Phosphorofluoridate Battery Electrolyte for Stable High-Voltage Cycling
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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, which stabilizes the positive electrode structure and suppresses side reactions, enhancing high-temperature storage stability and output characteristics.
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 electrolytic solution is prone to evaporation and ignition at high temperature causing safety problems
Solution Approach 1:
A coating film (SEI film) is formed on the surface of the negative electrode through reaction between the organic electrolytic solution and the electrode. This coating film acts as an intermediary layer that prevents direct contact between the electrolytic solution and the negative electrode, thereby suppressing evaporation and ignition at high temperature while still allowing lithium ion transport
2Productivity
If potential of positive electrode is increased to improve battery performance, then charge and discharge capacity increases, but metal ions are eluted from positive electrode and electrodeposited on negative electrode causing deterioration
Solution Approach 1:
The coating film formed on the negative electrode surface acts as a protective intermediary that prevents eluted metal ions from the positive electrode from directly contacting and depositing on the negative electrode, thereby maintaining electrode stability even at increased potentials
Solution Approach 2:
The invention uses specific compounds (cyclic carboxylate and/or cyclic sulfate) as additives in the electrolytic solution to modify the properties of the coating film, making it more effective at suppressing metal ion elution and electrodeposition at higher potentials
3Reliability
If SEI film is formed to suppress side reactions, then battery performance degradation is minimized, but the SEI film may not be stable at high temperature leading to performance degradation
Solution Approach 1:
The invention changes the chemical composition parameters of the electrolytic solution by adding specific compounds (cyclic carboxylate and/or cyclic sulfate) to modify the SEI film formation process, creating a more thermally stable SEI film that maintains its protective function at high temperatures
Solution Approach 2:
The SEI film becomes a composite structure formed by the interaction of multiple electrolyte components (organic electrolytic solution, cyclic carboxylate, and cyclic sulfate), creating a more stable and multifunctional coating that provides both ion transport and high-temperature stability
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 electrolytic solution improves battery life characteristics, reduces internal resistance, and maintains excellent output characteristics even under high voltage and temperature conditions, with a high capacity recovery rate and improved cycle stability.
Implementation Method 1
the phosphorofluoridate compound stabilizes the positive electrode structure and suppresses side reactions
Implementation Method 2
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
Implementation Method 3
lithium ions from a lithium metal oxide which is a positive electrode at initial charge move to a carbon electrode which is a negative electrode and are intercalated in carbon
Implementation Method 4
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
Data Source
Figure 1~2
AI summary
The present disclosure relates to an electrolytic solution containing a phosphorofluoridate compound for a lithium secondary battery, and a lithium secondary battery comprising the electrolytic solution, wherein the lithium secondary battery comprising the electrolytic solution according to one embodiment produces an output that does not degrade even under high-voltage conditions, has excellent lifespan characteristics, and exhibits excellent storage stability and a high capacity-recovery rate at high temperatures. Additionally or alternatively, the lithium secondary battery comprising the electrolytic solution 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 in high-temperature and high-voltage conditions.