Aqueous Separator Coating for Wetting Polyolefin Substrates

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Solution Overview

Problem

Current methods for manufacturing separators for electrochemical devices using organic solvent-based slurries are hazardous, environmentally unfriendly, and inefficient, with poor wetting properties on polyolefin-based substrates, leading to safety concerns and suboptimal performance, especially at high temperatures.

Innovation Solution

A method involving an aqueous slurry with inorganic particles, a binder polymer, and an aqueous medium is used to form an organic-inorganic composite porous coating layer on a porous polymer substrate, with controlled capillary number to enhance wetting and coating efficiency, using additives like hydrophilic surfactants to adjust viscosity and surface tension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an organic solvent-based slurry is used for coating the separator, then the coating process can proceed, but it creates safety hazards and environmental pollution

Engineering Contradiction:

Improvecoating process feasibilityVSAvoidsafety hazards and environmental pollution

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental parameter of the slurry medium from organic solvent-based to aqueous-based. This substitution eliminates the safety hazards and environmental pollution associated with organic solvents while maintaining the coating process feasibility through careful adjustment of the aqueous slurry composition and coating parameters

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a disposable aqueous slurry system that can be easily prepared and discarded without environmental contamination concerns. The aqueous-based formulation allows for simple waste disposal compared to organic solvent systems requiring special handling and disposal procedures

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If an aqueous slurry is used for coating the separator, then safety and environmental friendliness are improved, but the high surface tension causes low wettability on polyolefin-based substrate

Engineering Contradiction:

Improvesafety and environmental friendlinessVSAvoidwettability on substrate

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent introduces surfactants as intermediary substances in the aqueous slurry formulation. These surfactants act as mediators that reduce the surface tension of water, enabling it to wet the hydrophobic polyolefin-based separator substrate effectively. The surfactants create an interface that facilitates adhesion between the aqueous slurry and the non-polar substrate

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the surface tension parameter of the aqueous slurry by adding surfactants and adjusting the slurry composition. This parameter change transforms the inherently poor wettability of water on polyolefin into effective wetting and coating, allowing the aqueous slurry to spread and adhere properly to the separator surface

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the capillary number is not controlled within the specified range, then coating may be simpler, but the wetting properties and coating quality deteriorate

Engineering Contradiction:

Improvecoating process simplicityVSAvoidcoating quality and wetting properties

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent establishes a feedback mechanism by defining the optimal capillary number range (0.01 to 100) based on the interplay between slurry viscosity, coating speed, and surface tension. By monitoring and adjusting these parameters to maintain the capillary number within this range, the process achieves both good wetting properties and coating quality without excessive complexity

Inventive Principle:

Principle #23Feedback

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

This approach ensures safer, more economical, and efficient production of separators with improved wetting properties, enhancing the safety and performance of electrochemical devices by preventing short circuits and thermal runaway.

Implementation Method 1

coating the aqueous slurry on at least one surface of a porous polymer substrate to form an organic-inorganic composite porous coating layer, wherein capillary number of the aqueous slurry is from 0.3 to 65

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

using additives like hydrophilic surfactants to adjust viscosity and surface tension

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Data Source

PatentEP3043403B1Method for manufacturing separator, separator manufactured therefrom, and electrochemical element comprising same

Publication Date: 2018.08.29 LG CHEM LTD

AI summary

A preparation method of a separator according to the present disclosure includes preparing an aqueous slurry including inorganic particles, a binder polymer, and an aqueous medium, and coating the aqueous slurry on at least one surface of a porous polymer substrate to form an organic-inorganic composite porous coating layer, wherein capillary number of the aqueous slurry has a range between 0.3 and 65.