Lithium Metal Battery Electrolyte for Dendrite and Side-Reaction Control

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Solution Overview

Problem

Lithium metal secondary batteries face challenges with large volume changes during charge and discharge, uncontrolled lithium dendrite growth, high reactivity leading to side reactions, and reduced initial discharge capacity and lifetime characteristics, especially when using local high-concentration electrolytes.

Innovation Solution

An electrolyte comprising a lithium salt, a non-aqueous organic solvent, an organic anti-solvent with low solubility for the lithium salt, and a fluorine-substituted ether compound as an additive, forming a coating film on the lithium metal layer to suppress side reactions and improve electrochemical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If local high-concentration electrolyte is applied to improve output characteristics and suppress side reactions, then lifetime characteristics are improved, but ionic conductivity decreases and viscosity increases

Engineering Contradiction:

Improvelifetime characteristicsVSAvoidionic conductivity

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies parameter changes by adjusting the concentration of lithium salt and anti-solvent in the electrolyte. Specifically, it uses a local high-concentration electrolyte configuration where lithium salt concentration is optimized to balance ionic conductivity and side reaction suppression. The patent also adjusts the ratio of anti-solvent to solvent to control viscosity while maintaining protective film formation on the lithium metal surface.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If local high-concentration electrolyte is applied to suppress side reactions, then lifetime characteristics are improved, but initial discharge capacity is reduced

Engineering Contradiction:

Improvelifetime characteristicsVSAvoidinitial discharge capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by creating a local high-concentration region of lithium salt near the lithium metal surface, while maintaining lower concentration in the bulk electrolyte. This is achieved by adding an anti-solvent that has low solubility for lithium salt, causing the lithium salt to concentrate locally. This local concentration provides protective film formation and side reaction suppression at the interface, while the bulk electrolyte maintains good ionic conductivity and discharge capacity.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If lithium metal is used as anode to achieve high energy density, then capacity is improved, but volume change and dendrite growth occur during charge-discharge

Engineering Contradiction:

Improveenergy densityVSAvoidvolume stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by forming a protective interface layer on the lithium metal surface before significant dendrite growth and volume change occur. The local high-concentration electrolyte configuration promotes the formation of a stable solid electrolyte interface (SEI) layer that constrains lithium ion deposition, preventing uncontrolled dendrite growth and reducing volume expansion during cycling.

Inventive Principle:

Principle #10Preliminary action

4Quantity of substance

If lithium metal is used as anode to achieve high energy density, then capacity is improved, but side reactions with electrolyte increase

Engineering Contradiction:

Improveenergy densityVSAvoidside reactions

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent applies the intermediary principle by introducing a local high-concentration electrolyte region that acts as a mediator between the lithium metal anode and the bulk electrolyte. This local region, formed by adding anti-solvent, creates a protective interface that reduces direct contact between the reactive lithium metal and the bulk electrolyte, thereby suppressing side reactions while maintaining high energy density.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the lithium metal battery's initial discharge capacity, lifetime characteristics, and output characteristics by reducing side reactions and increasing electrolyte activity, while minimizing gas generation.

Implementation Method 1

an additive including a fluorine-substituted ether compound... forming a coating film on the lithium metal layer

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Implementation Method 2

the anti-solvent surrounds the high-concentration region of the lithium salt to thereby suppress side reactions between the lithium metal layer and the electrolyte

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentEP4715942A1Electrolyte for lithium secondary battery and lithium metal secondary battery

Publication Date: 2026.03.25 LG ENERGY SOLUTION LTD

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AI summary

The present disclosure relates to an electrolyte for a lithium secondary battery that can improve the initial discharge characteristics, lifetime characteristics and output characteristics, etc. of a lithium metal secondary battery, and a lithium metal secondary battery comprising the same. The electrolyte may include a lithium salt; a non-aqueous organic solvent; an organic anti-solvent that exhibits a solubility for the lithium salt that is at least 10 times lower than that of the non-aqueous organic solvent; and an additive including a fluorine-substituted ether compound.