Enhanced energy storage performance in NBT-based MLCCs via cooperative optimization of polarization and grain alignment

Dielectric ceramics possess a unique competitive advantage in electronic systems due to their high-power density and excellent reliability. Na_1/2Bi_1/2TiO₃-based ceramics, one type of extensively studied energy storage dielectric, however, often experience A-site element volatilization and Ti⁴⁺ reduction during high-temperature sintering. These issues may result in increased energy loss, reduced polarization and low dielectric breakdown electric field, ultimately making it challenging to achieve both high energy storage density and efficiency. To address these issues, we introduce a synergistic optimization strategy that combine polarization engineering and grain alignment engineering. First principles calculations and experimental analyses show that the doping of Mn²⁺ can suppress the reduction of Ti⁴⁺ in Na_1/2Bi_1/2TiO₃-based ceramics and enhance ion off-centering displacements, thereby reducing energy loss and improving polarization. In addition, we prepared multilayer ceramic capacitors with grains oriented along the <111> direction using the template grain growth method. This approach effectively reduces electric-field-induced strain by 37% and markedly enhances breakdown electric field by 42% when compared with nontextured counterpart. As a result of this comprehensive strategy, <111 >-textured Na_1/2Bi_1/2TiO₃-based multilayer ceramic capacitors achieve an ultra-high energy density of 15.7 J·cm^-3 and an excellent efficiency beyond 95% at 850 kV·cm^-1, exhibiting a superior overall energy storage performance.