Polyolefin Separator Composition with Dual Diluent System
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Solution Overview
Problem
Existing electrochemical device separators face challenges in achieving high-temperature stability and mechanical properties, as well as controlled pore size, which limits their performance and lifespan.
Innovation Solution
A composition comprising a polyolefin, a first diluent, and a second diluent with specific interaction energy, blended and processed to form a separator with controlled pore size, enhanced high-temperature stability, and improved mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polyethylene separator is prepared using a conventional wet process with a single diluent, then the separator can be easily manufactured with good chemical resistance, but the pore size cannot be suitably controlled and high-temperature stability is insufficient
Solution Approach 1:
The patent uses a composite diluent system comprising two different diluents (first diluent and second diluent) with specific interaction energy (2-3.5 cal/cm³) to prepare the polyolefin separator. This composite approach allows simultaneous control of pore size and enhancement of high-temperature stability, resolving the contradiction between manufacturing precision and reliability.
Solution Approach 2:
The patent changes the key parameter of diluent interaction energy to a specific range (2-3.5 cal/cm³) to achieve optimal phase separation behavior. This parameter control enables precise pore size formation while maintaining thermal stability, solving the contradiction between pore size control and high-temperature performance.
2Reliability
If the pore size is increased to improve ionic conductivity, then the mechanical property of the separator deteriorates
Solution Approach 1:
By controlling the interaction energy between diluents within 2-3.5 cal/cm³, the patent optimizes the phase separation process to create an optimal pore structure. This parameter control achieves sufficient porosity for good ionic conductivity while maintaining the mechanical integrity of the separator.
Solution Approach 2:
The patent creates a controlled porous structure through dual-diluent phase separation, where the pore size and distribution are optimized to balance ionic conductivity and mechanical strength, resolving the contradiction between these two properties.
3Reliability
If the crystallization temperature of polyolefin is increased to improve thermal stability, then the ease of pore formation is reduced
Solution Approach 1:
The patent introduces a dual-diluent system as an intermediary that facilitates pore formation at lower temperatures. The specific interaction energy between diluents (2-3.5 cal/cm³) enables controlled phase separation that creates pores without requiring high crystallization temperatures, thus maintaining both thermal stability and ease of manufacture.
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 effectively controls pore size and enhances the high-temperature stability and mechanical properties of the separator, thereby extending the lifespan and improving the performance of electrochemical devices.
Implementation Method 1
cooling the obtained single-phase liquid composition for preparing a separator to a temperature less than or equivalent to a temperature at which the blend is liquid-liquid phase separated, to carry out the phase separation of the composition
Implementation Method 2
extracting the first diluent and the second diluent from the phase-separated composition for preparing a separator using an extraction solvent
Data Source
AI summary
The present invention relates to a composition for preparing a separator for an electrochemical device, a method preparing a separator for an electrochemical device, and an electrochemical device having a separator prepared therefrom, more particularly, a composition for preparing a separator for an electrochemical device, comprising a polyolefin, a first diluent, and a second diluent, wherein an interaction energy between the first diluent and the second diluent is in the range of 2 to 3.5 cal/cm3, a method preparing a separator for an electrochemical device using the composition, and an electrochemical device having a separator prepared therefrom. In accordance with the present invention, the pore size of a polyolefin separator can be suitably controlled into a size desired by a user, and the high-temperature stability and mechanical property of the separator can be remarkably improved, thereby enhancing the life time and stability of an electrochemical device having the same.