Non-Aqueous Lithium Battery Electrolyte for High-Temperature SEI Stability
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Solution Overview
Problem
Lithium secondary batteries experience increased resistance and capacity degradation due to the decomposition of electrolyte components under high temperature conditions, leading to instability of the SEI film and transition metal ion elution, which affects battery performance.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries containing a compound with a propargyl group and fluorocarbon functional group forms a low-resistance SEI film, preventing additional decomposition and elution of transition metal ions, thereby stabilizing the electrode surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions are used under high temperature conditions, then lithium ion conductivity is maintained, but PF6- anions decompose to form Lewis acids that destruct SEI films and cause transition metal ion elution
Solution Approach 1:
The fluorinated cyclic carbonate compound performs preliminary action by forming a stable SEI film on the electrode surface before conventional electrolyte components can decompose. This pre-formed protective layer prevents subsequent Lewis acid attacks and transition metal ion elution that would otherwise occur under high temperature conditions.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate compounds with specific fluorine substitution patterns. This parameter change increases the decomposition temperature and stability of the SEI film, preventing thermal decomposition of conventional electrolyte components like LiPF6.
2Quantity of substance
If transition metal ions are eluted from the positive electrode, then battery capacity increases initially, but lattice structure becomes unstable leading to active oxygen generation and electrolyte decomposition
Solution Approach 1:
The fluorinated cyclic carbonate compound acts as an intermediary protective layer between the positive electrode and electrolyte. This intermediary SEI film prevents direct contact and reaction between electrolyte components and the positive electrode surface, thereby preventing transition metal ion elution and subsequent lattice structure instability.
3Reliability
If SEI film is destroyed and regenerated under high temperature, then electrode surface is re-passivated, but additional lithium ions are consumed and resistance increases
Solution Approach 1:
The fluorinated cyclic carbonate compound performs preliminary passivation by forming a stable SEI film before high temperature conditions can cause film destruction. This pre-formed robust SEI layer maintains electrode passivation without requiring regeneration, thereby preventing additional lithium ion consumption and resistance increase.
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 solution suppresses self-discharge reactions and increases output characteristics by forming a robust SEI film, reducing initial resistance and maintaining battery performance at various temperatures.
Implementation Method 1
it may be reduced before the organic solvent to form a low-resistance SEI film including a fluorocarbon component on the surface of the electrode
Implementation Method 2
suppressing additional reductive decomposition of the non-aqueous electrolyte solution
Implementation Method 3
prevents a self-discharge reaction of the negative electrode
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery including the same. Specifically, the non-aqueous electrolyte solution for a lithium secondary battery includes a lithium salt, an organic solvent and a compound represented by Formula 1 to form a robust SEI film, thereby improving battery performance.