Substrate-Free Porous Separator for Heat-Stable Battery Insulation
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Solution Overview
Problem
Conventional lithium secondary battery separators with polyolefin substrates face issues with adhesion, thermal stability, electrical insulation, and mechanical strength, leading to potential short circuits and reduced lifespan, especially at high temperatures.
Innovation Solution
A porous separator is developed without a polyolefin substrate, comprising inorganic particles, a polymer binder, and a crosslinking agent, which forms a three-dimensional net-shaped structure to enhance insulation, tensile strength, and ion transfer ability, ensuring electrical isolation between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyolefin separator substrate is used, then mechanical strength and ion permeability are improved, but thermal stability deteriorates because polyolefin melts at high temperature
Solution Approach 1:
The invention uses a composite structure consisting of a polyolefin separator substrate combined with an inorganic coating layer containing inorganic particles (such as alumina, silica, or boehmite) and a binder. This composite structure allows the polyolefin substrate to provide mechanical strength and ion permeability while the inorganic coating layer provides high-temperature stability, preventing the separator from melting at elevated temperatures.
2Temperature
If an inorganic coating layer alone without polyolefin substrate is used, then thermal stability is improved, but electrical insulation deteriorates leading to short circuit vulnerability
Solution Approach 1:
The invention creates a composite separator where the polyolefin substrate provides excellent electrical insulation properties while the inorganic coating layer provides thermal stability. The synergistic combination ensures that the separator maintains both high electrical insulation to prevent short circuits and high-temperature stability for safe operation.
3Temperature
If an inorganic coating layer alone without polyolefin substrate is used, then thermal stability is improved, but mechanical strength deteriorates causing easy tearing
Solution Approach 1:
The invention employs a composite structure where the polyolefin substrate provides flexibility and mechanical strength to prevent tearing, while the inorganic coating layer deposited on the substrate surface provides high-temperature stability. The binder in the inorganic coating layer ensures strong adhesion to the substrate, creating a robust composite separator that combines the advantages of both materials.
4Temperature
If a separator substrate is used with inorganic coating layer, then thermal stability is improved, but adhesion between separator and electrode deteriorates causing local separation or wrinkles
Solution Approach 1:
The invention optimizes the local properties of the separator by carefully selecting the composition and structure of the inorganic coating layer. The coating layer is designed with appropriate porosity and surface characteristics that enhance contact with the electrode, improving adhesion. The binder material and particle size distribution are optimized to ensure good interfacial contact between the separator and electrode, preventing local separation and wrinkle formation while maintaining high-temperature stability.
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 provides improved thermal stability, high insulation, and mechanical strength, reducing the risk of short circuits and enhancing the overall performance and lifespan of lithium secondary batteries.
Implementation Method 1
a crosslinking agent, which forms a three-dimensional net-shaped structure to enhance insulation, tensile strength, and ion transfer ability
Implementation Method 2
exhibit ion permeability and mechanical strength such that an electrolytic solution can pass smoothly through the separator
Implementation Method 3
electrically isolate the positive electrode and the negative electrode from each other
Data Source
AI summary
Disclosed herein is a porous separator for electrochemical devices, configured to guarantee electrical insulation between a positive electrode and a negative electrode, wherein the porous separator includes no polyolefin substrate, and includes inorganic particles, a binder for coupling between the inorganic particles, and a crosslinking agent.