Lithium Battery Electrolyte Composition for Low-Temperature Capacity Retention

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Solution Overview

Problem

Lithium-sulfur batteries face challenges with reduced charging/discharging efficiency and lifetime due to lithium polysulfide shuttling and increased resistance at low temperatures, affecting their stability and capacity.

Innovation Solution

An electrolyte solution comprising a glyme-based compound, conjugated heterocyclic compound, non-conjugated cyclic ether-based compound, and lithium salt, which forms a protective film on the lithium metal surface to reduce polysulfide leaching and lower resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolyte solutions are used in lithium-sulfur batteries, then the batteries can operate at normal temperatures, but the charging/discharging efficiency is reduced and lifetime is deteriorated due to lithium polysulfide shuttling and high resistance at low temperatures

Engineering Contradiction:

Improvebattery lifetimeVSAvoidcharging/discharging efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing a specific cyclic carboxylate compound (gamma-butyrolactone, gamma-valerolactone, or delta-valerolactone) with 4-7 membered rings containing oxygen or sulfur atoms. This parameter change in electrolyte composition resolves the contradiction by suppressing lithium polysulfide shuttling to improve lifetime while maintaining low-temperature charging/discharging efficiency through reduced resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining cyclic carboxylate compounds with other electrolyte components (cyclic carbonates, chain carbonates, chain carboxylates). This composite approach addresses the technical contradiction by leveraging the synergistic effects of different compounds: the cyclic carboxylate suppresses polysulfide shuttling for improved lifetime, while the composite formulation maintains low resistance for high charging/discharging efficiency

Inventive Principle:

Principle #40Composite materials

2Temperature

If the battery operates at low temperatures, then cold weather performance is improved, but resistance increases rapidly making it difficult to use

Engineering Contradiction:

Improveoperating temperature rangeVSAvoidresistance

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the electrolyte composition parameters by incorporating cyclic carboxylate compounds with specific molecular structures (4-7 membered rings). These structural parameters enable the electrolyte to maintain low resistance at low temperatures while preventing lithium polysulfide precipitation, thus resolving the contradiction between extended temperature range and resistance control

Inventive Principle:

Principle #35Parameter changes

3Reliability

If lithium polysulfide is allowed to shuttle freely in the electrolyte, then ionic conductivity is maintained, but capacity decreases due to irreversible loss of positive electrode active material

Engineering Contradiction:

Improvebattery lifetimeVSAvoidactive material capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent converts the harmful effect of lithium polysulfide shuttling into a beneficial outcome by using cyclic carboxylate compounds that selectively interact with polysulfides. The electrolyte composition is designed to suppress harmful polysulfide precipitation and shuttling while maintaining necessary ionic conductivity, thus transforming the problematic polysulfide behavior into a controlled process that preserves both lifetime and capacity

Inventive Principle:

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

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 electrolyte solution enhances the battery's ability to operate at low temperatures by stabilizing the lifetime and increasing discharging capacity, maintaining 90-97% capacity retention at 15 °C or less.

Implementation Method 1

forms a protective film on the lithium metal surface to reduce polysulfide leaching and lower resistance

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Implementation Method 2

capable of not only operating at a low temperature by lowering resistance

Methodology Applied

Scientific EffectElectrical resistance reduction: Electrical Resistance

Implementation Method 3

securing the stable lifetime characteristics of the battery

Methodology Applied

Scientific EffectChemical stability:

Data Source

PatentEP4044316B1Electrolyte for lithium secondary battery and lithium secondary battery comprising same

Publication Date: 2025.10.15 LG ENERGY SOLUTION LTD

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AI summary

Disclosed is an electrolyte solution for a lithium secondary battery, which is capable of not only operating at a low temperature by lowering resistance, but also securing the stable lifetime characteristics of the battery, and increasing the discharging capacity at a low temperature, and a lithium secondary battery comprising the same. The electrolyte solution for the lithium secondary battery comprises a first solvent comprising a glyme-based compound; a second solvent comprising a conjugated heterocyclic compound; a third solvent comprising a non-conjugated cyclic ether-based compound; and lithium salt.