Composite Separator Thermal Stability via Inorganic Particles
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Solution Overview
Problem
Existing methods for manufacturing separators for electrochemical devices face challenges in achieving improved structural stability, increased production yield, and reduced process costs, particularly due to limitations in heat setting processes that can cause thermal contraction and structural instability in polyolefin porous substrates.
Innovation Solution
A method involving extruding a polyolefin resin composition, stretching to form a porous film, extracting the diluent, coating a slurry with inorganic and organic particles, and heat setting the coated film to create a composite separator with a porous coating layer, allowing for improved mechanical and thermal performance while reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat setting is performed at high temperature to improve production efficiency and reduce costs, then productivity increases, but the polyolefin film may melt causing structural instability
Solution Approach 1:
The patent applies composite materials by combining polyolefin resin with heat-resistant inorganic particles (such as alumina, silica, or boehmite) to create a porous substrate that can withstand high-temperature heat setting. The inorganic particles form a skeletal structure that prevents film melting while maintaining porosity, enabling heat setting at temperatures that would otherwise damage pure polyolefin films.
Solution Approach 2:
The patent changes the thermal parameters of the substrate by incorporating heat-resistant inorganic components, raising the temperature threshold at which structural instability occurs. This allows the heat setting process to be conducted at higher temperatures and for longer durations without risking film melting, thereby improving productivity while maintaining reliability.
2Manufacturing precision
If additional heat setting process is performed after slurry coating to improve coating adherence, then coating quality improves, but the coating layer may be destroyed due to structural instability
Solution Approach 1:
The heat-resistant inorganic particle composite structure provides a stable framework that can tolerate the thermal stress of post-coating heat setting. This stable framework prevents the coating layer from being destroyed while still allowing the heat setting to enhance coating adherence to the substrate.
Solution Approach 2:
The heat-resistant inorganic particles are incorporated into the substrate structure before coating, creating a pre-stabilized framework. This preliminary structural reinforcement ensures that subsequent heat setting processes will not destroy the coating layer, as the inorganic skeleton maintains structural integrity at elevated temperatures.
3Productivity
If polyolefin porous substrate is used to ensure porosity and ion transport, then electrochemical performance improves, but thermal contraction occurs at temperatures ≤150°C causing short circuits
Solution Approach 1:
The patent creates a composite structure where heat-resistant inorganic particles form a thermal stability framework that counteracts the natural thermal contraction tendency of polyolefin. This composite structure maintains the porosity needed for ion transport while preventing the harmful thermal contraction that would cause short circuits between electrodes.
Solution Approach 2:
The inorganic particles are distributed throughout the porous substrate structure, providing localized thermal stability at critical points where thermal contraction would otherwise occur. This local reinforcement prevents short circuits while maintaining the overall porosity and ion transport pathways of the polyolefin matrix.
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 approach enhances the mechanical and thermal stability of the separator, improves production yield, and reduces costs by enabling higher temperature heat setting without melting the polyolefin film, thus maintaining structural integrity and increasing the interfacial contact area for better coating adherence.
Implementation Method 1
a polyolefin porous substrate commonly used for a separator of an electrochemical device shows serious thermal contraction behaviors at temperature less than or equal to 150°C due to material characteristics and procedural characteristics in the manufacturing process including stretching
Implementation Method 2
a slurry including inorganic particles or organic particles and a binder polymer is coated on at least one surface of a polyolefin porous substrate
Implementation Method 3
heat setting the porous film
Data Source
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AI summary
A method of manufacturing a separator for an electrochemical device according to an exemplary embodiment of the present disclosure includes extruding a resin composition including polyolefin and a diluent, stretching the extruded resin composition to obtain a polyolefin film, extracting the diluent from the obtained polyolefin film to obtain a porous polyolefin film, coating a slurry for forming a porous coating layer on at least one surface of the porous polyolefin film, and heat setting the porous polyolefin film coated with the slurry to obtain a composite separator with a porous coating layer.