Ultrahigh Temperature Lead-Free Film Capacitors via Strain and Dielectric Constant Double Gradient Design

Area of Science:

• Materials Science
• Electrical Engineering
• Solid State Physics

Background:

• Miniaturization of electronic devices necessitates high-temperature dielectric capacitors.
• High temperatures degrade breakdown strength and polarization in conventional capacitors due to thermal effects.

Purpose of the Study:

• To design a capacitor structure achieving high breakdown strength, high working temperature, and high energy storage density simultaneously.
• To investigate the energy storage performance of a novel double gradient structure.

Main Methods:

• Design of a multilayer capacitor structure featuring dielectric constant and strain gradients.
• Fabrication and characterization of BaHf$_{0.17}$ Ti$_{0.83}$ O$_{3}$ /1mol% SiO$_{2}$ doped BaZr$_{0.35}$ Ti$_{0.65}$ O$_{3}$ /0.85BaTiO$_{3}$ -0.15Bi(Mg$_{0.5}$ Zr$_{0.5}$ )O$_{3}$ multilayer capacitors.
• Testing of energy storage density and efficiency at various temperatures and electric fields.

Main Results:

• Achieved an energy storage density of 127.3 J cm$^{-3}$ with 79.6% efficiency at room temperature for N=2 multilayer.
• Demonstrated stable energy storage density of 84.62 J cm$^{-3}$ with 78.42% efficiency from -100 to 200 °C for N=4 multilayer at 6.86 MV cm$^{-1}$.

Conclusions:

• The designed double gradient capacitor structure exhibits excellent energy storage performance under harsh temperature conditions.
• The design principle offers a pathway for developing high-performance dielectric capacitors for demanding applications.