Composite Separator Using Inorganic Nanowires for Battery Safety
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Solution Overview
Problem
Polyolefin-based separators in secondary batteries face issues with chemical stability and performance degradation due to organic binders reacting with electrolyte solutions, leading to clogging, gas generation, and increased battery volume, compromising safety and performance.
Innovation Solution
A composite separator is developed with an inorganic particle layer and a multi-dimensional heterogeneous material-containing composite layer using inorganic nanowires as a binder, eliminating the need for organic binders and enhancing adhesive strength, heat resistance, and lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polymer binder is used to adhere the ceramic layer to the porous sheet, then adhesive strength is improved, but chemical stability deteriorates due to reactions with electrolyte solution causing clogging, gas generation, and swelling
Solution Approach 1:
The patent removes the organic polymer binder from the ceramic layer composition entirely. The ceramic particles are adhered to the porous polyolefin sheet through physical interaction and sintering processes without any organic binding agent, thereby eliminating the source of chemical reactions with the electrolyte solution while maintaining adequate adhesive strength
Solution Approach 2:
The patent introduces a porous coating layer composed of inorganic particles (such as alumina, silica, or boehmite) as an intermediary between the ceramic layer and the porous sheet. This inorganic coating layer serves as both the adhesive interface and the structural support, replacing the function previously performed by organic binders while providing chemical inertness
2Temperature
If the ceramic layer is coated onto the porous sheet to improve safety, then thermal stability is improved, but manufacturing complexity increases due to the need for polymer binder application and drying processes
Solution Approach 1:
The patent combines the ceramic particle layer and the adhesive layer into a single integrated structure. The ceramic particles themselves form the adhesive interface with the porous sheet through direct contact and sintering, eliminating the need for separate binder application and drying steps while maintaining both thermal stability and adhesion
Solution Approach 2:
The patent changes the processing parameters from low-temperature binder curing to high-temperature sintering. By heating the coated ceramic particles to temperatures sufficient for sintering (typically 800-1500°C), the particles fuse together and bond to the porous sheet, simplifying the process by eliminating intermediate drying and curing steps
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 a chemically and thermally stable separator with improved adhesive strength, reduced resistance, and enhanced lithium ion migration, maintaining battery performance and safety over time, even with large capacity and size batteries.
Implementation Method 1
using inorganic nanowires as a binder... having excellent adhesive strength
Implementation Method 2
excellent lithium ion conductivity... lithium ions smoothly migrate
Implementation Method 3
completely or sufficiently preventing clogging of porous pores... by an organic binder
Data Source
AI summary
The present disclosure relates to an organic/inorganic composite porous separator that has excellent thermal stability and an excellent adhesive property between a porous substrate and a porous active layer, has a small change in Gurley permeability before and after coating of the porous active layer, and has excellent electrochemical stability, excellent lithium ion conductivity, and a low resistance increase rate in comparison to a polyolefin-based separator according to the related art, and an electrochemical device capable of implementing both securing of safety and performance improvement by including the separator.