Hydrophilic Battery Separator Coating for Faster Electrolyte Wetting
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Solution Overview
Problem
Lithium secondary battery separators with hydrophobic porous polymer substrates face challenges in electrolyte wettability and lithium-ion transport due to their hydrophobic nature, which affects battery safety and performance.
Innovation Solution
A separator with a hydrophilic modification layer comprising a polymer compound and a surfactant, applied to the porous polymer substrate, enhances electrolyte infiltration and lithium-ion transport by modifying the substrate's hydrophobic properties to hydrophilic, including a porous coating layer with inorganic particles and a binder polymer for improved ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of a porous polymer substrate is increased, then the mechanical strength and safety are improved, but the electrolyte wettability deteriorates due to hydrophobic property
Solution Approach 1:
The patent applies surface treatment methods (corona treatment, plasma treatment, or chemical treatment) to modify the surface energy and chemical composition of the porous polymer substrate. This changes the surface parameters from hydrophobic to hydrophilic, improving electrolyte wettability while maintaining the original substrate thickness and mechanical strength.
Solution Approach 2:
The patent creates a composite structure by coating the porous polymer substrate with hydrophilic materials such as metal oxides (Al2O3, SiO2, TiO2), metal hydroxides (Al(OH)3, Mg(OH)2), or polymers (polyacrylic acid, polyvinyl alcohol). This composite approach combines the mechanical strength of the polymer substrate with the hydrophilic properties of the coating material.
2Reliability
If a hydrophobic porous polymer substrate is used, then the chemical stability and safety are improved, but the lithium-ion transport rate deteriorates
Solution Approach 1:
Surface treatment methods alter the surface chemistry of the porous polymer substrate, introducing polar groups and increasing surface energy. This parameter change improves electrolyte penetration and lithium-ion transport kinetics while preserving the bulk chemical stability of the polyolefin material.
Solution Approach 2:
Coating the porous polymer substrate with metal oxides, metal hydroxides, or hydrophilic polymers creates a composite structure where the coating layer provides enhanced electrolyte affinity and ion transport pathways, while the underlying polymer substrate maintains chemical stability and safety.
3Reliability
If a thick porous polymer substrate is used, then the safety and structural integrity are improved, but the electrolyte infiltration ability deteriorates
Solution Approach 1:
The patent applies surface treatment or coating only to the surface layer of the porous polymer substrate, leaving the bulk material unchanged. This local modification improves electrolyte infiltration at the interface where contact occurs, while the thicker substrate maintains its safety and structural integrity functions.
Solution Approach 2:
Surface treatment methods modify only the surface parameters (surface energy, chemical composition) of the porous polymer substrate without affecting the bulk thickness. This enables improved electrolyte infiltration at the surface while maintaining the original safety and mechanical properties of the thick substrate.
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 modified separator significantly improves electrolyte wettability and lithium-ion transport rates, leading to enhanced battery output and cycle characteristics.
Implementation Method 1
the hydrophilic modification layer includes a polymer compound represented by the following Chemical Formula 1 and a surfactant
Implementation Method 2
it is not easy to wet the porous polymer substrate with an electrolyte
Implementation Method 3
provides a channel for transporting lithium ions
Implementation Method 4
a porous coating layer with inorganic particles and a binder polymer for improved ion conductivity
Data Source
AI summary
Disclosed is a separator for a lithium secondary battery including a porous polymer substrate and a hydrophilic modification layer disposed inside of the porous polymer substrate, or disposed inside of the porous polymer substrate and on at least one surface of the porous polymer substrate, the hydrophilic modification layer including a polymer compound represented by the disclosed Chemical Formula 1 and a surfactant. According to an embodiment of the present disclosure, it is possible to increase the electrolyte wettability and lithium-ion transport rate in a separator by using a polymer compound having a specific structure and a surfactant. Therefore, a battery using the separator may provide improved output characteristics and cycle characteristics.