The effect of CuO doping on dielectric properties and energy storage performance of 0.8KNN-0.2BLN ceramics

A series of 0.8K 0.5 Na 0.5 NbO 3 -0.2Bi(Li 0.5 Nb 0.5 )O 3 ceramics with x mol CuO (abbreviated as 0.8KNN-0.2BLN- x CuO, x = 0, 0.005, 0.0075, 0.01, 0.02, 0.025, 0.03) were synthesized via the conventional solid-state reaction method. The effects of CuO doping on the sintering behavior and electrical properties of the 0.8KNN-0.2BLN ceramics were investigated. The results show that CuO doping can promote ceramics sintering. Furthermore, the incorporation of CuO enhances the relaxor characteristics, increase the dielectric constant, and improve the energy storage performance by reducing the remnant polarization. The sample with 0.025 mol CuO presents excellent dielectric properties ( ε r = 1294, tan δ = 1.14%) with a broad temperature stability range (−55 °C to 300 °C, Δ C / C 25°C ≤ ±10%), meeting the EIA X9R specification. Meanwhile, the sample also exhibits a recoverable energy storage density of 1.71 J/cm 3 , a breakdown strength of 200 kV/cm, and an energy storage efficiency of 80%. The CuO-doped 0.8KNN-0.2BLN ceramics are promising candidates for high-temperature multilayer capacitors application.