Propargyl Lewis Base Additive for Lithium-Ion Battery SEI Stability
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Solution Overview
Problem
Lithium-ion batteries suffer from low-voltage failure due to reduced passivation ability of the solid electrolyte interphase (SEI), metallic impurities, and dissolution of transition metals, leading to self-discharge and internal short-circuits.
Innovation Solution
A non-aqueous electrolyte solution additive containing compounds with a Lewis base functional group, such as those represented by Formulae 1 and 2, which include a nitrogen element and a propargyl group, is used to improve adhesion to metal impurities, suppress decomposition products, and form a stable SEI, thereby reducing transition metal dissolution and enhancing passivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a graphite-based negative electrode is used, then high energy density is achieved, but the SEI film has insufficient passivation ability causing electrolyte decomposition and self-discharge
Solution Approach 1:
The patent introduces a mediating substance (additive) into the electrolyte that acts as an intermediary between the graphite negative electrode and the electrolyte. This additive preferentially reacts with the electrolyte to form a stable SEI film with sufficient passivation ability, preventing direct harmful interactions while maintaining the high energy density benefits of graphite electrodes.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding specific compounds (such as lithium oxalate nonafluorobutanesulfonate) to change the properties of the formed SEI film. This parameter change transforms the SEI film from having insufficient passivation ability to having adequate protective properties, thereby reducing self-discharge while preserving high energy density.
2Reliability
If metal powder is contained during electrode preparation, then conductivity is improved, but metal impurities cause dendrite formation and internal short-circuits
Solution Approach 1:
The additive serves as an intermediary that preferentially interacts with metal impurities in the electrolyte, forming stable complexes or adsorbing them at the electrode interface. This prevents metal ions from participating in dendrite-forming electrodeposition reactions while maintaining the conductive network provided by metal powder in the electrode structure.
Solution Approach 2:
The patent converts the harmful effect of metal impurities into a beneficial outcome by using the additive to selectively bind or passivate metal ions. The metal impurities that would otherwise cause dendrites are transformed into stable complexes that remain in the electrolyte without causing harm, while the original conductive function of intentionally added metal powder is preserved.
3Productivity
If transition metals are dissolved in the electrolyte, then charge-discharge cycling occurs, but transition metal ions electrodeposit on electrodes causing increased resistance and self-discharge
Solution Approach 1:
The additive acts as a mediating agent that competes with electrode surfaces for transition metal ions in the electrolyte. It forms stable soluble complexes with transition metals, preventing their electrodeposition on electrodes. This intermediary action allows charge-discharge cycling to proceed while blocking the harmful pathway of metal ion deposition that would increase resistance and cause self-discharge.
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 stabilizes the SEI, prevents self-discharge, and reduces internal short-circuits, leading to improved low-voltage performance and high-temperature durability of lithium-ion batteries.
Implementation Method 1
it may not only strengthen the SEI as film of a negative electrode, but may also suppress the dissolution of metal by being adsorbed on a metal foreign matter. Particularly, with respect to the non-aqueous electrolyte solution additive of the present invention, since it has a functional group containing a nitrogen element which is a Lewis base functional group, it may remove a decomposition product, such as HF or PF5, which is formed due to the decomposition of a lithium salt.
Implementation Method 2
since a Lewis base compound including a nitrogen element and a propargyl group is used as a non-aqueous electrolyte solution additive to improve a low-voltage phenomenon of a lithium-ion battery, a Lewis acid formed due to anion decomposition of a lithium salt may be removed and a more stable solid electrolyte interphase (SEI) may be formed on surfaces of a negative electrode and a positive electrode
Implementation Method 3
it may not only strengthen the SEI as film of a negative electrode, but may also suppress the dissolution of metal by being adsorbed on a metal foreign matter.
Implementation Method 4
a Lewis acid formed due to anion decomposition of a lithium salt may be removed
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte solution additive, and a non-aqueous electrolyte solution for a lithium-ion battery and a lithium-ion battery which include the same, and particularly, to a non-aqueous electrolyte solution, which may remove an acid generated by the decomposition of a lithium salt while being able to suppress the dissolution of metal impurities causing failure in the battery by using and including a Lewis base compound containing a propargyl group as a non-aqueous electrolyte solution additive for a lithium-ion battery, and a lithium secondary battery in which transition metal dissolution in a positive electrode and a low-voltage phenomenon are improved.