Positive Electrode Slurry Composition for Lithium Secondary Battery Safety
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Solution Overview
Problem
Lithium secondary batteries face instability and safety concerns due to thermal, mechanical, and electrical shocks, which can lead to ignition or explosion, especially in extreme environments, necessitating improved interfacial resistance and safety features.
Innovation Solution
A positive electrode slurry composition incorporating a fluorine-containing polymer, a conductive agent, and a polymer or oligomer with specific units that form a gel-type film upon heating, reducing interfacial resistance and enhancing safety by suppressing exothermic reactions without the need for a gel polymer electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lithium secondary battery uses conventional electrode materials and structure, then high energy density is achieved, but thermal stability and safety are compromised leading to ignition or explosion risks
Solution Approach 1:
A gel-type film is introduced as an intermediary layer between the positive electrode and the electrolyte solution. This film acts as a mediator that provides thermal stability and safety without interfering with the battery's high energy density performance. The gel film contains cross-linked polymer chains that remain stable at high temperatures, preventing thermal runaway while allowing ionic conductivity for normal operation.
Solution Approach 2:
The patent creates a composite structure by combining conventional electrode materials with a gel-type film composed of cross-linked polymer chains. This composite approach integrates the high energy density benefits of traditional lithium secondary batteries with the thermal stability of the gel film, achieving both performance and safety requirements.
2Adaptability or versatility
If the battery operates in extreme environments, then versatility is improved, but interfacial resistance increases causing performance degradation
Solution Approach 1:
The gel-type film's physical and chemical parameters are optimized to maintain stability across a wide temperature range. The cross-linked polymer structure provides thermal stability while the gel matrix maintains ionic conductivity, allowing the battery to adapt to extreme environments without significant increase in interfacial resistance.
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 achieves improved electrical and physical safety, as well as enhanced high-temperature storage characteristics, by forming a stable gel-type film on the positive electrode, thereby preventing ignition and maintaining battery performance.
Implementation Method 1
the cyano group, as a substituent contained in the polymer or oligomer containing a unit represented by Formula 1, causes cationic polymerization as shown in the following Reaction Formula 1 so that gelation may occur
Implementation Method 2
a polymer or oligomer which may be gelated by heat
Implementation Method 3
PF5 is generated while a lithium salt, for example, LiPF6 present in an electrolyte solution, is thermally decomposed when applying heat
Data Source
AI summary
The present invention relates to a positive electrode slurry composition, and a positive electrode for a secondary battery and a lithium secondary battery which include the positive electrode slurry composition, and particularly, to a positive electrode slurry composition which includes a positive electrode active material, a fluorine-containing polymer, a conductive agent, a solvent, and a polymer or oligomer containing a unit represented by Formula 1, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode slurry composition.