High-Energy-Density Polypropylene Nanocomposite Dielectrics Incorporating Nonpolar TiO₂ Nanorod

Polymer dielectric capacitors are essential for advanced electronics and electric power systems. Polypropylene, known for its low dielectric loss, high breakdown strength, and long cycle life, has become the industrial standard in the capacitor market. However, its relatively low dielectric constant (approximately 2.2 at 10 3 Hz) limits its energy storage density to below 2 J/cm 3, which falls short of meeting the growing energy demands of advanced power systems. In this work, we describe a high-energy-density polypropylene-based nanocomposite incorporating nonpolar TiO 2 nanorods for the first time. We demonstrated that nonpolar TiO 2 nanorods, functionalized with oleic acid ligands, exhibit excellent compatibility and are well-dispersed within the polypropylene matrix. The resultant polypropylene nanocomposite exhibits a remarkable discharged energy density of 4.72 J/cm 3 at 650 MV/m, representing a 103.4% increase compared to pristine polypropylene. Moreover, we highlight that the uniform dispersion and large aspect ratio of the nonpolar TiO 2 nanorods are essential factors driving the superior dielectric performance of the polypropylene nanocomposite. This work presents an effective approach for designing homogeneous polypropylene nanocomposites by incorporating nonpolar TiO 2 nanorods, offering a promising pathway for the development of high-energy-density polymer nanocomposites.