Inorganic-Coated Battery Separator for High Adhesion, Low Resistance

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Solution Overview

Problem

Existing separators for electrochemical devices face challenges in achieving high adhesion between the separator and electrode, leading to potential detachment during deformation, reduced energy density, and increased resistance, while also requiring improved manufacturing processes for mass production.

Innovation Solution

A separator with an inorganic coating layer containing a combination of polyvinyl acetate (PVAc) and polyvinylidene fluoride (PVDF)-based binder resins, where the PVDF main chain is modified with a —C(═O)O— group, and a specific ratio of binder resins, along with a high concentration of binder resin at the top layer, enhances adhesion and ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the content or coating amount of the binder resin is increased to improve adhesion, then the adhesion between separator and electrode is improved, but the adhesive layer becomes thick causing decrease in energy density and increase in resistance

Engineering Contradiction:

ImproveadhesionVSAvoidenergy density

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The patent changes the chemical composition parameters of the binder resin by introducing carboxyl groups (-COOH) through reaction with carbon dioxide or carboxylic acid anhydride. This chemical modification enhances the adhesion mechanism from simple physical bonding to chemical bonding, allowing effective adhesion at lower binder resin content (5-30 wt%), thus resolving the contradiction between adhesion strength and energy density

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite binder resin system combining PVDF polymer matrix with carboxyl functional groups. This composite structure provides both the mechanical binding function of PVDF and the chemical adhesion function of carboxyl groups, achieving high adhesion with reduced binder resin content and maintaining low resistance

Inventive Principle:

Principle #40Composite materials

2Strength

Engineering Contradiction:

ImproveadhesionVSAvoidresistance

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the binder resin parameters by introducing carboxyl groups that enable chemical bonding with the electrode. This chemical bonding mechanism provides strong adhesion without requiring thick layers, maintaining ion conductivity and low resistance while achieving high adhesion strength

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a PVDF-based resin is used as binder resin to provide durability and heat resistance, then the separator substrate gains durability and heat stability, but the adhesion is low making it difficult to ensure high level of binding force

Engineering Contradiction:

ImprovedurabilityVSAvoidadhesion

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent modifies the PVDF resin parameters by introducing carboxyl functional groups through reaction with carbon dioxide or carboxylic acid anhydride. This chemical modification transforms PVDF from a material with only physical adhesion to one with chemical bonding capability, significantly enhancing adhesion while preserving the durability and heat resistance of the PVDF matrix

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure where PVDF provides the durable matrix and carboxyl groups provide the adhesive function. This composite binder resin combines the advantages of both properties, achieving high adhesion strength while maintaining the reliability, durability, and heat stability of PVDF-based resin

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 solution provides excellent adhesion between the separator and electrode, prevents separation of inorganic particles, reduces electrolyte solubility, and maintains low resistance, thereby improving battery performance and manufacturing efficiency.

Implementation Method 1

an inorganic coating layer which uses a PVAc-based binder resin and a PVDF-based binder resin having a —C(═O))— group introduced thereto

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

a porous polymer substrate and an inorganic coating layer on at least one surface of the porous polymer substrate

Methodology Applied

Scientific EffectIon transport: Permeation

Data Source

PatentUS12451562B2Separator for electrochemical device and electrochemical device including the same

Publication Date: 2025.10.21 LG ENERGY SOLUTION LTD

AI summary

A separator for an electrochemical device, including a porous polymer substrate and an inorganic coating layer on at least one surface of the porous polymer substrate. The inorganic coating layer includes inorganic particles and a binder resin. The binder resin includes a PVAc-containing first binder resin and a PVDF-containing second binder resin.