Non-Aqueous Electrolyte Composition for Low-Impedance Battery SEI
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Solution Overview
Problem
Existing non-aqueous electrolytes in secondary batteries suffer from poor thermal stability, high impedance, and reduced kinetic performance due to the decomposition of lithium hexafluorophosphate, leading to impaired safety and capacity retention.
Innovation Solution
A non-aqueous electrolyte containing specific concentrations of metal cations (Me n+< ) such as Ni 2+<, Co 2+<, Mn 2+<, Al 3+<, and Fe 2+< ) and difluoroxalate borate anions (DFOB -< ) within defined ranges, along with other anions, to form a stable SEI film and enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium hexafluorophosphate is used as the electrolyte salt, then the electrolyte can provide ionic conductivity, but it decomposes thermally leading to poor thermal stability and high impedance
Solution Approach 1:
The patent changes the chemical composition parameters by introducing metal cations (Me n+) and difluoroxalate borate anions (DFOB -) to replace lithium hexafluorophosphate. This parameter change transforms the electrolyte's thermal stability while maintaining ionic conductivity, directly resolving the decomposition issue of traditional lithium salts.
Solution Approach 2:
The patent creates a composite electrolyte system combining metal cations (Me n+), difluoroxalate borate anions (DFOB -), and conventional lithium salts. This composite approach leverages the thermal stability of metal cations while maintaining the ionic conductivity properties of lithium-based electrolytes, solving both thermal stability and conductivity requirements simultaneously.
2Reliability
If conventional electrolyte composition is used, then the battery can operate, but it exhibits high impedance and reduced kinetic performance
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating metal cations and difluoroxalate borate anions in specific ratios. This parameter optimization reduces interfacial impedance and improves charge transfer kinetics, directly enhancing kinetic performance while minimizing harmful impedance effects.
3Duration of action of stationary object
If the electrolyte contains metal cations and difluoroxalate borate anions in appropriate ratios, then a stable SEI film is formed improving cycling performance, but the electrolyte composition becomes more complex
Solution Approach 1:
The patent optimizes the concentration ratios of metal cations to difluoroxalate borate anions within specific ranges (0.01-10 mmol/L and 0.1-100 mmol/L respectively). This parameter optimization ensures effective SEI film formation and long cycling life while controlling composition complexity to practical manufacturing levels.
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 electrolyte achieves improved cycling, safety, and kinetic performance by reducing irreversible lithium consumption, increasing electronic conductivity, and forming a low-impedance SEI film, while maintaining high capacity retention and low volume swelling.
Implementation Method 1
forming a stable SEI film and enhance electrochemical performance
Implementation Method 2
the first cations do not deteriorate the electrochemical performance of the secondary battery
Implementation Method 3
containing a non-aqueous solvent and lithium ions, first cations, and first anions dissolved therein
Implementation Method 4
increasing electronic conductivity
Implementation Method 5
the synergistic effect of the first cations and first anions... enables the secondary battery to have good cycling performance
Data Source
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AI summary
This application provides a non-aqueous electrolyte and a preparation method thereof, and a secondary battery and an electric apparatus containing the same. The non-aqueous electrolyte contains a non-aqueous solvent and lithium ions, first cations, and first anions dissolved therein, where the first cation is a metal cation Men+ other than the lithium ion, n representing a chemical valence of the metal cation; the first anion is a difluoroxalate borate anion DFOB-; mass concentration of the first cations in the non-aqueous electrolyte is D1 ppm, and mass concentration of the first anions in the non-aqueous electrolyte is D2 ppm, both based on total mass of the non-aqueous electrolyte; and the non-aqueous electrolyte satisfies that D1 is 0.5 to 870 and that D1/D2 is 0.02 to 2. The non-aqueous electrolyte in this application enables the secondary battery to have good cycling performance, safety performance, and kinetic performance.