pH-Responsive Separator Coating for Low-Resistance Battery Wetting
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Solution Overview
Problem
Existing separators in secondary batteries face issues with high resistance and reduced performance due to inadequate adhesive force and electrolyte impregnability, particularly with aqueous variable binders, leading to potential safety and capacity issues.
Innovation Solution
A separator with a coating layer containing a variable binder whose size changes with pH, composed of an aqueous binder with an ester group and high crosslinking degree, is applied to a polyolefin substrate, incorporating an inorganic material to enhance adhesion and reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based porous substrate is used as a separator, then chemical inertness and electrochemical stability are improved, but wettability is poor and affinity with electrolyte solution is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the surface properties of the polyolefin-based porous substrate through plasma treatment. This treatment introduces polar groups and changes surface energy, thereby improving wettability and electrolyte affinity while preserving the bulk chemical inertness and electrochemical stability of the polyolefin material.
Solution Approach 2:
The patent creates a composite structure by combining polyolefin-based porous substrate with surface-modified layers or coatings that enhance wettability. The composite maintains the chemical stability of polyolefin while adding surface properties that improve electrolyte interaction, effectively resolving the contradiction between inertness and wettability.
2Temperature
If crosslinking is performed on the porous substrate, then heat resistance is improved, but homogeneous crosslinking is difficult to achieve
Solution Approach 1:
The patent uses silane compounds as intermediary agents to achieve homogeneous crosslinking. The silane compounds first graft onto the porous substrate uniformly, then undergo hydrolysis and condensation to form crosslinked structures. This two-step process with silane as intermediary ensures uniform heat resistance throughout the separator.
Solution Approach 2:
The patent replaces direct thermal or mechanical crosslinking methods with chemical crosslinking through silane grafting. This substitution allows for more controlled and homogeneous crosslinking at lower temperatures, achieving uniform heat resistance without the inhomogeneity problems associated with conventional crosslinking methods.
3Reliability
If a polyolefin-based porous substrate is used, then shutdown function is provided, but affinity with electrolyte solution and wettability are insufficient
Solution Approach 1:
The patent modifies surface parameters of the polyolefin-based porous substrate through plasma treatment or surface coating, introducing polar functional groups that enhance electrolyte affinity and wettability. The bulk material retains its shutdown function, while surface properties are optimized for better electrolyte interaction.
Solution Approach 2:
The patent applies local quality modification by treating only the surface layer of the porous substrate to improve wettability and electrolyte affinity, while the bulk material maintains its shutdown function. This localized modification resolves the contradiction by optimizing different regions for different functions.
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 variable binder's pH-dependent size reduction enhances adhesion, increases inorganic material density, and improves battery performance by reducing resistance and extending lifespan.
Implementation Method 1
variable binder having size varying according to pH
Data Source
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AI summary
The present invention relates to a separator including a variable binder having a size changed depending on pH and a method of manufacturing the same, and more particularly to a separator configured such that a variable binder having a size changed depending on pH is used in a separator coating layer to reduce resistance of a battery and to maintain uniform adhesive force while improving air permeability and a method of manufacturing the same.