Organosilicon Additive Scavenges HF to Stabilize SEI Layer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium secondary batteries using nonaqueous electrolytes face performance deterioration due to the decomposition of the solid electrolyte interface (SEI) layer and elution of metal ions caused by hydrogen fluoride (HF) generated during operation, leading to reduced battery lifespan and stability.

Innovation Solution

Incorporating an organosilicon compound with a silicon-nitrogen bond into the nonaqueous electrolyte, which reacts with HF to form a silicon-fluorine bond, thereby stabilizing the SEI layer and improving battery performance by scavenging HF, and containing a carbon-carbon double bond for electron acceptance and homopolymerization to enhance the SEI layer stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a fluorine-containing lithium salt is used in the nonaqueous electrolyte, then high energy density and discharge voltage are achieved, but hydrogen fluoride is generated during battery operation causing SEI layer decomposition and metal ion elution

Engineering Contradiction:

Improveenergy densityVSAvoidbattery lifespan

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The organosilicon compound acts as an intermediary substance that mediates between the HF generated from fluorine-containing lithium salt decomposition and the SEI layer. It preferentially reacts with HF to form silicon-fluorine bonds, protecting the SEI layer from HF attack and preventing metal ion elution, thus resolving the contradiction between maintaining high energy density and ensuring battery reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of HF generation into a beneficial process by utilizing the organosilicon compound to scavenge HF. The HF that would normally decompose the SEI layer is instead captured by the organosilicon compound to form stable silicon-fluorine bonds, transforming a harmful byproduct into a protective mechanism that enhances battery lifespan while maintaining the energy density benefits of fluorine-containing lithium salts

Inventive Principle:

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

2Device complexity

If conventional nonaqueous electrolytes are used, then simple composition is maintained, but SEI layer decomposition occurs due to HF generation leading to performance deterioration

Engineering Contradiction:

Improveelectrolyte compositionVSAvoidbattery stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The invention creates a composite electrolyte system by combining fluorine-containing lithium salt, organosilicon compound, and organic solvent. This composite approach integrates multiple functional components: the fluorine-containing lithium salt provides high energy density, the organosilicon compound scavenges HF to protect the SEI layer, and the organic solvent maintains ion conductivity, achieving both simple overall composition and enhanced battery stability

Inventive Principle:

Principle #40Composite materials

3Reliability

If the SEI layer is stabilized to prevent decomposition, then battery lifespan is improved, but ion conductivity may be reduced

Engineering Contradiction:

Improvebattery lifespanVSAvoidion conductivity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The organosilicon compound provides local protection to the SEI layer by preferentially reacting with HF at the interface where HF is generated. This localized action stabilizes the SEI layer exactly where it is needed (at the electrode-electrolyte interface) without requiring changes to the bulk electrolyte composition, thereby maintaining ion conductivity while improving battery lifespan

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 organosilicon compound improves the lifespan and stability of lithium secondary batteries by stabilizing the SEI layer, reducing resistance, and maintaining high capacity characteristics and ion conductivity, while effectively managing HF generation.

Implementation Method 1

the organosilicon compound reacts with HF to form a silicon-fluorine bond, thereby stabilizing the SEI layer

Methodology Applied

Scientific EffectChemical reaction (silicon-nitrogen bond to silicon-fluorine bond transformation): Chemical Bonding

Implementation Method 2

containing a carbon-carbon double bond for electron acceptance and homopolymerization to enhance the SEI layer stability

Methodology Applied

Scientific EffectElectron acceptance and homopolymerization: Photopolymerisation

Implementation Method 3

maintaining high capacity characteristics and ion conductivity

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS10153515B2Nonaqueous electrolyte for lithium secondary battery and lithium secondary battery employing the same

Publication Date: 2018.12.11 SAMSUNG ELECTRONICS CO LTD

AI summary

A nonaqueous electrolyte for a lithium secondary battery, the nonaqueous electrolyte including: a fluorine-containing lithium salt, an organic solvent, and an organosilicon compound represented by Formula 1:wherein, in Formula 1, R1 to R6 are each independently a C1-C10 alkyl group or a C1-C10 alkoxy group. Also a lithium secondary battery including the nonaqueous electrolyte.