Lithium Imide Electrolyte for Low Resistance Battery
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Solution Overview
Problem
Existing lithium secondary battery electrolyte solutions fail to adequately lower resistance and improve cycle characteristics, as seen in prior art using methyl difluoroacetate, LiPF6, and vinylene carbonate, which suffer from side reactions and insufficient performance.
Innovation Solution
An electrolyte solution comprising a lithium imide salt, methyl difluoroacetate as a solvent, and an unsaturated carboxylic acid anhydride compound, such as maleic anhydride, with a lithium imide salt concentration of 1.5 to 2.5 mol/L, minimizing side reactions and enhancing coating film formation on the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an electrolyte solution containing methyl difluoroacetate, LiPF6, and vinylene carbonate is used to improve charging/discharging characteristics, then initial efficiency is improved, but resistance and cycle characteristics are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solution by replacing LiPF6 with lithium imide salt and adding unsaturated carboxylic acid anhydride compound, while optimizing the concentration of methyl difluoroacetate to 10-30 vol%, thereby improving both resistance and cycle characteristics while maintaining charging/discharging performance
Solution Approach 2:
The patent creates a composite electrolyte system by combining methyl difluoroacetate solvent with lithium imide salt and unsaturated carboxylic acid anhydride compound additive, forming a synergistic composition that simultaneously achieves low resistance and high cycle stability
2Productivity
If vinylene carbonate is added to improve initial efficiency, then initial efficiency is improved, but side reactions occur and cycle characteristics are insufficient
Solution Approach 1:
The unsaturated carboxylic acid anhydride compound acts as a sacrificial additive that preferentially reacts to form a stable coating film on the negative electrode, preventing further side reactions during cycling. This disposable-like mechanism consumes the additive initially to protect the main electrolyte system from harmful side reactions
Solution Approach 2:
The unsaturated carboxylic acid anhydride compound serves as an intermediary substance that mediates between the electrolyte and negative electrode, forming a protective interface layer that prevents direct harmful interactions between the electrolyte components and the electrode, thereby suppressing side reactions
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
This configuration effectively reduces battery resistance and enhances cycle characteristics by suppressing reductive decomposition and side reactions, leading to improved performance and capacity retention.
Implementation Method 1
use of an electrolyte solution having such a constitution enables a coating film to be sufficiently formed on a negative electrode of a lithium secondary battery and enables side reactions to be suppressed
Data Source
AI summary
Provided is an electrolyte solution for a lithium secondary battery, which can lower the resistance of a lithium secondary battery and impart the lithium secondary battery with high cycle characteristics. The electrolyte solution for a lithium secondary battery disclosed here includes an electrolyte salt consisting essentially of a lithium imide salt, a solvent containing methyl difluoroacetate, and an unsaturated carboxylic acid anhydride compound represented by formula (1) below as an additive (in the formula, R1 and R2 each independently denote a hydrogen atom, a fluorine atom, or an alkyl group that may be fluorine-substituted, or R1 and R2 bond to each other to form a ring structure).