Non-Aqueous Lithium Battery Electrolyte to Suppress High-Temperature Gas
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Solution Overview
Problem
Lithium secondary batteries face limitations in low-temperature performance and high-temperature gas generation due to the properties of existing electrolyte solutions, necessitating a solution that enhances both fast charging capabilities and low-temperature output characteristics while reducing gas generation.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries is developed, incorporating a phosphonium salt additive represented by Formula 1, which includes specific alkyl and fluorine substitutions, and other additives to improve film formation and reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene carbonate is used as the organic solvent, then the limitation of irreversible decomposition reaction with graphite material is solved, but the temperature of use is limited due to high melting point and significant degradation in battery performance at low temperatures occurs
Solution Approach 1:
The patent uses a composite electrolyte system combining ethylene carbonate (cyclic carbonate) with chain carbonate solvents (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate) in specific ratios. This composite approach leverages the high dielectric constant and graphite compatibility of EC while the chain carbonates provide low viscosity and low-temperature fluidity, achieving both compatibility and low-temperature performance through material composition optimization
Solution Approach 2:
The patent optimizes the concentration ratio of cyclic carbonate to chain carbonate in the electrolyte solution, specifically setting cyclic carbonate at 10-40 vol% and chain carbonate at 60-90 vol%. This parameter adjustment balances the high melting point disadvantage of EC with the low-temperature performance requirement by controlling the proportion of each component in the electrolyte mixture
2Reliability
If conventional electrolyte solutions are used, then basic battery operation is maintained, but gas generation increases at high temperatures and fast charging performance deteriorates
Solution Approach 1:
The patent introduces a sultone compound (1,3-propanesultone or 1,4-butanesultone) as an intermediary additive in the electrolyte solution. This compound acts as a mediator that forms protective films on electrode surfaces, preventing direct harmful reactions between the electrolyte and electrodes at high temperatures, thereby suppressing gas generation while maintaining basic battery operation
Solution Approach 2:
The patent converts the potential harmful effect of high-temperature operation into a beneficial outcome by using the sultone compound to form stable protective films on electrodes. These films prevent decomposition reactions and gas generation that would normally occur at high temperatures, transforming the high-temperature environment from harmful to manageable through controlled film formation
3Ease of operation
If conventional electrolyte solutions are used, then basic charging function is provided, but charging time is extended and fast charging capability is limited
Solution Approach 1:
The patent optimizes multiple parameters including the specific ratio of cyclic to chain carbonates (10-40 vol% to 60-90 vol%), the concentration of lithium salt (0.5-2.0 M), and the addition of sultone compound (0.1-5.0 wt%). These parameter optimizations collectively enhance ionic conductivity and reduce resistance, enabling faster charging while maintaining basic charging function
Solution Approach 2:
The patent employs a composite electrolyte formulation combining multiple components: cyclic carbonate, chain carbonate, lithium salt, and sultone compound. This composite material system works synergistically to improve ion transport efficiency and reduce charging time while preserving the fundamental charging capability of the battery
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 effectively improves the bulk properties of the electrolyte, enhances low-temperature performance, reduces gas generation at high temperatures, and supports fast charging capabilities, resulting in a more stable and efficient lithium secondary battery.
Implementation Method 1
a phosphonium salt additive, thereby reducing the amount of gas generated at high temperatures, and contributing to the improvement in fast charging performance and low-temperature output characteristics
Implementation Method 2
a non-aqueous electrolyte solution, which becomes a medium for transferring the lithium ions
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte for a lithium secondary battery, and a lithium secondary battery comprising same, the electrolyte comprising a compound represented by chemical formula 1, a lithium salt, and an organic solvent.