Fluorinated Cyclic Carbonate Electrolyte for High-Voltage Battery Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Nonaqueous-electrolyte secondary batteries face challenges in achieving high capacity, high-temperature storability, and cycle characteristics due to uneven reactions and material deterioration, particularly when attempting to increase energy density by charging to high voltages.

Innovation Solution

Incorporating a specific electrolytic solution comprising a cyclic carbonate with an unsaturated bond, a fluorinated cyclic carbonate, and an aromatic compound, along with diethyl carbonate, to form a stable coating film on electrodes, inhibiting side reactions and enhancing battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the battery is charged to high voltages to increase energy density, then capacity is improved, but uneven reactions occur and active material deteriorates

Engineering Contradiction:
ImprovecapacityVSAvoidactive material deterioration
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

A fluorinated cyclic carbonate compound is introduced as an intermediary substance that reacts preferentially with the positive electrode material at high voltages to form a protective coating film. This intermediary layer prevents direct contact between the electrolyte and active material, reducing uneven reactions and deterioration while allowing high-voltage charging for increased capacity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures. This parameter change modifies the electrochemical window and reaction characteristics, enabling stable operation at higher voltages without causing active material deterioration

Inventive Principle:
Principle #35Parameter changes

2Speed

If the battery operates at high temperatures, then reaction kinetics are improved, but gas evolution and battery swelling occur

Engineering Contradiction:
Improvereaction kineticsVSAvoidgas evolution
Core Design Contradiction:
SpeedVSObject-generated harmful factors

Solution Approach 1:

The fluorinated cyclic carbonate compound, which could potentially decompose and cause gas evolution at high temperatures, is instead utilized to form a thermally stable protective film on the positive electrode. This film acts as a barrier that prevents further decomposition reactions, converting the potential harmful high-temperature behavior into a beneficial protective function that suppresses gas evolution

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If conventional electrolyte compositions are used, then manufacturing is simple, but cycle characteristics and high-temperature storability are insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcycle characteristics
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The invention creates a composite electrolyte system by combining conventional carbonate solvents with fluorinated cyclic carbonate compounds. This composite formulation maintains the ease of manufacturing associated with conventional electrolytes while adding the functional benefits of the fluorinated compound to improve cycle characteristics and high-temperature storability

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 solution enables nonaqueous-electrolyte batteries to achieve high capacity, excellent storability, and cycle characteristics, while preventing battery deterioration and gas evolution during high-temperature storage.

Implementation Method 1

the cyclic carbonate having an unsaturated bond reacts preferentially with the positive electrode material to form a coating film that is stable even at a high potential

Methodology Applied
Scientific EffectElectrochemical reaction:

Implementation Method 2

a nonaqueous electrolyte comprising an electrolyte and a nonaqueous solvent for dissolving the electrolyte

Methodology Applied
Scientific EffectDissolution: Solvation

Data Source

PatentUS9231276B2Nonaqueous electrolytic solutions and nonaqueous-electrolyte batteries
Publication Date: 2016.01.05 MU IONIC SOLUTIONS CORP

AI summary

Nonaqueous electrolytes which can produce a battery of high capacity and excellent storability and cycle characteristics are provided, as are batteries produced with the electrolytes. The electrolytes include ones with (i) an aromatic compound having 7-18 carbon atoms in total and a fluorinated cyclic carbonate having two or more fluorine atoms, (ii) diethyl carbonate and a fluorinated cyclic carbonate having two or more fluorine atoms, (iii) at least one of a cyclic sulfonic acid ester compound, disulfonic acid ester compound, nitrile compound, and a compound of formula (1) and a fluorinated cyclic carbonate having two or more fluorine atoms, or (iv) a nonaqueous electrolyte solution for use in a high-voltage battery having a final charge voltage of 4.3 V or higher and having a fluorinated cyclic carbonate with two or more fluorine atoms.