Electrolyte Additives for Lithium-Sulfur Battery SEI Formation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium-sulfur and lithium-selenium batteries experience shuttling effects and self-discharge due to the migration of lithium-polysulfide or lithium-polyselenide intermediates, leading to reduced battery life and capacity.

Innovation Solution

An electrolyte solution comprising a fluorinated ether and an additive, such as RSxR′ or R—(SnSem)—R, is used to form a stable SEI layer on the negative electrode, preventing undesirable reactions and reducing shuttling, thereby enhancing battery stability and capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolyte solutions are used in lithium-sulfur and lithium-selenium batteries, then the batteries can operate, but they experience shuttling effects and self-discharge due to migration of lithium-polysulfide or lithium-polyselenide intermediates, leading to reduced battery life and capacity

Engineering Contradiction:

Improvebattery lifeVSAvoidself-discharge

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent introduces a film-forming additive as an intermediary substance in the electrolyte solution that mediates between the lithium-polysulfide/polyselenide intermediates and the electrode. This additive forms a protective film that prevents direct harmful interactions while allowing ionic conduction, thereby reducing self-discharge and shuttling effects without compromising battery operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte solution by incorporating specific film-forming additives (such as fluoroethylene carbonate, cyclic sulfate esters, or cyclic sulfonate esters). This parameter change transforms the electrolyte's properties to enable stable film formation on electrodes, which subsequently reduces self-discharge and improves battery reliability

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If conventional electrolyte solutions are used in lithium-sulfur and lithium-selenium batteries, then the batteries can operate, but they experience shuttling effects due to migration of lithium-polysulfide or lithium-polyselenide intermediates, leading to reduced capacity

Engineering Contradiction:

Improvebattery capacityVSAvoidshuttling effects

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The film-forming additive acts as an intermediary that creates a selective barrier film on the electrode surface. This film mediates the interaction between lithium-polysulfide/polyselenide intermediates and the electrode, allowing beneficial ionic transport while blocking harmful shuttling of polysulfide/polyselenide species, thereby preserving battery capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a thin film formed by the additive on the electrode surface as a flexible barrier. This film is thin enough to allow ionic conduction but sufficient to prevent the shuttling of lithium-polysulfide or lithium-polyselenide intermediates, thus maintaining high battery capacity while eliminating harmful effects

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If stable SEI layer is formed to prevent shuttling and self-discharge, then battery reliability improves, but the electrolyte solution composition becomes more complex

Engineering Contradiction:

Improvebattery stabilityVSAvoidelectrolyte solution composition

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent achieves stable SEI layer formation by carefully controlling the concentration parameters of film-forming additives in the electrolyte (typically 5-50 mM). By optimizing this single parameter, the system forms protective films that improve reliability without requiring complex multi-component formulations or extreme conditions

Inventive Principle:

Principle #35Parameter changes

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 increases battery capacity and stability, reducing self-discharge and improving the life cycle performance of lithium-sulfur and lithium-selenium batteries by forming a resistant SEI layer that inhibits the migration of lithium-polysulfide or lithium-polyselenide intermediates.

Implementation Method 1

An electrolyte solution comprising a fluorinated ether and an additive, such as RSxR′ or R—(SnSem)—R, is used to form a stable SEI layer on the negative electrode

Methodology Applied

Scientific EffectSEI layer formation:

Implementation Method 2

Methodology Applied

Scientific EffectMigration inhibition:

Data Source

PatentUS10084204B2Electrolyte solution and sulfur-based or selenium-based batteries including the electrolyte solution

Publication Date: 2018.09.25 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

An example of an electrolyte solution includes a solvent, a lithium salt, a fluorinated ether, and an additive. The additive is selected from the group consisting of RSxR′, wherein x ranges from 3 to 18, and R—(SnSem)—R, wherein 2<n<8 and 2<m<8. R and R′ are each independently selected from a straight alkyl group having from 1 carbon to 6 carbons or branched alkyl group having from 1 carbon to 6 carbons. The electrolyte solution may be suitable for use in a sulfur-based battery or a selenium-based battery.