Aluminum Trihydroxide Separator Coating for Heat-Shrinkage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polyolefin-based porous film separators in lithium secondary batteries exhibit severe heat shrinkage above 100°C, leading to potential short circuits and performance degradation, and existing inorganic particle solutions often include impurities that cause side reactions and reduce capacity retention.
Innovation Solution
Aluminum trihydroxide particles with controlled D50, BET, and Li content are used in an organic-inorganic composite coating on separators, replacing NaOH with LiOH to minimize impurities and enhance ionic conductivity, thereby improving capacity retention and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin-based porous film is used as separator, then manufacturing ease and cost are improved, but heat shrinkage above 100°C causes short circuits and safety deteriorates
Solution Approach 1:
The patent applies composite materials by combining polyolefin-based porous film with inorganic particles (alumina, silica, titania, zirconia, magnesia) to create a separator that maintains the manufacturing ease of polyolefin while adding heat resistance through inorganic components. The inorganic particles are dispersed in the polymer matrix or coated on the film surface, forming a composite structure that prevents heat shrinkage-induced short circuits while retaining the base material's processability.
2Temperature
If inorganic particles are applied to separator by mixing with polymer and coating, then heat resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes the porous structure of the polyolefin-based film to simplify inorganic particle application. The inorganic particles are introduced into the pores or coated on the surface, leveraging the existing porous architecture rather than creating entirely new complex structures. This approach maintains relative manufacturing simplicity while achieving heat resistance.
3Temperature
If conventional inorganic particles with impurities are used, then heat resistance is improved, but side reactions occur and capacity retention deteriorates
Solution Approach 1:
The patent applies parameter changes by strictly controlling the purity and particle size distribution of inorganic particles. The inorganic particles have controlled D50 values (0.5-5.0 μm) and high purity levels to minimize impurity-induced side reactions. This parameter control ensures that heat resistance is achieved without compromising capacity retention through harmful chemical reactions.
4Device complexity
If inorganic particles with larger size are used, then manufacturing simplicity is maintained, but surface area and ionic conductivity improvement deteriorates
Solution Approach 1:
The patent optimizes the particle size parameter by controlling D50 values within 0.5-5.0 μm. This size range balances manufacturing simplicity with enhanced surface area for ionic conductivity improvement. The controlled particle size ensures sufficient surface area for electrolyte interaction while maintaining ease of handling and uniform distribution during manufacturing.
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 use of aluminum trihydroxide particles with specific characteristics in lithium secondary batteries improves capacity retention rates and prevents side reactions, enhancing both performance and safety by reducing heat shrinkage and impurity-related issues.
Implementation Method 1
aluminum trihydroxide particles having a D50 of about 3.0 μm or less, a BET of about 3.0 m2/g or more, and a lithium (Li) content of about 500 ppm or more
Implementation Method 2
A polyolefin-based porous film, which is commonly used as a separator for a lithium secondary battery, exhibits a severe heat shrinkage behavior at a temperature equal to or greater than 100° C.
Data Source
AI summary
There are disclosed aluminum trihydroxide particles in which a D50 of the particles is about 3.0 μm or less, a BET of about 3.0 m2/g or more, and a Li content of about 500 ppm or more.