Pouch Battery Short Circuit Structure for Overcharge Safety

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Solution Overview

Problem

Pouch-shaped secondary batteries lack an effective mechanism to safely interrupt current flow when swelling due to gas generation or overcharging, leading to potential explosions and safety risks.

Innovation Solution

A short circuit structure is introduced that mechanically cuts the electrode tab and/or lead when the battery case volume increases, using a unit cell configuration with coupled concave and convex units and a cutting layer to physically sever the connections, thereby preventing current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical current interrupt device is used to physically interrupt series connection using pressure from thermal expansion, then current flow is interrupted when overcharged, but no short circuit formation unit is capable of interrupting current in pouch-shaped batteries when volume increases

Engineering Contradiction:

Improvecurrent interruptionVSAvoidapplicability to pouch-shaped batteries

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies the short circuit structure specifically at critical locations within the pouch-shaped battery where electrode leads connect to the battery case. The local mechanical structure is designed to respond to volume increase at these specific points, making the solution adaptable to the unique geometry and swelling characteristics of pouch-shaped batteries.

Inventive Principle:

Principle #3Local quality

2Reliability

If additional current interrupt devices are added to enhance safety, then battery safety is improved, but device complexity and energy density are reduced

Engineering Contradiction:

Improvebattery safetyVSAvoidprotection circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the safety function directly into the existing battery structure by using the electrode leads and battery case as integral components of the short circuit mechanism. This eliminates the need for separate current interrupt devices, reducing overall device complexity while maintaining safety functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electrode leads serve dual functions: normal current conduction during operation and safety trigger mechanism when swelling occurs. The battery case also serves both as containment structure and as the swelling element that activates the short circuit, eliminating the need for dedicated safety components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If the pouch-shaped battery case is sealed to maintain structure, then structural integrity is maintained, but gas generated during abnormal states increases internal pressure and causes swelling

Engineering Contradiction:

Improvestructural integrityVSAvoidinternal pressure from gas

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The patent converts the harmful effect of gas generation and internal pressure into a beneficial safety trigger. The swelling force that would normally be dangerous is instead utilized to activate the short circuit structure, pushing electrode leads apart to create a safety gap and interrupt current flow.

Inventive Principle:

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

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 solution effectively prevents current flow in abnormal states, enhancing battery safety by maintaining energy density and eliminating the need for additional current interrupt devices.

Implementation Method 1

A short circuit structure is introduced that mechanically cuts the electrode tab and/or lead when the battery case volume increases

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

Heat may be generated from such a lithium secondary battery due to a short circuit by external impacts, the overcharge or the overdischarge of the lithium secondary battery

Methodology Applied

Scientific EffectHeat generation from electrochemical reaction:

Implementation Method 3

an electrolyte may be decomposed into gas in the lithium secondary battery

Methodology Applied

Scientific EffectElectrolyte decomposition: Decomposition (biological)

Data Source

PatentUS10644345B2Short circuiting structure for lithium secondary battery having excellent stability against overcharge and pouch type lithium secondary batter comprising the same

Publication Date: 2020.05.05 LG ENERGY SOLUTION LTD

AI summary

Disclosed herein are a short circuit structure for mechanically cutting an electrode tab and/or an electrode lead of a pouch-shaped battery cell in order to secure the safety of the pouch-shaped battery cell when the pouch-shaped battery cell swells due to gas generated in the pouch-shaped battery cell while the pouch-shaped battery cell is in an abnormal state or when the pouch-shaped battery cell is overcharged, and a pouch-shaped secondary battery including the same. Current is prevented from flowing in the pouch-shaped secondary battery when the pouch-shaped secondary battery is overcharged or when the pouch-shaped secondary battery is in an abnormal state. In addition, a reduction in the energy density of the pouch-shaped secondary battery is prevented when a voluminous device is further provided in the pouch-shaped secondary battery.