Battery Separator Coating With Surface-Modified CaCO3 for Thermal Runaway

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Solution Overview

Problem

Lithium secondary batteries face safety concerns due to thermal runaway issues, which can lead to high-temperature fires and explosions, and existing separators with inorganic particles have poor wettability and dispersibility, leading to aggregation and increased surface roughness.

Innovation Solution

A separator for lithium secondary batteries is developed with a porous coating layer containing surface-modified calcium carbonate, which includes fatty acid- and organosilane-derived functional groups to enhance dispersibility and wettability, eliminating the need for dispersants and wetting agents, and incorporating inorganic particles like Pb(Zr,Ti)O3 and binder polymers for improved heat resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If inorganic particles are added to the porous coating layer, then heat resistance is improved, but wettability and dispersibility deteriorate causing aggregation

Engineering Contradiction:

Improveheat resistanceVSAvoiddispersibility

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The surface properties of calcium carbonate particles are modified by introducing functional groups (fatty acid-derived and organosilane-derived groups) to change their chemical composition and surface characteristics. This allows the particles to maintain heat resistance while improving dispersibility and wettability in the coating layer

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite calcium carbonate particles with multiple functional groups grafted onto the surface. These composite particles combine the heat resistance of inorganic calcium carbonate with the dispersibility and wettability benefits of organic functional groups, resolving the contradiction between heat resistance and compositional stability

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If dispersants and wetting agents are used to improve dispersibility, then surface roughness is reduced, but battery resistance characteristics deteriorate

Engineering Contradiction:

Improvesurface roughnessVSAvoidresistance characteristics

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent removes dispersants and wetting agents from the coating layer composition entirely. Instead, the functional groups are grafted directly onto the calcium carbonate particles themselves, extracting the harmful additives while maintaining their beneficial functions of improving dispersibility and reducing surface roughness

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The calcium carbonate particles are self-modified with functional groups that provide both dispersibility and wettability improvements. The particles serve their own function as dispersible fillers without requiring external dispersant chemicals, thus maintaining resistance characteristics while achieving low surface roughness

Inventive Principle:

Principle #25Self-service

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 separator prevents or delays thermal transfer during thermal runaway events by maintaining low surface roughness and excellent resistance characteristics, enhancing safety and performance of lithium secondary batteries.

Implementation Method 1

The surface-modified calcium carbonate includes first surface-modified calcium carbonate, second surface-modified calcium carbonate, or a combination thereof. The first surface-modified calcium carbonate includes first calcium carbonate; and a fatty acid-derived functional group chemically bonded to a surface of the first calcium carbonate, and the second surface-modified calcium carbonate includes second calcium carbonate; and an organosilane-derived functional group chemically bonded to a surface of the second calcium carbonate.

Methodology Applied

Scientific EffectSurface modification with fatty acid and organosilane functional groups: Chemical Bonding

Implementation Method 2

The separator prevents or delays thermal transfer during thermal runaway events by maintaining low surface roughness and excellent resistance characteristics

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS20250372816A1Separator for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2025.12.04 LG ENERGY SOLUTION LTD

AI summary

A separator for a lithium secondary battery, includes: a porous polymer substrate; and a porous coating layer formed on at least one surface of the porous polymer substrate, the porous coating layer including inorganic particles and a binder polymer. The inorganic particles include surface-modified calcium carbonate (CaCO3). The surface-modified calcium carbonate includes first surface-modified calcium carbonate, second surface-modified calcium carbonate, or a combination thereof. The first surface-modified calcium carbonate includes first calcium carbonate; and a fatty acid-derived functional group chemically bonded to a surface of the first calcium carbonate. The second surface-modified calcium carbonate includes second calcium carbonate; and an organosilane-derived functional group chemically bonded to a surface of the second calcium carbonate.