Lithium Fluorosulfonate Electrolyte Additive for Battery

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Solution Overview

Problem

Lithium secondary batteries face challenges in maintaining high output and capacity retention at varying temperatures, particularly at high temperatures, and require improved charging efficiency and lifespan due to increased resistance and reduced recovery capacity.

Innovation Solution

An electrolyte additive with a specific compound structure, represented by Chemical Formula 1, is introduced, which reduces charging resistance, enhances electron flow stability, and forms a stable film on electrodes, preventing decomposition and improving cycle characteristics, especially at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional methods (ammonium fluorosulfonate mixed with lithium hydroxide aqueous solution) are used to produce lithium fluorosulfonate, then lithium fluorosulfonate can be obtained, but the production process becomes complex and contamination with ammonia occurs

Engineering Contradiction:

Improvepurity of lithium fluorosulfonateVSAvoidcomplexity of production process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the problematic intermediate step involving ammonium fluorosulfonate and cation exchange. Instead of using the conventional two-step process (forming ammonium salt then exchanging cations), the patent directly synthesizes lithium fluorosulfonate by reacting fluorosulfonic acid with lithium salt in acetonitrile solvent, removing the source of ammonia contamination and process complexity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces acetonitrile as an intermediary solvent that enables direct reaction between fluorosulfonic acid and lithium salt. This intermediary medium allows the reaction to proceed without forming the problematic ammonium intermediate, achieving both simplification and high purity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of stationary object

If LiClO4 is used as electrolyte additive, then cycle stability is improved, but HF generation occurs due to decomposition at electrode interfaces

Engineering Contradiction:

Improvecycle stabilityVSAvoidHF generation

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The invention changes the chemical composition parameter of the electrolyte additive from LiClO4 to lithium fluorosulfonate (LiFSO3). This parameter change maintains the beneficial cycle stability improvement while eliminating the harmful HF decomposition product, as lithium fluorosulfonate decomposes to form protective films without generating HF

Inventive Principle:

Principle #35Parameter changes

3Productivity

If LiBF4 is used as electrolyte additive, then initial charge-discharge efficiency is improved, but active solvent consumption increases due to solvent cage formation

Engineering Contradiction:

Improveinitial charge-discharge efficiencyVSAvoidactive solvent consumption

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The invention changes the electrolyte additive composition from LiBF4 to lithium fluorosulfonate. This parameter change maintains the improvement in initial charge-discharge efficiency while preventing the formation of solvent cages, thereby eliminating the associated active solvent consumption problem

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 electrolyte additive significantly improves charging efficiency, output, and capacity retention at high temperatures, extending the battery's lifespan and ensuring better storage properties, making it suitable for vehicle batteries.

Implementation Method 1

A method for preparing a lithium fluorosulfonate battery electrolyte additive, comprising: reacting fluorosulfonic acid with a lithium salt in an acetonitrile solvent to perform the preparation of the lithium fluorosulfonate

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

the electrolyte additive forms stable interface films on electrode surfaces, effectively reducing side reactions

Methodology Applied

Scientific EffectElectrochemical reaction: Electrolysis

Implementation Method 3

improving the charge transfer efficiency and cycle stability of secondary batteries

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentEP3993125A2Electrolyte solution additive, electrolyte solution for battery comprising same, and secondary battery comprising same

Publication Date: 2022.05.04 SOULBRAIN CO LTD

AI summary

The present invention relates to an electrolyte additive, a battery electrolyte including the electrolyte additive, and a secondary battery, and more particularly, to an electrolyte additive including a compound represented by Chemical Formula 1, an electrolyte including the electrolyte additive, and a secondary battery including the electrolyte. According to the present invention, due to low charging resistance, charging efficiency and output may be improved. In addition, the present invention has an effect of providing a secondary battery having a long lifespan and excellent capacity retention at high temperature.