Separator Coating for Battery Electrodes
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Solution Overview
Problem
Existing separator technologies for electrochemical devices face challenges in achieving simultaneous enhanced adhesion to electrodes and safety, while also improving productivity and uniformity of the coating layer, due to limitations in current coating methods such as dip coating which result in non-uniformity and increased volume.
Innovation Solution
A separator with a porous substrate coated using a die coating method on one surface with a combination of inorganic particles and binder polymer, and a roll coating method on the other surface with a binder polymer, enhancing adhesion and safety by optimizing the thickness and density of the coating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dip coating method is used to coat the separator, then the coating process is simple, but the coating layer uniformity deteriorates and productivity decreases
Solution Approach 1:
The patent replaces the traditional dip coating mechanical system with a die coating system that uses a doctor blade to precisely control coating thickness. The die coating apparatus includes a die body with a coating chamber and a doctor blade that刮s excess coating material, ensuring uniform coating layer thickness and composition on the separator surface, thereby resolving the uniformity issue while maintaining manufacturing simplicity.
2Reliability
If an excess amount of inorganic particles and binder polymer is used in the coating layer, then safety against nail penetration is improved, but adhesion to electrodes deteriorates
Solution Approach 1:
The patent optimizes the composition parameters of the coating layer by controlling the weight ratio of inorganic particles to binder polymer within 90:10 to 99:1, and the thickness of the coating layer within 1-10 μm. This parameter optimization ensures that the coating layer has sufficient mechanical strength for safety while maintaining adequate adhesion to electrodes through the binder polymer component.
Solution Approach 2:
The patent uses a composite coating layer consisting of inorganic particles (such as Al2O3, SiO2, TiO2) dispersed in a binder polymer matrix. This composite structure provides both the mechanical strength needed for safety against nail penetration from the inorganic particles and the adhesion properties needed for electrode bonding from the binder polymer, resolving the contradiction between safety and adhesion.
3Strength
If the content of binder polymer is increased to improve adhesion, then adhesion to electrodes is improved, but safety level deteriorates
Solution Approach 1:
The patent precisely controls the binder polymer content within 10-30 wt% of the total coating layer composition and the coating thickness within 1-10 μm. This parameter control ensures that sufficient binder polymer is present for adequate electrode adhesion while preventing excessive binder content that would compromise the mechanical strength and safety performance of the separator.
4Reliability
If coating layer thickness is increased to improve safety, then safety is improved, but productivity and uniformity deteriorate
Solution Approach 1:
The patent employs die coating technology that enables precise control of coating thickness at 1-10 μm through the gap between the die body and the separator surface. This mechanical control system allows for thin, uniform coating layers to be applied efficiently, improving productivity while maintaining safety through optimized coating composition rather than increased thickness.
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 improves the adhesion between the separator and electrodes, enhances safety by reducing the risk of electrode shorting, and increases productivity and uniformity of the coating layer, thereby improving the performance and efficiency of the battery.
Implementation Method 1
coating a first coating agent and a second coating agent on one surface of the porous separator substrate by means of a first coating part of a die coating method that includes a first roller
Implementation Method 2
coating a third coating agent on the other surface of the porous separator substrate by means of a second coating part of a roll coating method that includes a second roller
Implementation Method 3
forming a first coating layer, a second coating layer, and a third coating layer by drying the porous separator substrate coated with the first coating agent, the second coating agent, and the third coating agent
Data Source
AI summary
A preparation method of a separator for an electrochemical device, and a preparation apparatus therefor are provided. The preparation method includes: supplying a porous separator substrate; coating one surface of the porous separator substrate with a first coating agent and a second coating agent by means of a first coating part of a die coating method that includes a first roller; coating the other surface of the porous separator substrate with a third coating agent by means of a second coating part of a roll coating method that includes a second roller; and forming a first coating layer, a second coating layer and a third coating layer by drying the porous separator substrate coated with the first coating agent, the second coating agent and the third coating agent coated thereon, in which a pattern is formed on the surface of the second roller.