Lithium Battery Separator Coating for Gas Decomposition
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Solution Overview
Problem
Polymer-type rechargeable lithium batteries face safety issues due to internal gas generation, which compromises their safety and performance.
Innovation Solution
A rechargeable lithium battery design featuring a porous substrate with a coating layer containing a fluorine-based polymer, ceramic, or their combination, and an additive represented by Chemical Formula 1, which enhances adherence between the electrode and separator, improving safety and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer-type rechargeable lithium battery is designed with a separator and electrolyte, then the battery can function as a rechargeable energy storage device, but internal gas generation occurs leading to safety problems
Solution Approach 1:
The patent converts the harmful effect of gas generation into a beneficial outcome by incorporating a coating layer with ceramic particles (such as Al2O3, MgO, TiO2) and fluorine-based polymers on the separator. This coating layer catalyzes the decomposition of generated gas back into liquid electrolyte components, thereby eliminating the harmful gas while maintaining battery functionality and improving safety.
Solution Approach 2:
The separator with its specialized coating layer acts as an intermediary between the electrodes and the electrolyte. The coating layer containing ceramic particles and fluorine-based polymer mediates the gas decomposition process, preventing direct harmful interactions while facilitating the conversion of gas to liquid components, thus resolving the safety issue without compromising battery operation.
2Reliability
If the separator is made with a porous substrate and coating layer to improve safety, then adherence between electrode and separator is enhanced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes a porous substrate as the base structure of the separator, which provides inherent mechanical strength and electrochemical stability. The porous structure allows for efficient ion transport while maintaining structural integrity, and serves as an ideal foundation for coating layer deposition, thereby achieving high adherence without excessive complexity.
Solution Approach 2:
The separator is constructed as a composite material system combining a porous substrate with a coating layer containing ceramic particles and fluorine-based polymers. This composite structure integrates the advantages of each material: the porous substrate provides mechanical support and ion transport pathways, while the coating layer enhances adherence and catalyzes gas decomposition, achieving improved reliability without prohibitively complex manufacturing.
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 enhanced adherence and safety features of the battery design lead to improved safety and extended cycle-life characteristics, as demonstrated by increased adherence measurements and reduced oxidation decomposition peaks in electrolyte analysis.
Implementation Method 1
a separator interposed between the positive electrode and the negative electrode and including a porous substrate and a coating layer formed on at least one side of the porous substrate... the coating layer includes a fluorine-based polymer, a ceramic, or a combination thereof
Implementation Method 2
the additive includes a compound represented by Chemical Formula 1... at least one of the R1 to R3 comprises a substituted or unsubstituted epoxy group
Implementation Method 3
a separator interposed between the positive electrode and the negative electrode and including a porous substrate
Data Source
AI summary
In an aspect, a rechargeable lithium battery that includes a positive electrode; negative electrode; a separator interposed between the positive electrode and the negative electrode and including a porous substrate and a coating layer formed on at least one side of the porous substrate; and an electrolyte including a lithium salt, a non-aqueous organic solvent, and an additive is provided.