Lithium-Ion Battery Electrolyte Composition to Reduce HF Erosion
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in improving characteristics such as structural durability and sealability, particularly due to the use of LiPF6, which can lead to hydrogen fluoride generation and erosion of electrodes and containers, reducing battery durability.
Innovation Solution
The use of a cyclic alkylene carbonate and methyl propionate combination as a nonaqueous solvent in the electrolytic solution, with lithium salt other than LiPF6 making up at least 30 mol% of the total lithium salt, enhances the battery's characteristics by improving ionic conductivity and reducing viscosity, thus inhibiting reduction in sealability and structural durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as the lithium salt in the electrolytic solution, then the ionic conductivity is improved, but hydrogen fluoride is generated which erodes electrodes and containers, reducing structural durability and sealability
Solution Approach 1:
The patent removes LiPF6 from the electrolytic solution composition entirely, extracting the harmful substance that generates hydrogen fluoride. This eliminates the source of erosion while maintaining battery functionality through alternative lithium salts that do not produce HF as a byproduct.
Solution Approach 2:
The patent converts the harmful chemical behavior of LiPF6 by replacing it with lithium salts that offer superior stability. The alternative salts provide the necessary ionic conductivity without the harmful side effect of hydrogen fluoride generation, effectively turning the lesson from the harmful substance into a benefit through informed material selection.
2Reliability
If LiPF6 is used as the lithium salt, then the electrolytic solution has good ionic conductivity, but the sealability and structural durability are reduced due to erosion
Solution Approach 1:
The patent extracts LiPF6 from the electrolytic solution to eliminate the erosion mechanism. By removing this specific lithium salt, the harmful interaction with electrodes and containers that compromises sealability is eliminated, while alternative salts maintain the necessary electrical properties.
3Productivity
If conventional electrolytic solution composition is used, then the battery has basic functionality, but the charge/discharge performance and capacity retention are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by replacing LiPF6 with alternative lithium salts and adjusting the solvent mixture ratios. These parameter changes optimize both the charge/discharge performance and capacity retention by selecting materials with superior electrochemical stability and ion transport properties.
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 electrolytic solution significantly improves the lithium ion secondary battery's characteristics, including structural durability and sealability, by reducing hydrogen fluoride generation and enhancing ionic conductivity, leading to better charge/discharge performance and capacity retention.
Implementation Method 1
enhances the battery's characteristics by improving ionic conductivity
Implementation Method 2
reducing viscosity, thus inhibiting reduction in sealability and structural durability
Data Source
AI summary
Provided is an electrolytic solution that includes: an electrolyte containing lithium salt; and a nonaqueous solvent containing cyclic alkylene carbonate and methyl propionate, the electrolyte contains lithium salt other than LiPF6 in an amount of not less than 30 mol % with respect to a total amount of the lithium salt, and the nonaqueous solvent contains 75 volume % or more of the methyl propionate.