Battery Separator Lamination for Thin-Film Coating Stability
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Solution Overview
Problem
Conventional separator manufacturing methods face challenges in achieving balanced productivity and quality, particularly with thin-film separators, due to issues such as mechanical properties and running stability during coating, leading to defects and reduced efficiency.
Innovation Solution
A method involving the extrusion of polyolefin compositions with pore-forming agents, stretching in machine and transverse directions, lamination, and removal of pore-forming agents to create a dual-layer support, followed by coating and dividing, to enhance both productivity and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of porous support is reduced to about 15 μm or less to meet high-capacity battery demands, then energy density and battery capacity are improved, but mechanical properties and running stability deteriorate, causing deformation such as wrinkling or sagging during coating and drying
Solution Approach 1:
The porous support is divided into multiple thin layers (first porous layer, second porous layer, third porous layer) instead of using a single thin layer. This segmentation allows each layer to be thinner and more flexible individually, while the combined multi-layer structure provides enhanced mechanical stability and prevents deformation during coating and drying processes.
Solution Approach 2:
The invention uses a composite structure combining multiple porous polymer layers (e.g., polyethylene and polypropylene layers) with different properties. This composite approach allows optimization of each layer's function while achieving overall improved mechanical properties and thermal resistance that a single material could not provide alone.
2Temperature
If ceramic particles are coated onto the surface of porous support to improve heat resistance, then thermal stability is improved, but air permeability is reduced due to pore clogging, significantly degrading charge and discharge performance
Solution Approach 1:
The invention uses porous polymer materials (such as polyethylene and polypropylene) as the base structure of the separator. These materials inherently provide both heat resistance and maintained porosity, allowing ceramic particles to be incorporated without completely blocking the pores, thus preserving air permeability while improving thermal stability.
Solution Approach 2:
The invention creates a composite separator structure combining porous polymer matrices with ceramic particles. The polymer matrix maintains the pore structure for ion transport while the ceramic particles provide heat resistance, achieving both improved thermal stability and preserved air permeability through synergistic material combination.
3Manufacturing precision
If the running speed of porous support is reduced during coating to improve workability and prevent deformation, then coating quality is improved, but productivity is significantly lowered
Solution Approach 1:
By segmenting the porous support into multiple thin layers, each layer becomes more compliant and easier to coat without deformation. This allows the coating process to be performed at higher speeds while maintaining coating quality, as the segmented structure naturally resists wrinkling and sagging even during faster processing.
Solution Approach 2:
The invention changes the structural parameters of the porous support (thickness, layer configuration, porosity distribution) to optimize the balance between workability and productivity. The multi-layer structure with controlled thickness ratios allows for higher running speeds during coating while preventing deformation, thus improving both coating quality and manufacturing efficiency.
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 method results in a separator with improved mechanical and thermal properties, reduced thickness deviation, and enhanced adhesion, ensuring high-quality separators with increased productivity and reduced defects.
Implementation Method 1
removing the first and second pore-forming agents from the laminate to obtain a dual-layer support
Implementation Method 2
forming functional layers by coating and drying a coating composition comprising a binder and a solvent on both sides of the dual-layer support
Implementation Method 3
coating and drying a coating composition
Data Source
AI summary
The present disclosure relates to a method for manufacturing a separator. The method includes: (a) producing a first sheet by extruding a first composition comprising a first polyolefin and a first pore-forming agent; (b) producing a second sheet by extruding a second composition comprising a second polyolefin and a second pore-forming agent; (c) stretching the first and second sheets respectively in a machine direction to produce a first and a second precursor films; (d) laminating the first and second precursor films to obtain a laminate; (e) stretching the laminate in a transverse direction, and removing the first and second pore-forming agents from the laminate to obtain a dual-layer support; (f) forming functional layers by coating and drying a coating composition comprising a binder and a solvent on both sides of the dual-layer support; and (g) dividing the dual-layer support into two separators along the interface formed by the lamination.