Polyethylene Battery Separator Coating Against Heat Shrinkage

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Solution Overview

Problem

Conventional polyolefin-based microporous membranes used in electrochemical device separators exhibit heat shrinking behavior above 100°C, leading to short-circuit generation and increased resistance, while attempts to improve insulation properties through additional coatings result in reduced ion conductivity and porosity, hindering high-output battery performance.

Innovation Solution

A separator with a porous polyethylene substrate having a molecular weight of 2,500 g/mol or less, porosity of 40-70%, and a resistance of 0.5 ohm or less, combined with an inorganic coating layer containing inorganic particles and a binder resin, maintains low thickness and high ion conductivity, enhancing output characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polyolefin-based microporous membrane is used as separator, then manufacturing ease improves, but heat shrinking behavior causes short-circuit generation

Engineering Contradiction:

Improvemanufacturing easeVSAvoidshort-circuit prevention

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a composite separator structure with a polyolefin-based microporous membrane substrate combined with a porous coating layer containing inorganic particles and binder polymer. The polyolefin substrate provides ease of manufacture and basic separation function, while the porous coating layer adds thermal stability to prevent heat shrinking above 100°C. This composite approach maintains manufacturing simplicity while solving the heat shrinking and short-circuit problem.

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 provides excellent resistance characteristics and ion conductivity, ensuring improved output characteristics and safety in electrochemical devices by preventing short-circuits and maintaining high energy density.

Implementation Method 1

a porous coating layer formed on at least one surface of the porous substrate and including a mixture of filler particles, such as inorganic particles, with a binder polymer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

show severe heat shrinking behavior at a temperature of 100° C. or more due to their material properties

Methodology Applied

Scientific EffectThermal expansion resistance: Thermal Expansion

Implementation Method 3

the polyolefin-based porous substrate has been controlled to a low level of porosity, pore size and air permeability

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 4

the porous substrate has a porosity of 40% to 70%

Methodology Applied

Scientific EffectPorosity: Porosity

Implementation Method 5

the polyethylene has an entangle molecular weight (Me) of 2,500 g/mol or less

Methodology Applied

Scientific EffectChain entanglement:

Implementation Method 6

highly entangled polymer chains

Methodology Applied

Scientific EffectEntropic elasticity:

Data Source

PatentUS20250343322A1Separator including polyethylene with highly entangled polymer chains, and electrochemical device including the same

Publication Date: 2025.11.06 LG ENERGY SOLUTION LTD

AI summary

Provided is a separator for an electrochemical device. The separator includes a separator substrate made of a porous polymer material, wherein the separator substrate has a small thickness, excellent resistance characteristics and ion conductivity, and high mechanical strength. When the separator is applied to a battery, it is possible to improve the output characteristics of the battery.