Ultrahigh Energy Storage Density in Superparaelectric-Like Hf0.2Zr0.8O2 Electrostatic Supercapacitors

Electrostatic capacitors attract great interest in energy storage fields due to their advantages of high power-density, fast charge/discharge speed, and great reliability. Intensive efforts have been placed on the development of high-energy-density of capacitors. Herein, a novel supercapacitor with Hf0.2Zr0.8O2/xAl(2)O(3)/Hf0.2Zr0.8O2 (HAHx) is designed to improve the breakdown strength (E-b) through optimizing Al2O3 (AO) film thickness. Low-temperature annealing is first proposed to enhance the polarization difference (P-m-P-r) due to the formation of dispersed polar nanoregions, which is called superparaelectric-like similar to previous super-paraelectric behavior of perovskite structures. As results, both large E-b and P-m-P-r values are obtained, leading to an ultrahigh energy storage density of 87.66 J cm(-3) with a high efficiency of 68.6%, as well as a reliable endurance of 10(7) cycles. This work provides a feasible pathway to improve both the polarization difference and breakdown strength of HfO2-based films by the combination of insulation insertion layer and low-temperature annealing. The proposed strategy can contribute to the realization of high-performance electrostatic supercapacitors with excellent microsystem compatibility.

Automated summary

A novel supercapacitor, HAHx, is designed to improve the breakdown strength (Eb) by optimizing the Al2O3 film thickness. Low-temperature annealing enhances the polarization difference (P-m-P-r), resulting in large Eb and P-m-P-r values, as well as high efficiency and reliable endurance. This work provides a feasible pathway to improve the polarization difference and breakdown strength of HfO2-based films.