Superior and ultrafast energy storage performance of relaxor-antiferroelectric HfO2-based supercapacitors

Abstract Compared to electrochemical energy storage, dielectric thin film-based capacitors possess the advantages of higher voltage stability and higher break-down voltage as well as lower leakage current etc. Since HfO 2 films are compatible to microelectronic process and its ferroelectricity is strategically important in memory device, the realization of their excellent energy storage comparable or better than those perovskite oxides will broaden their applications in microelectronic devices. In this work, to combine the merits of relaxor-ferroelectric and antiferroelectric, we experimentally demonstrate that a superparaelectric-like relaxor antiferroelectric behavior can be realized in the HfO 2 -based thin films and corresponding recoverable energy density over 100 J cm -3 can be achieved at efficiency higher than 80% as well as extremely high dielectric strength > 6 MV cm -1 , compared to perovskite oxide materials. This is a record high energy density in all reported HfO 2 -based energy storage thin films, and beyond that, we also demonstrate their superfast charging/discharging as a capacitor. Targeting at high-speed supercapacitor applications in integrated circuit, HfO 2 -based dielectric may win the competition with perovskite oxides in terms of dielectric breakdown strength and charging/discharging speed etc. Our fundamental understanding of the physics behind also enriches the knowledge of materials science and dielectric physics.