Ultra-fast charge-discharge and high-energy storage performance realized in KNaNbO3-Bi(MnNi)O3 ceramics

Lead-free relaxor ceramics (1 − [Formula: see text])K[Formula: see text]Na[Formula: see text]NbO3 − [Formula: see text]Bi(Mn[Formula: see text]Ni[Formula: see text])O3 ((1 − [Formula: see text] )KNN- [Formula: see text]BMN) with considerable charge–discharge characteristics and energy storage properties were prepared by a solid state method. Remarkable, a BMN doping level of 0.04, 0.96KNN–0.04BMN ceramic obtained good energy storage performance with acceptable energy storage density [Formula: see text][Formula: see text] of 1.826 J/cm3 and energy storage efficiency [Formula: see text] of 77.4%, as well as good frequency stability (1–500 Hz) and fatigue resistance (1–5000 cycles). Meanwhile, a satisfactory charge–discharge performance with power density [Formula: see text][Formula: see text] [Formula: see text] 98.90 MW/cm3, discharge time [Formula: see text][Formula: see text] < 70 ns and temperature stability (30–180∘C) was obtained in 0.96KNN–0.04BMN ceramic. The small grain size ([Formula: see text]150 nm) and the high polarizability of Bi[Formula: see text] are directly related to its good energy storage capacity. This work proposes a feasible approach for lead-free KNN-based ceramics to achieve high-energy storage and ultra-fast charge–discharge performance as well as candidate materials for the application of advanced high-temperature pulse capacitors.