Weili Li

Mn doping to enhance energy storage performance of lead-free 0.7NBT-0.3ST thin films with weak oxygen vacancies

In this study, we present an effective strategy to enhance energy-storage density by the Mn2+ substitution of Ti4+ into 0.7(Na0.5Bi0.5)TiO3-0.3SrTiO3 (0.7NBT-0.3ST) relaxor ferroelectric thin films. The influence of Mn doping on the microstructures, ferroelectric properties, and energy-storage performances of the as-prepared films was investigated in detail. The results show that the values of electric break-down field strength and the difference values between maximum polarization and remnant polarization of the thin films are markedly improved by appropriate Mn doping. Owing to the high break-down field strength of 1894u2009kV/cm and the huge difference value between the maximum polarization and the remnant polarization of 56u2009μC/cm2, a giant recoverable energy-storage density of 27u2009J/cm3 was obtained for the 1u2009mol. % Mn-doped 0.7NBT-0.3ST thin film. These results indicate that the appropriately Mn-doped 0.7NBT-0.3ST thin films are promising for the application of advanced capacitors with high-energy storage...

0.6ST-0.4NBT thin film with low level Mn doping as a lead-free ferroelectric capacitor with high energy storage performance

Srx(Na0.5Bi0.5)1−xTi0.99Mn0.01O3 (xu2009=u20090.2, 0.4, 0.6, and 0.8) relaxor ferroelectric thin films were grown on Pt/Ti/SiO2/Si substrates by the Sol-Gel method. The influence of the Sr content on the microstructures, ferroelectric properties, and energy-storage performances of the thin films were investigated in detail. The Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film exhibits very slim hysteresis loops with the highest electric breakdown field strength due to reduced oxygen vacancies. Owing to the high breakdown field strength of 3134.3u2009kV/cm, the Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film shows a giant recoverable energy-storage density of 33.58u2009J/cm3. These results indicate that the Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film is promising for applications of advanced capacitors with high energy-storage density.

Polymer/metal multi-layers structured composites: A route to high dielectric constant and suppressed dielectric loss

In order to obtain polymer-based composites with a high dielectric constant and suppressed dielectric loss, polyvinylidene fluoride (PVDF)/silver (Ag) multi-layer structured composites were fabricated via vacuum evaporation and hot-press methods. The dielectric constant of the PVDF/Ag(5/4) composite (including five PVDF layers and four Ag layers) is up to 31, and dielectric loss can be suppressed below 0.02 (smaller than that of pure PVDF) at 1u2009kHz. The enhanced interfacial polarization in multi-layer structured composites is determined via temperature dependence of electrical modulus, which is regarded as the origin of dielectric constant enhancement. The suppressed dielectric loss at low frequency is attributed to the difficulty in the formation of a percolation conductive network in this multi-layer system. This promising multi-layer strategy could be generalized to a variety of polymers to develop polymer-based composites with a high dielectric constant and low dielectric loss.