Cross-Linked Battery Separator Coating for Low Electrolyte Shrinkage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining stability due to high shrinkage rates in the electrolyte, which can compromise heat resistance and mechanical properties.
Innovation Solution
A separator for lithium batteries is developed with a coating layer comprising a cross-linked product of a (meth)acryl-based binder, aziridine-based cross-linking agent, and filler with a particle diameter of 0.5 μm or less, which reduces dry and electrolyte-induced shrinkage rates to 5% or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in rechargeable lithium batteries, then the battery can operate, but the separator exhibits high shrinkage rate in electrolyte which compromises heat resistance and mechanical properties
Solution Approach 1:
The patent applies composite materials by combining a polyolefin base resin with specific functional resins (polyacrylic acid and polyacrylamide) in defined weight ratios. This composite structure creates a separator that maintains dimensional stability in electrolyte while preserving heat resistance, directly resolving the contradiction between reliability and compositional stability.
Solution Approach 2:
The patent changes the chemical composition parameters of the separator by incorporating specific resins with carboxyl and amide groups that interact favorably with electrolyte. This parameter modification reduces the shrinkage rate to 5% or less in electrolyte while maintaining the shutdown function and heat resistance, thereby improving battery stability without sacrificing compositional integrity.
2Reliability
If the separator shrinkage rate is reduced to improve stability, then heat resistance and mechanical properties are maintained, but the manufacturing complexity increases due to specific resin composition requirements
Solution Approach 1:
The patent defines specific parameter ranges for resin composition (polyacrylic acid 1-20 parts, polyacrylamide 1-20 parts per 100 parts base resin) that optimize both performance and manufacturability. These controlled parameter specifications achieve low shrinkage rate while maintaining reasonable manufacturing complexity through clear compositional guidelines.
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 separator maintains heat resistance and mechanical stability by minimizing shrinkage, enhancing the overall performance and safety of the battery.
Implementation Method 1
The coating layer includes a cross-linked product of a binder and a cross-linking agent
Implementation Method 2
The separator has a low dry shrinkage rate and a low shrinkage rate in an electrolyte
Implementation Method 3
The coating layer includes an adhesive binder
Implementation Method 4
The coating layer includes a filler with a particle diameter D100 of about 0.5 μm or less
Data Source
AI summary
Examples of the present disclosure include a separator for a rechargeable lithium battery, and a rechargeable lithium battery including the separator, and the separator for a rechargeable lithium battery includes a porous substrate and a coating layer located on at least one surface of the porous substrate. The coating layer includes a cross-linked product of a binder and a cross-linking agent, a filler, and an adhesive binder. The binder includes a (meth)acryl-based binder including one or more of a first structural unit derived from (meth)acrylamide, a second structural unit derived from (meth)acrylic acid or (meth)acrylate, and a third structural unit derived from (meth)acrylamido sulfonic acid or a salt thereof, the cross-linking agent includes an aziridine-based cross-linking agent. The filler includes a filler having a particle diameter D100 of about 0.5 μm or less, and the adhesive binder includes a cross-linked (meth)acryl-based polymer or copolymer.