Ultra-Weak Polarization-Strain Coupling Effect Boosts Capacitive Energy Storage

In pulse power systems, multilayer ceramic capacitors (MLCCs) encounter significant challenges due to the heightened loading electric field (E), which can lead to fatigue damage and ultrasonic concussion caused by electrostrictive strain. To address these issues, an innovative strategy focused on achieving an ultra-weak polarization-strain coupling effect is proposed, which effectively reduces strain in MLCCs. Remarkably, an ultra-low electrostrictive coefficient (Q₃₃) of 0.012 m⁴ C^-2 is achieved in the composition 0.55(Bi_0.5Na_0.5)TiO₃-0.45Pb(Mg_1/3Nb_2/3)O₃, resulting in a significantly reduced strain of 0.118% at 330 kV cm^-1. At the atomic scale, the local structural heterogeneity leads to an expanded and loose lattice structure, providing ample space for large ionic displacement polarization instead of lattice stretching when subjected to the applied E. This unique behavior not only promotes energy storage performance (ESP) but also accounts for the observed ultra-low Q₃₃ and strain. Consequently, the MLCC device exhibits an impressive energy storage density of 14.6 J cm^-3 and an ultrahigh efficiency of 93% at 720 kV cm^-1. Furthermore, the superior ESP of the MLCC demonstrates excellent fatigue resistance and temperature stability, making it a promising solution for practical applications. Overall, this pivotal strategy offers a cost-effective solution for state-of-the-art MLCCs with ultra-low strain-vibration in pulse power systems.