Rechargeable Lithium Battery Electrolyte for Stable High-Temperature Storage

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Solution Overview

Problem

Rechargeable lithium batteries face issues with increased resistance during high-temperature storage and gas generation due to the decomposition of LiPF6, leading to degraded performance and safety concerns.

Innovation Solution

An electrolyte composition for rechargeable lithium batteries is developed, incorporating a non-aqueous organic solvent, a lithium salt, and an additive comprising compounds represented by Chemical Formulae 1 and 2. These compounds help suppress side reactions, stabilize the electrolyte, and form a stable SEI film, reducing gas generation and resistance increases at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If LiPF6 is used as the lithium salt in the electrolyte, then the battery can achieve good electrochemical performance, but it reacts with the electrolytic solvent causing solvent depletion and gas generation

Engineering Contradiction:

Improveelectrochemical performanceVSAvoidgas generation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a cyclic carboxylate compound as an intermediary substance that mediates between LiPF6 and the electrolytic solvent. This additive forms a protective interface layer that prevents direct contact and reaction between LiPF6 and the solvent, thereby eliminating gas generation while preserving the electrochemical performance provided by LiPF6.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful reaction between LiPF6 and solvent into a beneficial effect by controlling the reaction through the cyclic carboxylate additive. The reaction is redirected to form a protective film on the electrode surface that prevents further harmful reactions, thus transforming the harmful gas-generating reaction into a beneficial protective mechanism.

Inventive Principle:

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

2Reliability

If LiPF6 is used as the lithium salt, then the battery achieves good performance, but decomposition generates LiF and PF5 leading to electrolyte depletion

Engineering Contradiction:

Improvebattery performanceVSAvoidelectrolyte depletion

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies preliminary action by having the cyclic carboxylate additive react first with LiPF6 to form a stable complex or protective layer before LiPF6 can decompose into LiF and PF5. This preliminary reaction prevents the decomposition pathway, thereby preventing electrolyte depletion while maintaining the performance benefits of LiPF6.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The cyclic carboxylate compound acts as an intermediary that stabilizes LiPF6, preventing its decomposition. The additive forms a protective interface that blocks the decomposition reaction, thereby preventing electrolyte depletion while allowing LiPF6 to continue providing good electrochemical performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If conventional electrolytes are used, then the battery can operate, but resistance increases during high-temperature storage

Engineering Contradiction:

Improvebattery operationVSAvoidresistance stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing a cyclic carboxylate compound with specific molecular structure and properties. This parameter change modifies the electrolyte's behavior at high temperatures, stabilizing the resistance characteristics during high-temperature storage while maintaining operational ease.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cyclic carboxylate additive acts as a sacrificial component that consumes itself to form a stable protective layer. This disposable-like behavior of the additive (consuming small amounts to provide long-term stability) prevents resistance increase during high-temperature storage while maintaining normal battery operation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 composition effectively suppresses resistance increases and gas generation during high-temperature storage, thereby enhancing the thermal stability and cycle-life characteristics of rechargeable lithium batteries.

Implementation Method 1

form a stable SEI film

Methodology Applied

Scientific EffectSEI film formation: Deposition (physical)

Implementation Method 2

suppress side reactions

Methodology Applied

Scientific EffectChemical reaction suppression: Chemical Bonding

Implementation Method 3

decomposition of LiPF6

Methodology Applied

Scientific EffectDecomposition: Decomposition (biological)

Data Source

PatentEP4009410B1Electrolyte for rechargeable lithium battery and rechargeable lithium battery

Publication Date: 2025.05.28 SAMSUNG SDI CO LTD

Figure 1

AI summary

An electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a compound represented by Chemical Formula 1 and a compound represented by Chemical Formula 2: wherein X is a fluoro group, a chloro group, a bromo group, or an iodo group, and A is a C1 to C10 alkylene group or (-C2H4-O-C2H4-)m, wherein m is an integer of 1 to 10.