Non-Aqueous Electrolyte Additive for Stable LiPF6 Battery SEI

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Solution Overview

Problem

Lithium ion batteries face issues with high-temperature stability and cycle life due to the thermal decomposition of lithium salts like LiPF6, which generates Lewis acids that degrade the solid electrolyte interphase (SEI) film, leading to increased resistance and reduced lifespan.

Innovation Solution

A non-aqueous electrolyte solution for lithium secondary batteries containing a Lewis base-based compound with a propargyl group and two nitrogen elements, which scavenges decomposition products and forms a stable film on electrodes, enhancing SEI and suppressing metal elution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If LiPF6 is used as lithium salt to achieve high energy density, then battery energy density is improved, but thermal decomposition occurs at high temperature generating Lewis acids that degrade SEI film and increase resistance

Engineering Contradiction:

Improveenergy densityVSAvoidhigh-temperature stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A Lewis base compound (Formula 1) is introduced as an intermediary substance between the lithium salt and the SEI film. This compound scavenges Lewis acids (PF5, HF) generated from LiPF6 decomposition, preventing direct attack on the SEI film while maintaining ionic conductivity. The compound acts as a buffer that mediates the harmful interaction between decomposition products and electrode interfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful thermal decomposition of LiPF6 into a beneficial process by having the Lewis base compound react with decomposition products to form stable complexes. The Lewis acid decomposition products, which would normally degrade the SEI film, are instead captured by the Lewis base compound to form protective films that enhance high-temperature stability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If LiPF6 is used as lithium salt, then ionic conductivity is improved, but SEI film deteriorates due to Lewis acid generation causing increased resistance

Engineering Contradiction:

Improveionic conductivityVSAvoidSEI film deterioration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The Lewis base compound serves as a protective intermediary that intercepts Lewis acids before they can damage the SEI film. It forms a protective barrier layer that maintains ionic conductivity while blocking harmful chemical reactions between PF5/HF and the electrode interface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The Lewis base compound performs preliminary neutralization of Lewis acids generated from lithium salt decomposition. By reacting with PF5 and HF in advance, it prevents subsequent harmful reactions with the SEI film, thereby maintaining film integrity and low resistance over time.

Inventive Principle:

Principle #9Preliminary anti-action

3Quantity of substance

If transition metal ions are eluted from positive electrode, then capacity is improved, but resistance increases due to re-deposition on electrode surfaces

Engineering Contradiction:

Improvelithium ion capacityVSAvoidelectrode resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The Lewis base compound acts as an intermediary that captures transition metal ions eluted from the positive electrode, preventing their re-deposition on electrode surfaces. It forms stable complexes with metal ions in the electrolyte, keeping them in solution and preventing resistance-increasing precipitation on the electrode interfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 improves high-temperature durability by preventing film deterioration and metal elution, thereby maintaining low resistance and extending the battery's cycle life.

Implementation Method 1

the LiPF6 is thermally decomposed and generates a Lewis acid such as PF5... the electrolyte solution additive having an excellent effect of scavenging decomposition products generated from a lithium salt

Methodology Applied

Scientific EffectLewis base-Lewis acid reaction:

Implementation Method 2

improving the passivation capability of an SEI film... implementing an effect of enhancing an SEI... form a stable film on the surface of each of positive and negative electrodes

Methodology Applied

Scientific EffectFilm formation:

Data Source

PatentUS12401063B2Lithium secondary battery

Publication Date: 2025.08.26 LG ENERGY SOLUTION LTD

AI summary

A non-aqueous electrolyte solution for a lithium secondary battery, and a lithium secondary battery including the same are disclosed herein. In some embodiments, the non-aqueous electrolyte solution for a lithium secondary battery includes a lithium salt, an organic solvent, and a compound represented by the following Formula 1, and has an excellent effect of scavenging decomposition products generated from the lithium salt, and thus, may improve overall performance of the battery:wherein in Formula 1,A is a C1 to C5 alkyl group.