Siloxane-Modified Electrolyte Mitigates Battery Swelling

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Solution Overview

Problem

Lithium secondary batteries with non-aqueous electrolyte solutions containing solvents with fluoro groups face issues of swelling due to gas generation at high temperatures, affecting their performance and capacity recovery.

Innovation Solution

Incorporating a siloxane compound into the non-aqueous electrolyte solution, specifically 1,3-divinyltetramethyldisiloxane, which reacts with hydrofluoric acid generated from the fluoro group solvents, reducing its content and mitigating swelling, along with using a lithium salt and organic solvents like ethylene carbonate and propylene carbonate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a solvent with a fluoro group (e.g., fluoroethylene carbonate) is added to improve ion conductivity and life cycle, then ion conductivity and life cycle are improved, but the battery exhibits great increase of thickness due to gas generation at high temperature

Engineering Contradiction:

Improvelife cycleVSAvoidswelling due to gas generation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A siloxane compound is introduced as an intermediary substance that reacts with hydrofluoric acid generated from the fluoro group solvent, forming a protective film on the electrode surface. This intermediary approach allows the beneficial effects of fluoro group solvents (improved ion conductivity and life cycle) while preventing the harmful swelling effect by controlling the decomposition products

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The hydrofluoric acid that would normally cause harmful swelling and electrode degradation is converted into a beneficial protective film through reaction with the siloxane compound. The harmful decomposition product becomes a useful protective layer that improves battery performance and stability

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 solution significantly reduces swelling and improves capacity recovery characteristics of lithium secondary batteries after high-temperature storage, maintaining performance and extending the battery's life cycle.

Implementation Method 1

a siloxane compound expressed by the following chemistry figure 1... which reacts with hydrofluoric acid generated from the fluoro group solvents

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentEP2235783B1Non-aqueous electrolyte solution for lithium secondary battery and lithium secondary battery comprising the same

Publication Date: 2014.03.12 LG CHEM LTD

Figure 1
Figure 2

AI summary

A non-aqueous electrolyte solution for a lithium secondary battery includes a lithium salt and an organic solvent and further includes a solvent having a fluoro group and a specific siloxane compound. A lithium secondary battery having the above non-aqueous electrolyte solution exhibits greatly improved capacity recovery characteristics after high temperature storage and also reduces side effects such as swelling.