Battery Separator Coating for Heat Shrinkage and Peel Strength
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Solution Overview
Problem
Current separators for electrochemical devices face challenges in maintaining dimensional stability at high temperatures, leading to potential internal short circuits and safety issues due to insufficient bonding characteristics and thermal stability of silane compounds used as binders.
Innovation Solution
A separator with an inorganic particle layer on a porous substrate, utilizing a hydrolytic condensate binder of a polar silane compound and an aqueous polymer binder, which enhances adhesion and cohesion to prevent particle release and improve thermal stability, characterized by a peel strength increase and reduced heat shrinkage rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a silane compound is used as the binder of the inorganic particle layer, then thermal stability is improved to some extent, but bonding characteristics are still lacking and inorganic particles may be released during cell assembly
Solution Approach 1:
The patent uses a composite binder system comprising both a silane compound and a polyvinylidene fluoride (PVDF) binder in a specific weight ratio range (silane compound: 1-10 parts by weight, PVDF: 90-90 parts by weight based on total binder weight). This composite approach combines the thermal stability benefits of silane compounds with the excellent bonding characteristics of PVDF, resolving the contradiction between thermal stability and bonding strength. The silane compound forms a hydrolytic condensate that provides thermal resistance, while PVDF ensures strong adhesion to the porous substrate and cohesion within the inorganic particle layer, preventing particle release during cell assembly.
2Stability of the object's composition
If the inorganic particle layer is made thicker to improve thermal stability, then heat shrinkage resistance improves, but peel strength decreases and inorganic particles are more likely to release
Solution Approach 1:
The patent optimizes the thickness of the inorganic particle layer to a specific range of 0.1-5 μm, and controls the weight ratio of silane compound to PVDF binder (1:90 to 10:90). By changing these parameters within optimal ranges, the invention achieves both adequate heat shrinkage resistance and sufficient peel strength. The controlled thickness prevents excessive brittleness while the optimized binder composition ensures strong adhesion, resolving the contradiction between heat shrinkage resistance and peel strength.
Solution Approach 2:
The composite binder system of silane compound and PVDF works synergistically to resolve the contradiction between heat shrinkage resistance and peel strength. PVDF provides flexible adhesion that maintains peel strength even in thinner layers, while silane compound contributes thermal stability and heat shrinkage resistance. The combination allows the inorganic particle layer to achieve both properties simultaneously without compromising either heat shrinkage resistance or peel strength.
3Strength
If a polar silane compound is used to improve adhesion through hydrolytic condensate, then bonding characteristics improve, but manufacturing complexity increases due to pH control requirements
Solution Approach 1:
The patent specifies a pH range of 4-6 for the coating slurry and controls the water content to be 70-90 wt% of the total slurry weight. By maintaining these specific parameter ranges, the hydrolytic condensation of the polar silane compound proceeds optimally to form strong bonds between the inorganic particle layer and the porous substrate, while avoiding excessive complexity in the manufacturing process. The defined pH range ensures consistent adhesion without requiring overly complex process control systems.
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 solution significantly improves the thermal stability and adhesion of the separator, preventing particle release and ensuring high battery safety at elevated temperatures by using a hydrolytic condensate binder of a polar silane compound and an aqueous polymer binder, resulting in enhanced peel strength and reduced heat shrinkage.
Implementation Method 1
a hydrolytic condensate binder of a polar silane compound
Implementation Method 2
a hydrolytic condensate binder of a polar silane compound
Implementation Method 3
dimensional stability at a high temperature
Data Source
AI summary
Provided are a separator, a method of manufacturing the separator, and an electrochemical device including the separator. According to an embodiment of the present disclosure, a separator including a porous substrate and an inorganic particle layer provided on at least one surface of the porous substrate, the inorganic particle layer including inorganic particles, a hydrolytic condensate binder of a polar silane compound, and an aqueous polymer binder, wherein an amount of change in peel strength, ΔP is 1.1 or more may be provided.