Secondary Battery Electrolyte High Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries using high-potential positive electrode materials face challenges with long-term cycle life at high temperatures due to electrolyte decomposition, leading to gas generation and pressure issues, and existing fluorine-containing ether compounds have limitations in oxidation resistance and compatibility.
Innovation Solution
A secondary battery electrolyte comprising a combination of two or more fluorine-containing ether compounds and one or more fluorine-containing phosphate ester or sulfone compounds, with specific content ratios and fluorine substitution rates to enhance voltage resistance and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-potential positive electrode materials (such as LiNi0.5Mn1.5O4 operating at 4.5V or higher) are used to increase energy density, then the operating voltage and energy density are improved, but the decomposition reaction of the electrolyte progresses, generating gas and causing swelling
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorine-containing ether compounds with specific fluorine substitution rates (50-100%) and controlling their content (1-50 vol%). This parameter modification enables the electrolyte to withstand high operating voltages of 4.5V or higher while suppressing decomposition reactions and gas generation, thus resolving the contradiction between energy density improvement and electrolyte stability.
Solution Approach 2:
The patent creates a composite electrolyte system by combining fluorine-containing ether compounds (as main solvent) with fluorine-containing carbonate esters or fluorine-containing phosphate ester compounds (as additives). This composite approach leverages the high voltage resistance of fluorinated compounds while maintaining良好的 ion conductivity, enabling stable operation at high potentials without excessive gas generation.
2Reliability
If fluorine-containing ether compounds are used to improve voltage resistance and suppress gas generation, then the life characteristics are improved, but the viscosity increases and compatibility with other solvents decreases
Solution Approach 1:
The patent applies local quality by using fluorine-containing ether compounds with specific fluorine substitution rates (50-100%) at controlled concentrations (1-50 vol%). This localized optimization ensures that the fluorinated compounds provide sufficient voltage resistance and gas suppression at the electrode interface without excessively increasing the bulk electrolyte viscosity or compromising compatibility with other necessary electrolyte components.
Solution Approach 2:
The patent modifies the electrolyte composition by incorporating fluorine-containing carbonate esters or fluorine-containing phosphate ester compounds as additives in specific amounts. This parameter adjustment compensates for the potential viscosity increase and compatibility issues caused by fluorine-containing ether compounds, maintaining overall electrolyte performance while preserving the life-extending benefits.
3Reliability
If the fluorine content in fluorine-containing ether compounds is increased to raise oxidation resistance, then the voltage resistance is improved, but the viscosity increases and reduction resistance decreases
Solution Approach 1:
The patent optimizes the fluorine substitution rate parameter within the range of 50-100% for the fluorine-containing ether compounds. This parameter control ensures sufficient oxidation resistance at the high potential positive electrode (4.5V or higher) while preventing excessive viscosity increase and maintaining adequate reduction resistance for proper ion transport, thus balancing multiple performance requirements.
Solution Approach 2:
The patent employs a composite electrolyte formulation combining fluorine-containing ether compounds (with optimized fluorine substitution rates) and fluorine-containing carbonate esters or fluorine-containing phosphate ester compounds. This composite approach balances the oxidation resistance provided by highly fluorinated compounds with the流动性 and compatibility of less fluorinated components, achieving both high voltage resistance and maintained reduction resistance.
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 improves the life characteristics of lithium secondary batteries, particularly at high voltages and temperatures, by reducing gas generation and maintaining oxidation resistance while ensuring compatibility with other solvents.
Implementation Method 1
the decomposition reaction of an electrolyte at the contact portion of a positive electrode with the electrolyte is liable to progress. The decomposition reaction generates gas... As electrolytes with high voltage resistance capable of suppressing the gas generation, fluorinated solvents and the like are thought of
Data Source
AI summary
The present invention relates to a secondary battery electrolyte, which contains a first fluorine-containing ether compound, a second fluorine-containing ether compound, and at least one selected from fluorine-containing phosphate ester compounds and sulfone compounds, wherein the fluorine substitution rate of the first fluorine-containing ether compound is lower than that of the second fluorine-containing ether compound, and the content of the first fluorine-containing ether compound is higher than that of the second fluorine-containing ether compound. According to the present invention, with respect to batteries operating at a high voltage, and batteries supposed to be used at a high temperature for a long period, there can be provided a lithium secondary battery suppressed in the decomposition reaction of the electrolyte and improved in the life characteristics.