Composite Separator Coating for High-Voltage Dielectric Stability

The patent applies composite materials by combining polyolefin base material with inorganic particles (such as alumina, silica) and binder polymers (such as polyacrylic acid, carboxymethyl cellulose). This composite structure maintains the ion conductivity of the polyolefin while the inorganic particles provide high-temperature stability and prevent shrinkage or melting at elevated temperatures, thereby resolving the contradiction between ion conductivity and heat resistance.

The patent modifies the physical and chemical parameters of the separator by controlling the particle size distribution (D10, D50, D90 values), inorganic particle content (30-200 parts by weight per 100 parts binder polymer), and binder polymer composition. These parameter changes enhance the heat resistance while maintaining porosity (30-80%) for ion conductivity, allowing the separator to withstand temperatures up to 200°C without structural collapse.

The patent utilizes porous inorganic particles with controlled pore structures to create a lightweight, thin separator structure. The porous network provides mechanical reinforcement through the inorganic particle framework while maintaining high porosity (30-80%) for ion transport. This allows the separator to be thinner (5-20 μm) for higher energy density while the interconnected porous structure of inorganic particles provides sufficient mechanical strength and insulation properties.

The composite structure of inorganic particles embedded in a binder polymer matrix provides exceptional mechanical strength for a thin separator. The inorganic particles form a rigid scaffold that prevents deformation and maintains insulation, while the binder polymer holds the particles together. This composite approach enables the separator to achieve both thinness (for high energy density) and mechanical robustness (for safety).