Composite Separator Coating for Adhesion and Pore Stability
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Solution Overview
Problem
Existing lithium battery separators face challenges with reduced adhesive strength due to delamination of inorganic particle coating layers, leading to accelerated side reactions and deteriorated cycle characteristics.
Innovation Solution
A composite separator is prepared by coating a binder composition containing a good-solvent, a binder, and inorganic particles on a porous substrate, followed by hot-air drying with a controlled non-solvent supply and hot-air supply speed ratio, resulting in enhanced adhesion force and constant pore size ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coating layer including inorganic particles is applied to improve heat resistance, then heat resistance is improved, but adhesive strength is reduced
Solution Approach 1:
A binder composition comprising a binder and a solvent is introduced as an intermediary between the porous substrate and the inorganic particles. The binder adheres to both the substrate and particles, creating a bridging layer that maintains adhesive strength while preserving the heat resistance benefits of the inorganic coating layer.
Solution Approach 2:
The coating layer is designed as a composite material system consisting of inorganic particles dispersed in a binder matrix. This composite structure combines the thermal stability of inorganic particles with the adhesive properties of the binder, achieving both heat resistance and adhesive strength simultaneously.
2Strength
If adhesive strength is enhanced to prevent delamination, then adhesive strength is improved, but pore size uniformity may be compromised
Solution Approach 1:
The solvent in the binder composition undergoes controlled evaporation during the coating process, with parameters such as solvent type, coating thickness, and drying conditions being optimized. This controlled parameter change enables the formation of a uniform pore structure while maintaining strong adhesion between layers.
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 composite separator achieves increased peel strength and bending strength, preventing delamination and internal resistance issues, thereby enhancing the energy density and cycle characteristics of lithium batteries.
Implementation Method 1
hot-air drying the porous substrate coated with the binder composition
Implementation Method 2
hot-air drying the porous substrate coated with the binder composition
Implementation Method 3
supplying a non-solvent during the hot-air drying
Data Source
AI summary
A method of preparing a composite separator for a lithium battery includes: coating a binder composition on one side or both sides of a porous substrate; hot-air drying the porous substrate coated with the binder composition; and supplying a non-solvent during the hot-air drying, such that a porous layer is on one side or both sides of the porous substrate, wherein the binder composition includes a good-solvent, a binder, and inorganic particles, an amount of the non-solvent supplied during the hot-air drying is from 12 g/m3 to 17 g/m3, and a ratio (e) of the hot-air supply speed to the moving speed of the porous substrate per unit transit time in the hot-air dryer is from 2.2 to 5.0.