Non-Aqueous Electrolyte Composition for Stable SEI and Low Gas Generation
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Solution Overview
Problem
Lithium secondary batteries face issues with gas generation, increased resistance, and reduced lifespan due to the decomposition of organic solvents and the destruction of the solid electrolyte interface (SEI) layer, particularly when exposed to high temperatures.
Innovation Solution
A non-aqueous electrolyte comprising ethylene carbonate and a sulfonamide-based compound in a specific volume ratio, which minimizes gas generation and enhances the stability of the SEI film, thereby improving the battery's durability and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as lithium salt in non-aqueous electrolyte, then high ionic conductivity is achieved, but thermal decomposition occurs at high temperatures generating Lewis acids (HF and PF5) that destroy SEI layer and cause gas generation
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the lithium salt and the SEI layer. This compound preferentially decomposes to form a stable protective layer, preventing direct contact and harmful reactions between LiPF6 and the SEI layer, thereby eliminating gas generation while maintaining ionic conductivity
Solution Approach 2:
The fluorinated cyclic carbonate compound performs preliminary protective action by forming a stable SEI layer before the harmful thermal decomposition of LiPF6 can occur. This pre-formed protective layer prevents the generation of Lewis acids and subsequent gas production, addressing the problem before it manifests
2Productivity
If conventional organic solvents are used in electrolyte, then good ion transport is achieved, but decomposition occurs at high temperatures destroying SEI layer and increasing resistance
Solution Approach 1:
The patent creates a composite electrolyte system combining conventional organic solvents with fluorinated cyclic carbonate compound. This composite approach allows the organic solvent to maintain ion transport efficiency while the fluorinated compound provides thermal stability and SEI protection, achieving both objectives simultaneously
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate compound. This parameter change alters the decomposition behavior and thermal stability characteristics, enabling the electrolyte to maintain stability at high temperatures while preserving ion transport properties
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 proposed electrolyte effectively prevents gas generation, maintains low resistance, and extends the lifespan of lithium secondary batteries by stabilizing the SEI film and improving the electrochemical stability of the electrolyte.
Implementation Method 1
destruction of a solid electrolyte interface (SEI) layer formed on the surface of a negative electrode active material
Implementation Method 2
there is a problem in that Lewis acids such as HF and PF5 are generated due to thermal decomposition of the lithium salt
Implementation Method 3
an electrolyte serving as a medium for transferring lithium ions
Implementation Method 4
oxidation stability, chemical stability, and electrochemical stability of the non-aqueous electrolyte may be improved
Data Source
AI summary
Provided are a non-aqueous electrolyte and a lithium secondary battery comprising the same, wherein the non-aqueous electrolyte comprises a lithium salt and an organic solvent, wherein the organic solvent includes ethylene carbonate and a compound represented by Formula 1 below, and a ratio of the volume of the compound represented by Formula 1 to the volume of the ethylene carbonate is 0.20 to 3.0:wherein R1 to R3 are described herein.