Non-aqueous Electrolyte Cell Safety via Tertiary Ester and Benzene Additives
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Solution Overview
Problem
Non-aqueous electrolyte secondary cells face safety issues during overcharge, as they can smoke or catch fire due to flammable organic solvents, and existing solutions compromise cell properties like cycle characteristic and preservation characteristic.
Innovation Solution
Incorporating 20-80 volume % tertiary carboxylic acid ester in the non-aqueous solvent, along with an alkylbenzene compound and/or a halogenated benzene compound, to prevent self-discharge and maintain cell properties during overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tertiary carboxylic acid ester is contained at 20 volume % or more in the non-aqueous solvent, then safety during overcharge is improved, but self-discharge occurs more easily and cell properties degrade
Solution Approach 1:
The patent introduces an alkylbenzene compound and/or halogenated benzene compound as an intermediary substance that mediates between the tertiary carboxylic acid ester and the electrodes/electrolyte. This intermediary forms a protective film that prevents direct harmful interactions while allowing the tertiary carboxylic acid ester to maintain its safety-enhancing function during overcharge.
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple components: tertiary carboxylic acid ester (for safety), alkylbenzene compound and/or halogenated benzene compound (to inhibit self-discharge), and conventional electrolyte additives. This composite approach allows each component to contribute its specific beneficial properties while mitigating their individual drawbacks.
2Reliability
If tertiary carboxylic acid ester is contained at 20 volume % or more in the non-aqueous solvent, then safety during overcharge is improved, but cycle characteristic and preservation characteristic are compromised
Solution Approach 1:
The alkylbenzene compound and/or halogenated benzene compound acts as a protective intermediary that forms stable films on electrode surfaces and interfaces. These films prevent direct degradation reactions between the high-potential negative electrode and the non-aqueous electrolyte, thereby preserving cell properties during storage while allowing the tertiary carboxylic acid ester to function for overcharge safety.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific aromatic compounds with particular functional groups. These parameter changes alter the electrochemical stability window and interface properties, enabling the system to maintain both safety and long-term stability.
3Reliability
If tertiary carboxylic acid ester is contained at 20 volume % or more in the non-aqueous solvent, then safety during overcharge is improved, but negative electrode potential increases and electrolyte decomposition occurs
Solution Approach 1:
The alkylbenzene compound and/or halogenated benzene compound serves as a protective intermediary that forms stable interfacial films on the negative electrode. These films act as barriers that prevent direct contact and decomposition reactions between the high-potential negative electrode and the non-aqueous electrolyte containing tertiary carboxylic acid ester.
Solution Approach 2:
The patent applies preliminary protective action by having the alkylbenzene compound and/or halogenated benzene compound form stable protective films on electrode surfaces before degradation can occur. This preliminary film formation prevents the subsequent harmful decomposition reactions that would otherwise take place between the high-potential electrode and electrolyte.
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 enhances safety during overcharge while minimizing self-discharge, maintaining cell voltage and preventing electrolyte decomposition, thus ensuring both safety and good cell characteristics.
Implementation Method 1
The alkylbenzene compound and the halogenated benzene compound serve to inhibit self-discharge of the non-aqueous electrolyte secondary cells containing tertiary carboxylic acid ester
Implementation Method 2
the non-aqueous electrolyte is not decomposed, thereby preventing the degradation of the cell properties
Data Source
AI summary
A non-aqueous electrolyte secondary cell is provided having enhanced safety against overcharge and reduced self-discharge. The non-aqueous electrolyte secondary cell includes: a positive electrode having a positive electrode active material; a negative electrode having a negative electrode active material; and a non-aqueous electrolyte containing a non-aqueous solvent and electrolytic salt. The non-aqueous solvent contains 20 to 80 volume % tertiary carboxylic acid ester represented by Formula 2 at 25° C. and 1 atm. The non-aqueous electrolyte contains a halogenated benzene compound.where R1 to R4 each denote a straight-chained or branched alkyl group having 4 or less carbon atoms and may be the same or different.