Lithium-Sulfur Battery Electrolyte for Shuttle Suppression

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Solution Overview

Problem

Lithium-sulfur batteries suffer from irreversible capacity loss due to the shuttle phenomenon, where lithium polysulfides are dissolved in the electrolyte and cause surface contamination of the negative electrode, leading to passivation and reduced lifespan.

Innovation Solution

Incorporating a nitrogen compound in the electrolyte solution and limiting the sulfur content in the negative electrode to 3 weight% or less, along with a solid electrolyte interphase (SEI) layer, to minimize the formation of sulfur compounds and enhance electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium-sulfur batteries use sulfur-based materials as positive electrode active material, then high capacity and high energy density are achieved, but sulfur passivation on negative electrode occurs during repeated charge and discharge, leading to short lifespan

Engineering Contradiction:
Improveenergy densityVSAvoidlifespan
Core Design Contradiction:
Use of energy by moving objectVSDuration of action of stationary object

Solution Approach 1:

A coating layer comprising nitrogen-containing inorganic compound is formed on the negative electrode surface to act as an intermediary barrier. This coating layer prevents direct contact between lithium polysulfide and the negative electrode, thereby suppressing sulfur passivation while maintaining the high energy density benefits of lithium-sulfur batteries

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameter of the negative electrode surface by introducing nitrogen-containing inorganic compounds (such as lithium nitrate, lithium nitrite, potassium nitrate, etc.). This parameter change modifies the surface properties to resist sulfur passivation, enabling long lifespan while preserving high capacity

Inventive Principle:
Principle #35Parameter changes

2Productivity

If lithium polysulfide is produced at positive electrode during discharging, then conversion reaction occurs, but lithium polysulfide dissolves in electrolyte and precipitates on negative electrode, causing irreversible loss of active material

Engineering Contradiction:
Improvecharge/discharge efficiencyVSAvoidactive material loss
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The invention converts the harmful dissolution and precipitation of lithium polysulfide into a beneficial process by using the nitrogen-containing coating layer to guide the formation of a stable solid electrolyte interphase (SEI) layer. This SEI layer captures dissolved lithium polysulfide and prevents its harmful precipitation on the negative electrode, thereby reducing active material loss while maintaining charge/discharge efficiency

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 lithium-sulfur battery achieves improved capacity retention and high energy density, retaining 80% of its initial capacity after 190 or more charge/discharge cycles with an energy density of 300 Wh/kg.

Implementation Method 1

a solid electrolyte interphase (SEI) layer on at least one surface of the lithium-containing layer

Methodology Applied
Scientific EffectSolid electrolyte interphase (SEI) layer formation:

Implementation Method 2

the electrolyte solution contains 1 weight% or more of a nitrogen compound based on the total weight of the electrolyte solution

Methodology Applied
Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

carbon-based materials capable of intercalation/deintercalation of lithium ions

Methodology Applied
Scientific EffectIntercalation:

Implementation Method 4

During discharging, the lithium-sulfur batteries undergo reduction reaction in which sulfur accepts electrons at the positive electrode

Methodology Applied
Scientific EffectReduction reaction: Reduction

Implementation Method 5

some of the lithium polysulfide are easily dissolved in the electrolyte solution and completely reduced, and then precipitate on the negative electrode in a solid form of lithium sulfide (Li2S)

Methodology Applied
Scientific EffectPrecipitation: Precipitation

Data Source

PatentEP4459698B1Lithium secondary battery having long lifespan
Publication Date: 2026.04.15 LG ENERGY SOLUTION LTD

AI summary

The present disclosure relates to a lithium-sulfur battery, comprising an electrode assembly, an electrolyte solution, and a case accommodating the electrode assembly, wherein the electrode assembly comprises a positive electrode comprising a sulfur-carbon composite, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; wherein the negative electrode comprises a lithium-containing layer; and a solid electrolyte interphase (SEI) layer on at least one surface of the lithium-containing layer, wherein the electrolyte solution contains 1 weight% or more of a nitrogen compound based on the total weight of the electrolyte solution, and / or wherein the negative electrode comprises sulfur (S) in an amount of 3 weight% or less based on a total weight of the negative electrode at a state of charge (SOC) 100. Furthermore, the present disclosure relates to a method for evaluating a lifespan of a lithium-sulfur battery.