Evaluation of energy storage performance of ferroelectric materials by equivalent circuit model

Abstract

Dielectric capacitors with large energy storage density, low hysteresis loss, low temperature dependence and high temperature adaptability show great advantages in high temperature applications of electronic devices. In this work, a large energy storage density (W ~ 28.776 J/cm3) and ultra-high efficiency (η ~ 87.36%) have been simultaneously achieved in the CuX(Ba0.88Ca0.12)1-X(Zr0.12Ti0.88)O3 (X = 0.1) lead-free relaxor ferroelectric thin film capacitors deposited on Pt(111)/TiOX/SiO2/Si(100) substrates by using a sol-gel method. The results show that the dielectric permittivity and dielectric loss change a little in the temperature range of 30–400 °C. The reason of low dielectric loss and temperature insensitivity is revealed by means of Raman spectrum fitting and equivalent circuit model (the I-E curve of ferroelectric materials is regarded as an equivalent circuit of equivalent capacitance (C), equivalent resistance (R) and polarization charge (Ip(t)) in parallel, given by the equation I(t)=V(t)/R+KC+Ip(t)). The results prove that the stability of slope (K) is positively correlated with the stability of energy storage performance of ferroelectric materials, which provides the basis for the evaluation of energy storage performance of ferroelectric materials.