Non-Aqueous Battery Separator Coating for Adhesion and Heat Stability

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Solution Overview

Problem

Existing separators for non-aqueous secondary batteries face issues with adhesion to electrodes during manufacturing, leading to potential peeling and short circuits, and have high thermal shrinkage ratios that compromise safety and cycle stability.

Innovation Solution

A separator comprising a heat-resistant porous layer with aromatic type resin and inorganic particles, and an adhesive layer with phenyl group-containing acrylic type resin particles, which provides excellent adhesiveness through both dry and wet heat pressing and low thermal shrinkage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separator includes an adhesive layer containing a resin having adhesiveness to an electrode, then adhesiveness to the electrode is improved, but thermal shrinkage resistance deteriorates

Engineering Contradiction:

Improveadhesiveness to electrodeVSAvoidthermal shrinkage resistance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The separator is divided into two distinct functional layers: a heat-resistant porous layer containing aromatic type resin and inorganic particles for thermal stability, and an adhesive layer containing phenyl group-containing acrylic type resin particles for electrode adhesion. This segmentation allows each layer to independently perform its specialized function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The separator employs a composite structure combining organic aromatic type resin with inorganic particles in the heat-resistant layer, and phenyl group-containing acrylic type resin particles in the adhesive layer. This composite material approach enables simultaneous achievement of heat resistance, adhesion, and mechanical properties that single materials cannot provide.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the separator is heat-pressed with electrodes, then adhesion is improved, but the separator may peel off when impregnated with electrolytic solution

Engineering Contradiction:

Improveadhesion strengthVSAvoidadhesion stability in electrolyte

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The adhesive layer uses phenyl group-containing acrylic type resin particles with specifically controlled properties: glass transition temperature of 80°C or lower, and specific functional groups that provide adhesion to both the heat-resistant porous layer and the electrode. These parameter optimizations ensure adhesion stability in electrolytic solution while maintaining bond strength from heat pressing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The adhesive layer acts as an intermediary between the heat-resistant porous layer and the electrode, providing chemical and physical bonding interfaces. The phenyl group-containing acrylic type resin particles form strong interfacial adhesion that prevents peeling during electrolyte impregnation and subsequent battery operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If the thermal shrinkage ratio of the separator is reduced, then safety is improved, but manufacturing complexity increases

Engineering Contradiction:

ImprovesafetyVSAvoidseparator structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The heat-resistant porous layer contains inorganic particles with average primary particle diameter of 0.01 μm to less than 0.50 μm, creating a porous structure that provides thermal stability and low thermal shrinkage ratio. The porous structure allows ion permeability while the inorganic particles prevent excessive thermal shrinkage, improving safety without requiring overly complex designs.

Inventive Principle:

Principle #31Porous materials

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 achieves strong adhesion to electrodes and reduces thermal shrinkage, enhancing safety and stability in non-aqueous secondary batteries.

Implementation Method 1

the adhesive resin particles having a phenyl group-containing acrylic type resin are adhered to the heat-resistant porous layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

suppress the thermal shrinkage ratio of the separator to a low level... the separator including: a heat-resistant porous layer that contains an aromatic type resin and inorganic particles

Methodology Applied

Scientific EffectThermal shrinkage resistance: Thermal Expansion

Data Source

PatentUS20250279541A1Separator for non-aqueous secondary battery, and non-aqueous secondary battery

Publication Date: 2025.09.04 TEIJIN LTD

AI summary

In one embodiment of the present invention, provided is a separator for a non-aqueous secondary battery, the separator including: a heat-resistant porous layer that contains an aromatic type resin and inorganic particles, and an adhesive layer that is provided on the heat-resistant porous layer, and that contains adhesive resin particles having a phenyl group-containing acrylic type resin, in which the adhesive resin particles having a phenyl group-containing acrylic type resin are adhered to the heat-resistant porous layer, and in which an average primary particle diameter of the inorganic particles is from 0.01 μm to less than 0.50 μm.