Improving energy storage performance of barium titanate-based ceramics by doping MnO2

MnO2 was used as a sintering additive to reduce sintering temperature of the 0.92(Ba0.94Li0.02La0.04)(Mg0.04Ti0.96)O3-0.08Bi(Zn1/2Ti1/2)O3 (0.92BLLMT-0.08BZT) ceramic thick film and promote sintering process. At the same time, MnO2 doping is beneficial for reducing dielectric loss and leakage current, and improving insulation performance, thus, breakdown field strength (BDS) of ceramics is increased. In addition, MnO2 doping introduces defect energy levels, and increases lattice distortion and polarization intensity, thereby changing the crystal structure and microstructure morphology, and improving energy storage density and thermal stability. The BDS reaches 650 kV/cm electric field with 0.5 mol% MnO2 doping, where the ceramic thick film achieves a discharge density (Wdis) of 5.51 J/cm3, ultra-high power density (PD = 443.87 MW/cm3) and current density (CD = 1365.74 A/cm2). The ceramic thick film exhibits good thermal stability with Wdis change rate of only 16.47 % within room temperature to 170 °C under 200 kV/cm. Such excellent comprehensive performance can be attributed to the decrease of grain size, defect concentration, and leakage current, and the formation of polar nano regions in the BT-based ceramics caused by MnO2 doping and cations substitution at A-site and B-site of the perovskite structure. This study provides valuable insights for the research of lead-free dielectric ceramic capacitors, and the 0.92BLLMT-0.08BZT-0.5 mol% Mn ceramic thick film presents good development prospect in high-power pulse energy storage system.