Outermost Electrode Assembly for Bend-Induced Battery Cutoff

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Solution Overview

Problem

Conventional lithium secondary batteries face safety risks due to breakage of the case and internal short circuits caused by external bending and distortion, leading to potential ignition or explosion, as the existing technologies fail to effectively prevent these mechanical issues.

Innovation Solution

The electrode assembly is designed with an outermost electrode having an electrode lead connection tab made of a different material than the current collector, with a higher tensile stress and lower Young's modulus, to be physically cut before the case breaks, thereby preventing internal short circuits and ensuring safety by disconnecting the current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the case is made durable to prevent breakage during repeated bending, then the battery reliability improves, but the device complexity increases due to additional reinforcing structures

Engineering Contradiction:

Improvebattery safetyVSAvoidcase structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electrode assembly is designed to undergo preliminary cutting of the outermost electrode before the case breaks. The current collector of the first electrode is intentionally made with lower tensile strength than the case, so that during repeated bending, the electrode cuts itself off first, preventing internal short circuits and electrolyte leakage before the case fails.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The outermost electrode acts as an intermediary safety mechanism between the external bending force and the internal battery components. By designing the electrode to fail first, it mediates the stress transfer, preventing the force from reaching the case and causing catastrophic failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the current collector material is changed to induce cutting before case breakage, then the safety improves, but the manufacturing precision requirements increase due to material selection and property matching

Engineering Contradiction:

ImprovesafetyVSAvoidmaterial property control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Different parts of the battery system are assigned different material properties tailored to their specific functions. The current collector of the first electrode uses a material with lower tensile strength than the case, while the second electrode uses a different material. This local differentiation of material quality enables the electrode to fail first under stress, prioritizing safety over uniform material properties throughout the battery.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the outermost electrode is designed to cut off under stress, then the harmful effects are reduced, but the loss of energy increases due to premature electrode failure

Engineering Contradiction:

Improveinternal short circuit preventionVSAvoidbattery capacity

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The potential harm of electrode failure under stress is converted into a beneficial safety feature. Instead of allowing the case to break and cause catastrophic failure with electrolyte leakage and internal short circuits, the design intentionally allows the electrode to fail first. This controlled failure prevents the more harmful scenarios, turning what could be a defect into a protective mechanism.

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 design effectively cuts off the current flow when external stress is applied, securing the safety of the battery by reducing its functionality and preventing potential ignition or explosion, while maintaining flexibility and stability during repeated bending.

Implementation Method 1

a current collector of a first electrode among the electrodes is made of a different material from a current collector of a second electrode having a different polarity so that the first electrode including an electrode lead connection tab is physically cut earlier than the second electrode during bending and distortion

Methodology Applied

Scientific EffectTensile stress: Tension

Implementation Method 2

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS11996512B2Electrode assembly having improved safety of use by means of outermost electrode structure and current collector material, and lithium-ion secondary battery having same

Publication Date: 2024.05.28 LIBEST

AI summary

An electrode assembly includes a plurality of unit cells each equipped with a pair of electrodes having different polarities. Electrode tabs protrude from the electrodes. The electrode tabs including at least one electrode parallel connection tab and at least one electrode lead connection tab. In a first unit cell of the plurality of unit cells, a current collector of a first electrode among the pair of electrodes is made of a different material from a current collector of a second electrode among the pair of electrodes having the different polarity.