Coated Lithium Battery Separator for Adhesion and Heat Stability
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, discharge capacity, and cycle-life characteristics while maintaining safety and adherence between electrodes, particularly in the context of down-sizing and high-performance applications.
Innovation Solution
A separator for rechargeable lithium batteries is designed with a porous substrate coated with a layer containing organic filler particles, fluorine organic binder particles, and (meth)acryl organic binder particles, where the organic filler particles have a larger average diameter than the fluorine organic binder particles, and the coating layer includes a specific weight ratio and thickness to enhance adherence and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is used to prevent short circuit between electrodes, then safety is improved, but adherence between electrodes and separator deteriorates
Solution Approach 1:
The separator is constructed as a composite material consisting of a polyolefin base layer combined with a coating layer containing fluorine-containing polymer and inorganic particles. This composite structure maintains the safety functions of the polyolefin while the coating layer provides enhanced adherence to electrodes through the fluorine-containing polymer's bonding properties and the inorganic particles' surface characteristics.
2Strength
If the separator is compressed to improve adherence, then adherence is improved, but the separator structure may deteriorate
Solution Approach 1:
The coating layer is applied to the separator surface before assembly, pre-establishing strong bonding sites on the separator. This preliminary action ensures that when compression occurs during battery assembly, the coating layer already provides sufficient adherence without requiring excessive compression force that could damage the separator structure.
3Productivity
If energy density is increased for down-sizing, then productivity is improved, but heat management and safety deteriorate
Solution Approach 1:
The separator utilizes a porous structure with controlled pore size and distribution, allowing efficient electrolyte penetration and ion transport even at high energy density configurations. The porosity facilitates heat dissipation through the separator matrix, preventing thermal runaway while maintaining the compact design required for high energy density.
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 adherence to electrodes, maintains battery efficiency, and enhances safety by suppressing contraction at high temperatures, thereby supporting high energy density and cycle-life characteristics.
Implementation Method 1
the coating layer includes organic filler particles, fluorine organic binder particles, and (meth)acryl organic binder particles... suppressing contraction at high temperatures
Data Source
AI summary
A separator for a rechargeable lithium battery and a rechargeable lithium battery including the separator, the separator including a porous substrate; and a coating layer on at least one surface of the porous substrate, wherein the coating layer includes organic filler particles, fluorine organic binder particles, and (meth)acryl organic binder particles, an average particle diameter of the organic filler particles is equal to or greater than an average particle diameter of the fluorine organic binder particles, and the fluorine organic binder particles are coated on the porous substrate as a part of the coating layer in an amount of less than about 0.1 g/m2 per surface.