Non-Aqueous Electrolyte Additive for High-Temperature Li-Ion Storage
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Solution Overview
Problem
Lithium ion batteries face performance degradation due to the decomposition of lithium salts at high temperatures, leading to increased resistance and reduced capacity, primarily caused by the deterioration of the electrolyte solution and the formation of decomposition products like HF and PF5, which affect the passivation ability of the solid electrolyte interphase (SEI).
Innovation Solution
Incorporating a Lewis base compound as an additive in the non-aqueous electrolyte solution, represented by a specific formula, which scavenges decomposition products such as HF and PF5, thereby maintaining the passivation ability of the SEI and improving high-temperature storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 lithium salt is used in the electrolyte solution, then good electrochemical properties are achieved, but decomposition products (HF, PF5) are generated at high temperatures that deteriorate the SEI film and cause self-discharge
Solution Approach 1:
A Lewis base compound is introduced as an intermediary substance that selectively reacts with and removes decomposition products (HF, PF5) generated from LiPF6. The Lewis base acts as a mediator between the harmful decomposition products and the SEI film, preventing direct damage to the film while maintaining the electrochemical benefits of LiPF6.
Solution Approach 2:
The harmful decomposition products (HF, PF5) are converted into beneficial effects by having them react with the Lewis base compound to form harmless complexes. This transforms the harmful acid generation into a useful scavenging mechanism that protects the SEI film while maintaining electrolyte functionality.
2Temperature
If high-temperature storage is performed, then battery capacity is reduced due to electrolyte decomposition and SEI deterioration, but adding more lithium salt increases decomposition products that worsen the problem
Solution Approach 1:
The Lewis base compound serves as a protective intermediary that remains stable at high temperatures while actively scavenging decomposition products. This allows the battery to undergo high-temperature storage without the usual capacity loss, as the Lewis base neutralizes harmful effects in real-time.
Solution Approach 2:
The addition of the Lewis base compound changes the chemical parameters of the electrolyte system, introducing a new component that alters the decomposition pathway and product distribution. This parameter change enables the system to maintain capacity stability under high-temperature conditions that would normally cause degradation.
3Reliability
If the SEI film passivation ability is insufficient, then additional electrolyte decomposition occurs causing self-discharge, but strengthening the film requires more additive that increases complexity
Solution Approach 1:
The Lewis base compound acts as a secondary intermediary that works in conjunction with the SEI film-forming additives. While the primary additives create the film, the Lewis base provides ongoing protection by scavenging acids that would otherwise degrade the film, achieving enhanced passivation without excessive additive loading.
Solution Approach 2:
The Lewis base compound provides continuous protection throughout the battery's operation and storage, continuously scavenging decomposition products as they form. This ongoing action maintains SEI integrity over time without requiring periodic intervention or complex multi-component systems.
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 Lewis base compound effectively alleviates self-discharge and reduces the degradation of the SEI, resulting in improved high-temperature storage performance and extended battery life by preventing additional decomposition reactions and metal dissolution at the electrodes.
Implementation Method 1
In order to suppress the damage and maintain the passivation ability of the SEI at high temperatures, there is proposed a method which may introduce an electrolyte solution additive containing a functional group that may be reduction-decomposed well in the electrolyte solution, or may remove factors that may affect the passivation ability, for example, decomposition products (HF, PF 5 , etc.) of the lithium salt generated due to heat or moisture.
Data Source
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AI summary
The present invention relates to a non-aqueous electrolyte solution fora lithium secondary battery, which includes a compound having an excellent effect of removing a decomposition product generated from a lithium salt in the electrolyte solution as an additive, and a lithium secondary battery in which high-temperature storage characteristics are improved by alleviating self-discharge by including the non-aqueous electrolyte solution for a lithium secondary battery.