Crosslinked Polyolefin Separator for High-Temperature Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face safety issues due to the low melting point and heat shrinkage of conventional polyolefin separators, leading to potential ignition and explosion risks at high temperatures.
Innovation Solution
A crosslinked structure-containing separator for lithium secondary batteries is developed, featuring a crosslinked polyolefin porous support, an inorganic composite porous layer, and a porous adhesive layer, which provides improved high-temperature safety and adhesion to electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyethylene separator is used, then it provides good insulation and ion conductivity, but it has low melting point and causes ignition and explosion at high temperatures
Solution Approach 1:
The patent applies parameter changes by crosslinking the polyethylene separator to fundamentally alter its thermal properties. The crosslinked structure raises the melting point from the original low temperature to above 200°C, while maintaining the shutdown function at 130-150°C. This transforms the material's thermal behavior to eliminate ignition risks while preserving insulation and ion conductivity properties.
Solution Approach 2:
The patent creates a composite structure by forming a crosslinked network within the polyethylene matrix. The crosslinked polyethylene combines the original polymer's insulation and ion conductivity with the crosslinked structure's high-temperature stability, producing a material that exhibits both the desired electrical properties and enhanced thermal safety.
2Reliability
If a polyethylene separator is used, then it provides good ion conductivity, but it shows severe heat shrinkage under high temperature conditions
Solution Approach 1:
The crosslinking process fundamentally changes the dimensional stability parameter of the polyethylene separator. The crosslinked network structure restricts chain mobility and prevents thermal contraction, reducing heat shrinkage to below 5% at 150°C while preserving the porous structure necessary for ion conductivity.
Solution Approach 2:
Instead of accepting heat shrinkage as an inherent property of polyethylene, the patent inverts the approach by introducing a crosslinked structure that actively counteracts thermal contraction forces. The crosslinked network serves as a rigid framework that maintains dimensional stability even when the polymer matrix attempts to shrink under thermal stress.
3Reliability
If a polyethylene separator is used, then it provides good insulation, but it causes internal short-circuit due to heat shrinkage
Solution Approach 1:
The crosslinking modification changes the thermal-mechanical parameters of the separator to prevent heat shrinkage-induced short circuits. The crosslinked structure maintains physical separation between electrodes at elevated temperatures, preserving insulation properties while eliminating the short-circuit hazard that plagues conventional polyethylene separators.
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 separator exhibits reduced heat shrinkage and increased meltdown temperature, ensuring enhanced safety and performance at high temperatures while maintaining excellent adhesion to electrodes.
Implementation Method 1
a crosslinked structure-containing polyolefin porous support having a crosslinked structure including 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 first binder polymer
Implementation Method 3
a porous adhesive layer disposed on the inorganic composite porous layer and including a second binder polymer
Data Source
AI summary
The present disclosure relates to a crosslinked structure-containing separator for a lithium secondary battery, including: a crosslinked structure-containing polyolefin porous support having a crosslinked structure including polymer chains interconnected directly with one another; 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 first binder polymer; and a porous adhesive layer disposed on the inorganic composite porous layer and including a second binder polymer. The present disclosure also relates to a method for preparing the separator and a lithium secondary battery including the separator. The crosslinked structure-containing separator for a lithium secondary battery shows improved high-temperature safety and excellent adhesion to an electrode. The method for manufacturing a crosslinked structure-containing separator for a lithium secondary battery includes adding a photoinitiator to a coating solution for forming a porous adhesive layer, and thus requires no additional equipment for the photo-crosslinking of a polyolefin porous support, thereby realizing a simplified process.