Separator coating composition containing antimony oxide, a separator using the same, and a secondary battery including the same

High-Strength Polyimide Separator Based on Fluoride Ion-Scavenging Sb2O3 Coating

This technology is a functional separator that controls pore size and enhances mechanical strength by coating antimony oxide (Sb2O3) onto a porous polyimide (PI) support. It also chemically removes fluoride ions (F-) from the electrolyte.

Conventional polyimide (PI) separators often have excessively developed porous structures, posing a risk of internal short circuits during initial cycles. Additionally, halogen species (F-) in the electrolyte can corrode electrode materials, leading to performance degradation.

This technology involves applying a coating composition containing Sb2O3 and a PVdF-HFP binder to one or both sides of a PI support. The coated antimony oxide finely adjusts pore size and reacts with fluoride ions in the electrolyte to form SbF3·SbOF, thereby suppressing side reactions and ensuring cycling stability. Applicable to NCM811 cells using LiPF6-based electrolytes and high-voltage cathode systems sensitive to hydrogen fluoride corrosion, the separator itself handles acidic impurity removal, reducing the need for separate scavenger additives.

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Key Features:

• Separator coating composition comprising antimony oxide (Sb2O3), a polyvinylidene fluoride-hexafluoropropylene binder, and an NMP solvent
• Antimony oxide coating layer that fills the pores of a porous support to reduce pore size and improve the mechanical strength of the separator
• Antimony oxide that removes F- species through chemical scavenging reactions and improves the wettability of the separator
• Lithium secondary battery comprising a poly(imide) (PI)-based separator interposed between a cathode and an anode, and an electrolyte

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