Coumarin Electrolyte Additive for Li-Ion Gas and Decomposition Control
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Solution Overview
Problem
Lithium-ion batteries face degradation and capacity loss due to side reactions involving reactive oxygen compounds and Lewis acids, leading to gas generation, electrolyte decomposition, and increased resistance, especially under high-temperature and high-voltage conditions.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries incorporating a coumarin derivative with a trialkylsilyl or trialkylsilyl ether group is used, which scavenges reactive species and forms a stable film on electrodes, preventing continuous decomposition and improving high-rate charge and discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium-ion battery uses a high-voltage positive electrode to increase energy density, then the energy storage capacity is improved, but reactive oxygen compounds are formed that decompose the carbonate-based solvent and intensify gas generation
Solution Approach 1:
The patent introduces a coumarin derivative compound as an intermediary substance between the high-voltage positive electrode and the carbonate-based solvent. This compound preferentially reacts with reactive oxygen compounds generated at high voltage to form stable products, preventing these reactive species from attacking and decomposing the main electrolyte solvent. The coumarin derivative acts as a sacrificial mediator that protects the bulk electrolyte from decomposition while enabling high-voltage operation.
2Productivity
If the battery operates in a high-temperature environment to improve reaction kinetics, then the charge and discharge rate is improved, but electrolyte decomposition is intensified and battery performance degrades
Solution Approach 1:
The patent applies preliminary action by having the coumarin derivative compound react with harmful species (reactive oxygen compounds and Lewis acids) before these species can cause significant damage to the electrolyte and electrode interfaces during high-temperature operation. The additive proactively neutralizes decomposition products as they form, preventing the cumulative degradation that would otherwise occur during high-temperature charging and discharging cycles.
3Reliability
If lithium salt is used as electrolyte to provide ionic conductivity, then the electrical conductivity is improved, but the lithium salt reacts with moisture to generate Lewis acid that erodes the passivation film and causes dissolution of transition metal ions
Solution Approach 1:
The patent converts the harmful effect of Lewis acid generation into a beneficial process by using the coumarin derivative to selectively react with and neutralize the Lewis acids. The harmful Lewis acid byproduct of lithium salt hydrolysis is transformed into a useful function: the coumarin compound acts as a Lewis base that binds to and deactivates the Lewis acid, preventing it from attacking the passivation film and dissolving transition metal ions, while the main electrolyte function remains intact.
4Reliability
If conventional electrolyte additives are used to form protective films, then some protection is provided, but they cannot simultaneously scavenge highly reactive Lewis acids and maintain stable films under high-voltage conditions
Solution Approach 1:
The patent achieves multi-functionality by designing a coumarin derivative compound that simultaneously performs multiple protective functions: (1) it acts as a film-forming additive to create stable passivation layers on electrodes, (2) it serves as a Lewis base to scavenge Lewis acids generated from lithium salt hydrolysis, and (3) it functions as an antioxidant to neutralize reactive oxygen compounds produced at high-voltage positive electrodes. This single compound addresses multiple degradation pathways that conventional single-function additives cannot handle.
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 effectively suppresses electrolyte decomposition, enhances battery stability, and improves high-rate charge and discharge performance by scavenging Lewis acids and reactive oxygen species, thereby maintaining capacity retention and reducing resistance.
Implementation Method 1
it reacts with moisture present in the cell to generate a Lewis acid such as HF. This Lewis acid erodes a passivation film formed at an electrode-electrolyte interface
Implementation Method 2
a reactive oxygen compound is formed above a certain voltage, wherein this reactive oxygen compound causes decomposition of a carbonate-based solvent
Implementation Method 3
there is a need to develop a novel electrolyte capable of forming a stable film on the surface of the electrode
Implementation Method 4
energy is stored through a redox reaction of transition metal
Implementation Method 5
an electrolyte solution that includes an organic solvent and a lithium salt
Implementation Method 6
energy is stored through a redox reaction of transition metal
Data Source
AI summary
A non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same are described herein. The non-aqueous electrolyte solution for a lithium secondary battery of the present disclosure may include a lithium salt, an organic solvent, and a compound represented by Formula 1 as an additive,wherein R1 to R6 are described herein.