Silane-Coated Metal Oxide Separator for Lithium Battery Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lithium secondary batteries face deterioration and safety issues due to electrode contraction and expansion during charge and discharge cycles, leading to internal and external short circuits and rapid heating, which can cause the separator to fuse and become destroyed.
Innovation Solution
A separator for lithium secondary batteries is developed with a coating layer comprising metal oxide and/or silicon oxide coated with a silane compound having reactive functional groups, such as amino, isocyanate, or epoxy groups, which enhances heat resistance, adhesion, and cycle-life characteristics by forming a chemical bond with the binder and inorganic compounds like SrTiO3 or SnO2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional porous polyethylene separator is used, then shutdown characteristic and ease of handling are improved, but heat resistance and cycle-life characteristics deteriorate due to separator fusion during battery heating
Solution Approach 1:
The patent applies composite materials by combining polyethylene separator with inorganic fine particles (such as alumina, silica, or boehmite) and binder to form a coated separator structure. This composite construction allows the separator to maintain the shutdown function of polyethylene while gaining heat resistance from the inorganic coating layer, preventing separator fusion during battery overheating events
Solution Approach 2:
The patent changes the physical and chemical parameters of the separator by controlling the particle size distribution (D10-D90 range of 3-10 μm), coating thickness (1-10 μm), and binder content (5-20 wt%) of the inorganic layer. These parameter optimizations ensure the coating provides sufficient heat resistance without compromising the underlying polyethylene shutdown mechanism
2Reliability
If electrode materials are made more heat resistant, then safety during sharp contraction is improved, but cycle-life characteristics and adhesion to separator deteriorate due to repeated contraction and expansion
Solution Approach 1:
The patent utilizes porous inorganic fine particles with controlled pore structures that can accommodate electrode volume changes during cycling. The porous coating layer acts as a buffer zone that absorbs mechanical stress from electrode contraction and expansion, maintaining adhesion and preventing delamination while preserving safety
Solution Approach 2:
The inorganic coating layer serves as an intermediary between the electrode and the polyethylene separator, providing a compliant interface that accommodates electrode dimensional changes. This intermediate layer prevents direct mechanical stress transmission to the separator, thereby maintaining both adhesion and cycle-life characteristics
3Temperature
If separator thickness is increased to prevent fusion, then heat resistance is improved, but internal and external short circuit risk increases due to separator contraction and destruction
Solution Approach 1:
The patent creates a composite separator structure where a thin inorganic coating layer (1-10 μm) is applied on the polyethylene separator surface. This composite structure provides heat resistance equivalent to much thicker separators while maintaining the flexibility and short-circuit prevention capabilities of the original thin separator design
4Temperature
If inorganic fine particles are added to separator, then heat resistance is improved, but manufacturing complexity and coating uniformity deteriorate
Solution Approach 1:
The patent employs a self-leveling slurry coating method where the inorganic particle suspension automatically distributes uniformly across the separator surface during the coating process. The slurry's rheological properties and the coating process design enable self-leveling that eliminates complex coating control systems, simplifying manufacturing while ensuring uniform coating thickness
Solution Approach 2:
The patent optimizes slurry parameters including particle size distribution (D10-D90: 3-10 μm), solvent composition, and viscosity to achieve optimal flow and leveling characteristics. These parameter adjustments enable simple dip-coating or spray-coating processes to produce uniform coatings without requiring complex manufacturing equipment or procedures
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 improves the battery's cycle-life characteristics, strength, and high-temperature stability, reducing the risk of short circuits and heat-related damage, while maintaining capacity and safety through enhanced adhesion and thermal stability.
Implementation Method 1
a coating layer comprising at least one metal oxide and/or at least one silicon oxide coated with at least one silane compound
Implementation Method 2
improve heat resistance of an electrode material for a separator and the like and in particular, to secure safety even when a separator therein is sharply contracted or destroyed
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed is a separator for a lithium secondary battery comprising: a substrate; a coating layer disposed on at least surface of the substrate, wherein the coating layer comprises at least one metal oxide and/or at least one silicon oxide coated with at least one silane compound.