Non-Aqueous Electrolyte Additives for High-Voltage Lithium Battery Stability
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Solution Overview
Problem
Secondary batteries experience deterioration of positive electrodes and negative electrodes due to side reactions and gas generation, leading to reduced cycle properties and high-temperature stability issues.
Innovation Solution
A non-aqueous electrolyte comprising lithium salt, organic solvent, and additives including a compound represented by Formula 1 and lithium difluoro(oxalato)borate (LiODFB), which stabilizes the electrolyte and suppresses transition metal elution, reducing gas generation and improving high-temperature durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a secondary battery is driven under high voltage for higher capacity, then the battery capacity increases, but the positive electrode and negative electrode deteriorate due to side reactions and transition metal ion elution
Solution Approach 1:
The patent introduces a film-forming additive as an intermediary substance that forms a protective interface layer between the electrode and electrolyte. This additive acts as a mediator that prevents direct harmful interactions between the high-voltage electrode and the electrolyte, thereby suppressing transition metal ion elution and side reactions while maintaining high battery capacity
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding specific film-forming additives. This parameter change alters the properties of the electrode surface film, making it more stable and less prone to transition metal ion elution under high-voltage conditions, thus resolving the contradiction between capacity and reliability
2Quantity of substance
If the potential of the positive electrode is increased to improve capacity, then the battery capacity increases, but the cycle properties deteriorate due to accelerated deterioration phenomena
Solution Approach 1:
The film-forming additive performs preliminary action by forming a stable protective film on the positive electrode surface before the electrode undergoes deterioration. This pre-formed protective layer prevents subsequent degradation reactions, allowing the battery to maintain high capacity over extended cycling periods
Solution Approach 2:
The protective film formed by the additive serves as an intermediary barrier between the high-potential positive electrode and the electrolyte. This intermediary layer suppresses the accelerated deterioration reactions that would otherwise occur at high potentials, thereby improving cycle properties while maintaining capacity
3Adaptability or versatility
If the battery is exposed to high temperatures, then the battery can operate in broader conditions, but the cycle properties and storage properties deteriorate due to accelerated side reactions and gas generation
Solution Approach 1:
The film-forming additive creates a thermally stable protective film that acts as an intermediary barrier at high temperatures. This protective layer suppresses temperature-accelerated side reactions and gas generation, allowing the battery to maintain reliability across a broader temperature range
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding film-forming additives that form thermally stable films. This parameter modification enhances the thermal stability of the electrode interface, suppressing gas generation and side reactions at high temperatures while expanding the operating temperature range
4Duration of action of moving object
If lithium secondary batteries are continuously used for long periods or stored at high temperatures, then the battery provides continuous service, but gas is generated causing swelling and increased battery thickness
Solution Approach 1:
The film-forming additive creates a protective film that acts as an intermediary barrier, suppressing the long-term and high-temperature-induced side reactions that generate gas. This protective layer prevents gas accumulation that would otherwise cause battery swelling and thickness increase during extended service periods
Solution Approach 2:
The additive performs preliminary action by forming a stable protective film before gas-generating side reactions can occur during long-term use or storage. This pre-formed film prevents the accumulation of decomposition gases, thereby preventing battery swelling and maintaining dimensional stability over extended service durations
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 stabilizes the positive electrode, suppresses negative electrode degradation, and enhances high-temperature cycle and storage properties of lithium secondary batteries.
Implementation Method 1
suppress the decomposition of a lithium salt
Implementation Method 2
in an environment in which a stable positive electrode film formed by the combination of the diisocyanate-based compound of Formula 1 and lithium difluoro(oxalato)borate (LiODFB) is sufficiently formed
Implementation Method 3
suppress the elution of transition metal ions from a positive electrode
Implementation Method 4
suppress a decomposition reaction of a carbonate-based solvent and a propionate-based solvent
Implementation Method 5
ethylene propionate (EP) and propyl propionate (PP) are less reactive with oxygen de-intercalated from a positive electrode material, so that carbon dioxide, an oxidizing gas, is suppressed
Implementation Method 6
The degradation in passivation capability of SEI at high temperatures may be suppressed to prevent the deterioration of a negative electrode
Data Source
AI summary
Provided are a non-aqueous electrolyte including a lithium salt, an organic solvent, and an additive, wherein the additive includes a compound represented by Formula 1 below and lithium difluoro(oxalato)borate (LiODFB), and the organic solvent includes ethylene carbonate (EC), propylene carbonate (PC), ethylene propionate (EP), and propyl propionate (PP):In Formula 1 above, n is an integer of 3 to 10.