Cross-linked Ceramic-coated Separator for Lithium Battery Thermal Safety
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Solution Overview
Problem
Lithium secondary batteries face issues with thermal safety, mechanical strength, and electrolyte affinity due to the use of polyolefin separators, which can lead to short circuits and performance deterioration, especially under high temperatures and mechanical stress.
Innovation Solution
A cross-linked ceramic-coated separator is developed by coating ceramic particles and a functional inorganic compound on a porous membrane substrate using an ionic polymer binder, followed by chemical cross-linking, to enhance adhesive strength and ion conductivity, thereby improving thermal and mechanical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin separator is used, then the separator provides basic separation function, but thermal shrinkage occurs at high temperatures causing short circuits
Solution Approach 1:
The patent applies composite materials by coating ceramic particles (alumina, silica, zirconia) and functional inorganic compounds on the polyolefin separator surface. This composite structure combines the flexibility and basic separation function of polyolefin with the thermal stability of ceramics, preventing thermal shrinkage at high temperatures while maintaining the separator's fundamental properties.
Solution Approach 2:
The patent changes the surface properties of the separator by introducing hydrophilic inorganic compounds and conducting chemical cross-linking reactions. These parameter changes modify the separator's thermal behavior, preventing the thermal shrinkage that occurs in conventional polyolefin separators at temperatures above 100°C.
2Reliability
If a polyolefin separator is used, then the separator structure is simple, but mechanical strength is low causing internal short circuits
Solution Approach 1:
The patent strengthens the separator by creating a composite structure where ceramic particles form a reinforcing network on the separator surface. The ceramic-coated layer acts as a mechanical reinforcement, significantly improving puncture resistance and tensile strength while maintaining the flexible membrane structure.
Solution Approach 2:
The patent applies local quality enhancement by concentrating the ceramic coating and cross-linking reactions at the separator surface where mechanical stress and potential damage occur. This localized reinforcement provides enhanced mechanical strength at critical areas without significantly increasing overall complexity.
3Reliability
If a polyolefin separator is used, then the separator is easy to manufacture, but electrolyte affinity is low causing electrolyte leakage
Solution Approach 1:
The patent changes the surface chemistry of the separator by coating hydrophilic inorganic compounds (alumina, silica, zirconia) that have high affinity for polar electrolytes. This parameter change in surface polarity dramatically improves electrolyte wettability and retention without fundamentally altering the manufacturing process flow.
Solution Approach 2:
The patent introduces an intermediary layer of inorganic compounds and ionic polymers between the polyolefin substrate and the electrolyte. This intermediary layer serves as a bridge, providing high electrolyte affinity while the underlying polyolefin maintains its easy manufacturability and basic separation function.
4Reliability
If ceramic particles are coated on the separator, then thermal and mechanical characteristics improve, but adhesive strength between coating and substrate decreases
Solution Approach 1:
The patent introduces ionic polymers as an intermediary layer between the ceramic particles and the polyolefin substrate. This intermediary layer provides chemical bonding sites for both the ceramic coating and the substrate, significantly improving adhesion strength and preventing coating delamination during battery operation.
Solution Approach 2:
The patent applies chemical cross-linking to change the molecular structure of the ionic polymer layer, creating a three-dimensional network that strongly bonds to both the ceramic particles and the substrate. This parameter change in molecular architecture transforms the coating from a loosely attached layer to a firmly integrated structure.
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, mechanical strength, and electrolyte affinity of the separator, reducing the risk of short circuits and maintaining battery performance and safety under severe conditions.
Implementation Method 1
a coating material containing ceramic particles for improving thermal and mechanical characteristics, a functional inorganic compound for improving cycle characteristics and high rate characteristics of a battery, and an ionic polymer for bonding the ceramic particles and the functional inorganic compound on a porous membrane substrate is suitably coated on the porous membrane substrate and then subjected to chemical cross-linking
Implementation Method 2
the porous separator serves to prevent physical contact between the negative and positive electrodes and, at the same time, allow lithium ions to pass through pores
Implementation Method 3
a coating material containing ceramic particles for improving thermal and mechanical characteristics
Data Source
AI summary
The present invention provides method for preparing a cross-linked ceramic-coated separator containing an ionic polymer, a ceramic-coated separator prepared by the method, and a lithium secondary battery using the same. According to preferred methods for preparing a cross-linked ceramic-coated separator, a coating material containing ceramic particles for improving thermal and mechanical characteristics, a functional inorganic compound for improving cycle characteristics and high rate characteristics of a battery, and an ionic polymer for bonding the ceramic particles and the functional inorganic compound on a porous membrane substrate is coated on the porous membrane substrate and subjected to chemical cross-linking.