Bicyclic Sulfate 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 layer 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 layer 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 layer degrade at high temperatures, reducing battery stability and lifespan

Engineering Contradiction:

Improvehigh-temperature stabilityVSAvoidbattery lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent introduces a bicyclic sulfate-based compound with specific molecular structure parameters (two five-membered rings containing sulfate groups) into the electrolytic solution. This compound changes the chemical composition parameters of the electrolyte, enabling the formation of a stable protective layer at high temperatures while maintaining battery performance and lifespan

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite protective layer on the electrode surface by combining the bicyclic sulfate-based compound with conventional electrolyte components. This composite structure provides both the stability needed for high-temperature operation and the durability required for extended battery lifespan

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If conventional organic electrolytic solutions are used, then the battery achieves basic discharge capacity, but organic solvent co-intercalates with lithium ions, degrading the protection layer and reducing capacity retention

Engineering Contradiction:

Improvedischarge capacityVSAvoidprotection layer stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The bicyclic sulfate-based compound acts as an intermediary substance that forms a protective barrier between the organic solvent and the electrode surface. This intermediary layer prevents the organic solvent from co-intercalating with lithium ions, thereby protecting the protection layer from degradation while maintaining lithium ion transport and discharge capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the electrolytic solution is designed to prevent co-intercalation, then protection layer stability improves, but electrolyte complexity increases

Engineering Contradiction:

Improveprotection layer stabilityVSAvoidelectrolyte composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the local quality principle by introducing a specific bicyclic sulfate-based compound that concentrates its protective function at the electrode-electrolyte interface. This localized approach enhances protection layer stability without requiring complex changes to the bulk electrolyte composition, maintaining relative simplicity while achieving improved reliability

Inventive Principle:

Principle #3Local quality

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 a 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 battery performance and stability.

Implementation Method 1

the degradation of the solid electrolyte interface (SEI) layer and protection layer formed by conventional organic electrolytic solutions

Methodology Applied

Scientific EffectSolid electrolyte interface (SEI) layer formation:

Implementation Method 2

forming a durable modified layer that prevents co-intercalation of organic solvent with lithium ions

Methodology Applied

Scientific EffectCo-intercalation prevention:

Implementation Method 3

an organic electrolytic solution between the cathode and the anode

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 4

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

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentUS11114694B2Lithium battery

Publication Date: 2021.09.07 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, an organic solvent, an oligomer compound, 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, in which both A1 and A2 are not a covalent bond and both A3 and A4 are not a covalent bond.