Battery Module Interlayer Using Expandable Resin to Limit Heat Transfer

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Solution Overview

Problem

In battery modules with multiple layered battery cells, there is a risk that heat generated by one battery cell can conduct and cause neighboring cells to also generate heat, leading to potential thermal management issues.

Innovation Solution

A battery module is designed with an elastic member between neighboring battery cells, where a thermally expandable resin composition body is integrated within the elastic member. This resin composition expands at temperatures of 80° C. or more and has a heat conductivity of 0.5 W/m·K or less after expansion, effectively reducing heat transfer between cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heat conductive member is arranged between battery cells to improve heat dissipation, then heat dissipation performance is improved, but heat conductivity among battery cells increases leading to thermal propagation risk

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidheat conductivity among battery cells

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by using a thermally expandable resin composition body that changes its physical state from compressed (low volume) to expanded (high volume) when temperature reaches 80°C or more. This phase transition allows the heat insulation performance to dynamically change: at normal temperatures the resin is compressed allowing thermal contact, but at elevated temperatures it expands to create thermal isolation between battery cells, preventing heat propagation while maintaining normal thermal management.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transitions of the thermally expandable resin composition body. The resin undergoes a temperature-induced phase transition at 80°C or more, transforming from a dense compressed state to a porous expanded state. This phase change fundamentally alters the thermal conductivity of the material, enabling automatic thermal isolation when battery cells overheat, thus preventing thermal runaway propagation without requiring external control systems.

Inventive Principle:

Principle #36Phase transitions

2Object-affected harmful factors

If an elastic member with thermally expandable resin is used to restrain heat conductivity at high temperature, then heat insulation performance is improved, but the structural complexity increases

Engineering Contradiction:

Improveheat insulation performanceVSAvoidstructural complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single integrated component: the elastic member and thermally expandable resin composition body are combined into one unit that simultaneously provides mechanical cushioning, thermal insulation, and automatic thermal response. This integration eliminates the need for separate heat insulation components or active control systems, reducing overall structural complexity while achieving sophisticated thermal management functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The thermally expandable resin composition body exhibits self-service behavior by automatically responding to temperature changes without external control. When battery cells generate excessive heat, the resin autonomously expands at 80°C or more to create thermal isolation, and maintains this state passively. This self-activating mechanism eliminates the need for sensors, actuators, or control systems, significantly simplifying the overall device structure while providing intelligent thermal protection.

Inventive Principle:

Principle #25Self-service

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 solution effectively restrains heat conductivity among battery cells during rising temperatures, preventing unwanted heat transfer and potential thermal issues such as chain smoke emission and cell deformation.

Implementation Method 1

a thermally expandable resin composition body is arranged in the elastic member; in a plan view along with the thickness direction, the resin composition body is arranged to include a center of the battery cell; a temperature at which the resin composition body starts to expand is 80° C. or more

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

heat conductivity after expansion of the resin composition body is 0.5 W/m·K or less; The solution effectively restrains heat conductivity among battery cells during rising temperatures, preventing unwanted heat transfer

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS12327877B2Battery module

Publication Date: 2025.06.10 TOYOTA JIDOSHA KK

AI summary

A battery module capable of restraining heat conductivity among battery cells in rising temperature includes: a plurality of a battery cells arranged along a thickness direction; an elastic member between neighboring battery cells of the plurality of battery cells; and a thermally expandable resin composition body arranged in the elastic member; wherein: in a plan view along with the thickness direction, the resin composition body is arranged to include a center of the battery cells; a temperature at which the resin composition body starts to expand is 80° C. or more; and heat conductivity after expansion of the resin composition body is 0.5 W/m·K or less.