Non-Aqueous Battery Electrolyte for High-Voltage Swelling Control

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Solution Overview

Problem

Lithium secondary batteries face challenges in suppressing gas generation and cell swelling, particularly at high voltages and elevated temperatures, due to increased interfacial reactions between the electrolyte and electrode materials, which affect their thermal durability and cycle life.

Innovation Solution

A non-aqueous electrolyte solution for lithium secondary batteries is developed, comprising a lithium salt, a carbonate-based solvent, propyl propionate, and a compound with a propargyl group and imidazole moiety, which forms a stable ion conductive film on the negative electrode, reducing side reactions and metal ion adsorption, thereby minimizing gas generation and cell swelling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the driving voltage of the lithium secondary battery is increased to achieve high capacity and high output, then the energy density and power output are improved, but thermal durability is reduced and gas generation increases causing cell swelling

Engineering Contradiction:

Improveenergy densityVSAvoidthermal durability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a specific compound (Formula 1) as an intermediary substance in the electrolyte that mediates between the electrode and electrolyte interaction. This compound forms a stable interface layer that prevents direct harmful reactions while allowing ionic conduction, thus enabling high voltage operation without sacrificing thermal durability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical composition parameters of the electrolyte by incorporating a specific compound with defined molecular structure (Formula 1) where R1 and R2 are specific alkyl groups. This parameter change in electrolyte composition enables the system to maintain stability at higher voltages while preventing gas generation and cell swelling.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If the driving voltage is increased to 4.35 V or more, then high capacity is achieved, but interfacial reaction between electrolyte and electrode increases causing severe cell swelling

Engineering Contradiction:

ImprovecapacityVSAvoidgas generation

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The compound represented by Formula 1 acts as an intermediary that forms a protective interface layer between the electrolyte and electrode at high voltage. This intermediary layer prevents direct contact and harmful interfacial reactions that would otherwise generate gas, while still permitting lithium ion transport for high capacity operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful interfacial reaction at high voltage into a beneficial protective film formation. The compound in Formula 1 undergoes controlled decomposition to form a stable solid electrolyte interface (SEI) layer that prevents further harmful reactions, thus converting the harmful high-voltage interfacial reaction into a protective mechanism.

Inventive Principle:

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

3Ease of operation

If conventional electrolyte composition is used at high voltage, then battery operation is maintained, but cell swelling occurs due to increased interfacial reaction

Engineering Contradiction:

Improvebattery operationVSAvoidcell swelling

Core Design Contradiction:

Ease of operationVSShape

Solution Approach 1:

The patent modifies the electrolyte composition parameters by adding a specific compound (Formula 1) with defined molecular structure and concentration range. This parameter change in composition enables the electrolyte to maintain operational stability at high voltage while preventing cell swelling through formation of a stable protective interface layer.

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 solution effectively suppresses gas generation and cell swelling at high voltages and during high-temperature storage, enhancing the thermal stability and cycle life of lithium secondary batteries by forming a stable ion conductive film and preventing metal deposition on the negative electrode.

Implementation Method 1

form a stable ion conductive film on the surface of a negative electrode

Methodology Applied

Scientific EffectSolid electrolyte interface (SEI) formation: Deposition (physical)

Implementation Method 2

metal ion adsorbability

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS11799133B2Non-aqueous electrolyte solution for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2023.10.24 LG ENERGY SOLUTION LTD

AI summary

An additive, a non-aqueous electrolyte solution including the same, and a lithium secondary battery including the same are disclosed herein. In some embodiments, a non-aqueous electrolyte solution includes a lithium salt, a non-aqueous solvent including a propyl propionate, and a compound represented by Formula 1:wherein, in Formula 1, R1 and R2 are each independently hydrogen or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.