Non-Aqueous Electrolyte for Stable SEI in High-Temperature Li Batteries
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Solution Overview
Problem
Lithium secondary batteries face degradation issues due to the dissolution of transition metal ions from the positive electrode, leading to a degradation of the solid electrolyte interphase (SEI) on the negative electrode, especially at high temperatures, which results in reduced stability and increased swelling.
Innovation Solution
A non-aqueous electrolyte containing a specific organic solvent compound, represented by Formula 1, is used to suppress the degradation of the positive electrode, reduce side reactions, and form a stable SEI film on the negative electrode, thereby enhancing the battery's high-temperature cycle and storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a nickel-rich positive electrode active material having high energy density is used to increase capacity, then the battery capacity increases, but the stability of the positive electrode decreases and transition metal ions dissolve
Solution Approach 1:
The patent introduces a specific organic compound (Formula 1) as an intermediary substance in the electrolyte that mediates between the nickel-rich positive electrode and the electrolyte. This compound forms a protective interface layer that prevents direct contact and harmful interactions, thereby suppressing transition metal ion dissolution while maintaining high capacity operation
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating a specific compound (Formula 1) with defined molecular structure characteristics. This parameter change in electrolyte composition leads to improved interfacial stability and reduced metal ion dissolution from the nickel-rich positive electrode
2Power
If the battery is operated at high voltage to increase output, then the power output increases, but side reactions between the positive electrode and electrolyte increase causing degradation
Solution Approach 1:
The organic compound (Formula 1) acts as a mediator that forms a stable interfacial layer between the positive electrode and electrolyte, preventing direct harmful interactions even at high operating voltages. This intermediary layer suppresses side reactions while allowing high voltage operation for increased power output
3Speed
If the battery is exposed to high temperature to increase reaction rate, then the discharge rate increases, but the swelling phenomenon is accelerated due to SEI degradation
Solution Approach 1:
The patent employs a compound (Formula 1) that performs preliminary protective action by forming a stable SEI film on the negative electrode before high-temperature operation begins. This pre-formed protective layer prevents subsequent thermal degradation and swelling phenomena that would otherwise occur during high-temperature discharge
4Quantity of substance
If transition metal ions are dissolved from the positive electrode, then the battery capacity temporarily increases through ion release, but the negative electrode is degraded due to SEI passivation ability loss
Solution Approach 1:
The organic compound (Formula 1) serves as an intermediary that prevents dissolved transition metal ions from reaching and degrading the negative electrode. It forms a protective barrier that filters out harmful ions while allowing lithium ion transport, thus protecting negative electrode integrity
Solution Approach 2:
The patent converts the potentially harmful effect of transition metal ion dissolution into a beneficial outcome by using these ions to form a stable SEI film through the mediating compound. The harmful dissolved ions are transformed into a protective interface layer that actually protects the negative electrode from further degradation
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 use of the non-aqueous electrolyte with the compound represented by Formula 1 results in improved electrode-electrolyte interface stability, reduced gas generation, and extended battery life by forming a polymer-inorganic material film rich in LiF, which prevents SEI degradation and maintains performance even at high temperatures.
Implementation Method 1
forming a stable solid electrolyte interphase (SEI) film on the negative electrode
Implementation Method 2
suppress degradation of a positive electrode, may reduce a side reaction between the positive electrode and the electrolyte
Implementation Method 3
minimizes formation of an organic material film derived from carbonate with high electrolyte solution permeability, and suppresses generation of oxidizing gas
Data Source
AI summary
Provided is a non-aqueous electrolyte including a lithium salt and an organic solvent, wherein the organic solvent includes a compound represented by Formula 1 in an amount of 25 wt % to 80 wt % based on the total non-aqueous electrolyte:[Formula 1]wherein, in Formula 1, R1 and R2 may each independently be any one selected from the group consisting of hydrogen (H), an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, and an aryl group having 6 to 20 carbon atoms, and X may be a perfluoroalkyl group having 1 to 5 carbon atoms.