Lithium secondary battery separator containing boron nitride, manufacturing method thereof, and lithium secondary battery comprising the same

High-Heat-Resistant PAN Separator Based on Boron Nitride-TNP Radical Scavenging Composite Coating

This technology involves coating the surface of a polyacrylonitrile (PAN)-based separator with a composite of boron nitride (BN) and tri-1-naphthylphosphine (TNP), a free radical scavenger. This process closes the large pores characteristic of PAN separators and improves their thermal and electrochemical stability.

While PAN-based separators offer excellent heat resistance, their macroscopic pore structure has historically made them prone to internal short circuits during battery assembly. These shorts pose significant risks, including current leakage and thermal runaway.

This technology utilizes dip-coating to apply nano-sized boron nitride with a PVdF-HFP binder to seal separator pores, while incorporating the free radical scavenger TNP to enhance high-temperature thermal stability and cycle performance. Specifically, by controlling the BN content to 1.87 mg/cm² or higher, the technology prevents short circuits and boosts capacity retention. Suitable for EV modules and large-capacity energy storage cells where preventing thermal runaway propagation is critical, the high thermal conductivity of BN also provides a heat dissipation effect by dispersing localized heat.

‍

‍

Key Features:

• A separator for lithium secondary batteries comprising boron nitride, with a boron nitride and tri-1-naphthylphosphine (TNP) composite coated on its surface
• Boron Nitride (BN) coated onto the separator via dip-coating at a content of 1.87 mg cm-2 or more
• A step of preparing a dispersion solution by dispersing boron nitride and TNP in a binder solution where PVdF-HFP binder is dissolved in acetone
• A step of dip-coating a polyacrylonitrile-based separator in the dispersion solution to coat the separator surface with boron nitride

‍