Simultaneous Improvement\nof Energy Storage Characteristics\nand Temperature Stability in K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub>‑Based Ceramics via LiF Modification

The splendid energy storage performances with eminent\nstability\nof dielectric ceramics utilized in pulsed power devices have been\npaid more attention by researchers. This scheme can be basically realized\nthrough introducing Li<sup>+</sup>, Bi(Mg<sub>2/3</sub>Ta<sub>1/3</sub>)O<sub>3</sub>, NaNbO<sub>3</sub>, and LiF into KNN-based ceramics.\nUnder the breakdown strength (BDS) of 460 kV/cm, an outstanding energy\nstorage density (<i>W</i>) of 6.05 J/cm<sup>3</sup> with\na high energy efficiency (η) of 85.9% is implemented. Within\nthe broad temperature range from 20 to 140 °C, the numerical\nfluctuations of energy storage characteristics can be maintained at\na relatively stable level (Δ<i>W</i><sub>rec</sub> ≈ 3.5%, Δη ≈ 2.8%). As for the charging–discharging\nperformances, this component possesses a fast discharging speed (<i>t</i><sub>0.90</sub> ≈ 51 ns) and remarkable temperature\nstability (the variations are smaller than 3.5%). Additionally, the\ninternal mechanisms of outstanding energy storage properties can be\nconfirmed via crystal structures and domain structures, the content\nof oxygen vacancies, dielectric and impedance spectra, and phase simulation.\nHence, the combination of outstanding energy storage with remarkable\nthermal stability can be fulfilled in one ceramic system according\nto this discovery, providing a research thought of developing the\nmaterials for dielectric capacitors.