Non-aqueous Electrolyte for Lithium Battery SEI Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges in improving high-temperature cycle characteristics, output characteristics after high-temperature storage, and low-temperature output characteristics due to non-uniform solid electrolyte interface (SEI) formation and decomposition issues, especially when using electrolyte solutions with poor additives or incorrect additive amounts.
Innovation Solution
A non-aqueous electrolyte solution comprising lithium bis(fluorosulfonyl)imide, a lithium salt (such as LiPF6), a vinylene carbonate-based compound, a sultone-based compound, ethylene sulfate, and lithium oxalyldifluoroborate, with specific molar ratios and concentrations to form a robust SEI, preventing cathode decomposition and enhancing ion tunneling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrolyte solution additives are used to improve low-temperature output characteristics, then low-temperature output is improved, but cathode decomposition occurs during high-temperature reaction
Solution Approach 1:
The patent adjusts the concentration parameters of electrolyte additives (VC at 0.5-5 wt%, PS at 0.1-5 wt%, and LiFSI at 0.1-2 mol/L) to optimize SEI formation. By precisely controlling these parameter ranges, the electrolyte forms a robust SEI that improves low-temperature output while preventing cathode decomposition at high temperatures, resolving the contradiction between low-temperature performance and high-temperature stability
Solution Approach 2:
The patent uses a composite electrolyte system combining multiple components: vinylene carbonate (VC), propane sultone (PS), and lithium bis(fluorosulfonyl)imide (LiFSI) together with conventional lithium salts like LiPF6. This composite electrolyte formulation creates a synergistic effect where the combination of additives forms a more robust and uniform SEI than individual additives alone, simultaneously improving low-temperature output characteristics and preventing high-temperature cathode decomposition
2Reliability
If electrolyte solution additive amount is increased to improve SEI formation, then SEI robustness improves, but oxidation reaction of electrolyte solution increases
Solution Approach 1:
The patent optimizes the concentration parameters of electrolyte additives to achieve the right balance. Specifically, VC is controlled at 0.5-5 wt%, PS at 0.1-5 wt%, and LiFSI at 0.1-2 mol/L. These parameter ranges are carefully selected to form sufficient SEI coverage for robustness while avoiding excessive additive concentrations that would trigger oxidation reactions, thus resolving the contradiction between SEI robustness and electrolyte stability
3Ease of operation
If conventional electrolyte additives are used, then low-temperature output may be improved, but high-temperature cycle characteristics deteriorate
Solution Approach 1:
The patent employs a composite electrolyte system combining VC, PS, and LiFSI with conventional lithium salts. This composite formulation creates a synergistic effect where the combination of additives forms a more robust and uniform SEI than individual additives alone. The multi-component system simultaneously improves low-temperature output characteristics and provides excellent high-temperature cycle stability, resolving the contradiction between low-temperature performance and high-temperature durability
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 significantly improves high-temperature cycle characteristics, output characteristics after high-temperature storage, and low-temperature output characteristics by forming a robust SEI, reducing irreversible capacity and maintaining battery stability and performance across various temperature conditions.
Implementation Method 1
a film may be formed on the surface of the anode. The film is denoted as 'solid electrolyte interface (SEI)'
Implementation Method 2
the SEI formed at an initial stage of charging may prevent a reaction of the lithium ions with the carbon anode or other materials during the charge and discharge
Implementation Method 3
The SEI may only pass the lithium ions by acting as an ion tunnel
Implementation Method 4
a process of intercalating and deintercalating lithium ions from a lithium metal oxide cathode into and out of a graphite anode
Data Source
AI summary
Provided are a non-aqueous electrolyte solution which includes a lithium salt including lithium bis(fluorosulfonyl)imide (LiFSI) and an additive including a vinylene carbonate-based compound and a sultone-based compound, and a lithium secondary battery including the non-aqueous electrolyte solution. The lithium secondary battery including the non-aqueous electrolyte solution of the present invention may improve low-temperature output characteristics, high-temperature cycle characteristics, output characteristics after high-temperature storage, and capacity characteristics.