Non-Aqueous Electrolyte for Stable SEI on Silicon Anodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium secondary batteries with silicon-based negative electrodes face instability and poor high-temperature stability due to volume changes during charge and discharge, leading to cracks in the SEI film and reduced durability.
Innovation Solution
A non-aqueous electrolyte solution containing a compound represented by Formula 1, which includes nitrogen and fluorine atoms, is used to form a stable SEI film on the silicon-based negative electrode, scavenging Lewis acids and enhancing high-temperature stability and durability by forming a robust organic-inorganic composite film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (ammonium fluorosulfonate mixed with lithium hydroxide aqueous solution) are used to produce lithium fluorosulfonate, then lithium fluorosulfonate can be obtained, but the production process becomes complex and contamination with ammonia occurs
Solution Approach 1:
The invention extracts and eliminates the problematic intermediate step involving ammonium fluorosulfonate and cation exchange. Instead of using the conventional two-step process (forming ammonium salt then exchanging cations), the patent directly synthesizes lithium fluorosulfonate by reacting fluorosulfonic acid with lithium salt in nonaqueous solvent, removing the source of ammonia contamination and process complexity
Solution Approach 2:
The invention introduces a nonaqueous solvent as an intermediary medium to enable direct reaction between fluorosulfonic acid and lithium salt. This intermediary allows the reaction to proceed without forming the problematic ammonium intermediate, achieving both simplification and high purity
2Productivity
If LiClO4 is used as electrolyte, then electrolyte can be provided, but active oxygen is formed due to decomposition at electropositive potential which attacks the solvent and accelerates decomposition
Solution Approach 1:
The invention changes the chemical composition parameter of the electrolyte from LiClO4 to lithium fluorosulfonate (LiFSO3). This parameter change fundamentally alters the decomposition behavior at electropositive potentials, preventing the formation of active oxygen while maintaining high discharge capacity and improving battery performance
3Productivity
If CF3SO3Li, LiBF4 or LiPF6 are used as electrolyte, then electrolyte can be provided, but fluorine is formed due to decomposition at electropositive potential which attacks the solvent and accelerates decomposition
Solution Approach 1:
The invention changes the electrolyte composition from fluorine-containing salts (CF3SO3Li, LiBF4, LiPF6) to lithium fluorosulfonate. Although lithium fluorosulfonate contains fluorine in its structure, the fluorine is bonded in a stable configuration that prevents decomposition and release of free fluorine at electropositive potentials, thereby eliminating solvent attack while maintaining high productivity
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 improves the high-temperature stability and durability of lithium secondary batteries by forming a stable SEI film that suppresses decomposition and maintains ion mobility, preventing cracks and maintaining capacity characteristics.
Implementation Method 1
A method of producing lithium fluorosulfonate which comprises reacting fluorosulfonic acid with a specific gravity of less than 1.5 in a nonaqueous solvent with a lithium salt
Implementation Method 2
nonaqueous electrolytic solution containing lithium fluorosulfonate
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte solution having improved high-temperature stability and high-temperature durability and a lithium secondary battery including the same. The non-aqueous electrolyte solution according to the present invention may include a lithium salt; a non-aqueous organic solvent; and a compound represented by Formula 1 of a specific structure.