Annealing atmosphere-dependent capacitive energy storage

Electrostatic capacitors based on dielectrics with high energy density and efficiency are desired for modern electrical systems owing to their intrinsic fast charging-discharging speed and excellent reliability. The longstanding bottleneck is their relatively small energy density. Herein, we report enhanced energy density and efficiency in the Aurivillius Pb₂Bi₄Ti₅O₁₈ films by controlling the post-annealing atmosphere. The results demonstrate that the fabrication atmosphere has significant effects on the film texture and defects. As the increase of the oxygen pressure of annealing atmosphere, the Pb₂Bi₄Ti₅O₁₈ films show a preferred growth orientation of (00l) and fewer defects, which leads to a higher polarization and breakdown field for the film annealed in air atmosphere and thus help to achieve an ultrahigh energy density of 59.4 J·cm⁻³ and an improved efficiency of 81.2%. Moreover, the film also exhibits excellent cycling reliability and good thermal stability. The Pb₂Bi₄T_i5O₁₈ films show a significant potential application for dielectric capacitors.