Composite Membrane for Lithium Air Battery Separator
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Solution Overview
Problem
Lithium air batteries face challenges in improving cell performance due to the need for a separator that effectively blocks moisture and gas while allowing lithium ions to pass through, while also preventing electrolyte-induced swelling and maintaining durability.
Innovation Solution
A composite membrane is developed with an organic film layer and ion conductive inorganic particles, where the organic film layer comprises a crosslinked copolymer containing a fluorine-containing repeating unit and fluorine-free units, providing ionic conductivity, gas and moisture blocking properties, and enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a separator is used to block moisture and gas, then gas and moisture blocking properties are improved, but ionic conductivity may be compromised
Solution Approach 1:
The patent employs a composite structure combining organic film and inorganic particles (such as ceramic particles) to create a separator that simultaneously achieves gas/moisture blocking and ionic conductivity. The organic film provides the barrier function while the inorganic particles provide ion conduction pathways, resolving the contradiction between blocking harmful factors and maintaining ionic transport.
Solution Approach 2:
The separator is designed with heterogeneous local properties: the organic film matrix provides gas and moisture blocking in certain regions, while embedded inorganic particles create conductive channels in other regions. This local differentiation allows the single component to fulfill multiple contradictory functions simultaneously.
2Reliability
If a separator allows lithium ion passage, then ionic conductivity is improved, but swelling caused by electrolyte may increase
Solution Approach 1:
The composite structure of organic film and inorganic particles creates a separator where the inorganic component provides dimensional stability and swelling resistance while the organic component maintains ionic conductivity. The inorganic particles act as structural scaffolds that prevent excessive swelling when the organic matrix absorbs electrolyte.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the separator materials, specifically using crosslinked organic polymers and inorganic particles with controlled pore sizes and surface properties. These parameter changes enable the separator to maintain porosity for ion transport while reducing overall swelling through the rigid inorganic framework.
3Stability of the object's composition
If the organic film is made more durable, then swelling resistance is improved, but manufacturing complexity may increase
Solution Approach 1:
The organic film is pre-crosslinked during the coating process before final assembly, establishing its dimensional stability and swelling resistance in advance. This preliminary crosslinking action simplifies subsequent manufacturing steps as the film's structural properties are already optimized, reducing the need for additional processing steps.
Solution Approach 2:
The patent uses porous inorganic particles embedded in the organic film to create a three-dimensional network structure that provides swelling resistance. This porous composite approach achieves durability through the rigid particle framework while maintaining a relatively simple manufacturing process of coating and drying.
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 composite membrane effectively suppresses electrolyte-induced swelling, maintains low resistance, and improves charging/discharging characteristics of lithium batteries by allowing lithium ion transfer while blocking oxygen and carbon dioxide, thereby enhancing the lifespan and performance of lithium air batteries.
Implementation Method 1
the organic film includes a crosslinked copolymer, and the cross-linked copolymer includes a fluorine-containing first repeating unit... Since the crosslinked copolymer includes the fluorine-containing first repeating unit, swelling of the organic film due to an electrolyte may be suppressed
Implementation Method 2
a plurality of ion conductive inorganic particles disposed in the organic film layer... allowing lithium ions to pass there through
Implementation Method 3
there is a need to provide an improved separator which blocks moisture and gas... blocking oxygen and carbon dioxide
Data Source
Figure 1
Figure 2A~2B
Figure 3~4A
AI summary
A composite membrane comprising an organic film layer; and a plurality of ion conductive inorganic particles disposed in the organic film layer, wherein the organic film layer comprises a crosslinked copolymer, and the crosslinked copolymer comprises a fluorine-containing first repeating unit and at least one repeating unit selected from a fluorine-free second repeating unit and a fluorine-free third repeating unit.