Crosslinked Separator Coating for Thin Lithium Battery Heat Resistance

The patent changes the chemical parameters of the coating material from polyethylene wax to poly(vinylamide)-based copolymer with crosslinking reactive groups. This parameter change enables the coating to maintain both shutdown function and high-temperature retention, as the crosslinking structure prevents dissolution while preserving the desired safety characteristics.

The patent creates a composite coating system combining poly(vinylamide)-based copolymer with crosslinking agent and inorganic particles. This composite structure provides multiple functions simultaneously: the polymer matrix offers shutdown capability, the crosslinked network ensures retention, and inorganic particles enhance thermal stability, resolving the contradiction between shutdown function and coating retention.

The patent applies composite materials by coating poly(vinylamide)-based copolymer with crosslinking agent and inorganic particles onto the olefin-based separator. This composite coating maintains the substrate's flexibility while adding thermal stability through the crosslinked polymer network and heat-resistant inorganic particles, preventing thermal contraction at high temperatures.

The patent applies local quality by providing a functional coating layer on the separator surface that specifically addresses thermal stability where needed, while the bulk olefin-based separator retains its inherent flexibility. The coating layer has different properties than the substrate, with the crosslinked structure providing localized thermal resistance at the critical separator surface.