Gel Polymer Electrolyte Anion Stabilization for LiPF6 Decomposition
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Solution Overview
Problem
Lithium secondary batteries face stability and performance issues due to side reactions caused by anions of lithium salts during charge, leading to degradation of the electrolyte solvent and electrodes, particularly with fluorinated Lewis acid-based salts like LiPF6, which generate harmful by-products like HF, affecting battery safety and performance.
Innovation Solution
A composition for a gel polymer electrolyte incorporating an oligomer with specific functional groups, an anion stabilizing additive such as phosphite-based or boron-based compounds, a polymerization initiator, and a lithium salt, which forms a polymer network to stabilize anions and suppress side reactions, thereby enhancing the battery's stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 or LiBF4 based lithium salts are used to achieve high ionic conductivity, then ionic conductivity is improved, but harmful by-products like HF are generated that decompose electrolyte solvent and cause electrode side reactions
Solution Approach 1:
A gel polymer electrolyte composition is introduced as an intermediary system between the lithium salt and the electrolyte solvent/electrode. This composition includes polymer matrices (polyacrylonitrile, polyvinylidene fluoride, carboxymethyl cellulose) and gel-forming agents that create a structured environment where lithium ions can conduct efficiently while the gel structure prevents direct contact and harmful reactions between lithium salt by-products and the electrolyte solvent or electrode materials.
Solution Approach 2:
The patent employs composite material strategy by combining multiple components: polymer matrices (providing structural framework), gel-forming agents (creating gel structure), and lithium salts (providing ionic conductivity). This composite gel polymer electrolyte system integrates the benefits of polymer stability with enhanced ionic conductivity while suppressing harmful side reactions through the synergistic interaction of components.
2Productivity
If gel polymer electrolyte is used to maintain battery thickness and improve contact, then battery performance is improved, but safety during wetting and heating processes decreases
Solution Approach 1:
The patent modifies the chemical composition parameters of the gel polymer electrolyte by selecting specific polymer matrices with inherent thermal stability (polyacrylonitrile, polyvinylidene fluoride, carboxymethyl cellulose) and optimizing the ratios of components. These parameter changes enable the gel electrolyte to maintain structural integrity during heating processes while ensuring safe wetting behavior, thus improving both performance and safety.
3Reliability
If liquid electrolyte is used to achieve good electrochemical stability, then electrochemical stability is improved, but thermal stability decreases leading to combustion risks
Solution Approach 1:
The patent utilizes phase transition from liquid to gel state by incorporating gel-forming agents into the polymer matrix. This phase transition creates a semi-solid gel structure that retains the electrochemical stability benefits of liquid electrolytes while introducing the thermal stability and safety advantages of solid-like structures, effectively eliminating combustion risks associated with liquid electrolytes.
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 proposed gel polymer electrolyte composition effectively stabilizes anions, reducing side reactions and solvent decomposition, resulting in improved high-temperature stability and overall battery performance, including reduced resistance and maintained capacity over time.
Implementation Method 1
a composition for a gel polymer electrolyte including: an oligomer represented by Formula 1; an anion stabilizing additive; a polymerization initiator; a lithium salt; and a non-aqueous solvent
Implementation Method 2
the salt may undergo a chemical reaction to generate anions of the salt... the anion stabilizing additive includes at least one selected from the group consisting of a phosphite-based compound represented by Formula 2 and a boron-based compound represented by Formula 3
Data Source
AI summary
The present invention relates to a composition for a gel polymer electrolyte, which includes an oligomer represented by Formula 1, an anion stabilizing additive, a polymerization initiator, a lithium salt, and a non-aqueous solvent, wherein the anion stabilizing additive includes at least one selected from the group consisting of a phosphite-based compound represented by Formula 2 and a boron-based compound represented by Formula 3, and a gel polymer electrolyte and a lithium secondary battery which are prepared by using the same.