Single-Layer Lithium Ion Battery Separator Nanofiber Microfiber
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current battery separators fail to simultaneously provide low air resistance, low pore size, high tensile strength, isotropic properties, chemical stability, and dimensional stability, especially under elevated temperatures, which are crucial for long-term reliable lithium battery performance.
Innovation Solution
A battery separator made from a single layer of enmeshed microfibers and nanofibers, produced through a wet-laid nonwoven fabrication process, allowing for adjustable pore size and porosity, with a combination of microfiber and nanofiber constituents that provide isotropic strength and high wettability, using high shear processing and calendering to achieve optimal thickness and pore size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a battery separator uses a film structure to reduce weight and volume, then the separator thickness is reduced, but the tensile strength and mechanical stability deteriorate
Solution Approach 1:
The patent uses a composite structure combining nanofibers (providing strength and small pore sizes) with microfibers (providing mechanical integrity and isotropic properties). This composite approach allows the separator to maintain high tensile strength despite reduced thickness, resolving the contradiction between thinness and mechanical strength.
2Reliability
If the separator pore size is reduced to improve safety, then the pore size decreases, but the air resistance and ion transport efficiency worsen
Solution Approach 1:
The patent employs a controlled porous structure where nanofibers create small pores for safety while the overall network architecture maintains adequate porosity (30-80%) for ion transport. The pore size is optimized to be small enough to prevent dendrite penetration but large enough to allow electrolyte flow, resolving the contradiction between safety and transport efficiency.
Solution Approach 2:
The separator exhibits different properties at different scales: nanoscale pores provide safety by blocking dendrites, while macroscale porosity ensures adequate ion transport. This multi-scale quality differentiation allows simultaneous achievement of low pore size for safety and low air resistance for efficiency.
3Device complexity
If the separator uses a single-layer structure to simplify manufacturing, then the device complexity is reduced, but the ability to simultaneously achieve multiple properties deteriorates
Solution Approach 1:
The patent achieves multiple properties (pore size, porosity, strength, wettability) by adjusting parameters of a single-layer nonwoven structure, including fiber diameter distribution, fiber orientation, basis weight, and nanofiber-to-microfiber ratio. This parameter optimization allows a simple single-layer structure to deliver complex performance requirements.
4Manufacturing precision
If the separator uses nanofiber constituents to reduce pore size, then the pore size decreases, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent segments the fiber structure into two distinct size ranges (nanofibers <1000 nm and microfibers >3000 nm) that work together in a single layer. This segmentation allows conventional manufacturing processes to produce each fiber type separately and combine them, avoiding the need for complex nanoscale manufacturing while achieving precise pore size control through the nanofiber component.
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 separator with low air resistance, low pore sizes, and high tensile strength, ensuring long-term reliability and stability, including resistance to elevated temperatures, thereby enhancing battery performance and safety.
Implementation Method 1
a single layer of enmeshed microfibers and nanofibers
Implementation Method 2
mixing said nanofiber dispersion under high shear conditions
Implementation Method 3
The web produced in step (f) is optionally further treated in a calendering procedure
Implementation Method 4
drying said web
Implementation Method 5
high wettability levels
Data Source
AI summary
An insulating (nonconductive) microporous polymeric battery separator comprised of a single layer of enmeshed microfibers and nanofibers is provided. Such a separator accords the ability to attune the porosity and pore size to any desired level through a single nonwoven fabric. Through a proper selection of materials as well as production processes, the resultant battery separator exhibits isotropic strengths, low shrinkage, high wettability levels, and pore sizes related directly to layer thickness. The overall production method is highly efficient and yields a combination of polymeric nanofibers within a polymeric microfiber matrix and/or onto such a substrate through high shear processing that is cost effective as well. The separator, a battery including such a separator, the method of manufacturing such a separator, and the method of utilizing such a separator within a battery device, are all encompassed within this invention.