Battery Module Bus Bar Shorting Triggered by Cell Expansion

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Solution Overview

Problem

Conventional battery modules struggle to reliably prevent overcharge and short circuits due to expansion, leading to potential swelling, heat generation, and safety hazards, as existing safety mechanisms fail to consistently interrupt current flow during abnormal conditions.

Innovation Solution

A battery module design featuring a short-circuit unit that moves to connect first and second bus bars upon cell expansion, causing a controlled short circuit and fracturing a fracturing portion to interrupt current flow, using a slide bar and buffering member to manage the expansion force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection circuit and PTC element are used to prevent overcharge and overheating, then safety is improved, but device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The battery cell's own expansion during overcharge directly drives the short-circuit mechanism through the slide bar, eliminating the need for external sensors or control circuits. The system uses its own abnormal state (expansion) to trigger the safety response, achieving self-protection without adding complex monitoring devices.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The harmful expansion of the battery cell during overcharge is converted into a useful force that drives the slide bar to create a short circuit. The adverse effect (expansion) becomes the triggering mechanism for safety protection, eliminating the need for separate detection and response systems.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If a short-circuit unit is designed to move and connect bus bars upon expansion, then overcharge prevention is improved, but device complexity increases

Engineering Contradiction:
Improveovercharge preventionVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The slide bar serves multiple functions: it acts as a mechanical connector between battery cells during normal operation, a displacement sensor that detects expansion, and a actuator that creates the short circuit path. This multi-functionality eliminates the need for separate components for each function, reducing overall device complexity while maintaining effective overcharge prevention.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The structural support function and the safety protection function are merged into a single integrated mechanism. The slide bar both maintains electrical connection between cells and triggers the short-circuit protection, combining what would traditionally require separate components into one unified system.

Inventive Principle:
Principle #5Merging (Combining)

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 design effectively prevents overcharge by creating a controlled short circuit and fracturing a fracturing portion to stop current flow, enhancing the stability and safety of the battery module.

Implementation Method 1

a short-circuit unit (300) configured to move toward the first bus bar (200a) and the second bus bar (200b) by receiving an expansive force due to a volume increase of a first battery cell (110a)

Methodology Applied
Scientific EffectExpansion: Thermal Expansion

Data Source

PatentEP3540818B1Battery module, and battery pack and vehicle including the same
Publication Date: 2025.09.03 LG ENERGY SOLUTION LTD
  • EP3540818B1 patent drawingFigure 1
  • EP3540818B1 patent drawingFigure 2
  • EP3540818B1 patent drawingFigure 3

AI summary

Disclosed is a battery module, which includes: a first bus bar electrically connected to a first electrode lead of a first battery cell; a second bus bar electrically connected to a second electrode lead of a second battery cell; a short-circuit unit configured to move toward the first bus bar and the second bus bar by receiving an expansive force due to a volume increase of the first battery cell and another battery cell adjacent to the first battery cell so that the first bus bar and the second bus bar are electrically connected to generate a short circuit; and a cartridge configured to accommodate or support at least a portion of the first electrode lead, the second electrode lead, the first bus bar, the second bus bar and the short-circuit unit.