Pouch Cell Swelling Detection Using a Sacrificial Filament

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Solution Overview

Problem

Rechargeable battery packs with pouch cells face the issue of swelling, which can lead to the outer cover bursting open, compromising operational safety.

Innovation Solution

Incorporating at least one electrically conductive filament that surrounds the pouch cell, which severs upon expansion, allowing for detection of swelling through a sensor circuit and control circuit for safety measures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If no monitoring system is used, then the device complexity is low, but the reliability decreases due to undetected swelling

Engineering Contradiction:

Improveoperational safetyVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical monitoring systems with a simple electrical resistance measurement system. The filament's electrical properties change when severed by swelling, providing a reliable detection mechanism without requiring complex sensors or actuators.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The filament is designed as a simple, inexpensive sacrificial element that may be severed during operation. Its low cost and simple structure allow it to be replaced if needed, while providing reliable swelling detection throughout the battery pack's service life.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If a rigid frame is used to counter expansion, then the reliability improves by preventing bursting, but the pouch cell may still swell undetected

Engineering Contradiction:

Improvestructural integrityVSAvoidswelling detection

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The monitoring function is separated from the structural frame by using an independent filament element. The filament runs through or alongside the pouch cell and provides electrical detection of swelling, while the rigid frame provides mechanical support. This segmentation allows both functions to operate independently and reliably.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If the filament is DC-connected to contacts, then electrical monitoring is simple, but safety is reduced due to potential short circuits

Engineering Contradiction:

Improveelectrical connection simplicityVSAvoidshort circuit risk

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary measurement arrangement that electrically connects the filament to the battery pack's electrical system without creating direct short-circuit paths. This intermediary circuitry allows monitoring while maintaining safety isolation between the filament and the high-current battery contacts.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12334524B2Safety mechanism for rechargeable battery pack with pouch cells

Publication Date: 2025.06.17 HILTI AG

AI summary

A rechargeable battery pack having at least one pouch cell, wherein the rechargeable battery pack has at least one electrically conductive filament which surrounds the pouch cell at least in sections in such a way that expansion of the pouch cell causes severing of the filament.