Patterned Separator Bonding Layer for Battery Ion Conductivity

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Solution Overview

Problem

Lithium secondary batteries face performance deterioration due to ion conductivity issues caused by binder penetration through separators and extreme heat shrinkage of porous substrates, leading to resistance and reduced lithium ion transfer.

Innovation Solution

A separator with a first bonding layer pattern on a porous substrate, featuring an aperture ratio of 5% to 40%, is printed using a low viscous bonding composition without additives, allowing for efficient ion transfer and reduced internal resistance through gravure printing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a binder is added to increase viscosity to prevent separator penetration, then binding strength is improved, but ion conductivity deteriorates due to additive interference

Engineering Contradiction:

Improvebinding strengthVSAvoidion conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention extracts and removes the harmful additive (thickener) from the binder composition. By using a binder without thickening agents, the patent eliminates the source of ion conductivity deterioration while maintaining adequate binding strength through proper binder selection and formulation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the viscosity parameter of the binder by selecting appropriate binder materials and formulations that provide sufficient binding strength without requiring thickening additives. This parameter optimization ensures both adequate adhesion and maintained ion conductivity.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If a coating layer is formed on the porous substrate to prevent heat shrinkage, then thermal stability is improved, but binding strength between electrode and separator is reduced

Engineering Contradiction:

Improveheat shrinkage resistanceVSAvoidbinding strength

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The invention applies local quality by forming a bonding layer pattern rather than a complete coating. The bonding layer is strategically positioned at specific locations where electrode-to-separator attachment is needed, leaving other areas open for ion transport. This localized approach maintains binding strength without compromising thermal stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention utilizes the porous structure of the separator substrate and designs the bonding layer to work in conjunction with this porosity. The bonding layer pattern allows the porous structure to remain accessible for ion transport while providing localized bonding functionality.

Inventive Principle:

Principle #31Porous materials

3Stability of the object's composition

If a full surface coating method is used to form a bonding layer, then heat shrinkage is prevented, but ion transfer is hindered due to resistance formation

Engineering Contradiction:

Improveheat shrinkage resistanceVSAvoidion transfer efficiency

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The invention segments the bonding layer into a patterned structure rather than applying a continuous full-surface coating. This segmentation creates discrete bonding regions that prevent heat shrinkage at critical points while leaving gaps for ion transfer pathways, thus resolving the contradiction between thermal stability and ion conductivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bonding layer is applied with local quality through patterned formation, concentrating the bonding function only where needed for structural stability while maintaining open pathways elsewhere for efficient ion transfer.

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 enables faster electrolyte wetting and improved bonding strength, resulting in enhanced battery performance by reducing internal resistance and maintaining lithium ion conductivity.

Implementation Method 1

the lithium secondary battery has a structure in which electricity is generated by an electrical flow in which lithium ions move through the electrolyte between the positive electrode and the negative electrode

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

Methodology Applied

Scientific EffectGravure printing:

Data Source

PatentUS10804559B2Patterned separator and battery comprising same

Publication Date: 2020.10.13 LG ENERGY SOLUTION LTD

AI summary

The present application relates to a separator and a battery comprising the same. A separator according to an exemplary embodiment of the present application includes: a porous substrate; and a first bonding layer pattern provided on at least one surface of the porous substrate, in which each pattern constituting the first bonding layer pattern is a pattern including a second bonding layer pattern having an aperture ratio of 5% or more and 40% or less.