then thermal conductivity is improved, but electrical resistivity is poor causing electrical short-circuit between battery cells

Engineering Contradiction:

Improvethermal conductivityVSAvoidelectrical short-circuit

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite material system combining graphite particles (for thermal conductivity) with polymer matrix (for electrical insulation). The graphite particles are dispersed throughout the polymer matrix, creating a composite that achieves both high thermal conductivity and high electrical resistivity, preventing electrical short-circuits while maintaining effective heat transfer from battery cells.

Inventive Principle:

Principle #40Composite materials

2Temperature

If traditional graphite matrix composite is used, then thermal management function is achieved, but mechanical characteristics are poor including low yield strength, brittleness, and inflexibility

Engineering Contradiction:

Improvethermal managementVSAvoidmechanical yield strength

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent creates a composite material combining graphite particles with a polymer matrix, where the polymer provides mechanical flexibility and toughness while graphite provides thermal conductivity. This composite structure eliminates the brittleness and low strength of pure graphite composites, enabling the material to withstand mechanical stresses during battery expansion and contraction cycles.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the material composition by incorporating polymer materials with specific mechanical properties into the composite. This changes the overall mechanical parameters of the composite, transforming it from a brittle graphite-dominated structure to a flexible, resilient composite that can accommodate dynamic mechanical stresses while maintaining thermal management functionality.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If graphite matrix composite is used, then thermal contact with cells is achieved, but the material is non-compressible and cannot withstand mechanical stresses during battery expansion and contraction

Engineering Contradiction:

Improvethermal contactVSAvoidcompressibility and flexibility

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The patent employs a composite structure where the polymer matrix provides compressibility and flexibility while maintaining thermal contact. The polymer's viscoelastic properties allow the composite to deform under compression and recover, accommodating battery expansion and contraction without losing thermal contact with the cells, unlike rigid graphite composites.

Inventive Principle:

Principle #40Composite materials

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 higher mechanical strength, flexibility, and thermal conductivity, preventing mechanical failure and electrical shorts, while maintaining thermal contact with battery cells, suitable for high-power applications like prismatic and pouch cells.

Implementation Method 1

The PCM absorbs large amount of heat close to its phase transition temperature thereby stabilizing and controlling battery temperature to safe operating limits

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

The PCM absorbs large amount of heat close to its phase transition temperature

Methodology Applied

Scientific EffectLatent heat: Latent Heat

Implementation Method 3

The heat released by Li-ion cells is conducted away by the graphite matrix to the PCM

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10005941B2Flexible phase change material composite for thermal management systems

Publication Date: 2018.06.26 BEAM GLOBAL INC

AI summary

A thermal management composite, comprising a phase change material within a carbon or graphite matrix. The matrix is coated with a polymer coating to improve flexibility. The matrix can be a molded carbon or graphite material or a carbon or graphite cloth.