Crosslinked Polyolefin Separator Structure for Battery Heat Resistance
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Solution Overview
Problem
Existing polyolefin microporous membranes used in lithium ion batteries face limitations in heat resistance, homogeneity of crosslinked structures, and safety during high-temperature conditions, particularly in high-energy density applications, leading to potential thermal runaway and short circuits.
Innovation Solution
A laminated polyolefin microporous membrane with functional groups that form a crosslinked structure via condensation or chemical reactions within the battery, enhancing heat resistance and preventing short circuits by controlling the crosslinking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin microporous membrane is used as a separator, then chemical inactivity and insulation are achieved, but heat resistance and membrane breaking temperature are limited
Solution Approach 1:
The patent applies composite materials by combining polyolefin with silane-modified components to create a crosslinked structure. This composite approach maintains the chemical inactivity of polyolefin while adding heat resistance through the crosslinked network, resolving the contradiction between chemical stability and temperature resistance.
Solution Approach 2:
The patent changes the physical-chemical parameters of polyolefin by introducing crosslinked structures through silane modification. This transformation alters the membrane's thermal properties without compromising its chemical inactivity, enabling higher membrane breaking temperatures while maintaining reliability.
2Temperature
If silane crosslinked structure is formed by contact with water, then membrane breaking temperature is improved, but shutdown function activation becomes problematic
Solution Approach 1:
The patent uses silane-modified polyolefin as an intermediary that can form crosslinked structures without requiring water contact. This intermediary approach allows the membrane to achieve heat resistance through alternative crosslinking mechanisms while preserving the shutdown function that relies on water-free operation.
Solution Approach 2:
The patent extracts the water dependency from the crosslinking process by employing silane modification that can crosslink through mechanisms other than water contact. This extraction resolves the contradiction by separating the heat resistance achievement from the shutdown function activation, allowing both to coexist.
3Temperature
If crosslinked structure is formed to improve heat resistance, then membrane breaking temperature increases, but homogeneity of crosslinked structure deteriorates
Solution Approach 1:
The patent applies local quality by creating uniformly distributed crosslinked structures through controlled silane modification. This ensures that the crosslinking occurs homogeneously throughout the membrane, maintaining composition stability while achieving the desired heat resistance improvement.
Solution Approach 2:
The patent performs preliminary silane modification before membrane formation to ensure uniform distribution of crosslinkable groups. This preliminary action prevents heterogeneous crosslinking during subsequent processing, maintaining homogeneity while achieving high heat resistance.
4Temperature
If polyolefin resin layers are stacked to improve mechanical structure, then membrane breaking temperature increases, but affinity with electrolyte solution remains insufficient
Solution Approach 1:
The patent changes the surface parameters of stacked polyolefin layers by applying silane modification. This modification alters the chemical properties of the membrane surface, improving electrolyte solution affinity while maintaining the heat resistance benefits of the stacked structure.
Solution Approach 2:
The patent creates a composite structure by combining stacked polyolefin layers with silane-modified components. This composite approach enhances both the mechanical strength and heat resistance of the stacked structure while improving electrolyte solution affinity through the modified surface properties.
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 crosslinked structure improves heat resistance and reduces the risk of thermal runaway, ensuring safer battery performance even under high-temperature conditions.
Implementation Method 1
the functional groups undergo a condensation reaction with each other, to form a crosslinked structure
Implementation Method 2
the membrane breaking temperature is improved
Data Source
AI summary
The purpose of the present disclosure is to provide: a safer polyolefin microporous membrane; an electricity storage device separator, electricity storage device assembly kit, and electricity storage device using the polyolefin microporous membrane; and an electricity storage device. In one embodiment, the polyolefin microporous membrane comprises at least one of each of a layer A and a layer B, a polyolefin contained in at least one of the layer A and the layer B has one or more types of functional groups, and a crosslinked structure is formed by (1) the functional groups undergoing condensation reactions with each other, (2) the functional group reacting with a chemical substance inside the electricity storage device, or (3) the functional group reacting with a different type of functional group, after accommodation in the electricity storage device.