Ceramic-Coated Battery Separator for High-Temperature Stability
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Solution Overview
Problem
Existing lithium ion battery separators face challenges in safety, cycle life, and high temperature performance, particularly in secondary lithium ion batteries.
Innovation Solution
A microporous membrane coated with a ceramic coating and polymeric binders is applied to the separator, forming an oxidized or reduced interfacial layer that prevents further oxidation or reduction reactions, enhancing safety and high temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in lithium ion batteries, then basic separation function is provided, but safety and high temperature performance are insufficient
Solution Approach 1:
The patent applies composite materials by combining a microporous polyolefin membrane base layer with a ceramic coating layer containing inorganic particles (such as alumina, silica, or boehmite) and polymeric binder. This composite structure provides both the separation function of the base layer and the thermal stability, mechanical strength, and safety improvements from the ceramic coating, directly resolving the contradiction between basic function and enhanced safety performance.
Solution Approach 2:
The patent applies local quality by coating the ceramic layer selectively on one or both surfaces of the microporous membrane rather than throughout the entire structure. This allows the bulk material to maintain its inherent properties while the surface regions provide enhanced thermal stability and safety characteristics, optimizing the balance between performance and material properties.
2Temperature
If the separator operates at elevated temperatures, then battery function continues, but dimensional stability deteriorates leading to safety issues
Solution Approach 1:
The patent applies parameter changes by modifying the thermal and mechanical properties of the separator through ceramic coating. The inorganic particles (alumina, silica, boehmite) and polymeric binder in the coating layer raise the decomposition temperature and maintain dimensional stability at elevated temperatures up to 150°C or higher, preventing the separator from shrinking or deforming while maintaining its separation function.
Solution Approach 2:
The patent addresses thermal expansion by using ceramic materials with low thermal expansion coefficients in the coating layer. These materials counteract the thermal expansion tendencies of the polyolefin base layer at elevated temperatures, maintaining overall dimensional stability and preventing safety issues related to separator deformation during high-temperature battery operation.
3Reliability
If oxidation or reduction reactions occur at the separator interface, then electrochemical processes proceed, but further reactions compromise safety and cycle life
Solution Approach 1:
The patent applies the intermediary principle by introducing a ceramic coating layer as a mediator between the electrolyte and the separator base layer. This coating layer acts as a protective barrier that prevents direct contact and harmful oxidation or reduction reactions at the interface, while still allowing ionic transport. The inorganic particles and polymeric binder in the coating provide chemical stability that eliminates harmful reactions and extends battery cycle life.
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 ceramic coated separator improves safety and cycle life by preventing further reactions and maintaining dimensional stability at elevated temperatures, with volatile component evolution above 250°C.
Implementation Method 1
undergoes an oxidation or reduction reaction at the interface of the coated separator and battery electrodes
Implementation Method 2
undergoes an oxidation or reduction reaction at the interface of the coated separator and battery electrodes
Implementation Method 3
a microporous membrane coated with a ceramic coating or layer
Data Source
AI summary
A ceramic-coated battery separator having a microporous polyolefin membrane and a ceramic coating on at least one surface of the microporous polyolefin membrane, wherein the ceramic-coated separator exhibits a strain shrinkage of 0% at temperatures greater than or equal to 120 degrees Celsius is provided.