Alkyl Benzonitrile Electrolyte Additive for Lithium Battery Overcharge Protection
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Solution Overview
Problem
Lithium rechargeable batteries face safety concerns and reduced cycle-life when overcharged, as existing electrolytes do not effectively prevent decomposition and heat generation during overcharging.
Innovation Solution
An electrolyte composition for lithium rechargeable batteries including a lithium salt, succinonitrile additive, and an alkyl benzonitrile compound, which decomposes at a lower voltage than the non-aqueous organic solvent, generating heat to prevent overcharge and enhancing cycle-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium rechargeable batteries, then the battery can operate with high energy density, but the battery safety is compromised and cycle-life is deteriorated when overcharged
Solution Approach 1:
The patent introduces an electrolyte additive that proactively decomposes at a lower voltage threshold (4.8-5.3V) before the main electrolyte solvent decomposes. This preliminary decomposition action generates heat that triggers the protection device to cut off charging, preventing overcharge conditions that would otherwise damage the battery and reduce cycle-life. The additive performs the protective function in advance, before harmful overcharging occurs.
Solution Approach 2:
The electrolyte additive acts as an intermediary substance between the electrolyte system and the protection device. It mediates the overcharge protection mechanism by decomposing first and generating heat signals that activate the protection device, thereby indirectly protecting the battery without requiring direct modification of the main electrolyte composition or protection device hardware.
2Reliability
If the electrolyte decomposition voltage is increased to prevent overcharge, then battery safety improves, but the operating voltage range and energy density are reduced
Solution Approach 1:
The patent applies local quality by introducing a small concentration (0.1-5 wt%) of electrolyte additive with specific decomposition characteristics into the bulk electrolyte system. This localized component has the quality of decomposing at a lower voltage (4.8-5.3V) than the main electrolyte solvent, creating a localized protective mechanism that does not alter the overall high operating voltage capability (up to 4.8V or higher) and energy density of the battery system.
Solution Approach 2:
The patent changes the decomposition voltage parameter of the electrolyte system by adding substances with specific electrochemical properties. The additive's decomposition voltage (4.8-5.3V) is deliberately set below the main electrolyte solvent's decomposition voltage, creating a two-stage decomposition profile that enables overcharge protection while preserving the battery's high energy density operating characteristics.
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 composition ensures superb safety during overcharge and excellent cycle-life by initiating decomposition of the alkyl benzonitrile at a lower voltage, cutting off protection devices and preventing further overcharge, while maintaining high battery performance.
Implementation Method 1
the alkyl benzonitrile compound, which decomposes at a lower voltage than the non-aqueous organic solvent, generating heat to prevent overcharge
Implementation Method 2
generating heat to prevent overcharge and enhancing cycle-life
Data Source
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AI summary
A solvent for an electrolyte for a rechargeable lithium battery including a lithium salt, a non-aqueous organic solvent, and an alkyl benzonitrile compound represented by the following Chemical Formula 1, and a rechargeable lithium battery including the same are provided. In Chemical Formula 1, R is a substituted or unsubstituted C1 to C10 alkyl group.