Fluorine-Doped Battery Separator Coating for Heat and Low Resistance
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Solution Overview
Problem
Existing separators for electrochemical devices, particularly lithium ion batteries, face challenges with heat resistance and stability, leading to potential short-circuits and degradation of electrolyte oxidation stability.
Innovation Solution
A separator with a heat-resistant coating layer containing fluorine-doped particle-shaped inorganic materials, such as alumina or aluminum hydroxide, which provides improved heat resistance and oxidation stability while maintaining low interfacial resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based porous polymer substrate is used as a separator, then it provides good electrochemical performance, but it shows severe heat shrinking behavior at 100°C or higher causing short-circuit between electrodes
Solution Approach 1:
The patent applies composite materials by combining polyolefin-based porous polymer substrate with inorganic particles (such as alumina, silica, or boehmite) to create a separator that maintains the electrochemical benefits of polyolefin while adding heat resistance through the inorganic component. The inorganic particles form a heat-resistant skeleton that prevents shrinkage at high temperatures, resolving the contradiction between electrochemical performance and heat resistance.
2Temperature
If a porous composite coating layer with inorganic particles and binder polymer is coated on the separator, then heat resistance is improved, but interfacial resistance between electrode and separator increases and oxidation stability of electrolyte degrades
Solution Approach 1:
The patent extracts and eliminates the binder polymer component from the coating layer, using only inorganic particles to form the heat-resistant coating. This removal of organic binder material prevents the oxidation reactions that would otherwise occur between the binder and electrolyte during charge/discharge cycles, thereby maintaining oxidation stability while still achieving heat resistance through the inorganic particle framework.
Solution Approach 2:
The patent employs porous inorganic particle structures that maintain ion conductivity while providing heat resistance. The porous structure allows electrolyte penetration and ion transport, preventing the formation of a dense barrier that would increase interfacial resistance, while the inorganic nature provides the necessary thermal stability.
3Temperature
If inorganic particles are added to the coating layer, then heat resistance increases preventing short-circuit, but interfacial resistance between electrode and separator increases
Solution Approach 1:
The patent applies local quality by creating a coating layer with specific inorganic particle characteristics (size, distribution, and morphology) that are optimized to provide heat resistance at the surface while maintaining porosity and surface properties that favor low interfacial resistance. The inorganic particles are distributed to form a heat-resistant network without creating a dense barrier, allowing ion transport while preventing thermal shrinkage.
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 exhibits enhanced heat resistance, improved ion conductivity, and increased oxidation stability of the electrolyte, leading to better electrochemical stability and safety of the battery.
Implementation Method 1
fluorine (F) atoms doped to a surface of the particle-shaped inorganic material
Implementation Method 2
a polyolefin-based porous polymer substrate used conventionally as a separator for an electrochemical device shows a severe heat shrinking behavior at a temperature of 100° C. or higher
Implementation Method 3
causes the problem of degradation of the oxidation stability of an electrolyte due to oxidation of inorganic particles during repetition of charge/discharge cycles
Data Source
AI summary
The separator according to the present disclosure and the electrochemical device including the same show low internal resistance between the separator and an electrode. The separator includes heat resistant particles in a heat resistant coating layer. The heat resistant particles include a particle-shaped inorganic material and fluorine (F) doped to a surface of the inorganic particles. When the internal temperature of a battery is increased during the operation of the battery, the separator shows improved heat resistance by virtue of an endothermic effect derived from a phase change of the heat resistant particles. In addition, decomposition of a lithium salt used as an ingredient of electrolyte is inhibited by the fluorine atoms introduced to the heat resistant particles, resulting in improvement of ion conductivity and resistance characteristics. Further, the separator including the heat resistant particles introduced thereto has excellent resistance characteristics and shows high oxidation stability of an electrolyte, resulting in improvement of the electrochemical stability of a battery.