Silyl phosphate-based electrolyte additive and lithium secondary battery containing the same

Lithium-ion battery with improved high-temperature cycle life for high-nickel cathodes using TMSPO additives and room-temperature formation

This technology is a lithium-ion battery that enhances high-temperature cycle life by combining a LiNi0.8Co0.1Mn0.1O2 high-nickel cathode active material with an electrolyte containing 2 wt% tris(trimethylsilyl) phosphate (TMSPO), followed by initial formation at room temperature.

While high-energy-density High-Ni NCM cathodes have gained attention for electric vehicles and energy storage systems, the instability of the cathode interface during high-temperature charging and discharging has led to continuous electrolyte decomposition and transition metal dissolution. As a result, capacity decreases rapidly as cycles progress, limiting the ability to fully leverage the advantages of high-capacity materials.

In this technology, the phosphate functional group of TMSPO creates a CEI protective layer on the cathode surface, while the silyl functional group removes fluorine-based substances that promote transition metal dissolution, maintaining 82% capacity even after 50 charge-discharge cycles at 60°C. It can be applied to electric vehicle battery cells requiring high energy density, helping to mitigate range reduction during high-temperature summer operation.

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Key Features:

• Lithium-ion battery using a ternary layered oxide represented by LiNi0.8Co0.1Mn0.1O2 as the cathode active material
• Electrolyte composition containing 2 wt% of tris(trimethylsilyl) phosphate (TMSPO) based on the total weight of the electrolyte
• Characteristics showing an 82% capacity retention rate after 50 charge-discharge cycles at 60°C by performing initial formation under room-temperature conditions
• Mechanism where the phosphate functional group of TMSPO forms a CEI layer on the high-nickel cathode surface and the silyl functional group removes fluorine-based substances

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