Coated Li-Ion Battery Separator for Thin Thermal-Stable Barrier Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium ion battery separators lack optimal combinations of low thickness, good dimensional stability, thermal stability, thermal conductivity, and barrier properties, necessitating an improved design that balances these factors.
Innovation Solution
A separator paper comprising 30-70 wt.% aramid shortcut fibers, 10-45 wt.% PET, and 5-40 wt.% binder, with a coating layer containing refractory particles and a binder, achieving a surface pore size where at least 90% of pores are ≤0.5 microns, ensuring effective barrier properties and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin-based separators are used, then adequate barrier properties are achieved, but thermal stability and thermal conductivity are insufficient
Solution Approach 1:
The separator combines polyolefin base material with aramid fibers and inorganic coating layers to create a composite structure that maintains the barrier properties of polyolefin while adding thermal stability from aramid and inorganic materials
2Volume of moving object
If separator thickness is reduced, then energy density is improved, but dimensional stability deteriorates
Solution Approach 1:
The use of aramid fibers combined with polyolefin creates a composite structure where aramid provides dimensional stability even at reduced thickness, allowing thin separators to maintain structural integrity
Solution Approach 2:
The inorganic coating is applied selectively on the separator surface to provide localized thermal stability and dimensional control without increasing overall thickness
3Volume of moving object
If separator thickness is reduced, then energy density is improved, but thermal stability deteriorates
Solution Approach 1:
The composite structure with aramid fibers and inorganic coating provides thermal stability in thin separators, as these materials maintain structural integrity at elevated temperatures even when the overall separator thickness is reduced
4Ease of manufacture
If polyolefin separators are used, then manufacturing simplicity is maintained, but thermal conductivity is insufficient
Solution Approach 1:
The separator uses a composite structure with inorganic materials (such as alumina or silica) incorporated into the polyolefin matrix, providing enhanced thermal conductivity while maintaining manufacturing processes similar to conventional separators
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 separator paper achieves enhanced barrier properties, dimensional stability, and thermal conductivity, preventing short-circuiting while allowing lithium ion passage, thereby improving the performance and safety of lithium ion batteries.
Implementation Method 1
at least one side of the core paper is provided with a coating layer, said coating layer comprising refractory particles and a coating binder, wherein the separator has a surface pore size on the side of the paper provided with the coating layer which is such that at least 90 number % of the surface pores has a pore size of at most 0.5 micron
Implementation Method 2
allowing lithium ions to pass through the electrolyte-containing separator
Implementation Method 3
a core paper comprising 30-70 wt. % aramid shortcut fiber, 10-45 wt. % PET, and 5-40 wt. % of a binder, the core paper having a grammage of 5-30 g/m2 and a thickness of 5-30 micron
Data Source
AI summary
The invention pertains to a separator suitable for use in lithium ion batteries which comprises a core paper comprising 30-70 wt. % aramid shortcut fiber, 10-45 wt. % PET, and 5-40 wt. % of a binder, the core paper having a grammage of 5-30 g/m2 and a thickness of 5-30 micron, wherein at least one side of the core paper is provided with a coating layer, said coating layer comprising refractory particles and a coating binder, wherein the separator has a surface pore size on the side of the paper provided with the coating layer which is such that at least 90 number % of the surface pores has a pore size of at most 0.5 micron.