Battery Pack Insulation Sheet With Controlled Gas Venting

The patent uses a composite structure combining hydrophobicized inorganic particles (dry type silica or silica aerogel) with a hydrophobic binder fiber. The binder fiber matrix embeds and secures the inorganic particles, preventing aggregation and powder falling while maintaining the low thermal conductivity of the dry type materials. This composite approach allows the heat insulating sheet to achieve excellent thermal insulation performance without sacrificing structural integrity.

The patent applies hydrophobicization treatment to both the inorganic particles and the binder fiber, changing their surface properties. This hydrophobic modification prevents water absorption that would cause aggregation, thereby maintaining particle dispersion and stability throughout the sheet's service life while preserving the low thermal conductivity of the dry type silica or silica aerogel.

The patent employs a resin film that fully encapsulates the heat insulating material, creating a sealed structure. This film prevents inorganic particles from being ejected during thermal runaway events while still allowing controlled gas discharge through designated pathways. The encapsulation maintains particle containment without compromising pressure relief functionality.

The resin film is designed with specific hole configurations - holes in the first and second surface-side films but fewer or no holes in the end surface-side film. This segmentation of discharge pathways allows gas to escape through controlled openings while the overall encapsulation structure prevents particle ejection, separating the functions of pressure relief and particle containment.