Alicyclic Polymer Separator for High Meltdown Secondary Battery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery separators do not achieve high enough meltdown and shutdown temperatures, which are necessary for enhanced safety and practicality.
Innovation Solution
A resin composition containing an alicyclic structure-containing hydrogenated polymer and an incompatible polymer, with the alicyclic polymer having a heat distortion temperature of 170°C or higher, is used to create a microporous film with a sea-island structure, resulting in a separator with a high meltdown temperature and low shutdown temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polymer compositions (polyethylene and polypropylene) are used for separators, then the separator can provide basic shutdown function, but the meltdown temperature is not high enough for enhanced safety
Solution Approach 1:
The invention uses a composite material system consisting of a high-melting-point polymer matrix (polypropylene or polyethylene with specific molecular weight) combined with a low-melting-point polymer component (such as polyethylene with lower molecular weight or other low-melting polymers). This composite structure enables the separator to maintain structural integrity at high temperatures while providing shutdown function at lower temperatures, thereby simultaneously achieving high meltdown temperature and safety reliability.
Solution Approach 2:
The invention changes the thermal parameters of the separator by selecting polymers with specific melting points and molecular weights. The matrix polymer is chosen with a melting point above 160°C (preferably 165-170°C or higher), while the dispersed polymer component has a lower melting point (100-150°C) to provide shutdown function. This parameter optimization allows the separator to achieve both high meltdown temperature and appropriate shutdown temperature for enhanced safety.
2Temperature
If a polymer with lower heat distortion temperature is used, then the shutdown function is activated at lower temperature, but the structural integrity is lost at higher temperature
Solution Approach 1:
The invention segments the polymer system into two distinct functional phases: a continuous matrix phase made of high-temperature polymer (polypropylene or high-molecular-weight polyethylene) that maintains structural integrity, and a dispersed phase made of low-temperature polymer (low-molecular-weight polyethylene or other low-melting polymers) that provides shutdown function. This segmentation allows each phase to independently perform its designated thermal function without compromising the other.
Solution Approach 2:
The invention applies local quality by creating a heterogeneous structure where different regions of the separator have different thermal properties. The matrix regions maintain high structural integrity at elevated temperatures, while the dispersed polymer regions provide localized shutdown function at lower temperatures. This spatial differentiation of thermal properties enables the separator to simultaneously achieve appropriate shutdown temperature and maintained structural integrity.
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 provides a secondary battery separator with improved safety and practicality by maintaining structural integrity at high temperatures and preventing ion movement, thus preventing ignition.
Implementation Method 1
a resin composition containing following polymer (A) and polymer (B), wherein a content of the polymer (A) is 1 to 80 wt % based on the total weight of the polymer (A) and the polymer (B)... a microporous film formed using the resin composition according to [1] or [2], which has a sea-island structure constructed by dispersing the polymer (A) in the polymer (B)
Implementation Method 2
when the temperature in the battery abnormally increases, a polymer having a lower heat distortion temperature melts to close the micropores, and a polymer having a higher heat distortion temperature holds the structure of the whole separator. These actions of each polymer can suppress movement of ions in the secondary battery to prevent ignition or the like of the secondary battery
Data Source
AI summary
The invention is a resin composition containing following polymer (A) and polymer (B), wherein a content of the polymer (A) is 1 to 80 wt % based on the total weight of the polymer (A) and the polymer (B), polymer (A) is a alicyclic structure-containing hydrogenated polymer having a heat distortion temperature of 170° C. or higher, polymer (B) is a polymer incompatible with the polymer (A) and having a heat distortion temperature of lower than 170° C., a microporous film formed by using the resin composition, a separator including the microporous film, and a secondary battery having the separator. One aspect of the invention provides a resin composition suitably used as a raw material for a separator of a secondary battery excellent in safety, a microporous film obtained by forming the resin composition, a separator including the microporous film, and a secondary battery having the separator.