Electrode-Integrated Separator With Inorganic Coating
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Solution Overview
Problem
Conventional lithium secondary battery separators face issues with insufficient adhesion to electrodes, thermal instability, and low insulating characteristics, leading to potential micro-scale short circuits and reduced lifespan.
Innovation Solution
An electrode-integrated separator for lithium secondary batteries is developed, comprising a porous layer with a polymer binder and inorganic fine particles of varying green densities, which forms a dense pore structure and high tortuosity to enhance insulation and minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a separator including a substrate and an inorganic coating layer is used, then thermal stability is improved, but adhesion force to electrodes is insufficient
Solution Approach 1:
The patent uses a composite structure consisting of a polyolefin substrate combined with an inorganic coating layer containing alumina and boehmite particles. This composite material approach allows the separator to simultaneously achieve thermal stability from the inorganic coating and adequate adhesion through the substrate-electrode interface, resolving the contradiction between thermal stability and adhesion force.
2Strength
If only an inorganic coating film is used without substrate, then adhesion force is improved, but insulating characteristics and mechanical strength are significantly reduced
Solution Approach 1:
The patent employs a composite material system where the inorganic coating layer (alumina and boehmite) is applied on top of a polyolefin substrate. This composite structure provides both the adhesion benefits of the inorganic layer and the insulating properties of the substrate, eliminating the vulnerability to internal short circuits while maintaining strong electrode adhesion.
Solution Approach 2:
The patent applies different materials with specific properties to different regions/layers: the polyolefin substrate provides bulk insulating properties and mechanical strength, while the inorganic coating layer at the electrode interface provides adhesion force. This local differentiation of material properties resolves the contradiction between adhesion and insulation.
3Strength
If polyolefin substrate is used, then mechanical strength is improved, but thermal stability is reduced due to melting at high temperature
Solution Approach 1:
The patent creates a composite separator where the polyolefin substrate provides mechanical strength and the inorganic coating layer (alumina and boehmite) provides thermal stability. The inorganic particles have high melting points that prevent separator failure at elevated temperatures while the polyolefin matrix maintains structural integrity and mechanical strength.
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 exhibits excellent insulation properties, low resistance, and high ionic conductivity while reducing the occurrence of defects, thereby improving the safety and performance of lithium secondary batteries.
Implementation Method 1
a porous layer stacked on an electrode substrate, wherein the porous layer comprises a polymer binder and inorganic fine particles dispersed within the polymer binder
Implementation Method 2
The separator exhibits excellent insulation properties, low resistance, and high ionic conductivity
Data Source
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AI summary
The present disclosure relates to an electrode-integrated separator for lithium secondary battery and a method for manufacturing the same. According to the present disclosure, the electrode-integrated separator for lithium secondary battery that can exhibit excellent insulation properties while minimizing the occurrence of defect, and a method for manufacturing the same are provided.