Fluorinated Li-Ion Electrolyte for High-Voltage Stability and Fire Resistance
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Solution Overview
Problem
Commercial lithium ion batteries face issues with energy density, oxidative decomposition of electrolytes, cathode metal ion emission, and flammability, especially at high voltages and temperatures, leading to performance degradation and safety concerns.
Innovation Solution
A lithium secondary battery electrolyte comprising fluoro carbonate, fluoro ester, and cyclic carbonate compounds, along with specific lithium salts, is developed to enhance stability and non-flammability, with optimized volume ratios and additives to maintain high voltage performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high voltage cathode material is used to improve energy density, then battery energy density is improved, but oxidative decomposition of electrolyte is deteriorated
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the high voltage cathode and the electrolyte. This compound forms a protective interface layer that prevents direct contact and reaction between the cathode and electrolyte, thereby reducing oxidative decomposition while maintaining high voltage operation and energy density
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (where R1-R6 are hydrogen, fluorine, or alkyl groups). This parameter change in electrolyte composition increases oxidation resistance while maintaining the high voltage characteristics needed for energy density improvement
2Quantity of substance
If high voltage battery is used to improve energy density, then battery energy density is improved, but cathode metal ion emission is deteriorated
Solution Approach 1:
The fluorinated cyclic carbonate compound acts as an intermediary layer between the cathode and electrolyte, preventing metal ions from the cathode from dissolving into the electrolyte. This intermediary protection reduces metal ion emission while allowing the high voltage battery to maintain its energy density advantages
Solution Approach 2:
The patent applies preliminary anti-action by having the fluorinated cyclic carbonate compound react first to form a stable protective film on the cathode surface before metal ion emission can occur. This preliminary protective action prevents the harmful metal ion emission that would otherwise happen during high voltage operation
3Quantity of substance
If conventional electrolyte is used to achieve high capacity, then battery capacity is improved, but flammability is deteriorated
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures containing fluorine atoms and cyclic carbonate groups. This parameter change in composition maintains the electrolyte's ability to support high capacity while fundamentally reducing its flammability through the presence of fluorinated groups
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 achieves improved stability, capacity retention, and non-flammability, with discharge capacities exceeding 170 mAhg−1 after 100 cycles at high voltages and self-extinguishing times less than 6 seconds, ensuring safer and more efficient battery operation.
Implementation Method 1
when a high temperature is added to the electrolyte, a reaction between a high voltage cathode and the electrolyte is further deteriorated such that an oxidative decomposition product of the electrolyte is constantly deposited on the surface of the cathode
Implementation Method 2
oxidative decomposition phenomenon of an electrolyte is deteriorated at the same time in a high voltage battery
Implementation Method 3
an organic carbonate, ester and an ionic liquid are used as a polar solvent
Data Source
AI summary
The present invention relates to a lithium secondary battery electrolyte and a lithium secondary battery including the same and, more specifically, to a flame retardant or nonflammable lithium secondary battery electrolyte having excellent stability even at a high voltage and a lithium secondary battery including the same.