Lithium Battery Electrolyte Additive for High-Temperature Cycle Stability

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Solution Overview

Problem

Lithium secondary batteries face challenges in maintaining uniform output and capacity during repeated charging and discharging, especially in high-temperature environments, due to surface damage of the cathode active material and side reactions with the electrolyte.

Innovation Solution

The development of an electrolyte for lithium secondary batteries that includes an additive represented by specific formulas, an organic solvent, and a lithium salt, which forms a stable solid electrolyte interphase (SEI) on the electrode surface, thereby improving high-temperature properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional electrolytes are used in lithium secondary batteries, then the batteries can operate at high temperatures, but the capacity decreases and resistance increases due to surface damage of cathode active material and side reactions with the electrolyte

Engineering Contradiction:

Improvehigh-temperature operationVSAvoidcapacity retention and resistance stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent introduces a mediator substance (additive compound represented by Formula 1 or Formula 2) that acts between the electrolyte and the cathode active material. This additive forms a protective interface layer that prevents direct contact and harmful interactions, thereby maintaining battery reliability at high temperatures while allowing normal operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte by incorporating specific additive compounds with defined molecular structures (Formulas 1 and 2). These parameter changes in the electrolyte composition alter the interfacial properties between electrolyte and electrode, improving high-temperature stability and preventing capacity degradation.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of moving object

If repeated charging and discharging occur in high temperature environment, then the battery undergoes normal cycling, but surface damage of cathode active material occurs leading to decreased output and capacity

Engineering Contradiction:

Improvecharging-discharging cyclesVSAvoidsurface integrity of cathode active material

Core Design Contradiction:

Duration of action of moving objectVSStrength

Solution Approach 1:

The additive compound performs preliminary protective action by forming a stable surface layer on the cathode active material before damage can occur. This pre-formed protective interface prevents subsequent surface degradation during repeated charging-discharging cycles in high-temperature environments, maintaining both cycle life and structural integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies beforehand cushioning by introducing the additive that creates a buffer protective layer between the electrolyte and cathode surface. This cushioning layer absorbs and dissipates harmful effects during cycling, preventing direct damage to the cathode active material surface and maintaining its structural strength over time.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If high temperature operation is maintained, then the battery can function in demanding environments, but side reactions between cathode active material and electrolyte occur

Engineering Contradiction:

Improveoperating temperatureVSAvoidside reactions between cathode and electrolyte

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potentially harmful high-temperature condition into a beneficial effect by using the heat to promote formation of a stable protective interface layer through controlled side reactions of the additive. This controlled initial reaction creates a protective barrier that prevents further harmful side reactions, turning the thermal energy that could cause damage into a protective mechanism.

Inventive Principle:

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

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 proposed electrolyte effectively suppresses the decrease in capacity and increase in resistance at high temperatures, enhancing the high-temperature lifespan and performance of lithium secondary batteries.

Implementation Method 1

forms a stable solid electrolyte interphase (SEI) on the electrode surface

Methodology Applied

Scientific EffectSolid electrolyte interphase (SEI) formation:

Data Source

PatentUS20250046871A1Electrolyte for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2025.02.06 SK ON CO LTD

AI summary

The electrolyte for a lithium secondary battery according to embodiments of the present disclosure may include an additive including a compound represented by a specific formula, an organic solvent, and a lithium salt. A lithium secondary battery including the electrolyte for a lithium secondary battery according to exemplary embodiments and having improved high-temperature properties, output properties, and lifespan properties may be provided.