Fluorite-Structured Ferroelectric-/Antiferroelectric-Based Electrostatic Nanocapacitors for Energy Storage Applications

To date, several portable, wearable, and even implantable electronics have been incorporated into ultracompact devices as miniaturized energy-autonomous systems (MEASs). Electrostatic supercapacitors could be a promising energy storage component for MEASs due to their high power density and ultrashort charging time. Several dielectric materials, including ceramics, polymers, and glass, have been studied for energy storage applications. However, due to their large thickness (in micrometers or larger), these materials are inappropriate for use as nanocapacitors. Recently, ferroelectric and antiferroelectric fluorite-structured dielectrics (e.g., zirconia and hafnia) have been studied intensively for data storage and energy-related applications. Their nanoscale (nm) thickness makes these materials suitable for use as nanocapacitors in MEASs. This work reviews the energy storage properties of fluorite-structured antiferroelectric oxides (HfO2 and ZrO2), along with 3-D device structures, the effect of negative capacitance on the energy storage characteristics of fluorites, and the future prospects of this research field.