Pouched Battery Case Equipotentiality for Corrosion Prevention

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Solution Overview

Problem

Conventional pouched lithium secondary batteries face issues with corrosion and swelling due to electrical contact between the negative electrode tab and the intermediate metallic layer of the case, making it difficult to accurately determine proper function and leading to deformation of the battery pack.

Innovation Solution

A pouched lithium secondary battery design where a positive electrode voltage is applied to both the positive electrode tab and the case, inducing a short circuit when the negative electrode tab contacts the case due to damage, allowing for easier detection of malfunctions through variations in open circuit voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the case is made with an intermediate metallic layer for flexibility and conductivity, then the battery structure is improved, but corrosion occurs when the negative electrode tab contacts the metallic layer

Engineering Contradiction:

Improvecase flexibilityVSAvoidcorrosion

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies equipotentiality by connecting the case to the positive electrode tab, ensuring both are at the same positive potential. This eliminates the potential difference between the negative electrode tab and case, preventing galvanic corrosion while maintaining the metallic layer's flexibility and conductivity benefits.

Inventive Principle:

Principle #12Equipotentiality

Solution Approach 2:

The patent introduces an intermediary connection between the positive electrode tab and the case, creating a controlled electrical pathway that equalizes potential. This intermediary connection prevents direct harmful interaction between the negative electrode tab and case while preserving the case's metallic properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the negative electrode tab is allowed to contact the case for structural support, then the battery assembly is simplified, but electrical short circuit and swelling occur

Engineering Contradiction:

Improveassembly structureVSAvoidelectrical safety

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

By connecting the case to the positive electrode tab, the patent ensures the case is at positive potential, the same as the positive electrode tab. This eliminates the risk of electrical short circuit between the negative electrode tab and case, allowing structural contact without compromising safety.

Inventive Principle:

Principle #12Equipotentiality

Solution Approach 2:

The patent converts the potentially harmful electrical contact between the negative electrode tab and case into a beneficial arrangement by making the case positive potential. What could have been a dangerous short circuit becomes a safe structural support mechanism.

Inventive Principle:

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

3Ease of operation

If corrosion detection is performed visually, then the inspection process is simple, but early-stage corrosion and swelling are not detected

Engineering Contradiction:

Improveinspection processVSAvoidmalfunction detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements feedback by using voltage measurement to detect corrosion. The voltage difference between the positive electrode tab and case serves as an early warning signal, providing continuous feedback on the battery's structural integrity before visible damage occurs.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces visual inspection with an electrical measurement system. Instead of relying on human visual detection, the system uses voltage measurement to automatically detect corrosion, significantly improving detection precision while maintaining operational simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 design enables the detection of malfunctioning batteries and prevents swelling by inducing a short circuit, ensuring safety and maintaining the battery pack's seal even when the case corrodes.

Implementation Method 1

a positive electrode voltage applying unit to apply a positive electrode voltage to the positive electrode tab and the case

Methodology Applied

Scientific EffectElectrical voltage application: Electric Field

Implementation Method 2

inducing a short circuit when the negative electrode tab contacts the case due to damage, allowing for easier detection of malfunctions through variations in open circuit voltage

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS7427453B2Pouched lithium secondary battery

Publication Date: 2008.09.23 SAMSUNG SDI CO LTD

AI summary

A pouched lithium secondary battery including a battery unit having a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate; a positive electrode tab electrically connected with the positive electrode plate; a negative electrode tab electrically connected with the negative electrode plate; a case having a space to accommodate the battery unit, and a sealing edge around the space; and a positive electrode voltage applying unit to apply a positive electrode voltage to both the positive electrode tab and the case.