Battery Module Strap With Folded Weld Joint for Swelling Control

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Solution Overview

Problem

Conventional straps for battery modules face challenges in securing easy mounting and sufficient binding force, with existing solutions either prone to release during welding or limited in diameter, affecting the safety and stability of the module due to swelling phenomena in lithium-polymer pouch-type secondary batteries.

Innovation Solution

A strap with a zigzag folded welding portion and a jig for compressing the strap, allowing for adjustable height and simultaneous compressing and welding, ensuring reliable binding force and easy assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a conventional strap is provided to surround the battery module and then welded, then the binding force is sufficient, but the strap may be easily released during the welding process and it is difficult to secure reliable compressing force

Engineering Contradiction:
Improvebinding forceVSAvoidreliability of compressing force
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The strap is pre-compressed around the battery module before welding to maintain stable contact between the strap and the battery module. This preliminary compression ensures that the strap remains firmly in position during the welding process, preventing release and ensuring reliable compressing force is maintained throughout assembly.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If a strap without welding is used to simplify structure and reduce fabrication cost, then the fabrication cost is reduced, but the diameter is limited which makes it difficult to assemble with the battery module

Engineering Contradiction:
Improvefabrication costVSAvoidassemblability
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The strap incorporates a variable cross-sectional design where the width changes along its length. This parameter change allows the strap to accommodate different battery module sizes and shapes while maintaining effective compression. The adjustable width provides adaptability for various assembly configurations without requiring welding, thus maintaining low fabrication cost while improving assemblability.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the outer shape of the battery module is changed by external force due to swelling, then the safety and stability are affected, but preventing swelling requires additional compression mechanisms

Engineering Contradiction:
Improvesafety and stabilityVSAvoidcomplexity of compression mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The strap is designed to automatically maintain compression force on the battery module through its elastic properties and pre-tensioning mechanism. The strap self-adjusts to compensate for swelling by maintaining constant contact pressure without requiring external control systems or complex active compression mechanisms. This self-service approach prevents swelling-related safety issues while keeping the device complexity low.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3509129B1Strap for battery module, battery module comprising same, and jig for compressing strap
Publication Date: 2024.08.28 LG ENERGY SOLUTION LTD
  • EP3509129B1 patent drawingFigure 1(a)~1(b)
  • EP3509129B1 patent drawingFigure 2
  • EP3509129B1 patent drawingFigure 3

AI summary

Disclosed is a strap, which compresses an outer surface of a battery module to prevent the battery module from being deformed by swelling of a battery cell, and the strap has a closed loop structure larger than an outer peripheral of the battery module, and at least a portion of the strap is folded at the closed loop to provide a welding portion at which the folded portions overlap each other when a predetermined compression is applied thereto.