Epoxy-Reactive Separator Membrane for Gel Electrolyte Interfaces
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Solution Overview
Problem
Conventional lithium secondary batteries using liquid electrolytes face safety issues due to degradation and combustion risks, while gel polymer electrolytes lack uniform adhesion to separation membranes, leading to interfacial resistance and short-circuits, which compromises battery safety and longevity.
Innovation Solution
A separation membrane with a multi-layer structure, comprising a substrate, a first coating layer with an organic binder capable of epoxy ring-opening reactions, and a second coating layer with an inorganic oxide, enhances adhesion with gel polymer electrolytes, improving bonding force and preventing short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gel polymer electrolyte is used instead of liquid electrolyte, then safety is improved, but adhesion to separation membrane is insufficient leading to interfacial resistance
Solution Approach 1:
The patent modifies the chemical parameters of the gel polymer electrolyte by incorporating functional groups (carboxyl, hydroxyl, amine, isocyanate, or mercaptan groups) that can chemically react with the separation membrane surface. This chemical modification changes the interaction mechanism from physical adhesion to chemical bonding, resolving the adhesion issue while maintaining safety benefits
Solution Approach 2:
The patent creates a composite structure by combining the gel polymer electrolyte with functional groups that have affinity for the separation membrane. This composite approach integrates the safety advantages of gel polymer electrolytes with improved adhesion properties through the introduced functional groups
2Productivity
If liquid electrolyte is used, then battery performance is maintained, but safety deteriorates due to combustion risk
Solution Approach 1:
The patent uses a gel polymer electrolyte which forms a flexible, solid-like structure that replaces the liquid electrolyte. This gel structure physically confines the electrolyte material, preventing leakage and reducing combustion risk while maintaining ionic conductivity necessary for battery performance
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte from liquid to gel phase. This phase change eliminates the safety hazards of liquid electrolytes (combustion, leakage) while preserving the essential ionic conduction function through the gel matrix
3Ease of manufacture
If polyethylene separation membrane is used, then manufacturing ease is improved, but thermal stability deteriorates above 130°C
Solution Approach 1:
The patent creates a composite separation membrane by combining polyethylene with materials having higher thermal stability. This composite structure maintains the manufacturing advantages of polyethylene while introducing thermal resistance from the additional materials, allowing the membrane to function at elevated temperatures
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 safety and lifespan of lithium secondary batteries by ensuring strong adhesion between the gel polymer electrolyte and separation membrane, reducing interfacial resistance and preventing thermal runaway and ignition.
Implementation Method 1
a first coating layer containing a first organic binder which is able to be bonded to a gel polymer electrolyte through an epoxy ring-opening reaction
Data Source
AI summary
The present invention provides a separation membrane for a lithium secondary battery and a lithium secondary battery including the same, the separation membrane including: a substrate; a first coating layer containing a first organic binder which is able to be bonded to a gel polymer electrolyte through an epoxy ring-opening reaction; and a second coating layer containing a second organic binder, wherein the first organic binder has a functional group capable of ring-opening reaction with an epoxy group, or a combination thereof, and the gel polymer electrolyte is formed by polymerizing an oligomer having an epoxy group, a functional group capable of ring-opening reaction with an epoxy group, or a combination thereof.