Battery Module Strain Sensing for Cell Thermal Expansion Detection

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Solution Overview

Problem

Existing battery modules and packs lack accurate detection methods for the thermal expansion and contraction states of battery cells, which is crucial for efficient performance and safety.

Innovation Solution

Incorporating an elongated battery cell sealed by a laminated film and a case with a strain sensor positioned on either the battery cell or the case, specifically at the middle portion of the long side wall or the end portion of the housing, to directly detect thermal expansion and contraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If indirect detection methods based on voltage information are used, then the detection system is simple, but the detection accuracy of thermal expansion and contraction states is insufficient

Engineering Contradiction:

Improvedetection accuracy of thermal expansion and contraction statesVSAvoiddetection system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces indirect electrical detection (voltage-based) with direct mechanical detection using a strain sensor. The strain sensor directly measures physical deformation of the battery cell or case during thermal expansion and contraction, providing accurate mechanical measurement without relying on electrical parameter correlations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The strain sensor acts as an intermediary element that directly contacts or is attached to the battery cell/case structure. It mediates between the thermal expansion/contraction phenomenon and the detection system, converting mechanical deformation into measurable signals with high accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the strain sensor is positioned at locations with smaller displacement, then the sensor is less affected by thermal expansion and contraction, but the detection accuracy of thermal expansion and contraction states decreases

Engineering Contradiction:

Improvedetection accuracy of thermal expansion and contraction statesVSAvoidsensor interference from thermal expansion and contraction

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by selecting specific locations on the battery cell or case where thermal expansion and contraction produce maximum displacement. The strain sensor is strategically positioned at these high-displacement zones (such as middle portions of long side walls or end portions of housing) to optimize detection sensitivity while the overall sensor system remains unaffected by excessive thermal stress.

Inventive Principle:

Principle #3Local quality

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 configuration allows for precise detection of thermal expansion and contraction states, enhancing the accuracy and reliability of battery performance and safety monitoring.

Implementation Method 1

a strain sensor configured to detect strain and provided on either or both of the battery cell and the case

Methodology Applied

Scientific EffectStrain detection: Elasticity

Data Source

PatentUS20250158144A1Battery module and battery pack

Publication Date: 2025.05.15 TOYOTA JIDOSHA KK

AI summary

The battery module includes an elongated battery cell composed of an electrode assembly sealed by a laminated film, a case capable of accommodating a battery cell group in which a plurality of battery cells is arranged, and a strain sensor provided in at least one of the battery cell and the case and capable of detecting strain.