Imidazoline Electrolyte Additive for High-Temperature Li-Ion Stability
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Solution Overview
Problem
Lithium-ion batteries face degradation issues due to the thermal decomposition of lithium salts like LiPF6, leading to the formation of Lewis acids that degrade the solid electrolyte interphase (SEI), increase resistance, and reduce the battery's lifetime and capacity, particularly at high temperatures.
Innovation Solution
An electrolyte solution additive comprising a compound represented by Formula 1, which includes a nitrogen atom acting as a Lewis base and a propargyl group, forms a stable film on the electrode surfaces to scavenge decomposition products and suppress transition metal dissolution, improving high-temperature stability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the battery operates at high temperatures, then power generation and power storage functions are maintained, but decomposition reactions increase causing SEI degradation and resistance increase
Solution Approach 1:
The patent applies preliminary anti-action by introducing the nitrogen-containing compound before high-temperature operation occurs. This compound proactively scavenges Lewis acids as soon as they form during thermal decomposition of LiPF6, preventing the cascade of harmful decomposition reactions that would otherwise degrade the SEI and increase resistance. The preliminary protective action enables the battery to maintain productivity at high temperatures without suffering from decomposition-related degradation.
2Ease of operation
If transition metal ions dissolve from the positive electrode, then ion transfer occurs, but the ions are re-deposited causing resistance increase and positive electrode degradation
Solution Approach 1:
The nitrogen-containing compound acts as an intermediary that modifies the electrode-electrolyte interface environment. By scavenging Lewis acids, it prevents the catalytic effect that would otherwise promote transition metal dissolution and re-deposition cycles. This intermediary protection maintains ease of ion transfer while simultaneously improving electrode stability and reducing resistance increase over cycling.
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 additive effectively forms a robust passivation film on electrodes, reducing degradation and enhancing the lithium secondary battery's high-temperature durability and cycle performance by scavenging Lewis acids and preventing transition metal dissolution.
Implementation Method 1
the nitrogen atom of the cationic moiety capable of acting as a Lewis base... it may effectively scavenge a Lewis acid generated as the decomposition product of the lithium salt
Implementation Method 2
forming a robust passivation film on the surface of the positive electrode and negative electrode... forms a stable film on the surface of the positive electrode or negative electrode
Data Source
AI summary
An electrolyte solution additive for a lithium secondary battery, a non-aqueous electrolyte solution for a lithium secondary battery comprising the same, and a lithium secondary battery are described. Specifically, the electrolyte solution additive for a lithium secondary battery may comprise a compound represented by Formula 1,wherein in Formula 1,R1 to R3, L and n are described herein.