Battery Separator Coating for Heat Resistance and Breakdown Voltage
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Solution Overview
Problem
Existing separators for lithium secondary batteries with inorganic coating layers exhibit unsatisfactory insulating properties and breakdown voltage characteristics, compromising battery performance.
Innovation Solution
A separator for lithium secondary batteries is developed with a coating layer containing heat-resistant organic particles, an organic heat-resistant binder, and an organic adhesive binder, with specific mixing ratios to enhance heat resistance and breakdown voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an inorganic coating layer is used on the separator, then heat resistance is improved, but insulating property deteriorates
Solution Approach 1:
The patent applies composite materials by combining organic particles with glass transition temperatures of 130°C to 200°C and organic binder resins in specific weight ratios (organic particles:organic binder resin = 95:5 to 50:50). This composite coating layer achieves both heat resistance through the high glass transition temperature of organic particles and satisfactory insulating properties through the organic binder resin matrix, resolving the contradiction between heat resistance and insulating property that plagues inorganic coating layers.
2Temperature
If an inorganic coating layer is used on the separator, then heat resistance is improved, but breakdown voltage characteristic deteriorates
Solution Approach 1:
The composite coating layer consisting of organic particles (providing heat resistance through high glass transition temperature) and organic binder resin (providing insulating properties) achieves improved breakdown voltage characteristics. The organic binder resin creates a uniform insulating matrix that prevents electrical breakdown, while the organic particles maintain thermal stability, thereby resolving the contradiction between heat resistance and breakdown voltage characteristic.
Solution Approach 2:
The patent employs parameter changes by carefully controlling the glass transition temperature range of organic particles (130°C to 200°C) and the weight ratio between organic particles and organic binder resin (95:5 to 50:50). These parameter optimizations ensure the coating layer maintains both heat resistance and satisfactory insulating properties, leading to improved breakdown voltage characteristics while preserving thermal stability.
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 improves insulating properties and thermal stability, enabling the production of lithium secondary batteries with enhanced breakdown voltage and simplified manufacturing processes.
Implementation Method 1
the organic heat-resistant binder is a first organic material having a glass transition temperature of 130° C. to 200° C.
Implementation Method 2
the organic adhesive binder is a second organic material having a glass transition temperature of −40° C. or lower
Data Source
AI summary
A battery substrate for separating a positive electrode and a negative electrode from each other in a rechargeable battery includes a porous substrate having a first surface and a second surface opposing each other and a first coating layer and a second coating layer respectively disposed on the first and second surfaces of the porous substrate. Each of the first and second coating layers contains heat-resistant organic particles, an organic heat-resistant binder, and an organic adhesive binder. The heat-resistant organic particles have a core/shell structure.