Coated Non-Woven Battery Separator for High-Temperature Stability
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Solution Overview
Problem
Existing battery separators face challenges such as insufficient porosity and flexibility, poor adhesion of coated particles, and poor affinity with organic solvents, leading to issues in handling and performance in lithium-ion batteries, particularly concerning high temperature resistance and dendrite formation.
Innovation Solution
A battery separator comprising a non-woven substrate with highly refined cellulosic and synthetic fibers, coated with a polymer binder that enhances porosity, flexibility, and solvent wettability, featuring a mean pore size of 0.4 to 3 μm and a binder with a melting point greater than 80°C, which improves adhesion and affinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microporous polyolefin membrane is used as the separator, then it provides basic separation function, but it shows shrinkage and poor resistance at elevated temperatures
Solution Approach 1:
The patent applies composite materials by combining polyolefin base material with ceramic coatings (alumina, silica, boehmite) to create a separator that maintains the flexibility and basic separation properties of polyolefin while adding high-temperature stability and dimensional stability through the ceramic layer. The ceramic particles form a stable network structure that prevents shrinkage at elevated temperatures.
Solution Approach 2:
The patent changes the physical and chemical parameters of the separator by incorporating ceramic particles with specific size distributions (0.1-10 μm), controlling pore sizes (0.01-1 μm), and adjusting ceramic content (1-50 wt%) to optimize both temperature resistance and dimensional stability while maintaining ionic conductivity.
2Reliability
If the separator porosity is increased to improve ionic conductivity, then ion exchange performance improves, but mechanical strength and handling flexibility deteriorate
Solution Approach 1:
The patent applies local quality by creating different functional zones within the separator structure: the bulk polyolefin matrix provides mechanical strength and flexibility, while the ceramic-coated regions provide thermal stability and controlled porosity. The ceramic particles are strategically distributed to form a percolating network that maintains structural integrity while allowing ion transport through controlled pores.
3Reliability
If ceramic particles are coated on the separator to improve temperature resistance, then thermal stability improves, but adhesion of the coating to the substrate deteriorates
Solution Approach 1:
The patent uses binder materials as intermediaries between the ceramic particles and the polyolefin substrate. The binder (1-20 wt% of total composition) acts as an adhesive matrix that chemically or physically bonds to both the ceramic particles and the base material, ensuring strong coating adhesion while maintaining porosity for ion transport. This intermediary layer prevents coating delamination at high temperatures.
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 provides improved flexibility for handling, enhanced wettability with organic solvents, and high ionic resistivity, reducing the risk of dendrite formation and current shortcuts, thereby improving the safety and performance of lithium-ion batteries.
Implementation Method 1
The porous coating comprises ceramic particles which are adhesively bonded to one another and to the non-woven substrate by means of the binder
Implementation Method 2
a porous coating that is applied onto the non-woven substrate and contains ceramic particles... enabling the exchange of lithium ions
Implementation Method 3
a binder that adheres the ceramic particles to the non-woven substrate and the ceramic particles to one another... with a melting point greater than 80°C
Data Source
AI summary
It is described herein a battery separator comprising a non-woven substrate and a binder. The non-woven substrate may comprise highly refined cellulosic fibers and synthetic fibers. The battery separator may have a mean pore size in a range of between 0.4 and 3 μm. It is also described herein a lithium-ion battery comprising the battery separator, and a process for producing a battery separator.