Battery Separator Porous Coating for Dry and Wet Adhesion

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Solution Overview

Problem

Existing secondary battery separators exhibit insufficient adhesion between electrodes and separators, leading to potential separation and dislodgment of inorganic particles, which can cause local defects and safety issues, with existing acrylic binders improving dry adhesion but not wet adhesion.

Innovation Solution

A separator with an organic-inorganic composite porous coating layer containing PVDF-containing and acrylic polymers, where the PVDF-containing polymer has a Hansen solubility parameter of 13 or less, ensuring both dry and wet adhesion, and a porous structure that maintains inorganic particle stability and insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an acrylic binder is used in the organic-inorganic composite porous coating layer, then dry adhesion is improved, but wet adhesion deteriorates because the coating layer swells or is eluted by electrolyte

Engineering Contradiction:

Improvedry adhesionVSAvoidwet adhesion

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the binder by incorporating PVDF-containing polymer with specific Hansen solubility parameter (13 or less) alongside acrylic polymer. This parameter adjustment allows the binder to maintain adhesion strength in both dry and wet states by controlling its interaction with electrolyte, preventing swelling and elution while preserving bonding capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite binder system combining PVDF-containing polymer and acrylic polymer in specific proportions. This composite material approach leverages the complementary properties of both polymers: acrylic provides strong adhesion while PVDF-containing polymer with appropriate HSP value provides electrolyte resistance, achieving both dry and wet adhesion simultaneously.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the separator uses a simple porous structure, then manufacturing is easier, but adhesion between electrodes and separator deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidadhesion

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention applies an organic-inorganic composite porous coating layer to the separator surface before electrode assembly. This preliminary action of coating the separator with a specialized layer containing inorganic particles and optimized binder creates enhanced adhesion properties in advance, ensuring strong electrode-separator bonding without complicating the overall manufacturing process.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If inorganic particles are added to improve thermal safety, then thermal stability is improved, but adhesion deteriorates due to insufficient binder resin

Engineering Contradiction:

Improvethermal stabilityVSAvoidadhesion

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The invention optimizes the ratio of inorganic particles to binder resin and adjusts the molecular characteristics of the binder (using PVDF-containing polymer with HSP≤13 and acrylic polymer in specific proportions). This parameter optimization ensures sufficient binder resin content to maintain adhesion while incorporating enough inorganic particles for thermal stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite porous coating layer combining inorganic particles with a dual-polymer binder system. The inorganic particles provide thermal stability while the composite binder (PVDF-containing polymer + acrylic polymer) provides adhesion, achieving both thermal stability and strong adhesion through material composition design.

Inventive Principle:

Principle #40Composite 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 high adhesion in both dry and wet states, maintaining form stability, improving thermal safety and electrical insulation, and preventing inorganic particle dislodgment, while maintaining ion conduction and reducing interfacial resistance.

Implementation Method 1

The PVDF-containing polymer has a Hansen solubility parameter (HSP) value of 13 or less and preferably 1 or more

Methodology Applied

Scientific EffectHansen solubility parameter:

Implementation Method 2

The organic-inorganic composite porous coating layer includes polymer resin particles and inorganic particles

Methodology Applied

Scientific EffectPorosity: Porosity

Data Source

PatentUS20250391999A1Separator with organic/inorganic porous coating layer for electrochemical device, and electrochemical device including same

Publication Date: 2025.12.25 LG ENERGY SOLUTION LTD

AI summary

A separator for an electrochemical device, in which the separator includes a separator substrate and an organic-inorganic composite porous coating layer on at least one surface of the separator substrate. The separator substrate is a porous film including a polyolefin-containing polymer. The organic-inorganic composite porous coating layer includes a polymer resin particles and inorganic particles, in which each particle of the polymer resin particles includes a polyvinylidene fluoride (PVDF)-containing polymer and an acrylic polymer, and the PVDF-containing polymer has a Hansen solubility parameter (HSP) value of 13 or less and 1 or more.