Core-Shell Separator Coating for Battery Shutdown and Heat Resistance
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high capacity, and improved safety with effective shutdown mechanisms to prevent overheating and fires.
Innovation Solution
A separator for lithium batteries featuring a porous substrate with a coating layer containing core-shell particles, where the core has a lower melting point than the substrate and the shell has a higher melting point, providing a uniform shutdown function and enhanced manufacturing processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied on the porous substrate to provide shutdown function, then battery safety is improved, but coating density increases and thickness increases which may affect manufacturing processability
Solution Approach 1:
The patent uses core-shell particles where the core provides shutdown function (low melting point organic material) and the shell provides heat resistance (high melting point inorganic material). This composite structure allows the coating layer to achieve both safety shutdown function and thermal stability without requiring excessive thickness, thereby maintaining manufacturing processability while improving battery safety.
Solution Approach 2:
The patent optimizes the melting point parameters of the core-shell particles, specifically setting the core material melting point between 80-150°C for shutdown function and the shell material melting point above 1000°C for heat resistance. By carefully controlling these parameter ranges, the coating layer achieves effective shutdown while maintaining thin profile and good manufacturing processability.
2Reliability
If core-shell particles with low melting point core are used for shutdown function, then safety is improved, but heat resistance may be compromised without the high melting point shell
Solution Approach 1:
The core-shell particle structure combines organic material (core) with low melting point for shutdown function and inorganic material (shell) with high melting point for heat resistance. The core provides the safety shutdown mechanism while the shell protects the structure at high temperatures, resolving the contradiction between shutdown sensitivity and thermal stability.
Solution Approach 2:
Different parts of the particle have different properties: the core is designed with low melting point for localized shutdown response, while the shell is designed with high melting point for overall structural heat resistance. This spatial differentiation of material properties allows simultaneous achievement of both shutdown function and heat resistance.
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 enhances battery safety by early shutdown in case of overheating, maintains high energy density, and improves manufacturing efficiency through increased adhesion and mechanical strength.
Implementation Method 1
the core includes an organic component having a melting point lower than a melting point of the porous substrate
Implementation Method 2
the shell includes an inorganic component having a melting point higher than the melting point of the organic component
Data Source
AI summary
Examples of the present disclosure relate to a separator for a rechargeable lithium battery, and a rechargeable lithium battery including the separator, and are directed to providing a separator for a rechargeable lithium battery. The separator includes a porous substrate and a coating layer located on at least one surface of the porous substrate. The coating layer includes a binder and a filler, the filler includes a core-shell particle as a first particle, the core includes an organic component having a melting point lower than a melting point of the porous substrate, and the shell includes an inorganic component having a melting point higher than the melting point of the organic component.