Flame-Retardant Electrode Layer for Thermal Runaway Resistance

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Solution Overview

Problem

Lithium secondary batteries used in electric vehicles face instability and thermal runaway issues due to internal short circuits and external damage, posing risks to safety and performance.

Innovation Solution

A flame-retardant electrode with a core-shell structured flame retardant layer, including a binder and conductive materials, is integrated between the electrode current collector and active material layer to enhance thermal stability and adhesion, thereby preventing thermal runaway and improving battery safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flame-retardant layer is inserted between the electrode current collector and active material layer, then thermal stability is improved, but device complexity increases

Engineering Contradiction:

Improvethermal stabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A flame-retardant layer is inserted as an intermediary between the electrode current collector and active material layer. This intermediate layer acts as a thermal barrier and safety buffer, preventing direct thermal runaway while maintaining electrochemical performance through proper material selection and thickness control (5-20 μm).

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The flame-retardant layer utilizes composite materials combining flame-retardant polymers (such as polyphosphazene, intumescent coatings) with conductive additives and binders. This composite structure provides both thermal protection and sufficient electrical conductivity for battery operation.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the flame-retardant layer is made thicker to improve thermal stability, then thermal runaway prevention is enhanced, but energy density decreases

Engineering Contradiction:

Improvethermal runaway preventionVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The thickness of the flame-retardant layer is optimized within a specific range (5-20 μm) to achieve the balance between thermal protection and energy density. This parameter optimization ensures sufficient thermal barrier function while minimizing the volume occupied by non-active materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The flame-retardant layer is applied selectively at critical interfaces where thermal runaway risks are highest (between current collector and active material), rather than uniformly throughout the entire battery structure. This localized approach provides maximum protection with minimum material usage.

Inventive Principle:

Principle #3Local quality

3Reliability

If a flame-retardant material is used without conductive coating, then thermal stability is improved, but electrical conductivity decreases

Engineering Contradiction:

Improvethermal stabilityVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The flame-retardant layer is formulated as a composite material system combining flame-retardant polymers with conductive additives (such as carbon black, graphite, or conductive oxides) and binders. This composite structure provides both thermal protection and sufficient electrical conductivity for battery operation.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different regions of the flame-retardant layer have different compositions: the base layer provides thermal stability while conductive additives are distributed throughout to maintain electrical conductivity. This spatial differentiation of properties allows simultaneous achievement of thermal protection and electrical performance.

Inventive Principle:

Principle #3Local quality

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 significantly increases thermal stability and adhesion of the electrode, reducing the risk of thermal runaway and maintaining electrochemical performance, while ensuring balanced energy density and conductivity.

Implementation Method 1

the flame retardant may include a core including a flame-retardant material and a shell including a second conductive material applied onto at least a portion of the surface of the core

Methodology Applied

Scientific EffectConduction (electrical): Conduction (electrical)

Data Source

PatentUS20250105370A1Flame-retardant electrode and all-solid-state battery including same

Publication Date: 2025.03.27 HYUNDAI MOTOR CO LTD

AI summary

An embodiment of a flame-retardant electrode includes a flame-retardant layer between an electrode current collector and an electrode active material layer, and an embodiment of an all-solid-state battery including the same, in which the flame-retardant layer includes a flame retardant configured such that the surface of a flame-retardant material is coated with a conductive material, thereby increasing thermal stability and adhesion to the electrode current collector.