Phase-Inversion hBN Composite Separator for High-Temperature Wettability
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Solution Overview
Problem
Conventional lithium-ion battery separators face limitations due to low wettability towards polar liquid electrolytes, low glass transition temperatures leading to shrinkage and mechanical integrity issues, and thermal instability, which can result in catastrophic failures at elevated temperatures.
Innovation Solution
Phase-inversion composite separators are developed using carbon-coated hexagonal boron nitride (hBN) nanosheets and electrochemically inert polymers like PVDF, where hBN nanosheets are exfoliated and coated with carbon through a scalable liquid-phase shear exfoliation method, enhancing porosity, electrolyte wettability, and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin separators are used, then chemical and mechanical stability is improved, but wettability towards polar liquid electrolytes deteriorates
Solution Approach 1:
The patent uses composite materials by combining polyolefin base material with hydrophilic inorganic particles (such as metal oxides) to create a separator that maintains the chemical and mechanical stability of polyolefin while adding electrolyte wettability through the hydrophilic particles on the surface
Solution Approach 2:
The patent applies local quality by modifying only the surface properties of the polyolefin separator through coating or grafting hydrophilic groups, while the bulk polyolefin structure retains its excellent chemical and mechanical stability
2Ease of manufacture
If polyolefin separators are used, then cost and manufacturing ease is improved, but thermal resistance deteriorates
Solution Approach 1:
The patent creates composite separators by incorporating thermally stable inorganic particles into the polyolefin matrix, which maintains the ease of manufacturing and cost-effectiveness of polyolefin while significantly improving thermal resistance through the high-temperature stability of the inorganic components
3Ease of operation
If ceramic particle coatings are applied, then electrolyte wettability and thermal stability are improved, but membrane porosity deteriorates
Solution Approach 1:
The patent applies ceramic particles primarily on the surface of the separator rather than throughout the bulk structure, which improves wettability and thermal stability at the interfaces where electrolyte contact occurs while preserving the porosity of the bulk membrane structure for ion transport
4Ease of operation
If ceramic particle coatings are applied, then wettability and thermal stability are improved, but organic binders reduce maximum safe operating temperature
Solution Approach 1:
The patent removes or eliminates organic binders from the ceramic particle coating system by developing binder-free coating methods or using inorganic binders instead, which allows the separator to achieve high wettability and thermal stability without the temperature limitations imposed by organic binder decomposition
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 composite separators exhibit improved ionic conductivity, thermal stability, and electrochemical performance, enabling safe lithium-ion battery operation up to 120°C, with potential for higher temperatures, surpassing the performance of traditional polyolefin separators.
Implementation Method 1
a scalable liquid-phase shear exfoliation method
Implementation Method 2
followed by thermal pyrolysis, thereby resulting in a carbon coating on the hBN nanosheets
Implementation Method 3
Phase-inversion composite separators are developed
Implementation Method 4
facilitating ion transport during charge and discharge by providing pathways for ionic conduction throughout an interconnected porous structure
Data Source
AI summary
A composite film usable as a separator of an electrochemical device includes hBN nanosheets and at least one polymer. The hBN nanosheets are uniformly dispersed within a matrix of said least one polymer to achieve a highly porous microstructure. Said at least one polymer comprises one or more electrically insulating and electrochemically inert polymers.