A lithium secondary battery comprising an electrolyte for a lithium secondary battery containing trimethoxymethylsilane

Lithium secondary battery with extended graphite anode life using trimethoxymethylsilane-derived Si-based SEI

This technology involves adding trimethoxymethylsilane (TMSi), a silyl ether-based additive, to the electrolyte to form a robust solid electrolyte interphase (SEI) layer containing Si-O-Si, Si-O, and Si-C functional groups on the graphite anode surface during charge/discharge, thereby suppressing continuous electrolyte decomposition.

Conventional batteries using carbonate-based electrolytes and graphite anodes suffer from unstable SEI layers caused by continuous electrolyte decomposition during charge/discharge cycles. This leads to limitations in cycle life and capacity retention.

This technology adds 0.25 wt% to less than 1.0 wt% of TMSi relative to the total electrolyte weight and uses an EC:EMC volume ratio of 1:2 to form a Si-based SEI layer on the graphite anode via electrochemical reduction. It can be applied to power cells for power tools and e-bikes using LMO spinel cathodes and graphite anodes, helping to suppress electrolyte consumption and improve capacity retention over long-term cycling.

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Key Features:

• An electrolyte layer disposed between the cathode and anode, containing a trimethoxymethylsilane additive, a solvent, and a lithium salt
• A trimethoxymethylsilane (TMSi) additive contained in an amount of 0.25 wt% to less than 1.0 wt% based on the total electrolyte weight
• An electrolyte solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 1:2 volume ratio
• A trimethoxymethylsilane-derived solid electrolyte interphase (SEI) layer disposed between the anode and the electrolyte layer, containing Si-O-Si, Si-O, and Si-C functional groups

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