Asymmetric Separator Coating for Curved Battery Permeability

Solution Overview

Problem

Conventional separators with heat-resistant layers in lithium batteries face challenges with reduced air permeability, ionic conductivity, and resistance due to uneven load distribution in curved areas, leading to potential safety issues and performance degradation.

Innovation Solution

A separator design featuring a porous substrate with inorganic particles and a heat-resistant layer on both surfaces, where the first heat-resistant layer has a lower density and faces the inside of the battery, and the second has a higher density and faces the outside, maintaining air permeability and ionic conductivity by optimizing the ratio of air permeability in curved to flat surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a heat-resistant layer containing ceramic particles is coated on the surface of the separator, then heat resistance is improved, but air permeability and ionic conductivity are reduced due to blocked pores

Engineering Contradiction:

Improveheat resistanceVSAvoidair permeability

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The patent applies different densities of heat-resistant layers at different locations on the separator surface. The first heat-resistant layer has a first density and the second heat-resistant layer has a second density different from the first, allowing optimization of heat resistance while maintaining air permeability in different regions of the separator

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the density parameter of the heat-resistant layer by controlling the content of porous particles. The first heat-resistant layer contains porous particles at a first content level and the second heat-resistant layer contains porous particles at a second content level different from the first, thereby adjusting air permeability and ionic conductivity while maintaining heat resistance

Inventive Principle:

Principle #35Parameter changes

2Temperature

If symmetrical heat-resistant layers are formed on both surfaces of the separator, then heat resistance is improved, but uneven load distribution in curved areas causes performance degradation and particle detachment

Engineering Contradiction:

Improveheat resistanceVSAvoidperformance stability in curved areas

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent introduces asymmetry in the heat-resistant layer configuration by setting different densities for the first and second heat-resistant layers. The first heat-resistant layer has a first density and the second heat-resistant layer has a second density different from the first, creating an asymmetric structure that adapts to the curved geometry of battery components and distributes mechanical loads more evenly

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies different densities of heat-resistant layers at different locations on the separator surface. The first heat-resistant layer has a first density and the second heat-resistant layer has a second density different from the first, allowing optimization of heat resistance while maintaining air permeability in different regions of the separator

Inventive Principle:

Principle #3Local quality

3Strength

If the density of heat-resistant layer is increased in curved areas to maintain structural integrity, then mechanical strength is improved, but air permeability, ionic conductivity, and resistance performance are reduced

Engineering Contradiction:

Improvemechanical strength in curved areasVSAvoidair permeability

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The patent applies different densities of heat-resistant layers at different locations on the separator surface. The first heat-resistant layer has a first density and the second heat-resistant layer has a second density different from the first, allowing optimization of heat resistance while maintaining air permeability in different regions of the separator

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the density parameter of the heat-resistant layer by controlling the content of porous particles. The first heat-resistant layer contains porous particles at a first content level and the second heat-resistant layer contains porous particles at a second content level different from the first, thereby adjusting air permeability and ionic conductivity while maintaining heat resistance

Inventive Principle:

Principle #35Parameter changes

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 effectively mitigates the degradation of air permeability, ionic conductivity, and resistance in curved areas, ensuring improved battery performance and safety by maintaining the required air permeability and ionic conductivity levels.

Implementation Method 1

facilitate the migration of lithium ions

Methodology Applied

Scientific EffectIon migration: Conduction (electrical)

Implementation Method 2

the heat-resistant layer is continuously exposed to an electrolyte in the battery

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Data Source

PatentUS20230378607A1Separator and electrochemical device including the same

Publication Date: 2023.11.23 W SCOPE KOREA CO LTD

AI summary

One aspect of the present invention provides a separator including a porous substrate, and a heat-resistant layer disposed on at least one surface of the porous substrate and including inorganic particles, wherein the ratio (F2/F1) of air permeability (F2, sec/100 mL) in a curved surface with a radius of curvature of 10 mm of the separator to the air permeability (F1, sec/100 mL) in a flat surface of the separator is 1.5 or less, and an electrochemical device including the same.