Cross-Linked Polyolefin Separator for Thermal Runaway Resistance

The patent applies composite materials by combining polyolefin microporous membrane with inorganic particles (alumina, silica, titania, etc.) and organic binder resins to create a separator composite structure. This composite structure maintains the electrical insulating properties and ion permeability of the polyolefin base while the inorganic particles provide thermal stability and prevent thermal runaway, thus resolving the contradiction between electrical performance and thermal safety.

The patent changes the physical and chemical parameters of the separator by controlling the mean particle size of inorganic particles (0.1-10 μm), the porosity (30-80%), and the composition ratios of different components. These parameter adjustments optimize both the electrical insulating properties and thermal stability, allowing the separator to maintain electrical performance while resisting thermal runaway and local short circuits.

The patent utilizes porous materials by forming a microporous structure with controlled porosity (30-80%) and specific pore size distribution. This porous structure is achieved through a phase separation process during membrane formation, which is relatively simple to manufacture. The porous structure provides both ease of manufacturing and excellent heat shrinkability, as the porous network maintains structural integrity at high temperatures while allowing ion transport.

The patent applies local quality by creating regions with different properties within the separator structure. The inorganic particles are distributed throughout the matrix to provide localized thermal stability, while the organic binder resins provide localized adhesive properties and flexibility. This localized functional distribution achieves high-temperature stability and heat shrinkability without complicating the overall manufacturing process.

The patent applies universality by selecting inorganic particles that serve multiple functions simultaneously. The inorganic particles (alumina, silica, titania, etc.) provide thermal stability, mechanical strength, and chemical inertness all at once. The organic binder resins also serve multiple purposes: binding inorganic particles, providing flexibility, and maintaining porosity. This multi-functionality approach improves heat resistance without significantly increasing device complexity.

The patent uses natural mineral particles that occur in various forms and sizes, selecting from naturally available materials like alumina, silica, and titania. By utilizing these naturally occurring inorganic particles with established properties, the patent avoids the need to create complex synthetic structures, thereby improving heat resistance while keeping the device structure relatively simple and manageable.