KNN+Nb2O5 co-modified BNBST-based relaxor ferroelectric ceramics for X8R energy storage capacitors

Environmentally friendly ceramics with high dielectric temperature stability and excellent energy storage properties are desired for next generation low-voltage driven pulsed power supply systems. Herein, (Bi0.5Na0.5)0.65(Ba0.3Sr0.7)0.35(Ti0.98Ce0.02)O3+x wt% K0.5Na0.5NbO3 (KNN) + y wt% Nb2O5 (abbreviated as BNBSTC + KxNy) lead-free relaxor ferroelectric ceramics are prepared to investigate the effect of KNN + Nb2O5 co-modification on the structure and dielectric energy storage properties. In optimized BNBSTC + K8N8 ceramics, a medium high εr = 1310 with low tanδ = 5 × 10−3 (@25 °C & 1 kHz) meeting the EIA X8R standard can be achieved in addition to a recoverable energy storage density Wrec = 0.92 J/cm3 with high efficiency η = 93% only at a low electric field of 100 kV/cm. Moreover, the BNBSTC + K8N8 ceramics exhibits excellent energy storage stability under different frequency, fatigue cycle and temperature testing environments, showing an attractive prospect in low-voltage driven X8R dielectric energy storage capacitors.