Ceramic-Coated Battery Separator Without Polymer Binder
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Solution Overview
Problem
The stability of the separator ceramic layer in lithium secondary batteries is a critical issue due to weak binding forces in existing methods, which affects cell resistance and output characteristics, and increasing polymer binder molecular weight complicates manufacturing and reduces ceramic particle amounts.
Innovation Solution
A binder-free ceramic coating separator is developed using chemically bonded ceramic particles with epoxide and amine groups, eliminating the need for a polymer binder and enhancing adhesion through chemical crosslinking between particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polymer binder is used to combine ceramic particles, then the binding force between particles is improved, but the manufacturing complexity increases and the amount of ceramic particles decreases
Solution Approach 1:
The invention extracts and eliminates the polymer binder from the ceramic coating layer, achieving particle binding through direct chemical bonding between ceramic particles themselves. This removes the problematic binder component entirely while maintaining binding strength through surface-modified chemical interactions between particles.
Solution Approach 2:
The invention introduces surface modifications on ceramic particles that act as intermediaries to facilitate chemical bonding between particles. These surface modifications enable direct particle-to-particle bonding without requiring a separate polymer binder, thus maintaining binding force while eliminating manufacturing complexity associated with binder processing.
2Strength
If the molecular weight of the polymer binder is increased to increase binding force, then the adhesion between particles is improved, but the coating solution becomes difficult to manufacture and the amount of ceramic particles relatively decreases
Solution Approach 1:
The invention extracts the polymer binder entirely from the coating system, replacing it with direct chemical bonding mechanisms between ceramic particles. This eliminates the trade-off between binder molecular weight and coating solution manufacturability, as no binder is present to complicate the coating solution formulation.
Solution Approach 2:
The invention changes the fundamental bonding mechanism from physical adhesion via polymer matrices to chemical bonding between particle surfaces. This parameter change in the bonding mechanism allows for high adhesion strength while maintaining simple coating solution composition with high ceramic particle content.
3Strength
If the molecular weight of the polymer binder is increased to increase binding force, then the binding force is improved, but the cell resistance increases and output characteristics deteriorate
Solution Approach 1:
The invention extracts the polymer binder from the system, eliminating the source of increased cell resistance. By achieving particle binding through direct chemical bonding rather than through polymer matrices, the coating layer maintains high ceramic particle content and proper porosity, ensuring low cell resistance and good output characteristics while still providing strong binding force.
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 adhesion between ceramic particles, reduces the amount of polymer binder required, and enhances the manufacturing process and output characteristics of lithium secondary batteries, ensuring price competitiveness and stability.
Implementation Method 1
the first ceramic particle comprises epoxide groups and a second ceramic particle comprising amine groups, and wherein the first ceramic particle chemically bonded to the second ceramic particle
Data Source
AI summary
Disclosed are a lithium secondary battery including: a positive electrode; a negative electrode; an electrolyte; and a separator including a separator substrate and a ceramic layer formed on one surface or both surfaces of the separator substrate. Particularly, the ceramic layer may include a first ceramic particle including an epoxide group and a second ceramic particle including an amine group, and the first ceramic particle may be chemically bonded to the second ceramic particle.