Self-Supporting Ceramic Separator for Heat-Resistant Battery Isolation
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Solution Overview
Problem
Existing electrochemical device separators made of polyolefin-based resin face issues with electrical short-circuits and thermal runaway due to high temperature exposure, leading to reduced battery safety and lifespan.
Innovation Solution
A self-standing ceramic separator is developed using first inorganic particles with a sheet shape and high aspect ratio, combined with second inorganic particles having a high specific surface area and adsorption capabilities, to form a dense stacking structure that prevents transition metal migration and enhances heat resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polyolefin-based resin is used as a porous polymer substrate for the separator, then the separator can be manufactured easily and cost-effectively, but the separator contracts at high temperatures causing electrical short-circuits and thermal runaway
Solution Approach 1:
The patent changes the material composition parameters by replacing polyolefin-based resin with a ceramic coating layer containing inorganic particles (such as alumina, silica, or boehmite) on a porous substrate. This parameter change eliminates thermal contraction at high temperatures while maintaining manufacturability through coating processes
Solution Approach 2:
The patent creates a composite structure by combining a porous substrate (such as polyolefin or ceramic foam) with a ceramic coating layer containing inorganic particles. This composite material approach provides both the structural integrity needed to prevent short-circuits and the thermal stability required to prevent thermal runaway
2Temperature
If the separator is made without polyolefin-based resin using only inorganic particles, then heat resistance and durability are improved, but the structural integrity and bonding strength may be compromised
Solution Approach 1:
The patent applies different material properties to different regions of the separator structure. The porous substrate provides structural integrity and porosity, while the ceramic coating layer with inorganic particles provides heat resistance and durability. This local differentiation of material quality allows each component to optimize its function
Solution Approach 2:
The patent applies a ceramic coating layer to the porous substrate before the separator is installed in the electrochemical device. This preliminary coating action ensures that the heat-resistant properties are already in place before the separator encounters high-temperature conditions, preventing thermal degradation
3Strength
If inorganic particles are added to the coating layer to improve mechanical strength, then the separator strength increases, but the complexity of the coating layer composition increases
Solution Approach 1:
The patent selects inorganic particles that serve multiple functions simultaneously: alumina or silica particles provide both mechanical strength enhancement and heat resistance improvement. This multi-functionality approach increases strength while minimizing the need for additional separate components, thereby reducing overall system complexity
4Force
If a polymer binder is added to the coating layer to bond the separator to the electrode, then bonding strength improves, but the thermal stability and flame resistance are reduced
Solution Approach 1:
The patent uses a polymer binder in the coating layer that is intentionally designed to decompose at high temperatures rather than sustain combustion. This sacrificial binder provides temporary bonding strength during assembly and operation, then decomposes to leave behind a thermally stable ceramic structure that resists flame and thermal runaway
Solution Approach 2:
The polymer binder acts as an intermediary material that facilitates bonding between the ceramic coating layer and the electrode during assembly, but is designed to decompose at operational temperatures. This intermediary approach allows strong initial bonding while ensuring thermal stability during actual device operation
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 separator improves battery stability and lifespan by preventing electrical short-circuits and thermal contraction, while maintaining ion conductivity and adsorbing gases, thereby enhancing safety and performance.
Implementation Method 1
first inorganic particles capable of preventing transition metal that has been eluted from a positive electrode from going on to a surface that faces a negative electrode by forming a dense stacking structure having a sheet shape
Implementation Method 2
second inorganic particles having a high specific surface area and capable of adsorbing a gas and transition metal
Implementation Method 3
capable of improving heat resistance and providing a high cell lifespan characteristic... capable of preventing an electrical short-circuit between electrodes
Data Source
AI summary
A self-standing ceramic separator and an electrochemical device including the same are provided. The self-standing ceramic separator includes first inorganic particles having a sheet shape and second inorganic particles, which is a zeolite-based inorganic matter, in an appropriate content and arrangement, thereby having an improved heat resistance, and providing improved safety of a battery by preventing an electrical short-circuit between electrodes and a high cell lifespan characteristic.