Composite Battery Separator With Ultrathin Inorganic Dielectric Layer
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Solution Overview
Problem
Existing composite separators for lithium-ion batteries face issues such as agglomeration of ceramic particles, large coating thickness, poor interfacial wettability, and reduced bonding force between the coating and the substrate, leading to cracking, aging, and safety concerns.
Innovation Solution
A composite separator with a porous substrate and an inorganic dielectric layer formed through vapor deposition, which is a continuous dense film with porosity lower than 10%, a thickness of 20nm-1000nm, and an interfacial peeling force of no less than 30 N/m, ensuring strong bonding and improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic coating is applied on the surface of a polymer substrate to improve safety performance, then thermal shrinkage resistance and electrolyte wettability are improved, but the coating thickness increases to several micrometers causing mechanical strength reduction and processing difficulty
Solution Approach 1:
The invention changes the thickness parameter of the ceramic coating from micrometer level (several μm) to nanometer level (50-500 nm), achieving both improved safety performance and reduced mechanical strength degradation through precise control of coating thickness parameters
Solution Approach 2:
The invention employs an ultrathin ceramic coating film (50-500 nm) that provides protective functions while maintaining flexibility and mechanical integrity, replacing traditional thick rigid coatings that compromise separator performance
2Reliability
If a ceramic coating is applied to improve safety performance, then thermal shrinkage resistance is improved, but agglomeration of ceramic particles occurs leading to poor coating uniformity
Solution Approach 1:
The invention replaces traditional mechanical mixing and coating methods that cause ceramic particle agglomeration with a chemical vapor deposition process, achieving uniform nanometer-thick coatings without particle aggregation
Solution Approach 2:
The invention changes the coating process parameters from conventional thick-film deposition to ultrathin-film deposition (50-500 nm), preventing ceramic particle agglomeration and achieving uniform coverage on the porous substrate
3Temperature
If a thick ceramic coating is applied to improve safety performance, then thermal stability is improved, but interfacial wettability between coating and substrate deteriorates
Solution Approach 1:
The invention changes the coating thickness parameter to ultrathin range (50-500 nm), maintaining intimate contact between ceramic coating and porous substrate, thereby preserving interfacial wettability while providing sufficient thermal stability
4Reliability
If a thick ceramic coating is applied to improve safety performance, then thermal shrinkage resistance is improved, but bonding force between coating and substrate decreases
Solution Approach 1:
The invention changes the coating thickness to ultrathin range (50-500 nm), maximizing the surface area to volume ratio and enhancing adhesion between ceramic coating and substrate, thereby improving bonding force while maintaining thermal shrinkage resistance
Solution Approach 2:
The invention employs an ultrathin ceramic film that maintains flexible bonding with the porous substrate, preventing delamination and maintaining strong interfacial adhesion while providing thermal protection
5Temperature
If a thick ceramic coating is applied to improve safety performance, then thermal stability is improved, but ion-conduction performance deteriorates
Solution Approach 1:
The invention changes the coating thickness parameter to ultrathin range (50-500 nm), maintaining ion conduction pathways open while providing thermal stability, preventing the blockage of pores that occurs with thick coatings
Solution Approach 2:
The invention utilizes the porous structure of the substrate in combination with ultrathin ceramic coating, preserving the pore network for ion transport while the coating provides thermal stability without blocking ion conduction paths
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 enhances the hydrophilicity, mechanical strength, and puncture resistance of the composite separator, thereby improving the cycling usage life, safety performance, and energy density of lithium-ion batteries.
Implementation Method 1
forming an inorganic layer on a surface of the substrate and at least a part of pores of the substrate by a vapor deposition method
Data Source
Figure 1
AI summary
The present disclosure relates to a composite separator, a preparation method of the composite separator, and an electrochemical device containing the composite separator. The composite separator includes a substrate and an inorganic layer disposed on at least one surface of the substrate. The substrate is a porous substrate, and the inorganic layer is an inorganic dielectric layer which is a continuous dense film layer with porosity lower than 10% and contains no binder. A thickness of the inorganic layer is 20 nm-1000 nm. An interfacial peeling force between the inorganic layer and the substrate is no less than 30 N/m. The separator of the present application has high wettability with respect to electrolyte, almost no thermal shrinkage, relatively high mechanical strength, and favorable corrosion resistance and durability performances, and thus, a battery using the separator has relatively high thermal stability and nailing strength.