Novel BaTiO₃-Based, Ag/Pd-Compatible Lead-Free Relaxors with Superior Energy Storage Performance

Ceramic dielectrics are reported with superior energy storage performance for applications, such as power electronics in electrical vehicles. A recoverable energy density (W_rec) of ∼4.55 J cm^-3 with η ∼ 90% is achieved in lead-free relaxor BaTiO₃-0.06Bi_2/3(Mg_1/3Nb_2/3)O₃ ceramics at ∼520 kV cm^-1. These ceramics may be co-fired with Ag/Pd, which constitutes a major step forward toward their potential use in the fabrication of commercial multilayer ceramic capacitors. Compared to stoichiometric Bi(Mg_2/3Nb_1/3)O₃-doped BaTiO₃ (BT), A-site deficient Bi_2/3(Mg_1/3Nb_2/3)O₃ reduces the electrical heterogeneity of BT. Bulk conductivity differs from the grain boundary only by 1 order of magnitude which, coupled with a smaller volume fraction of conducting cores due to enhanced diffusion of the dopant via A-site vacancies in the A-site sublattice, results in higher breakdown strength under an electric field. This strategy can be employed to develop new dielectrics with improved energy storage performance.