Separator for lithium secondary batteries containing a tungsten oxide and trimesitylborane composite, method for manufacturing the same, and lithium secondary battery comprising the same

WO3-TMB Composite Coated Separator Using Boron Vacant p-Orbital Radical Trapping

This technology involves coating a separator with a composite that embeds the radical scavenger trimesitylborane (TMB) onto the surface of tungsten oxide (WO3) to chemically remove radical species generated by electrochemical side reactions within the battery and suppress electrolyte decomposition.

When using high-energy-density Ni-rich NCM cathodes, unstable Ni4+ species on the surface react with the surrounding electrolyte to generate highly reactive radical species, which leads to chain-reaction electrolyte decomposition and reduced battery lifespan.

This technology involves manufacturing a WO3-TMB composite by anchoring TMB to tungsten oxide and coating it onto the separator surface in a layer approximately 12 μm thick. The boron atom at the center of the TMB binds to and scavenges radical species via its vacant p-orbital. It can be applied to premium electric vehicle cells using high-nickel cathodes and power storage modules requiring long-cycle operation, effectively trapping Ni4+-originated radicals at the separator surface before they spread throughout the electrolyte.

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Key Features:

• A tungsten oxide-trimesitylborane composite included in a separator, formed by embedding trimesitylborane (TMB) on the surface of tungsten oxide (WO3)
• A trimesitylborane (TMB) component that acts as a radical scavenger by forming a bond between boron (B) and radicals
• A tungsten oxide-trimesitylborane layer disposed on the surface of the separator with an average thickness of 12 μm
• A step of preparing the composite by embedding trimesitylborane on the surface of tungsten oxide (WO3) via a condensation reaction

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