Electrolyte for lithium secondary batteries containing silyl ether and lithium secondary battery comprising the same

Electrolyte for Suppressing Manganese Dissolution Using Fluoride Ion Scavenging Reaction of Methoxytrimethylsilane

This technology introduces silyl ether compounds, such as methoxytrimethylsilane, as electrolyte additives. By removing fluoride ions (F-) generated from electrolyte decomposition through a nucleophilic substitution reaction, it suppresses metal dissolution from LMO cathodes and enhances interface stability.

In lithium secondary batteries, electrolyte decomposition during charge and discharge cycles generates fluoride ions (F-). These ions corrode and dissolve transition metals in manganese-based spinel (LMO) cathodes, leading to increased internal resistance and a significant reduction in cycle life.

This technology involves adding methoxytrimethylsilane (MTSi) at a concentration of 0.1 to 1.0 wt%, preferably 0.25 wt%, to the electrolyte. The Si-O functional group reacts with fluoride ions to convert them into fluorosilane and methanol. This suppresses cathode surface cracking and manganese deposition on graphite anodes. It can be applied to cells for electric two-wheelers and hybrid vehicles using low-cost LiMn2O4 cathodes, effectively addressing the inherent lifespan limitations of manganese-based materials with a single additive.

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Key Features:

• Electrolyte for lithium secondary batteries comprising a methoxytrimethylsilane additive, a solvent, and a lithium salt
• Methoxytrimethylsilane additive contained at 0.1 to 1.0 wt% of the electrolyte to remove F-
• Additive that undergoes a nucleophilic substitution reaction with F- to produce methanol and fluorosilane
• Cathode containing LiMn2O4 manganese-based spinel active material, combined with an electrolyte layer disposed between the cathode and anode

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