Superior multilayer ceramic energy-storage capacitors using NaNbO3-based relaxor ferroelectrics with heterogeneous nanodomains

Dielectric energy storage capacitors characterizing high power density and ultrafast charge-discharge rate are indispensable in advanced electronics and pulsed power systems. However, desirable comprehensive energy storage features, including high energy density (Wrec), high efficiency (n) and outstanding thermal stability, are difficult to be achieved for practical applications. Herein, coexisted spherical polar nanoregions and stripe-like polar nanodomains with the same orthorhombic FE symmetry were engineered in 0.68NaNbO3-0.32 (Bi0.5Li0.5)1-xBaxTiO3 lead-free relaxor ferroelectrics, as revealed by piezoresponse force microscopy and transmission electron microscopy. The formation of such heterogeneous nanodomain structures not only concurrently optimizes the polarization hysteresis and maximum polarization but also enhances the thermal stability of dielectric properties, contributing to high Wrec of 9.49 J/cm3 and n of 88.1 % as well as a temperature coefficient of capacity of X8R. The corresponding multilayer ceramic capacitors exhibit outstanding comprehensive energystorage performances of giant Wrec approximate to 16.4 J/cm3, high n approximate to 82.3 % and excellent temperature stability (Wrec = 10.2 +/- 2 % J/cm3, n = 85.5 +/- 2 %, @25-150 degrees C), demonstrating great potentials for capacitive energy storage applications. This work demonstrates an effective and feasible strategy to optimize overall energy storage performance of dielectric capacitors.