Abstract
Alumina nanoparticle (alumoxane) doped polyurethane films were prepared by the template directed synthesis method with highly controlled physical dimensions and tested as a Li-ion battery separator. Monodispersed silica spheres are used as a template around which polyurethane monomer is infiltrated and cross-linked by UV light (320 nm). The silica is subsequently removed by etching to leave an alumina NP doped polyurethane membrane. The choice of substitutent on the alumina nanoparticle [methoxy(ethoxyethoxy)acteic acid (MEEA), acetic acid, and lysine] was chosen to alter the surface properties of the polyurethane. The MEEA-alumoxane doped membranes were characterized by SEM, and the conductivity of the electrolyte in the separators was measured using AC impedance spectroscopy. The MacMullin number for all of the template directed polyurethane separators was greater than that of the commercial porous membrane suggesting that despite a high pore volume the conductivity is limited by the size of the interconnects.