Lithium Battery Electrolyte with Fluoride Salt Additive
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Solution Overview
Problem
The reactivity of Li ions is lowered due to the formation of stable complexes with glyme in lithium batteries, making it difficult for Li ions to react with electrode active materials, which affects the charge-discharge properties.
Innovation Solution
A liquid electrolyte comprising a glyme, a Li amide salt with a sulfonylamide anion, and a fluoride salt (XF where X represents Li, Na, K, Rb, or Cs) is used, which suppresses the lowering of reactivity between Li ions and electrode active materials by interacting with the glyme complex, improving charge-discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glyme is used as a solvent in the liquid electrolyte, then thermal stability and chemical stability are improved, but the reactivity of Li ions with electrode active material is lowered due to stable complex formation
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a fluoride salt (LiF, NaF, KF, RbF, or CsF) at a specific concentration range (0.1-5.0 mol/L). This parameter change modifies the solvation structure around Li ions, reducing the stability of glyme-Li ion complexes and enhancing Li ion reactivity with electrode materials while preserving the thermal and chemical stability benefits of glyme.
Solution Approach 2:
The patent creates a composite electrolyte system combining three components: glyme (as solvent), Li amide salt (as electrolyte salt), and fluoride salt (as additive). This composite approach allows the fluoride salt to interact with the glyme-Li ion complex, disrupting its stability and improving Li ion reactivity while maintaining the overall thermal and chemical stability provided by the glyme-based system.
2Reliability
If a glyme forms a stable complex with Li salt, then thermal stability is improved, but charge-discharge speed is reduced due to lowered Li ion reactivity
Solution Approach 1:
The patent modifies the electrolyte composition by adding fluoride salt at optimized concentrations (0.1-5.0 mol/L), which changes the solvation dynamics and reduces the stability of Li ion-glyme complexes. This parameter adjustment enables faster Li ion transport and reaction kinetics at electrodes, improving charge-discharge speed while preserving thermal stability through the glyme solvent system.
Solution Approach 2:
The fluoride salt acts as an intermediary substance that interacts with the glyme-Li ion complex, modifying its structure and reducing its stability. This intermediary effect facilitates faster Li ion release from the solvation shell and enhances reaction speed with electrode materials, while the glyme solvent continues to provide thermal stability.
3Reliability
If the reactivity of Li ions is lowered by glyme complexation, then chemical stability is improved, but rate characteristics of the battery are worsened
Solution Approach 1:
The patent adjusts the chemical composition parameters by incorporating fluoride salt at specific concentrations (0.1-5.0 mol/L) in the glyme-based electrolyte. This parameter modification reduces the stability of Li ion-glyme complexes, enhancing Li ion reactivity and improving rate characteristics (charge-discharge performance) while the glyme solvent maintains chemical stability.
Solution Approach 2:
The patent develops a composite electrolyte formulation combining glyme (for chemical stability), Li amide salt (for ionic conductivity), and fluoride salt (for enhancing Li ion reactivity). This composite material approach allows simultaneous achievement of chemical stability and improved rate characteristics through the synergistic interaction of components.
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 addition of a fluoride salt to the glyme and Li amide salt enhances the reaction resistance and charge-discharge speed of lithium batteries, allowing for faster charging and discharging with improved rate characteristics.
Implementation Method 1
a glyme having a chain structure is coordinated so as to surround (wrap) Li ions, thereby forming a stable complex
Implementation Method 2
a liquid electrolyte in which at least a part of a glyme and a Li salt forms a complex
Data Source
Figure 1~2D
Figure 3A~3C
Figure 4A~4B
AI summary
An object of the present invention is to provide a liquid electrolyte for a lithium battery in which lowering of reactivity of a Li ion and an electrode active material due to a glyme is suppressed. In the present invention, the above object is achieved by providing a liquid electrolyte for a lithium battery comprising: a glyme represented by general formula: R1-O(CH2CH2O)n-R2 (in which R1 and R2 each independently represent an alkyl group with 4 or less carbon atoms or a fluoroalkyl group with 4 or less carbon atoms, and n is in the range of 2 to 10); a Li amide salt having a Li ion and a sulfonylamide anion; and a fluoride salt represented by XF (in which X represents Li, Na, K, Rb, or Cs).