Energy storage properties of 0.87BaTiO₃-0.13Bi(Zn_2/3(Nb_0.85Ta_0.15)_1/3)O₃ multilayer ceramic capacitors with thin dielectric layers

Multilayer ceramic capacitors (MLCCs) for energy storage applications require a large discharge energy density and high discharge/charge efficiency under high electric fields. Here, 0.87BaTiO₃-0.13Bi(Zn_2/3(Nb_0.85Ta_0.15)_1/3)O₃ (BTBZNT) MLCCs with double active dielectric layers were fabricated, and the effects of inner electrode and sintering method on the energy storage properties of BTBZNT MLCCs were investigated. By using the pure Pt as inner electrode instead of Ag_0.6Pd_0.4 alloys, an alternating current (AC) breakdown strength (BDS) enhancement from 1047 to 1500 kV/cm was achieved. By investigating the leakage current behavior of BTBZNT MLCCs, the Pt inner electrode and two-step sintering method (TSS) were confirmed to enhance the Schottky barrier and minimize the leakage current density. With relatively high permittivity, dielectric sublinearity, and ultra-high BDS, the Pt TSS BTBZNT MLCCs exhibited a surprisingly discharge energy density (U_dis) of 14.08 J/cm³. Moreover, under an operating electric field of 400 kV/cm, the MLCCs also exhibited thermal stability with U_dis variation < ±8% over a wide temperature (t) range from -50 to 175 ℃ and cycling reliability with U_dis reduction < 0.3% after 3000 charge-discharge cycles. These remarkable performances make Pt TSS BTBZNT MLCCs promising for energy storage applications.