Enhancement of Energy Storage and Efficiency in Antiferroelectric Hf᙮Zr᙮₋₁O₂ Supercapacitors Through Tailored Phase Engineering by Oxygen Vacancy

In this letter, the antiferroelectric (AFE) performance of Hf_xZr_1-xO₂ (HZO) film is significantly improved by regulating its oxygen vacancy (V_O). The gas with different O₂ flow is used in the HZO films sputter process. Introducing appropriate O₂ flow enhances both energy storage density (ESD) and efficiency (η) of the AFE HZO energy storage capacitors (ESCs). X-ray diffraction (XRD) and capacitance–electric (C–E) measurements demonstrate that the t-phase/o-phase ratio in HZO films was adjusted by regulating the V_O concentration to promote t-phase crystallization. The optimal crystallization of the t-phase in HZO films, achieved with 8.0% V_O and 0.82 Zr concentration, results in an ESD of ~86.3 J/cm³ and an efficiency of ~74%. Moreover, we attained exceptional durability, surpassing 10⁹ cycles while maintaining 98% of the initial ESD. The results obtained herein provide a novel and effective method to achieve high-performance AFE HZO ESCs.