Lithium Battery Electrode with Expandable Safety Layer Shutdown

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Solution Overview

Problem

Rechargeable lithium batteries face safety risks due to overheating and potential explosions caused by internal short-circuits, which current technologies fail to adequately address, especially in high-capacity or high-power batteries.

Innovation Solution

Incorporating a safety functional layer with a thermal expandable polymer within the electrode structure, which increases internal resistance when the battery temperature rises, thereby preventing overheating and explosions by restricting lithium ion and electron flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high-capacity or high-power battery is realized, then energy density is improved, but thermal safety and physical safety deteriorate

Engineering Contradiction:

Improveenergy densityVSAvoidthermal safety

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A safety functional layer is introduced as an intermediary component within the electrode structure. This layer contains a thermal expandable polymer that acts as a mediator between the active material layer and current collector, preventing direct harmful interactions while allowing normal battery operation. The polymer layer mediates the thermal runaway process by expanding to block ion transport pathways when temperature exceeds a predetermined threshold.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent utilizes parameter changes in the thermal expandable polymer material, specifically its phase transition from a compact state to an expanded state at elevated temperatures. This parameter change (volume expansion) is triggered by temperature increase during thermal runaway, automatically altering the physical properties of the safety functional layer to block ion transport and prevent further thermal escalation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If internal resistance is increased at elevated temperature, then thermal safety is improved, but battery performance at normal temperature may deteriorate

Engineering Contradiction:

Improvethermal safetyVSAvoidbattery performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The thermal expandable polymer undergoes a phase transition at a predetermined temperature threshold. Below this threshold, the polymer remains in a compact phase that allows efficient lithium ion transport, maintaining normal battery performance. Above the threshold, the polymer transitions to an expanded phase that increases internal resistance and blocks ion transport, thereby preventing thermal runaway while preserving normal operation.

Inventive Principle:

Principle #36Phase transitions

3Reliability

If safety functional layer is added to electrode, then thermal runaway is prevented, but device complexity increases

Engineering Contradiction:

ImprovesafetyVSAvoidelectrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The safety functional layer is nested within the existing electrode structure, specifically positioned between the active material layer and the current collector. This nested configuration integrates the safety function into the existing electrode architecture without requiring separate safety components or complex additional structures, thereby minimizing device complexity while achieving thermal runaway prevention.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 solution effectively suppresses thermal and physical safety risks by maintaining normal battery function at room temperature while ensuring shutdown and preventing overheating at elevated temperatures, thus securing both thermal and physical safety in high-capacity or high-power batteries.

Implementation Method 1

a safety functional layer positioned inside the active material layer as a separated layer and including a thermal expandable polymer

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

increasing the internal resistance of a battery when the temperature of the battery is increased

Methodology Applied

Scientific EffectPositive temperature coefficient (PTC) effect: Thermo-resistive Effect

Data Source

PatentUS20230335806A1Electrode for rechargeable lithium battery and rechargeable lithium battery comprising same

Publication Date: 2023.10.19 SAMSUNG SDI CO LTD

AI summary

The present invention relates to an electrode for a rechargeable lithium battery and a rechargeable lithium battery comprising same, the electrode for a rechargeable lithium battery comprising a current collector, and active material layer positioned on the current collector, and a safety functional layer that is positioned inside the active material layer as a separate layer and comprises a thermally expandable polymer.