Cathode Slurry Gel Layer for Battery Safety and Adhesion
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Solution Overview
Problem
Lithium secondary batteries face instability and safety concerns due to thermal, mechanical, and electrical shocks, leading to potential ignition and explosion risks, especially in extreme environments, as they have high interfacial resistance and adhesion issues between the separator and electrode.
Innovation Solution
A positive electrode slurry composition is developed, including a fluorine-containing polymer, a conductive agent, and a polymer or oligomer with specific units that can be gelated by heat, forming a gel-type film on the electrode surface, which reduces interfacial resistance and enhances safety by improving adhesion and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lithium secondary batteries are used to achieve high energy density, then capacity is improved, but safety deteriorates due to instability under thermal, mechanical, and electrical shocks
Solution Approach 1:
The patent introduces a polymer gel layer as an intermediary substance between the positive electrode and the electrolyte solution. This gel layer acts as a mediator that provides thermal insulation and mechanical protection to the positive electrode, thereby improving safety without compromising the energy density of the battery system.
Solution Approach 2:
The patent creates a composite structure by combining the polymer gel material with the existing battery components (positive electrode and electrolyte solution). This composite approach allows the battery to maintain its high energy density characteristics while adding the safety benefits of the polymer gel layer, resolving the contradiction between energy density and safety.
2Device complexity
If conventional electrode structures are used to maintain simplicity, then device complexity is low, but adhesion between separator and electrode deteriorates leading to high interfacial resistance
Solution Approach 1:
The polymer gel layer serves as an intermediary between the separator and the positive electrode, providing improved adhesion without requiring complex structural modifications. This intermediary layer fills gaps and creates better contact between the separator and electrode, reducing interfacial resistance while maintaining the overall simplicity of the battery structure.
3Device complexity
If no polymer gel layer is used to maintain simplicity, then device complexity is low, but interfacial resistance increases leading to poor adhesion
Solution Approach 1:
The patent changes the physical and chemical parameters of the interface between the positive electrode and electrolyte solution by introducing the polymer gel layer. This layer modifies the interfacial properties, improving adhesion and reducing interfacial resistance without significantly increasing the overall complexity of the battery structure.
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 effectively suppresses interfacial resistance and enhances the safety and high-temperature storage characteristics of lithium ion batteries, preventing ignition and explosion risks while maintaining high energy density and capacity.
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
Implementation Method 4
an interfacial resistance between the positive electrode and a separator may be suppressed
Implementation Method 5
flame retardancy similar to that of a gel polymer electrolyte may be achieved
Implementation Method 6
a lithium ion battery having improved electrical (overcharge) and physical (impact) safety as well as improved high-temperature storage characteristics may be prepared
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.