Porous Polyolefin Separator Coating for Heat Shrinkage Resistance
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Solution Overview
Problem
Dry-stretching separators in lithium-ion batteries exhibit high thermal shrinkage, leading to potential short circuits when the battery temperature exceeds 130° C., and they also have poor wettability with electrolytes.
Innovation Solution
A method for manufacturing a low thermal shrinkage separator involves applying a precursor solution containing titanium alkoxide and hexamethyldisilazane to a porous polyolefin substrate, followed by an alcohol solution to form a low thermal shrinkage thin film on the substrate's surfaces and sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a dry-stretching separator is used, then mechanical properties and ion permeability are improved, but thermal shrinkage resistance deteriorates
Solution Approach 1:
The patent applies composite materials by coating a porous polyolefin substrate with a ceramic coating layer containing inorganic particles (such as Al2O3, SiO2, TiO2, or ZrO2) suspended in a binder resin. This composite structure combines the mechanical strength and ion permeability of the polyolefin substrate with the thermal stability of the ceramic coating, resolving the contradiction between mechanical properties and thermal shrinkage resistance.
Solution Approach 2:
The patent changes the thermal and mechanical parameters of the separator by controlling the coating process parameters, including the concentration of inorganic particles (0.1-10 wt%), binder resin (1-20 wt%), and solvent (70-98.9 wt%). By adjusting these parameters, the coating forms a stable layer that reduces thermal shrinkage while maintaining mechanical integrity.
2Ease of manufacture
If a dry-stretching separator is used, then cost and safety are improved, but wettability with electrolyte deteriorates
Solution Approach 1:
The patent changes the surface energy parameters of the separator by selecting appropriate binder resins (such as polyvinylidene fluoride, polyacrylonitrile, or carboxymethyl cellulose) and controlling their concentration (1-20 wt%). These materials modify the surface properties of the porous polyolefin substrate, enhancing electrolyte wettability while maintaining the cost-effectiveness of the dry-stretching manufacturing process.
3Reliability
If a ceramic coating is applied to improve thermal shrinkage resistance, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-mixing the inorganic particles, binder resin, and solvent to create a stable coating slurry before application. This pre-prepared slurry ensures uniform distribution of ceramic particles and proper adhesion to the substrate, simplifying the coating process and reducing manufacturing complexity while achieving the desired thermal stability.
Solution Approach 2:
The patent uses a binder resin as an intermediary material that facilitates the attachment of inorganic ceramic particles to the porous polyolefin substrate. The binder resin acts as a mediator, providing adhesion between the substrate and ceramic coating, and enabling the coating to be applied using simple dip-coating or spray-coating methods without requiring complex equipment.
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 resulting separator demonstrates improved thermal shrinkage resistance, with thermal shrinkage rates less than 20% at 130° C. and less than 40% at 150° C., while also enhancing electrolyte wettability without significantly increasing the substrate's thickness.
Implementation Method 1
a low thermal shrinkage thin film formed on the surfaces and sidewalls of the porous structures of the porous polyolefin substrate; wherein the low thermal shrinkage thin film is a composite thin layer formed of titanium oxide and/or titanium hydroxide reacted by the titanium alkoxide and the alcohol solution
Implementation Method 2
providing a porous polyolefin substrate with a plurality of porous structures on surfaces and interiors thereof
Data Source
AI summary
A low thermal shrinkage separator and a method for manufacturing thereof is disclosed. The method comprises providing a porous polyolefin substrate with a plurality of porous structures on surfaces and interiors thereof, and applying a prescursor solution comprising a titanium alkoxide and hexamethyldisilazane and subsequently applying an alcohol solution to form a low thermal shrinkage thin film formed on the surfaces and the sidewalls of the porous structures of the porous polyolefin substrate. The present method can enhance the low thermal shrinkage and electrolyte wettability of the separator.