Lithium Battery Electrolyte Additives Suppress Thickness Increase

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Solution Overview

Problem

Lithium secondary batteries face degradation in high-temperature environments due to structural deformation, side reactions, and increased internal resistance, leading to reduced lifespan and capacity retention.

Innovation Solution

An electrolyte solution for lithium secondary batteries is developed, comprising a lithium salt, organic solvent, and additives such as a lactone-based compound, fluorine-containing phosphate-based compound, fluorine-containing carbonate-based compound, sultone-based compound, and sulfate-based compound, which form a robust solid electrolyte interphase to prevent solvent decomposition and enhance high-temperature stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolyte solutions are used in lithium secondary batteries, then the batteries can operate with basic charging and discharging functions, but the batteries experience accelerated degradation including battery expansion, increased internal resistance, and reduced lifespan when exposed to high-temperature environments

Engineering Contradiction:

Improvehigh-temperature stabilityVSAvoidbattery expansion and internal resistance increase at high temperature

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a mediating substance (specific additive compound) that acts between the electrolyte solution and the battery components to prevent harmful interactions. The additive serves as an intermediary that forms protective interfaces, preventing direct contact and reaction between the electrolyte and electrode materials at high temperatures, thereby suppressing battery expansion and internal resistance increase.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte solution by incorporating specific additives (e.g., cyclic carboxylate compounds, sulfur compounds) at controlled concentrations. This parameter change transforms the electrolyte's properties to enhance its thermal stability and ability to form protective SEI layers, directly addressing the high-temperature degradation issue without compromising basic battery functionality.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If repeated charging and discharging are performed to utilize the battery's capacity, then energy storage and release functions are achieved, but structural deformation of lithium metal oxide and side reactions of the electrolyte occur, deteriorating lifespan properties

Engineering Contradiction:

Improvecharging and discharging capacityVSAvoidlifespan properties and capacity retention

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary action by having the additive compounds react first during initial charging cycles to form stable protective layers (SEI) on the electrode surfaces. This preliminary reaction prevents subsequent structural deformation of lithium metal oxide and electrolyte side reactions during repeated charging and discharging, thereby extending battery lifespan while maintaining productivity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a composite electrolyte system by combining conventional electrolyte components with specific additive compounds (cyclic carboxylates, sulfur compounds). This composite formulation works synergistically to protect electrode structures during cycling, reducing degradation from structural deformation and side reactions while preserving charging and discharging capacity.

Inventive Principle:

Principle #40Composite materials

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 electrolyte solution significantly improves high-temperature stability by suppressing battery thickness increase and internal resistance, while maintaining capacity retention, as demonstrated by the specific composition and concentration ranges of the additives.

Implementation Method 1

additives such as a lactone-based compound, fluorine-containing phosphate-based compound, fluorine-containing carbonate-based compound, sultone-based compound, and sulfate-based compound, which form a robust solid electrolyte interphase to prevent solvent decomposition

Methodology Applied

Scientific EffectSolid electrolyte interphase formation:

Implementation Method 2

an electrolyte solution for a lithium secondary battery including an organic solvent, a lithium salt and an additive

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS20230054122A1Electrolyte Solution for Lithium Secondary Battery and Lithium Secondary Battery Including the Same

Publication Date: 2023.02.23 SK ON CO LTD

AI summary

An electrolyte solution for a lithium secondary battery includes a lithium salt, an organic solvent, a first additive including a lactone-based compound represented by a specific chemical formula, and a second additive including a fluorine-containing phosphate-based compound, a fluorine-containing carbonate-based compound, a sultone-based compound and a sulfate-based compound. A lithium secondary battery including the electrolyte solution is also provided.