Anode Flame-Retardant Coating for Battery Thermal Runaway

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Solution Overview

Problem

Lithium secondary batteries are prone to internal deterioration and thermal runaway due to external impacts, leading to chain-like exothermic reactions and potential ignition, which can spread throughout the battery pack.

Innovation Solution

A flame-retardant polymer layer is applied to the negative electrode active material layer, converting to char at 150°C to block heat transfer and oxygen inflow, preventing thermal runaway and ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flame-retardant polymer layer is applied to the negative electrode, then thermal runaway and ignition are prevented, but battery performance may deteriorate

Engineering Contradiction:

Improvethermal safetyVSAvoidbattery performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

A flame-retardant polymer layer is applied to the negative electrode as a thin film coating. This flexible protective layer provides thermal safety by preventing thermal runaway and ignition while maintaining sufficient ion transport properties to preserve battery performance.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The polymer layer undergoes parameter changes at different temperatures: at normal operating temperatures it remains permeable to lithium ions, but at thermal runaway temperatures it transforms to block heat and mass transfer, thus preventing ignition while maintaining battery performance during normal use.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the flame retardant is converted to char at high temperature, then oxygen inflow is blocked and thermal runaway is prevented, but battery operation is restricted

Engineering Contradiction:

Improveignition preventionVSAvoidbattery operation range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The flame retardant in the polymer layer undergoes a phase transition when converted to char at high temperature (150°C or higher). This phase change creates a protective char layer that blocks oxygen inflow and prevents thermal runaway, while the layer remains permeable during normal operation.

Inventive Principle:

Principle #36Phase transitions

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 flame-retardant polymer layer delays thermal runaway by blocking oxygen and preventing direct contact between electrodes, maintaining battery performance and safety under high temperatures.

Implementation Method 1

the flame-retardant polymer layer includes a flame retardant that is converted to char when combusted at a temperature of 150°C or higher

Methodology Applied

Scientific EffectChar conversion: Pyrolysis

Data Source

PatentEP4697404A1Anode, and lithium secondary battery and battery pack comprising same

Publication Date: 2026.02.18 LG ENERGY SOLUTION LTD

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AI summary

The present specification relates to an anode (100) and a lithium secondary battery and a battery pack comprising same, the anode comprising a flame retardant polymer layer (3) provided on an anode active material layer (2), wherein the flame retardant polymer layer includes a flame retardant that is converted into char (later forming an oxygen-blocking layer (4)) during combustion at a temperature of 150 °C or higher. The anode according to the embodiment can ensure desired battery characteristics under normal conditions while preventing thermal runaway under specific temperature conditions.