Lithium Ion Battery Electrolyte Gas Generation Mitigation
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Solution Overview
Problem
Existing non-aqueous electrolytes for lithium ion batteries containing fluorinated solvents generate excessive gas during high-temperature storage, leading to safety hazards and performance degradation, while attempts to improve high-temperature cycle performance with fluorocarboxylic acid ester result in compatibility issues with carbon cathodes.
Innovation Solution
A non-aqueous electrolyte comprising a compound A, such as fluoroethylene carbonate, and a compound B, selected from specific structural formulas, which form a dense passivation film on the negative electrode, inhibiting gas generation and enhancing high-temperature and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorinated solvent is added to improve high-temperature cycle performance, then cycle performance is improved, but gas generation increases causing safety hazards
Solution Approach 1:
The patent introduces a mediator substance (lithium difluoromalonate or lithium monofluoromalonate) that acts as an intermediate compound to regulate the interaction between fluorinated solvent and electrode materials. This mediator forms a stable interface layer that prevents direct harmful reactions while maintaining the beneficial cycle performance enhancement, thereby reducing gas generation without sacrificing reliability
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding specific lithium salts (lithium difluoromalonate or lithium monofluoromalonate) at controlled concentrations (0.1-5 wt%). This parameter modification alters the electrochemical behavior of the system, enabling the fluorinated solvent to improve cycle performance while the lithium salt suppresses gas generation through formation of a stable protective film
2Reliability
If fluorocarboxylic acid ester is added to improve high-temperature cycle performance, then cycle performance is improved, but compatibility with carbon cathode material deteriorates causing battery inflation
Solution Approach 1:
The lithium malonate compounds serve as intermediary substances that mediate between fluorocarboxylic acid ester and carbon cathode material. They form a stable interfacial layer that prevents direct incompatibility reactions, allowing the fluorocarboxylic acid ester to improve cycle performance while the intermediary prevents battery inflation and maintains compositional stability
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorocarboxylic acid ester with lithium difluoromalonate or lithium monofluoromalonate. This composite formulation synergistically combines the high-temperature cycle performance enhancement of fluorocarboxylic acid ester with the stability-providing properties of lithium malonate, resolving the compatibility issue with carbon cathode material
3Use of energy by moving object
If working voltage is increased to improve energy density, then energy density is improved, but electrolyte stability deteriorates causing oxidative decomposition
Solution Approach 1:
The patent changes the electrochemical stability window parameters of the electrolyte by incorporating fluorinated solvents and lithium malonate compounds. These additions raise the oxidation resistance of the electrolyte, enabling stable operation at higher working voltages (4.5-5V) that correspond to higher energy density, while the lithium malonate forms a protective film that prevents oxidative decomposition
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 combination significantly improves high-temperature cycle and storage performance, while maintaining low-temperature performance and ensuring thermal stability, thus addressing safety concerns and performance degradation issues.
Implementation Method 1
compound A and a compound B, wherein the compound A is at least one of compounds represented by the following structural formula I, formula II and formula III; the compound B is a compound represented by the following structural formula IV
Data Source
AI summary
To solve the problems that the existing non-aqueous electrolyte for lithium ion battery containing fluorinated solvent generates serious gas expansion when improving high-temperature cycle performance and affects high-temperature safety performance of battery. The application provides a non-aqueous electrolyte for lithium ion battery. The non-aqueous electrolyte for lithium ion battery comprises a compound A and a compound B, wherein the compound A is at least one of compounds represented by the following structural formula I, formula II and formula III; the compound B is a compound represented by the following structural formula IV; formula I: R1—COO—R2; formula II: R3—OCOO—R4. The non-aqueous electrolyte for lithium ion battery provided by the invention contains both the compound A and the compound B, the synergistic effect of compound A and compound B can effectively improve high-temperature cycle performance and high-temperature storage performance of battery, and can also give consideration to low-temperature performance of battery.