Bicyclic Sulfate Electrolyte Additive for Lithium Battery SEI Stability

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Solution Overview

Problem

Lithium batteries face challenges in maintaining high-temperature stability and lifespan due to the degradation of the solid electrolyte interface (SEI) layer and protection layers formed by conventional organic electrolytic solutions, which are prone to degradation at elevated temperatures.

Innovation Solution

Incorporating a bicyclic sulfate-based compound into the organic electrolytic solution, which enhances the stability of the SEI layer and protection layers by forming a durable modified layer that prevents co-intercalation of organic solvent with lithium ions, thereby improving the battery's high-temperature characteristics and lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional organic electrolytic solutions are used, then the battery can operate at room temperature, but the SEI layer and protection layers degrade at high temperatures, reducing battery lifespan and stability

Engineering Contradiction:

Improvehigh-temperature stabilityVSAvoidbattery lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The bicyclic sulfate-based compound performs preliminary action by forming a stable protective layer on the electrode surface before high-temperature degradation can occur. This pre-formed layer prevents subsequent degradation of the SEI layer and protection layers, thereby extending battery lifespan and maintaining reliability at elevated temperatures

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention uses a composite electrolytic solution system combining conventional organic electrolytes with bicyclic sulfate-based compounds. This composite approach leverages the benefits of both components: the conventional electrolyte provides basic ionic conductivity while the bicyclic sulfate compound contributes thermal stability and forms protective interfaces, resolving the contradiction between room-temperature operation and high-temperature durability

Inventive Principle:

Principle #40Composite materials

2Productivity

If organic solvent co-intercalates with lithium ions, then the battery shows high discharge capacity, but the protection layers degrade, reducing capacity retention at high temperatures

Engineering Contradiction:

Improvedischarge capacityVSAvoidcapacity retention ratio

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The bicyclic sulfate-based compound acts as an intermediary between the organic solvent and lithium ions. It forms a protective interface layer that allows lithium ion transport while blocking organic solvent co-intercalation. This mediator maintains high discharge capacity by permitting lithium ion movement while preventing the harmful co-intercalation that would otherwise degrade protection layers and reduce capacity retention

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the SEI layer is formed by conventional electrolytes, then lithium ion transport is enabled, but the layer degrades at elevated temperatures, reducing thermal stability

Engineering Contradiction:

Improvelithium ion transportVSAvoidthermal stability

Core Design Contradiction:

Ease of operationVSTemperature

Solution Approach 1:

The invention changes the chemical composition parameters of the electrolytic solution by introducing bicyclic sulfate-based compounds. This compositional change modifies the properties of the formed SEI layer, making it thermally stable while maintaining lithium ion transport capability. The parameter change in electrolyte composition directly improves thermal stability without sacrificing ionic conductivity

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 use of the bicyclic sulfate-based compound in the electrolytic solution significantly enhances the discharge capacity and capacity retention ratio at both room and high temperatures, leading to improved thermal stability and extended battery lifespan.

Implementation Method 1

enhances the stability of the SEI layer and protection layers by forming a durable modified layer that prevents co-intercalation of organic solvent with lithium ions

Methodology Applied

Scientific EffectSEI layer formation:

Implementation Method 2

enhances the stability of the SEI layer and protection layers by forming a durable modified layer

Methodology Applied

Scientific EffectProtective layer formation:

Data Source

PatentUS11264644B2Lithium battery

Publication Date: 2022.03.01 SAMSUNG SDI CO LTD

AI summary

A lithium battery includes a cathode including a cathode active material, an anode including an anode active material, and an organic electrolytic solution between the cathode and the anode. The organic electrolytic solution includes a first lithium salt, a second lithium salt different from the first lithium salt, an organic solvent, and a bicyclic sulfate-based compound represented by Formula 1 below:wherein, in Formula 1, each of A1, A2, A3, and A4 is independently a covalent bond, a substituted or unsubstituted C1-C5 alkylene group, a carbonyl group, or a sulfinyl group, wherein both A1 and A2 are not a covalent bond and both A3 and A4 are not a covalent bond.