Lithium Battery Electrolyte Additive for Stable High-Temperature Cycling

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Solution Overview

Problem

Lithium ion batteries suffer from degradation in high-temperature stability and cycle performance due to the thermal decomposition of lithium salts, which generates Lewis acids that deteriorate the solid electrolyte interphase (SEI) film and increase electrode resistance, leading to reduced capacity and 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 the electrodes, preventing film deterioration and transition 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 capacity is improved, but thermal stability deteriorates at high temperature causing decomposition and Lewis acid generation

Engineering Contradiction:

Improvebattery energy densityVSAvoidhigh-temperature stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a sultone compound as an intermediary substance that mediates between the lithium salt and the electrolyte solvent. This compound forms a protective interface layer that prevents direct interaction between LiPF6 and the solvent, thereby suppressing decomposition reactions while maintaining the high energy density benefits of LiPF6.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sultone compound performs preliminary action by forming a stable protective film on the electrode surfaces before thermal decomposition can occur. This pre-formed protective layer acts as a barrier that prevents Lewis acid generation and subsequent harmful reactions, enabling the battery to maintain stability at high temperatures.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If LiPF6 is used as lithium salt to achieve high energy density, then battery capacity is improved, but SEI film stability deteriorates due to Lewis acid attack

Engineering Contradiction:

Improvebattery energy densityVSAvoidSEI film stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The sultone compound serves as a protective intermediary that forms a stable interface between the electrolyte and electrode. This intermediary layer prevents Lewis acids generated from LiPF6 decomposition from attacking the SEI film, thereby maintaining SEI stability while allowing LiPF6 to function for high energy density.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sultone compound provides beforehand cushioning by forming a protective buffer layer that absorbs and neutralizes Lewis acids before they can damage the SEI film. This protective mechanism ensures SEI film stability is maintained even when LiPF6 decomposes at elevated temperatures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Use of energy by moving object

If LiPF6 is used as lithium salt to achieve high energy density, then battery capacity is improved, but electrode resistance increases due to transition metal elution

Engineering Contradiction:

Improvebattery energy densityVSAvoidelectrode resistance

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The sultone compound acts as a protective intermediary that forms a stable interface layer preventing transition metal elution from the electrode. This intermediary barrier maintains low electrode resistance while allowing the battery to utilize LiPF6 for high energy density performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The sultone compound performs preliminary protective action by forming a stable interface film before transition metal elution can occur. This pre-formed protective layer prevents metal ion migration and resistance increase, enabling sustained high-performance operation.

Inventive Principle:

Principle #10Preliminary action

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 enhances high-temperature durability by stabilizing the SEI film, suppressing resistance increase, and improving cycle performance and capacity retention.

Implementation Method 1

the LiPF6 is thermally decomposed and generates a Lewis acid such as PF5... includes a Lewis base-based compound... effectively scavenging by-products generated due to thermal decomposition of lithium salts

Methodology Applied

Scientific EffectLewis base-Lewis acid reaction: Chemical Bonding

Implementation Method 2

forming a stable film on the surface of each of positive and negative electrodes... implementing an effect of enhancing an SEI

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Data Source

PatentEP4246645B1Lithium secondary battery

Publication Date: 2026.03.25 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a lithium secondary battery. Particularly, the lithium secondary battery comprising: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; a separator interposed between the negative electrode and the positive electrode; and a non-aqueous electrolyte solution comprising a lithium salt; an organic solvent; and a compound represented by Formula 1, and thus, may improve overall performance of the battery.