High energy density with ultrahigh discharging efficiency obtained in ceramic-polymer nanocomposites using a non-ferroelectric polar polymer as matrix

To overcome the low discharging efficiency of ceramic-polymer composites using ferroelectric polymers as matrix and to take the advantage in fabrication offered by the polar polymer, a polar but non-ferroelectric polymer - poly(methyl methacrylate) (PMMA) - was selected as the matrix in the development of high performance composites for energy storage. Ba0.5Sr0.5TiO3 (BST) nanoparticles were selected as the filler. Freestanding and flexible BST-PMMA ceramic-polymer nanocomposites with BST content up to 30 vol.% were fabricated in thickness of about 5 mu m using spin-coating process and were systemically studied. Due to the strong interaction between the polar groups of PMMA and the hydroxyl groups on the surface of BST nanoparticles, the suspension of BST nanoparticles in PMMA solution exhibits excellent stability and, hence, the nanocomposite films have excellent microstructure uniformity and compatibility between the BST nanoparticles and PMMA matrix. All the BST-PMMA films exhibit excellent frequency (100 Hz to 1 MHz) and temperature (-90 to 100 degrees C) stabilities in their dielectric properties with a high energy-storage density of more than 11 J/cm(3). Most importantly, an ultra-high discharging efficiency of almost 100% is obtained in all the nanocomposites.