Alkyl Trifluoroacetate Electrolyte for Lithium Dendrite Control

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Solution Overview

Problem

The degradation of lithium secondary batteries due to lithium dendrite formation, which leads to reduced lifespan and stability, particularly in lithium-sulfur batteries, where dendrites can cause internal short circuits and combustion of the electrolyte solution.

Innovation Solution

Incorporating alkyl trifluoroacetate as an additive in the electrolyte solution to suppress dendrite formation by uniformly depositing and peeling lithium on the negative electrode, forming a protective film and increasing the solubility of lithium polysulfide, thereby enhancing the battery's lifetime and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used as the negative electrode material to achieve high capacity and low density, then the energy density is improved, but lithium dendrite formation occurs leading to reduced stability and lifetime

Engineering Contradiction:

Improveenergy densityVSAvoidstability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A fluorinated cyclic carbonate additive is introduced as an intermediary substance in the electrolyte solution. This additive mediates between the lithium metal negative electrode and the electrolyte, preferentially decomposing to form a stable protective film that prevents direct harmful interactions while allowing beneficial lithium deposition. The additive acts as a buffer that modifies the electrode-electrolyte interface to enable safe high-capacity operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical composition and molecular structure of the electrolyte additives are modified by introducing fluorinated cyclic carbonate compounds with specific molecular weight ranges (100-300 g/mol). This parameter change in the additive's chemical properties alters the decomposition behavior and film-forming characteristics, creating a more stable protective layer that suppresses dendrite formation while maintaining high lithium capacity.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If lithium metal is used as the negative electrode material to achieve high capacity, then the energy storage density is improved, but dendrite formation causes internal short circuits reducing lifetime

Engineering Contradiction:

ImprovecapacityVSAvoidlifetime

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The fluorinated cyclic carbonate additive performs preliminary action by preferentially decomposing during initial charging cycles to form a stable protective film on the lithium metal surface before dendrites can form. This pre-formed protective layer prevents subsequent dendrite growth and internal short circuits, enabling long-term stable operation while maintaining high lithium capacity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The fluorinated cyclic carbonate compound serves as an intermediary that modifies the electrode-electrolyte interface. It decomposes to form a stable protective film that mediates between the high-capacity lithium metal and the electrolyte, preventing direct harmful reactions and dendrite formation that would otherwise limit battery lifetime.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional electrolyte solution is used to maintain simple composition, then the manufacturing cost is reduced, but dendrite formation occurs reducing Coulombic Efficiency

Engineering Contradiction:

Improvemanufacturing costVSAvoidCoulombic Efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The electrolyte composition is modified by incorporating fluorinated cyclic carbonate additives with specific molecular weight parameters (100-300 g/mol). This parameter change in the additive's molecular structure optimizes the film-forming properties and dendrite suppression capability, significantly improving Coulombic Efficiency while maintaining cost-effective manufacturing through the use of simple additive compounds.

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 use of alkyl trifluoroacetate in the electrolyte solution effectively improves the lithium secondary battery's lifetime by preventing dendrite formation, increasing the utilization of lithium, and enhancing the stability of lithium polysulfide, resulting in improved capacity retention and extended cycle life.

Implementation Method 1

forming a protective film and increasing the solubility of lithium polysulfide

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Implementation Method 2

increasing the solubility of lithium polysulfide through chemical interaction

Methodology Applied

Scientific EffectChemical interaction: Chemical Bonding

Implementation Method 3

uniformly depositing (plating) and peeling (stripping) lithium on the surface of the negative electrode

Methodology Applied

Scientific EffectElectrochemical reaction: Electrodeposition

Data Source

PatentUS20230275270A1Electrolyte solution and lithium secondary battery comprising same

Publication Date: 2023.08.31 LG ENERGY SOLUTION LTD

AI summary

An electrolyte solution and a lithium secondary battery comprising the same are provided. The electrolyte solution comprises a lithium salt, an organic solvent and an additive, the additive comprising an alkyl trifluoroacetate, which is a compound of Formula 1.