Silver nanoparticle-modified alumina microsphere hybrid composites for enhanced energy density and thermal conductivity

Dielectric polymer composites consisting of inorganic fillers and polymers have wide applications in high energy density electronic devices. However, development of dielectric polymer composites with enhanced energy storage density and thermal conductivity is desired but challenge. Herein, we report polymer composites consisting of epoxy resin and silver nanoparticle-decorated Al2O3 microspheres (Al2O3-AgNPs), which show enhanced energy storage density and thermal conductivity (1.11 W/m K), at 70 wt% Al2O3-AgNPs. The discharged energy density of Al2O3-AgNPs/epoxy resin composites with 70 wt% hybrid fillers is 4.28 × 10-3 J cm−3, while the composites without AgNPs is 3.09 × 10-3 J cm−3 at 200 kV cm−1. The enhanced energy storage density and thermal conductivity are attributed to the enhanced the interfacial polarization and the bridge role of AgNp in facilitating the heat flow across the interfacial boundary, respectively. The results support the potential applications of the Al2O3-AgNPs/epoxy resin composites used as dielectric materials in modern electronics and electric power systems.