Lithium Battery Current Collector as an Internal Short-Circuit Fuse

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Solution Overview

Problem

Lithium batteries are prone to short circuiting and high temperature occurrences, leading to thermal runaway and fires due to manufacturing defects and degradation, which poses significant safety risks and regulatory challenges.

Innovation Solution

The use of thin metallized current collectors made from materials like aluminum and copper, which become nonconductive upon exposure to high temperatures, creating an internal fuse mechanism to prevent excessive heat generation during short circuits, combined with thermally stable separators to manage thermal degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional current collectors are used, then electrical conductivity is maintained, but thermal runaway risk increases during short circuits

Engineering Contradiction:

Improvesafety during short circuitVSAvoidheat generation during short circuit

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The current collector's electrical conductivity parameter is changed by coating it with a material that is conductive at operating temperature but becomes non-conductive at elevated temperatures. This parameter change allows the current collector to function normally during operation while automatically preventing heat generation during thermal runaway events

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The harmful effect of high temperature during short circuits is converted into a beneficial safety mechanism. When the temperature rises during a short circuit, the coating material undergoes a phase change or degradation that stops conductivity, thereby converting the harmful thermal energy into a protective action that prevents further heat generation

Inventive Principle:

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

2Reliability

If thin metallized current collectors are used, then short circuit containment is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveshort circuit containmentVSAvoidcoating thickness uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

An intermediate coating layer is introduced between the metal current collector and the electrode materials. This intermediate layer serves as a mediator that provides the thermal response functionality while the underlying metal structure maintains electrical conductivity. The coating acts as a buffer that simplifies manufacturing by decoupling the electrical and thermal functions

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If flammable organic electrolytes are used, then energy density is improved, but fire risk increases

Engineering Contradiction:

Improveenergy densityVSAvoidignition risk

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

A preliminary protective action is implemented by coating the current collector with a material that will decompose or change properties at temperatures below the ignition point of the organic electrolyte. This preliminary anti-action prevents the temperature from reaching the ignition threshold, thereby protecting the flammable electrolyte from ignition while allowing its use for high energy density

Inventive Principle:

Principle #9Preliminary anti-action

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 contains short circuit events by breaking conductive pathways, reducing heat generation, and preventing thermal runaway, thereby enhancing the safety and reliability of lithium batteries while allowing the use of flammable organic electrolytes without risk of ignition.

Implementation Method 1

thin metallized current collectors (aluminum and/or copper, as examples), which become nonconductive upon exposure to high temperatures, creating an internal fuse mechanism to prevent excessive heat generation during short circuits

Methodology Applied

Scientific EffectTemperature-dependent conductivity change: Electrical Resistance

Implementation Method 2

high shrinkage rate materials... thermally stable separators to manage thermal degradation

Methodology Applied

Scientific EffectThermal shrinkage: Thermal Contraction

Data Source

PatentUS11799125B2Lithium storage device with improved safety architecture

Publication Date: 2023.10.24 SOTERIA BATTERY INNOVATION GROUP INC

AI summary

Improvements in the structural components and physical characteristics of lithium battery articles are provided. Standard lithium ion batteries, for example, are prone to certain phenomena related to short circuiting and have experienced high temperature occurrences and ultimate firing as a result. Structural concerns with battery components have been found to contribute to such problems. Improvements provided herein include the utilization of thin metallized current collectors (aluminum and/or copper, as examples), high shrinkage rate materials, materials that become nonconductive upon exposure to high temperatures, and combinations thereof. Such improvements accord the ability to withstand certain imperfections (dendrites, unexpected electrical surges, etc.) within the target lithium battery through provision of ostensibly an internal fuse within the subject lithium batteries themselves that prevents undesirable high temperature results from short circuits. Battery articles and methods of use thereof including such improvements are also encompassed.