Novel Sodium Niobate-Based Lead-Free Ceramics as New Environment-Friendly Energy Storage Materials with High Energy Density, High Power Density, and Excellent Stability

Recently, ceramic capacitors with fast charge–discharge performance and excellent energy storage characteristics have received considerable attention. Novel NaNbO3-based lead-free ceramics (0.80NaNbO3-0.20SrTiO3, abbreviated as 0.80NN-0.20ST), featuring ultrahigh energy storage density, ultrahigh power density, and ultrafast discharge performance, were designed and prepared in this study. These 0.80NN-0.20ST ceramics exhibited a high breakdown strength of 323 kV/cm, attributable to their small grain size and dense microstructure, a recoverable energy storage density of 3.02 J/cm3, and an energy storage efficiency of 80.7% at an applied electric field of 310 kV/cm. The excellent stability of energy storage properties in frequency (0.1–1000 Hz), temperature (20–120 °C), and fatigue resistance (cycle number: 105) were also observed in the 0.80NN-0.20ST ceramics. In contrast with other recently reported lead-free ceramic-based dielectric capacitors, the 0.80NN-0.20ST ceramics display a high energy storage efficiency combined with a high recoverable energy storage density, which indicates that they have wide application foreground and potential in the field of energy storage. These ceramics also show a considerable current density of 677 A/cm2, an ultrahigh power density of 23.7 MW/cm3, and a short release duration (∼225 ns). This study brings the NaNbO3-based ceramics into a new chapter of research and application of energy storage dielectric capacitors.