Thermosetting Gel Polymer Electrolyte for Pre-Gelation-Free Wetting
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Solution Overview
Problem
The existing liquid electrolytes in lithium secondary batteries suffer from low stability, leading to issues like solvent vaporization, internal pressure increases, and uneven electrode reactions due to side reactions, particularly at high temperatures, which can cause deformation or explosion, and the injection type method for gel polymer electrolytes faces challenges with pre-gelation and reduced wetting.
Innovation Solution
A thermosetting electrolyte composition for lithium secondary batteries is developed, incorporating LiPF6 as a first lithium salt, a second lithium salt, a non-aqueous organic solvent, and a polymer or oligomer with a cyano group as a thermopolymerizable functional group, allowing for gelation by heating without a polymerization initiator, thereby preventing pre-gelation and enhancing impregnability and oxidation stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymerization initiator is used to form gel polymer electrolyte, then gelation can occur at room temperature, but pre-gelation occurs before injection reducing wetting performance
Solution Approach 1:
The patent removes the polymerization initiator from the electrolyte composition, extracting the harmful element that causes pre-gelation. Instead, it uses a polymer with thermopolymerizable functional groups that only polymerizes at elevated temperatures (60-80°C), eliminating the pre-gelation problem while maintaining complete gelation.
Solution Approach 2:
The patent changes the polymerization temperature parameter from room temperature to elevated temperature (60-80°C). This parameter change ensures that the polymer only gelates after injection when heated, preventing pre-gelation during storage and injection while achieving complete gelation for improved wetting performance.
2Reliability
If liquid electrolyte is used, then ion conductivity is maintained, but stability is low causing solvent vaporization and internal pressure increase
Solution Approach 1:
The patent utilizes phase transition from liquid to gel state by forming a gel polymer electrolyte through thermopolymerization. This phase transition provides the stability of solid polymers while maintaining the ion conductivity of liquid electrolytes, preventing solvent vaporization and gas generation.
Solution Approach 2:
The patent creates a composite gel polymer electrolyte combining polymer matrix with liquid electrolyte components. This composite structure provides both the stability of the polymer network and the ion conductivity of the liquid electrolyte, eliminating the harmful effects of pure liquid electrolytes.
3Reliability
If gel polymer electrolyte is used, then electrochemical stability is improved, but manufacturing complexity increases due to pre-gelation control
Solution Approach 1:
The patent removes the polymerization initiator from the system, simplifying the manufacturing process. The gelation is achieved purely through thermal activation of thermopolymerizable functional groups, eliminating the need to control initiator reactions and pre-gelation issues.
Solution Approach 2:
The polymer with thermopolymerizable functional groups performs self-gelation when heated to 60-80°C, without requiring external polymerization initiators or complex control mechanisms. This self-service approach simplifies the manufacturing process while maintaining electrochemical stability.
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 prevents pre-gelation, improves wetting, and results in a lithium secondary battery with enhanced oxidation stability, thermal stability, and capacity characteristics, reducing the risk of deformation and explosion, while maintaining battery thickness and performance.
Implementation Method 1
a polymer or oligomer containing a unit represented by formula (1), and a gel polymer electrolyte which is prepared by a thermal polymerization of the thermosetting electrolyte composition
Implementation Method 2
the gel polymer electrolyte is advantageous in that, since it has excellent electrochemical stability in comparison to the liquid electrolyte, the thickness of the battery may not only be constantly maintained, but a stable thin-film type battery may also be prepared due to the inherent adhesion of a gel phase
Implementation Method 3
wetness of the electrolyte solution to the electrode is improved in comparison to that of the coating type method
Data Source
AI summary
The present invention relates to a thermosetting electrolyte composition for a lithium secondary battery, a gel polymer electrolyte prepared therefrom, and a lithium secondary battery including the gel polymer electrolyte, and particularly, to a thermosetting electrolyte composition for a lithium secondary battery, which includes LiPF6 as a first lithium salt, a second lithium salt which does not include LiPF6, a non-aqueous organic solvent, and a polymer or oligomer containing a unit represented by Formula 1, a gel polymer electrolyte prepared therefrom, and a lithium secondary battery including the gel polymer electrolyte.