Electrolytic Solution with Magnesium Fluoride for High-Rate Battery Performance
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Solution Overview
Problem
Lithium-ion secondary batteries face deteriorated initial capacity and capacity retention rates during high-rate charge and discharge, limiting their performance in electric vehicle applications.
Innovation Solution
An electrolytic solution comprising magnesium fluoride, lithium salt, a first solvent with a permittivity of less than 10, and a second solvent with a permittivity of more than 50, where the volume ratio of the second solvent to the total solvents is between 6% and 12%, and the magnesium fluoride content is between 0.3% and 1.0% by mass, forming a uniform solid electrolyte interface coating that enhances battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electrolytic solutions are used, then the battery can operate, but initial capacity and capacity retention rate during high-rate charge and discharge are deteriorated
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolytic solution by adding magnesium fluoride at 0.3-1.0 mass% and optimizing the solvent ratio (cyclic carbonate 6-12 vol%, chain carbonate 88-94 vol%). This parameter optimization resolves the contradiction by achieving both high initial capacity (4.35-4.65 mAh) and high capacity retention rate (85-95%) during high-rate charge and discharge operations.
Solution Approach 2:
The patent creates a composite electrolytic solution system combining magnesium fluoride additive with a dual-solvent system (cyclic carbonate + chain carbonate). This composite approach forms a uniform SEI coating film that simultaneously improves initial capacity and maintains high capacity retention during high-rate operations, resolving the performance contradiction.
2Productivity
If the electrolytic solution composition is optimized for high-rate performance, then capacity retention improves, but solution complexity increases
Solution Approach 1:
The patent applies local quality by introducing magnesium fluoride at a specific concentration range (0.3-1.0 mass%) that locally optimizes SEI film formation at the electrode interface. This localized optimization achieves high capacity retention (85-95%) without requiring complex overall solution formulation, maintaining relative simplicity while improving performance.
Solution Approach 2:
The patent optimizes specific parameters (magnesium fluoride content 0.3-1.0 mass%, cyclic carbonate 6-12 vol%, chain carbonate 88-94 vol%) to achieve high capacity retention during high-rate operations. By precisely controlling these parameters rather than complicating the overall composition, the patent resolves the contradiction between performance improvement and solution complexity.
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 improves initial capacity and capacity retention rates during high-rate charge and discharge, reducing resistance and maintaining high-rate battery performance.
Implementation Method 1
an SEI (solid electrolyte interface) coating film is formed on an interface between an electrode and an electrolytic solution during charge and discharge
Implementation Method 2
lithium hexafluorophosphate (LiPF6) dissolved in a mixed solvent including ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC)
Implementation Method 3
oxidation-reduction potential of lithium is low, but continuous decomposition of the electrolytic solution can be suppressed
Data Source
AI summary
There is provided an electrolytic solution including magnesium fluoride, lithium salt, a first solvent, and a second solvent, the first solvent having a dielectric constant of less than 10, and the second solvent having a dielectric constant of more than 50.