Crosslinked Polyolefin Separator for Uniform Silane Bonding
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Solution Overview
Problem
Existing methods for manufacturing crosslinked polyolefin separators face issues such as side reactions between diluting agents and initiators, difficulty in handling silane crosslinking agents, and increased extruder pressure, leading to non-homogeneous crosslinking and die-drooling phenomena.
Innovation Solution
A method involving the use of surface-treated inorganic particles with alkoxysilane containing a carbon-carbon double bonded group, where the alkoxysilane is chemically bound to inorganic particles, which are then mixed with polyolefin, initiator, and catalyst in an extruder, followed by reactive extrusion, sheet molding, diluting agent extraction, and thermal fixing to produce a crosslinked polyolefin separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diluting agent and initiator are introduced to extruder at once, then crosslinking reaction occurs, but side reaction between diluting agent and initiator occurs
Solution Approach 1:
The patent divides the crosslinking process into two separate stages: first introducing the diluting agent and silane crosslinking agent to the extruder, then separately introducing the initiator in a subsequent step. This segmentation prevents the diluting agent and initiator from contacting and reacting prematurely, eliminating side reactions while ensuring uniform crosslinking when the initiator is finally added.
Solution Approach 2:
The patent performs preliminary mixing of the diluting agent and silane crosslinking agent in the extruder before adding the initiator. This preliminary action prepares the composition for crosslinking without triggering the reaction prematurely, allowing all components to be properly distributed before the crosslinking reaction begins upon initiator addition.
2Manufacturing precision
If silane crosslinking agent is introduced in combination with diluting agent, then crosslinking can occur, but handling difficulty increases
Solution Approach 1:
The patent segments the introduction of chemicals into distinct steps: first the diluting agent, then the silane crosslinking agent, and finally the initiator. This segmentation simplifies handling by allowing each chemical to be introduced and distributed separately, avoiding the complexity of handling pre-mixed combinations while maintaining crosslinking capability.
3Manufacturing precision
If crosslinking components are mixed and extruded, then crosslinked separator is formed, but extruder pressure increases causing die-drooling
Solution Approach 1:
The patent performs preliminary mixing of the diluting agent and silane crosslinking agent before adding the initiator. This preliminary action ensures uniform distribution of crosslinking components without triggering premature crosslinking that would increase pressure. The controlled addition of initiator afterward allows crosslinking to proceed uniformly at manageable pressure levels.
Solution Approach 2:
The patent controls the timing and sequence of component addition to manage reaction parameters. By introducing components in a specific sequence and controlling the extrusion temperature profile, the patent maintains manageable pressure levels while achieving complete crosslinking, preventing die-drooling phenomenon.
4Temperature
If crosslinking is performed to increase meltdown temperature, then heat resistance improves, but side reactions and handling difficulties occur
Solution Approach 1:
The patent segments the crosslinking process to achieve heat resistance without side reactions. By separating the introduction of the diluting agent/silane crosslinking agent from the initiator addition, the patent ensures that crosslinking occurs uniformly throughout the polyolefin matrix without premature side reactions, achieving the desired meltdown temperature improvement.
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
This method prevents side reactions, reduces die-drooling, and results in a crosslinked polyolefin separator with improved heat resistance, low resistance, and high air permeability, suitable for lithium secondary batteries.
Implementation Method 1
surface-treated inorganic particles are prepared by surface-treating with an alkoxysilane containing a carbon-carbon double bonded group
Implementation Method 2
reactively extruding the mixture to form a silane-grafted polyolefin composition
Implementation Method 3
mixing a polyolefin, a diluting agent, an initiator, a crosslinking catalyst and surface-treated inorganic particles in an extruder, and then reactively extruding the mixture
Implementation Method 4
reactively extruding the mixture to form a silane-grafted polyolefin composition
Implementation Method 5
mixing a polyolefin, a diluting agent, an initiator, a crosslinking catalyst and surface-treated inorganic particles in an extruder
Implementation Method 6
extracting the diluting agent from the oriented sheet to obtain a porous membrane
Implementation Method 7
thermally fixing the porous membrane
Implementation Method 8
crosslinking the thermally fixed porous membrane in the presence of moisture
Implementation Method 9
crosslinking the thermally fixed porous membrane in the presence of moisture
Implementation Method 10
crosslinking the thermally fixed porous membrane in the presence of moisture
Implementation Method 11
surface-treated inorganic particles are prepared by surface-treating with an alkoxysilane containing a carbon-carbon double bonded group
Data Source
Figure 1
Figure 2(a)~2(e)
AI summary
A crosslinked polyolefin separator and a method of making the same are disclosed herein. In some embodiments, a crosslinked polyolefin separator includes inorganic particles and a crosslinked polyolefin having Si-O-Si crosslinking bonds, wherein the inorganic particles are chemically bound to silicon (Si) atoms of the Si-O-Si crosslinking bonds by oxygen (O) atoms. The crosslinked polyolefin separator has low resistance, high air permeability and improved heat resistance.