Electrostatic capacitors are critical components in the power system of electric vehicles (EVs). The current commercially available solutions are largely based on ferroelectric oxides of which the permittivity decrease with increasing electric field. Here, we propose a high entropy modulation design in a quantum paraelectric-ferroelectric/antiferroelectric matrix, which enables a stable and field-independent energy charge/discharge response across a wide voltage range. By effectively synergizing the high efficiency (η) of quantum paraelectrics and the high polarization of the ferroelectric/anti-ferroelectric matrix with the entropy regulator, a high recoverable energy density (W rec ) of 13.3 J cm − 3 with an η of 92.4% is achieved in the bulk state of the perovskite material, promising for device scale-up. Versatile polar regions as well as a defect-less microstructure is achieved by the optimized compositional design and material processing. On a mesoscopic level, the electrical microstructure of the material is engineered to provide a large breakdown strength ( E b ) of 750 kV/cm, which is confirmed by the resolved electrochemical information and finite-element simulation. The proposed strategy provides a new path for designing high performance next generation energy storage/power converting dielectrics. This demonstration of quantum paraelectrics for energy storage application is expected to stimulate extensive efforts in the area.
Photovoltaic effects of single-layer films, with simple structure and low cost, are generally found in ferroelectric films , but their applications in solar cell are restricted by the large band gap of ferroelectrics . Here, we demonstrate a large photovoltaic effect can be obtained in paraelectric single-layer BiVO 4 (BVO) film based on the gradient distribution of charges. The circuit current density ( J SC ) and open circuit voltage ( V OC ) of the BVO film with best performance are 1.63 mA/cm 2 and 0.38 V, respectively. The J SC of BVO film kept 86% of the maximum value after continuous operation for 16 h. The high thermal stability of BVO is proved by long time operation and stable photovoltaic performance at high temperature. This work not only proposes a novel built-in electric field mechanism, but also indicates that the single-layer paraelectrics can be used as the next generation photovoltaic materials.
Electrostatic energy storage capacitors based on dielectrics have attracted much attention due to their wide applications in advanced electrical technology and electronic devices. Generally, high energy density is achieved at a high electric field, while conduction loss becomes nonnegligible, which harms practical applications. Here distinctly suppressed leakage current in BaZr 0.5 Ti 0.5 O 3 -based films by entropy engineering is realized. With increased entropy, the leakage current density decreases by two orders of magnitude at the electric field of 3 MV cm −1 , leading to a markedly improved energy efficiency of 87% at an ultrahigh breakdown strength of 8 MV cm −1 in high-entropy films. Thereby, a high energy density of 51.9 J cm −3 is achieved. This work demonstrates the effectiveness of entropy engineering in improving the breakdown strength of dielectric films and shows great potential in enhancing the energy storage performance of capacitors.
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