Battery Separator Nonwoven Structure for Heat-Resistant Fine Pores
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Solution Overview
Problem
Conventional battery separators exhibit high thermal shrinkage, large pore diameters, and low tensile strength, leading to internal short-circuits, dendrite formation, and reduced lifetimes due to inhomogeneous ion conduction and adhesion issues.
Innovation Solution
A battery-separator nonwoven fabric comprising nanofibers (100-1000 nm), thermal adhesive ultrafine fibers (100-2000 nm), and thermal adhesive fibers (0.1 dtex or more) with a specific weight ratio, laminated with an organic or inorganic porous layer, achieving a thickness of 30 µm or less and porosity of 40-70%, enhancing heat resistance and tensile properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a nonwoven fabric separator with thermal adhesive fibers is used to improve heat resistance, then thermal shrinkage properties are improved, but pore diameter becomes large leading to internal short-circuits and dendrite formation
Solution Approach 1:
The patent applies local quality by creating a dual-structure nonwoven fabric where nanofibers (100-1000 nm) provide small pore diameters in specific regions to prevent short-circuits, while thermal adhesive ultrafine fibers (100-2000 nm) provide heat resistance in other regions. This spatial differentiation of fiber functions resolves the contradiction between heat resistance and pore size control.
Solution Approach 2:
The patent uses composite materials by combining three types of fibers (nanofibers, thermal adhesive ultrafine fibers, and thermal adhesive fibers) with different diameters and properties in a single nonwoven fabric structure. This composite approach allows simultaneous achievement of small pore diameter, high heat resistance, and adequate mechanical strength.
2Reliability
If a microporous film with small pore diameter is used to prevent short-circuits, then short-circuit prevention is improved, but resistance increases reducing fast charge-discharge properties
Solution Approach 1:
The patent optimizes pore structure by using nanofibers (100-1000 nm) that create small pores effective for short-circuit prevention, while the specific fiber arrangement and porosity control (30-80%) maintain adequate ion transport channels. This resolves the contradiction between small pore diameter and ion conduction efficiency.
3Temperature
If a coating material-resin support layer is formed on an inhomogeneous nonwoven fabric, then heat resistance is improved, but thickness unevenness occurs reducing adhesion and ion conduction homogeneity
Solution Approach 1:
The patent achieves homogeneity by carefully controlling the composition ratios of different fibers (nanofibers: 20-80 wt%, thermal adhesive ultrafine fibers: 10-50 wt%, thermal adhesive fibers: 5-30 wt%) to create a uniformly distributed nonwoven fabric structure. This uniform base structure enables even coating material application and consistent thickness, resolving the contradiction between heat resistance and thickness uniformity.
4Quantity of substance
If the nonwoven fabric thickness is reduced to improve battery energy density, then energy density is improved, but mechanical strength and thrust strength decrease
Solution Approach 1:
The patent changes the parameter of fiber diameter to ultra-fine scales (100-2000 nm) which allows achieving high mechanical strength and adequate thrust strength even at reduced thickness (15-50 μm). The high aspect ratio and small diameter of nanofibers provide superior strength-to-weight ratio, enabling thin separator design that maintains mechanical integrity while improving energy density.
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 solution results in a battery separator with improved heat resistance, small pore diameter, high tensile elongation, and thrust strength, preventing minute short-circuits and extending battery life while maintaining low resistivity.
Implementation Method 1
a fiber B including a thermal adhesive ultrafine fiber having a fiber diameter of 100 to 2000 nm, and a fiber C including a thermal adhesive fiber having a single fiber fineness of 0.1 dtex or more
Data Source
AI summary
An object is to provide a battery-separator nonwoven fabric and a battery separator that are excellent in heat resistance, have a small pore diameter, and have a high tensile elongation and a high thrust strength, and a solution is to configure a battery-separator nonwoven fabric with a fiber A including a nanofiber having a fiber diameter of 100 to 1000 nm, a fiber B including a thermal adhesive ultrafine fiber having a fiber diameter of 100 to 2000 nm, and a fiber C including a thermal adhesive fiber having a single fiber fineness of 0.1 dtex or more, in which a tensile elongation of the nonwoven fabric is 10% or more.