Phosphorofluoridate Electrolyte for High-Voltage Lithium Batteries
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Solution Overview
Problem
Existing lithium secondary batteries face issues with high-temperature stability, charge and discharge characteristics, and output characteristics due to the instability of the solid electrolyte interface (SEI) film and metal ion elution, leading to battery degradation and safety concerns.
Innovation Solution
An electrolytic solution for lithium secondary batteries comprising a lithium salt, a nonaqueous organic solvent, and a phosphorofluoridate compound represented by Chemical Formula 1, which stabilizes the positive electrode structure and suppresses side reactions, thereby enhancing battery performance under high voltage and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic electrolytic solution is used in lithium secondary battery, then charge and discharge reactions can proceed, but the electrolyte is prone to evaporation and ignition at high temperature causing safety problems
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound with specific molecular structure parameters (fluorine substitution at specific positions) to modify the electrolyte's thermal stability parameters, raising the decomposition temperature and eliminating ignition risks while maintaining ionic conductivity
Solution Approach 2:
The patent creates a composite electrolyte system by combining fluorinated cyclic carbonate compound with other carbonate solvents and lithium salts, where the fluorinated compound acts as a stabilizing component that forms protective interface films, preventing evaporation and ignition of the organic electrolyte at high temperatures
2Power
If positive electrode potential is increased to improve battery performance, then output characteristics improve, but metal ions are eluted from positive electrode and electrodeposited on negative electrode causing deterioration
Solution Approach 1:
The fluorinated cyclic carbonate compound acts as an intermediary substance that forms a protective interface film between the positive electrode and electrolyte, preventing metal ion elution at high potentials while allowing lithium ion transport, thus enabling high output characteristics without electrode deterioration
Solution Approach 2:
The patent modifies the electrode interface parameters by introducing the fluorinated compound, which changes the electrochemical window and stability characteristics, allowing operation at higher potentials without metal ion elution and electrodeposition issues
3Reliability
If SEI film is formed on negative electrode to suppress side reactions, then electrolyte decomposition is prevented, but the SEI film may collapse due to co-intercalation of electrolyte solvent causing performance degradation
Solution Approach 1:
The fluorinated cyclic carbonate compound modifies the SEI film formation parameters by introducing fluorine atoms that strengthen the chemical bonds in the SEI film, preventing collapse due to solvent co-intercalation while maintaining lithium ion conductivity and suppressing electrolyte 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 lithium secondary battery exhibits excellent life characteristics, high capacity recovery rate, and storage stability at high temperatures with reduced internal resistance, maintaining excellent cycle characteristics and stability even under high voltage and temperature.
Implementation Method 1
the phosphorofluoridate compound included in the electrolytic solution is coordinated with the transition metal of a positive electrode to further stabilize a positive electrode structure
Implementation Method 2
the phosphorofluoridate compound included in the electrolytic solution is coordinated with the transition metal of a positive electrode to further stabilize a positive electrode structure, thereby preventing a battery swelling phenomenon
Implementation Method 3
A lithium secondary battery produces electric energy by oxidation and reduction reactions when lithium ions are inserted into and desorbed from the positive and negative electrodes
Implementation Method 4
a surface of a carbon particle, which is a negative electrode active material, reacts with an electrolyte, while a coating film which is referred to as a solid electrolyte interface (SEI) film is formed on a surface of the negative electrode
Data Source
Figure 1~2
AI summary
The present disclosure relates to a lithium secondary battery electrolyte comprising a phosphorofluoridate compound represented by chemical formula 1 and a lithium secondary battery comprising same. The lithium secondary battery comprising the electrolyte according to one embodiment produces an output that does not degrade even under high voltage, and has excellent lifespan characteristics, a high capacity recovery rate at high temperature, and excellent storage stability. In addition, the lithium secondary battery comprising the electrolyte according to one embodiment has excellent output characteristics resulting from reduced internal resistance of the battery, and exhibits excellent cycle characteristics and stability even when charged under high temperature and high voltage.