Solvent-Free Separator Coating via Electrostatic Deposition

Solution Overview

Problem

Conventional methods for preparing separators for lithium secondary batteries require solvents for coating, leading to increased costs, handling hazards, and decreased productivity due to the need for drying steps.

Innovation Solution

A method involving the formation of a porous coating layer on a substrate with inorganic particles, followed by electrostatic charging of polymer particles for transfer and fixation with heat and pressure to create a functional coating layer without solvents, allowing for easy handling and storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a solvent-based coating method is used to form a functional coating layer on the separator, then proper dispersion and viscosity of polymer particles can be achieved, but costs increase, handling becomes hazardous, and productivity decreases due to required drying steps

Engineering Contradiction:

Improvedispersion and viscosity of polymer particlesVSAvoidproduction yield

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent extracts and eliminates the solvent from the coating process entirely. Instead of using a solvent-based slurry, the invention applies polymer particles directly in a dry state onto the porous coating layer, removing the harmful solvent component while still achieving proper polymer dispersion and coating formation without requiring drying steps.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical state parameter of the coating material from a liquid slurry (solvent-based) to a dry powder form (solvent-free). This parameter change eliminates the need for solvent evaporation and drying steps, directly improving productivity while maintaining coating quality through controlled application of dry polymer particles.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If a solvent-based coating method is used to form a functional coating layer on the separator, then proper dispersion and viscosity of polymer particles can be achieved, but additional costs are incurred for solvent handling and storage

Engineering Contradiction:

Improvedispersion and viscosity of polymer particlesVSAvoidcosts for solvent handling and storage

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent extracts and eliminates the solvent from the coating process entirely. Instead of using a solvent-based slurry, the invention applies polymer particles directly in a dry state onto the porous coating layer, removing the harmful solvent component while still achieving proper polymer dispersion and coating formation without requiring drying steps.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If a solvent-based coating method is used to form a functional coating layer on the separator, then proper dispersion and viscosity of polymer particles can be achieved, but the coating process requires drying steps that decrease productivity

Engineering Contradiction:

Improvedispersion and viscosity of polymer particlesVSAvoiddrying time after coating

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent extracts and eliminates the solvent from the coating process entirely. Instead of using a solvent-based slurry, the invention applies polymer particles directly in a dry state onto the porous coating layer, removing the harmful solvent component while still achieving proper polymer dispersion and coating formation without requiring drying steps.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary action by pre-drying the polymer particles before application. The polymer particles are prepared in advance in a dry, dispersed state, eliminating the need for post-coating drying steps. This preliminary preparation ensures proper dispersion is achieved before application, and the coating can be immediately used without additional drying time.

Inventive Principle:

Principle #10Preliminary action

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 reduces costs and enhances productivity by eliminating the need for solvents and drying steps, while ensuring effective adhesion with electrodes and improved battery performance.

Implementation Method 1

a porous substrate, the porous coating layer comprising inorganic particles

Methodology Applied

Scientific EffectPorosity: Porosity

Implementation Method 2

bringing polymer particles into electric charging to obtain electrically charged polymer particles; transferring the electrically charged polymer particles on the top surface the porous coating layer

Methodology Applied

Scientific EffectElectrostatic deposition: Electrostatic Deposition

Implementation Method 3

fixing the functional coating layer with heat and pressure

Methodology Applied

Scientific EffectThermal bonding: Heating

Data Source

PatentUS10411234B2Method of preparing separator for lithium secondary battery, separator prepared therefrom, and lithium secondary battery comprising the same

Publication Date: 2019.09.10 LG ENERGY SOLUTION LTD

AI summary

The present invention provides a method of preparing a separator for a lithium secondary battery, comprising: forming a porous coating layer on at least one surface of a porous substrate, the porous coating layer comprising inorganic particles; bringing polymer particles into electric charging to obtain electrically charged polymer particles; transferring the electrically charged polymer particles on the top surface the porous coating layer to form a functional coating layer; and fixing the functional coating layer with heat and pressure, a separator prepared by the method, and a lithium secondary battery comprising the separator.