Lithium Battery Electrolyte Additives for Temperature Performance

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Solution Overview

Problem

Current lithium secondary batteries face challenges in achieving both high temperature and low temperature performance characteristics simultaneously, with existing non-aqueous electrolyte solutions failing to optimize both aspects effectively.

Innovation Solution

A non-aqueous electrolyte solution for lithium secondary batteries is developed, comprising LiN(CF3SO2)2 as the lithium salt, a sulfate-based compound, and vinylene carbonate, with a preferred content ratio and concentration, which also includes LiTFSI to enhance high temperature storage and cycle characteristics while improving low temperature power characteristics by forming specific solid electrolyte interphase (SEI) films.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vinylene carbonate is used to improve high temperature cycle performance, then high temperature characteristics are improved, but low temperature power performance deteriorates

Engineering Contradiction:

Improvehigh temperature cycle performanceVSAvoidlow temperature power performance

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent combines vinylene carbonate (VC) with ethylene sulfate (ES) in a specific ratio (VC:ES = 1:4 to 1:1 by weight) to create a synergistic effect. VC provides high temperature stability while ES improves low temperature power characteristics, and their combination resolves the contradiction between high temperature cycle performance and low temperature power performance that cannot be achieved by either additive alone.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a composite additive system comprising VC and ES together, rather than a single additive. This composite approach allows the electrolyte to exhibit both high temperature stability (from VC) and improved low temperature power characteristics (from ES), simultaneously resolving the performance contradiction.

Inventive Principle:

Principle #40Composite materials

2Power

If ethylene sulfate is used to improve low temperature characteristics, then low temperature power characteristics are improved, but high temperature cycle performance deteriorates

Engineering Contradiction:

Improvelow temperature power characteristicsVSAvoidhigh temperature cycle performance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent combines ethylene sulfate (ES) with vinylene carbonate (VC) in a specific ratio to create a synergistic effect. ES provides improved low temperature power characteristics while VC provides high temperature stability, and their combination resolves the contradiction between low temperature power characteristics and high temperature cycle performance that cannot be achieved by either additive alone.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If conventional electrolyte compositions are used, then high temperature performance is maintained, but low temperature power characteristics remain insufficient

Engineering Contradiction:

Improvehigh temperature performanceVSAvoidlow temperature power characteristics

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing a specific combination of VC and ES additives in optimized ratios. This parameter change transforms the electrolyte's performance characteristics, enabling it to deliver both high temperature stability and improved low temperature power characteristics simultaneously.

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 maintains excellent high temperature storage and cycle characteristics while improving low temperature power characteristics by optimizing the content and ratio of sulfate-based compounds and vinylene carbonate, resulting in reduced battery resistance at low temperatures and enhanced performance across temperature ranges.

Implementation Method 1

improving high temperature storage and cycle characteristics while improving low temperature power characteristics by forming specific solid electrolyte interphase (SEI) films

Methodology Applied

Scientific EffectSolid electrolyte interphase (SEI) film formation:

Implementation Method 2

a non-aqueous electrolyte solution for a lithium secondary battery comprises a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent, wherein the lithium salt includes LiN(CF3SO2)2

Methodology Applied

Scientific EffectIon dissolution and supply: Solvation

Implementation Method 3

resulting in reduced battery resistance at low temperatures and enhanced performance across temperature ranges

Methodology Applied

Scientific EffectElectrical resistance reduction: Electrical Resistance

Data Source

PatentUS8822085B2Non-aqueous electrolyte solution for lithium secondary battery and lithium secondary battery comprising the same

Publication Date: 2014.09.02 LG ENERGY SOLUTION LTD

AI summary

A non-aqueous electrolyte solution for a lithium secondary battery includes a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent. The lithium salt includes LiN(CF3SO2)2. The non-aqueous electrolyte solution further includes a sulfate-based compound and vinylene carbonate. A lithium secondary battery having the above non-aqueous electrolyte solution may keep overall high temperature performance in a high level and also improve low temperature power characteristics.