Mixed Additive Electrolyte for Lithium Battery High-Temperature Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face issues with high-temperature durability and stability due to the collapse of the solid electrolyte interface (SEI) film, leading to battery swelling, deformation, and potential fires or explosions, which existing solutions fail to adequately address while also reducing overall battery performance.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries is developed, incorporating a mixed additive of lithium difluorophosphate, tertiary alkylbenzene, and tetra-vinyl silane in specific weight ratios, along with additional SEI-forming additives, to reduce interfacial resistance and suppress side reactions, thereby enhancing high-temperature storage and life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an SEI forming material is added to prevent SEI film collapse, then high-temperature stability is improved, but overall battery performance is reduced due to side effects
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific mixed additive system comprising lithium difluorophosphate (0.5-2 wt%), tertiary alkylbenzene (1-5 wt%), and tetra-vinyl silane (0.1-0.5 wt%). This parameter modification enables the formation of a stable SEI film that prevents collapse at high temperatures while maintaining good battery performance through synergistic effects of the additive mixture.
Solution Approach 2:
The patent uses a composite additive system combining three different chemical compounds (lithium difluorophosphate, tertiary alkylbenzene, and tetra-vinyl silane) in specific ratios. This composite approach creates a synergistic effect where each component contributes different functions: lithium difluorophosphate forms the SEI film, tertiary alkylbenzene stabilizes it, and tetra-vinyl silane reduces resistance, collectively solving the contradiction between stability and performance.
2Quantity of substance
If organic solvent is stored at high temperature for long period, then battery energy density is maintained, but gas is generated causing battery swelling and deformation
Solution Approach 1:
The patent converts the harmful oxidation reaction of organic solvent at high temperature into a beneficial process by introducing tertiary alkylbenzene as a sacrificial additive. This compound preferentially reacts with oxygen and free radicals generated during storage, converting harmful oxidation that causes gas formation into a controlled reaction that forms a protective film, thereby preventing battery swelling while maintaining energy density.
Solution Approach 2:
The patent introduces tertiary alkylbenzene as an intermediary substance that mediates between the organic solvent and oxygen during high-temperature storage. This intermediary compound reacts with oxygen and free radicals before they can attack the main electrolyte components, preventing gas generation and battery deformation while preserving the energy-storing capability of the electrolyte system.
3Reliability
If SEI film is collapsed during high-temperature storage, then ion conductivity is improved, but negative electrode is exposed causing side reactions and safety issues
Solution Approach 1:
The patent applies preliminary action by forming a stable, protective SEI film during initial charging cycles using the mixed additive system before high-temperature storage begins. The tertiary alkylbenzene and tetra-vinyl silane components prepare a pre-stabilized SEI structure that resists collapse during subsequent high-temperature storage, preventing negative electrode exposure and associated side reactions while maintaining appropriate ion conductivity.
Solution Approach 2:
The patent provides beforehand cushioning by creating a robust SEI film structure during initial charging that acts as a protective buffer during high-temperature storage. The mixed additives, particularly tertiary alkylbenzene and tetra-vinyl silane, form a cushioning layer that prevents complete SEI collapse, thereby cushioning against the harmful effects of electrode exposure and side reactions while allowing sufficient ion transport.
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 forms a stable SEI film, reducing interfacial resistance and side reactions, which improves the battery's high-temperature storage and life characteristics, maintaining capacity and suppressing resistance and thickness changes, thus preventing fires or explosions.
Implementation Method 1
a non-aqueous electrolyte solution for a lithium secondary battery including an ionizable lithium salt, an organic solvent, and an additive, wherein the additive is a mixed additive which includes lithium difluorophosphate (LiDFP), tertiary alkylbenzene represented by Formula 1, and tetra-vinyl silane (TVS)
Implementation Method 2
The SEI film formed at an initial stage of charging may prevent a reaction of the lithium ions with the carbon negative electrode or other materials during charge and discharge
Implementation Method 3
The SEI film formed at an initial stage of charging may prevent a reaction of the lithium ions with the carbon negative electrode or other materials during charge and discharge, and may act as an ion tunnel that only passes the lithium ions between an electrolyte solution and the negative electrode
Implementation Method 4
an additive which may reduce interfacial resistance of a surface of an electrode and may simultaneously suppress an electrolyte solution side reaction during high-temperature storage
Implementation Method 5
gas is generated while the organic solvent is oxidized by a transition metal oxide discharged from the positive electrode
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same, and particularly, to a non-aqueous electrolyte solution for a lithium secondary battery which includes an ionizable lithium salt, an organic solvent, and an additive, wherein the additive is a mixed additive which includes lithium difluorophosphate, tertiary alkylbenzene, and tetra-vinyl silane in a weight ratio of 1:1 to 4:0.05 to 0.5, and the additive is included in an amount of 2.5 wt% to 4.5 wt% based on a total weight of the non-aqueous electrolyte solution for a lithium secondary battery, and a lithium secondary battery including the same.