Large Energy Density, Excellent Thermal Stability, and High Cycling Endurance of Lead-Free BaZr0.2Ti0.8O3 Film Capacitors

A large energy storage density (ESD) of 30.4 J/cm3 and high energy efficiency of 81.7% under an electrical field of 3 MV/cm was achieved at room temperature by the fabrication of environmentally friendly lead-free BaZr0.2Ti0.8O3 epitaxial thin films on Nb-doped SrTiO3 (001) substrates by using a radio-frequency magnetron sputtering system. Moreover, the BZT film capacitors exhibit great thermal stability of the ESD from 16.8 J/cm3 to 14.0 J/cm3 with efficiency of beyond 67.4% and high fatigue endurance (up to 106 cycles) in a wide temperature range from room temperature to 125 °C. Compared to other BaTiO3-based energy storage capacitor materials and even Pb-based systems, BaZr0.2Ti0.8O3 thin film capacitors show either high ESD or great energy efficiency. All of these excellent results revealed that the BaZr0.2Ti0.8O3 film capacitors have huge potential in the application of modern electronics, such as locomotive and pulse power, in harsh working environments.