Crosslinked Polyolefin Porous Support for High-Temperature Battery Separators
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to the low melting point and heat shrinkage of traditional polyolefin separators, leading to potential ignition and internal short-circuits during abnormal conditions.
Innovation Solution
A crosslinked structure-containing polyolefin porous support with a controlled number of double bonds and a crosslinking degree, integrated with an inorganic composite porous layer and a porous adhesive layer, to enhance high-temperature safety and minimize side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyethylene separator is used, then the separator can provide basic separation function, but it shows severe heat shrinking behavior and low melting point causing safety problems
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of polyethylene through controlled introduction of double bonds (0.01-0.6 per 1000 carbon atoms) and creating crosslinked structures. This changes the fundamental thermal properties of the material, raising the melting point from typical polyethylene levels to above 160°C while maintaining the separator function.
Solution Approach 2:
The patent creates a composite structure by combining polyethylene chains with crosslinked structures formed through controlled double bond reactions. The crosslinked network (10-45% crosslinking degree) integrates with the polyethylene matrix to form a new material system that exhibits both the separation properties of polyethylene and the high-temperature stability of crosslinked structures.
2Reliability
If the number of double bonds is increased to enable crosslinking, then high-temperature safety is improved, but side reactions may increase
Solution Approach 1:
The patent precisely controls the double bond concentration parameter (0.01-0.6 per 1000 carbon atoms) to achieve optimal crosslinking while minimizing side reactions. This parameter optimization ensures sufficient crosslinking sites for forming the desired crosslinked network without excessive double bonds that would lead to harmful side reactions during battery operation.
Solution Approach 2:
The patent applies local quality by introducing double bonds at specific locations within the polyethylene chains rather than uniformly throughout. This localized introduction (0.01-0.6 per 1000 carbon atoms) creates sufficient crosslinking points while leaving the majority of the polymer structure intact and free from side reaction-prone double bonds.
3Reliability
If crosslinking degree is increased to improve heat resistance, then high-temperature safety is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical or chemical crosslinking processes with a simplified method involving controlled introduction of double bonds followed by crosslinking. This substitution reduces manufacturing complexity while achieving the desired crosslinking degree (10-45%) and high-temperature safety performance.
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 improved high-temperature safety and minimized degradation of battery performance, maintaining energy density and preventing shutdowns and ignitions.
Implementation Method 1
a crosslinked structure-containing polyolefin porous support which has a number of double bonds present in the polyolefin chains of 0.01-0.6 per 1000 carbon atoms, as determined by 1H-NMR, and includes a crosslinked structure having polymer chains interconnected directly with one another
Implementation Method 2
an inorganic composite porous layer disposed on at least one surface of the crosslinked structure-containing polyolefin porous support and including an inorganic filler and a binder polymer
Implementation Method 3
crosslinked structure-containing polyolefin porous support which has a number of double bonds present in the polyolefin chains of 0.01-0.6 per 1000 carbon atoms
Data Source
AI summary
The present disclosure relates to a crosslinked structure-containing polyolefin porous support which has a number of double bonds present in the polyolefin chains of 0.01-0.6 per 1000 carbon atoms, as determined by 1H-NMR, and includes a crosslinked structure having polymer chains interconnected directly with one another, a crosslinked structure-containing separator for a lithium secondary battery including the same and a method for manufacturing the same, and a lithium secondary battery including the separator. The crosslinked structure-containing separator for a lithium secondary battery has improved high-temperature safety, and thus can minimize degradation of the performance of a lithium secondary battery including the separator, even after storing the lithium secondary battery at high temperature.