Atomic Layer Deposition Heat-Resistant Battery Separator
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Solution Overview
Problem
Lithium-ion secondary batteries face safety issues due to the decomposition of non-aqueous electrolyte solutions under abnormal conditions, leading to potential ignition, and existing separators lack sufficient heat resistance, which can cause internal short circuits when they shrink during thermal events.
Innovation Solution
A battery separator with a porous base material and a heat-resistant layer formed by atomic layer deposition, covering the surface and inner holes, using inorganic materials like aluminum oxide, silicon oxide, or titanium oxide to enhance heat resistance while maintaining electrolyte permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microporous polyolefin membrane is used as a separator to achieve shutdown function, then safety against short circuit is improved, but heat resistance is insufficient causing thermal contraction and secondary failure
Solution Approach 1:
The patent applies composite materials by combining a polyolefin resin base material with a heat-resistant resin coating layer. The heat-resistant resin coating layer contains inorganic filler particles (such as alumina, silica, or boehmite) dispersed in a binder resin, creating a composite structure that provides both the shutdown function of the polyolefin and the heat resistance of the inorganic-filled coating, preventing thermal contraction at elevated temperatures
2Productivity
If the separator is stretched to obtain porous property and improve strength, then ion permeability is improved, but thermal contraction increases causing electrode contact
Solution Approach 1:
The patent changes the thermal parameters of the separator by introducing a heat-resistant resin coating layer with inorganic filler. This coating layer has a higher glass transition temperature and thermal stability than the base polyolefin, allowing the separator to maintain its porous structure and dimensional stability at elevated temperatures while preserving ion permeability through the stretched porous structure
3Temperature
If a glass layer is formed on polyolefin skeleton to improve heat resistance, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses a porous heat-resistant resin coating layer containing dispersed inorganic filler particles rather than a dense glass layer. This porous coating can be applied by conventional coating methods and maintains ion permeability while providing heat resistance, simplifying the manufacturing process compared to forming a dense glass layer that would require more complex sintering or melting processes
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 solution improves heat resistance and reduces thermal contraction, preventing shutdown failures and enhancing safety by ensuring effective ion conduction and electrolyte penetration, while maintaining the primary shutdown function of the separator.
Implementation Method 1
The heat-resistant layer is formed of an inorganic material and deposited by an atomic layer deposition method
Implementation Method 2
suppressing ion conduction in the non-aqueous electrolyte solution
Implementation Method 3
it has been demanded to reduce thermal contraction by improving heat resistance of the separator
Data Source
AI summary
A battery separator includes a porous base material and a heat-resistant layer. The porous base material includes a first surface, a second surface opposed to the first surface, and a hole. The hole is formed in the porous base material and causes the first surface and the second surface to communicate with each other. The heat-resistant layer is configured to cover at least the first surface and a surface of the hole. The heat-resistant layer is formed of an inorganic material and deposited by an atomic layer deposition method.